AUTHOR INFORMATION

Section 1 of 12

Authored by Jaime Shalkow, MD, Division of Surgery, Chief, Department of Surgical Oncology, National Institute of Pediatrics, Mexico City, Professor of Surgery and Ped, Universidad Nacional Autonoma de Mexico

Coauthored by Jose Asz, MD, Professor of Embryology, Assistant Professor of Surgery and Pediatrics, Faculty of Medicine, Universidad Nacional Autonoma de Mexico; Consulting Staff, Department of General Surgery, National Institute of Pediatrics, Mexico; Nicholas A Shorter, MD, Professor of Clinical Surgery and Clinical Pediatrics, State University of New York-Downstate University; Division Chief, Department of Surgery, Division of Pediatric Surgery, State University of New York-Downstate Medical Center; Bruce Friedberg, MD, Staff Physician, Department of Emergency Medicine, Mount Diablo Medical Center; Mainor Antillon, MD, Director, Pancreaticobiliary Endoscopy and Endosonography Program, Department of Internal Medicine, Division of Gastroenterology, King-Drew Medical Center; Associate Clinical Professor, Department of Medicine, University of California at Los Angeles; Thomas Tsou, MD, Director of Fast Tract and Pediatrics, Associate Professor, Departments of Medicine and Emergency Medicine, Charles R Drew University and University of California at Los Angeles

Edited by Jorge Vargas, MD, Professor, Department of Pediatrics, Division of Pediatric Gastroenterology, University of California at Los Angeles School of Medicine; Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine.com, Inc; B UK Li, MD, Director, Division of Gastroenterology, Hepatology and Nutrition, Children's Memorial Hospital of Chicago; Professor, Department of Pediatrics, Northwestern University; Steven M Schwarz, MD, FAAP, FACN, Chair, Department of Pediatrics, Long Island College Hospital; Professor of Pediatrics, State University of New York, Downstate Medical Center College of Medicine; and Carmen Cuffari, MD, Associate Professor, Department of Pediatrics, Division of Gastroenterology/Nutrition, The Johns Hopkins University School of Medicine

Author's Email:	Jaime Shalkow, MD
Editor's Email:	Jorge Vargas, MD

eMedicine Journal, October 3 2006, VOLUME 7, Number 10

INTRODUCTION

Section 2 of 12

Background: Small-bowel obstructions in pediatric patients are uncommon but should be suspected in any child with persistent vomiting, distention, and abdominal pain because delayed diagnosis and treatment can have devastating consequences. Infants and young children with intestinal obstruction present with pain, irritability, vomiting, and abdominal distension. Small-bowel obstructions progress to decreased or no bowel movements. Undiagnosed or improperly managed obstructions can lead to vascular compromise, which causes bowel ischemia, necrosis, perforation, sepsis, and death.

Many different pathologic processes can cause small-bowel obstructions. These processes can be divided into acute intestinal obstructions and chronic partial intestinal obstructions. These conditions can be further subdivided into those that present in the immediate postnatal period and those that occur later in childhood.

Causes of Acute Intestinal Obstructions

Intussusceptions

Intussusception is the most common cause of intestinal obstruction in infants and children aged 3 months to 6 years and is the second most common cause of acute abdomen in this age group. It occurs when a proximal segment of the intestine (called intussusceptum) telescopes or invaginates into the lumen of another immediately adjacent distal segment (called intussuscipiens). The peak age of presentation is between 5 and 10 months. Intussusception is more common in males. Less than 1% of intussusceptions are found in neonates; however, cases have been reported in newborns and premature babies. Early diagnosis and prompt treatment prevent catastrophic complications in this group of patients. In 95% of cases, the intussusception is in the ileocecal area. Ileoileal and colocolic intussusceptions are rare. Occasionally, an ileoileal intussusception of the terminal ileum may progress through the ileocecal valve, a condition known as ileoileocolic intussusception.

Incarcerated hernias

Incarcerated hernias occur when the contents of a hernia sac cannot be reduced back into the abdominal cavity. Incarcerated hernias can be inguinal, femoral, or umbilical. Inguinal and femoral incarcerated hernias are most common in both sexes. The vast majority of inguinal hernias in children are indirect hernias. Most direct hernias in the pediatric population occur following repair of an indirect hernia. Femoral hernias, which tend to incarcerate, are extremely rare in children and are the only hernias that occur in girls more often than boys.

Incarceration represents the most common complication associated with inguinal hernias. In several large series, incarceration was reported in 6-18% of patients. The incidence could be as high as 30% for infants younger than 2 months.

Umbilical hernias are very common in children, rarely incarcerate, and often close spontaneously by age 5 years.

Malrotation of bowel with midgut volvulus

Intestinal malrotation refers to errors of midgut rotation around the superior mesenteric artery axis and the subsequent fixation of the midgut in the peritoneal cavity. Nonrotation, incomplete rotation, reversed rotation, and alterations of fixation including the internal hernias (mesocolic, paraduodenal) and the mobile cecum are among the many embryonic variants of the anomaly. Malrotation is always present in patients with abdominal wall defects (gastroschisis, omphalocele) and patients with congenital diaphragmatic hernia. It is often associated with other congenital and acquired lesions of the GI tract, such as Hirschsprung disease, intussusception, and atresia of the jejunum, duodenum, and esophagus. In children, the most common form of malrotation occurs when the process of rotation is incomplete and the ligament of Treitz or the cecum is abnormally located or fixed. The mesenteric attachment of the midgut to the posterior abdominal wall is narrow and predisposes the midgut to twist around an axis formed by the superior mesenteric artery (midgut volvulus). Complete volvulus of the bowel for more than 1-2 hours can totally obstruct blood supply to the bowel, leading to complete necrosis of the involved segment.

Postoperative adhesions

Adhesive small-bowel obstruction is an annoying surgical complication. It is incidence seems to be lower after laparoscopic procedures than after laparotomy. Postoperative adhesions are responsible for about 7% of the intestinal obstructions in infants and children. A single adhesion causes most obstructions, regardless of the nature of the previous illness or type of abdominal surgery. Onset of obstructive symptoms can range from 2 days to 10 years postsurgery, although most adhesions (>50%) occur within the first 3-6 postoperative months, and few occur after 2 years.

Annular pancreas

This rare condition involves a lesion that consists of a thin flat ring of histologically normal pancreatic tissue that surrounds the descending duodenum in an anomalous position. Annular pancreas results from abnormal rotation of the ventral pancreatic bud and usually functions normally, barring development of pancreatitis or an obstruction of the duct of Wirsung. An annular pancreas can be asymptomatic or can cause external compression on the second portion of the duodenum, which creates a partial or complete obstruction. Annular pancreas is almost invariably associated with an intrinsic cause of duodenal obstruction (duodenal atresia).

Mesocolic hernia

Mesocolic hernia is a malrotation abnormality. Nonfixed colonic and duodenal mesenteries lead to formation of potential hernia pouches, which transiently and recurrently entrap the bowel and cause partial obstructions. Their exact incidence is still unknown, but, fortunately, they are rather rare. The internal hernias may be right- or left-sided and can sometimes incarcerate and strangulate. The mesocolic hernia is not a malrotation anomaly per se but occurs in the presence of a rotational anomaly. Mesocolic hernias can also occur as a consequence of retroperitoneal surgery in cases in which a mesenteric defect is not properly closed during the procedure.

Necrotizing enterocolitis

Strictures from previous necrotizing enterocolitis (NEC) occur most often in premature infants. These strictures account for 15% of deaths in infants older than 1 week whose birth weights were less than 1500 g. In 11-36% of patients, NEC can produce strictures that subsequently cause intestinal obstruction. Strictures usually occur within 1-6 months following an acute NEC episode. While the exact cause of NEC remains unknown, multiple factors probably lead to ischemic or hypoxemic insult of the intestinal mucosa, followed by bacterial invasion of the denuded mucosa with gram-negative septicemia and intestinal necrosis. The most common sites for these strictures are the terminal ileum and the colon.

Causes of Chronic Partial Intestinal Obstructions

Most chronic partial intestinal obstructions are due to anatomic abnormalities such as intestinal duplications, hernias, and intestinal stenosis.

Cecal volvulus

Cecal volvulus is a rare disorder of nonfixation (ie, a mobile cecum), rather than a pure malrotation. Cecal volvulus most commonly occurs as axial twisting of the cecum, ascending colon, and terminal ileum. It has also been described in patients who have undergone a Malone antegrade continence enema (MACE) procedure, in which the cecal appendix is used as a tubular conduit between the abdominal wall and the cecum, creating a stoma through which the patient can get an antegrade enema to achieve “social continence.”

Duplication cysts

Duplications of the alimentary tract comprise a group of rare malformations that vary greatly in appearance, size, location, and symptoms. Foley et al reported on 12 cases of enteric duplications during an 11-year period. Duplication cysts are either cystic or tubular in shape. They have been reported to occur anywhere along the GI tract from the tongue to the anus, although most are located in the terminal ileum near the ileocecal valve. Duplications are seen in 1 of every 4500 autopsies; 85% of cases are detected by age 2 years.

The 3 characteristics of alimentary tract duplications proposed by Ladd and Gross include (1) contiguity with and strong adherence to some part of the alimentary tract, (2) a smooth muscle coat (usually in 2 layers), and (3) a mucosal lining that consists of one or more types of cells normally observed in the alimentary tract.

Most duplications are truly enteric cysts; only a select group actually represent attempts to double the alimentary tract. The intestinal epithelium may or may not correspond to the epithelium of the adjacent intestinal structure. Gastric mucosa is the most common ectopic tissue found.

Intestinal obstruction, bleeding, infection, and carcinomatous degeneration have been observed with these anomalies, and early correct diagnosis is vital. Most symptoms are caused by the mass effect, and the duplication causes either a partial or complete small-bowel obstruction.

Causes of Immediate Postnatal Small-Bowel Obstructions

Most of these obstructions are the result of jejunoileal atresia, meconium ileus (MI), and extrinsic and intrinsic duodenal obstructions. Jejunoileal atresia (ie, complete obstruction) and stenosis (ie, incomplete obstruction) are extremely important causes of neonatal intestinal obstruction. Atresia, which accounts for 95% of cases, is a congenital obstruction secondary to complete occlusion of the intestinal lumen. In about 25% of these patients, atresia is associated with major GI anomalies (eg, malrotation, MI, volvulus, omphaloceles-gastroschisis). Stenosis, the cause of the remaining 5% of cases, is a partial congenital obstruction caused by incomplete intraluminal occlusion. Patients with intestinal atresia are epidemiologically characterized by low gestational age and low birth weight.

MI occurs almost exclusively in patients with cystic fibrosis (CF)—prevalence is 10-20% in US patients with CF—and is the earliest clinical manifestation of CF. MI is caused by hyperviscous secretions produced by the small intestinal mucous glands. MI is the most severe clinical expression of exocrine pancreatic insufficiency; the lack of normal pancreatic exocrine secretions is the most important factor in the formation of the thick meconium. These secretions cause a thick and tarlike in utero meconium that has a low water content. This abnormally sticky meconium adheres firmly to the small intestinal mucosa and produces intraluminal obstructions. The involved bowel segment may dilate and even perforate or develop a volvulus.

Duodenal atresia and stenosis, collectively, are relatively rare causes of obstruction that occur at a rate of just 1 case per 10,000 live births. Duodenal obstructions in newborns may be partial or complete and they may be secondary to extrinsic or intrinsic abnormalities. In addition to atresia and stenosis, intrinsic duodenal obstructions in newborns may include duodenal webs or diaphragms. Duodenal atresia completely obliterates the duodenal lumen; duodenal stenosis only partially or incompletely obstructs the duodenal lumen.

Although duodenal atresia is at least 4 times more common than duodenal stenosis, stenosis occurs more often in the duodenum than in other portions of the GI tract and may remain undetected until adulthood. The incidence is about 1 per 7000 live births. About 50% of these patients have major associated anomalies (eg, Down syndrome, malrotation, congenital heart disease, renal anomalies, other small-bowel atresias, biliary atresia). Polyhydramnios occurs in approximately 40% of patients, and this clinical finding suggests a high intestinal obstruction in the fetus. Duodenal atresia is believed to be caused by a failure of revacuolization of the duodenal lumen at 8-10 weeks’ gestation. In prior stages of fetal development, the duodenal lumen is obliterated by the proliferating layers of duodenal wall.

Pathophysiology: The normal bowel contains gas and chyle, which is the sum of food and salivary, gastric, biliary, pancreatic, and intestinal secretions. Chyle continues to accumulate, even without oral intake. Intrinsic or extrinsic blockage of the small bowel leads to accumulating secretions that dilate the intestine proximal to the obstruction.

Increased peristaltic contractions and intraluminal pressure may cause frequent loose stools and flatus early in the disease course. Vomiting also occurs in proximal obstructions. Intestinal absorption and lymphatic drainage decrease if intraluminal pressure exceeds capillary and venous pressure in the bowel wall.

The bowel becomes ischemic when capillary blood flow stops, allowing bacteria to enter the blood stream and septicemia to develop, a process known as bacterial translocation. The peritoneal fluid is constantly secreted by the visceral peritoneum and absorbed by the parietal peritoneum, mostly in the diaphragmatic abdominal surface, where the diaphragmatic pores can be distended to 3 times their normal size to allow the passage of bacteria. The colonized fluid is then transported via the lymphatic channels into the thoracic duct, which drains in the jugulosubclavian angle of Pirogoff, allowing bacteria to enter the circulation and causing septicemia.

Perforation can develop as the ischemia leads to bowel necrosis. First, lymphatic obstruction occurs because of the lesser pressure in these vessels. This is followed by venous obstruction, which accelerates the edema process because blood enters the affected bowel segment but does not have a drainage route. Finally, the continuous increase in the bowel wall pressure blocks the arterial vessels, leading to ischemic necrosis and perforation. Massive third spacing of fluids rapidly leads to shock, contributing to morbidity and mortality. This sequence may occur more rapidly in a closed-loop obstruction with no proximal escape for bowel contents.

Most intussusceptions are idiopathic. A lead point is identified in only 2-8% of cases. Intussusceptions are believed to begin with an intestinal spasm around a lead point; the bowel relaxes just distally to this spasm, which allows the longitudinal muscle fibers to draw the contracted portion of bowel into the relaxed portion. Because of the seasonal incidence that seems to follow peak viral illness seasons, these lead points may be enlarged lymphoid tissue from proliferation of Peyer patches.

In some patients, recognizable lead points are found, such as Meckel diverticulum, intestinal polyps, duplications, lymphosarcomas, and, rarely, foreign bodies. Compression of the mesentery at the point of invagination occurs from the start, leading to immediate venous compression, venous stasis, and edema. Goblet cells pour copious amounts of mucus into the intestinal lumen. The engorged hyperemic intestinal mucosa seeps blood, which mixes with the mucus to form the currant jelly stool that occurs in 60% of patients. Tissue pressure eventually exceeds arterial pressure, and necrosis ensues within 24 hours.

In patients with NEC, whether a systemic inflammatory response triggered by a perinatal physiologic stress results in intestinal ischemia, bacterial overgrowth, breakdown of the mucosal barrier, and bacterial translocation is unclear.

Frequency:

• In the US: Malrotation of the bowel with midgut volvulus occurs at a rate of 1 case per 600 infants. Jejunoileal atresia and stenosis have a combined reported incidence of 1 case per 330-1500 live births. These conditions are common among patients with maternal polyhydramnios; 38% have jejunal atresia, and 15% have ileal atresia. Overall, the atresia is almost equally divided between the jejunum (51%) and ileum (49%). Jejunoileal atresia is twice as common as duodenal atresia and is more common than colonic atresia. Duodenal atresia and stenosis, collectively, are relatively rare causes of obstruction that occur at a rate of just 1 case per 10,000 live births.

Mortality/Morbidity: Mortality and morbidity depend on the type of lesion that causes the small-bowel obstruction, whether it is a closed-loop or strangulated obstruction, and the time elapsed before diagnosis and definitive adequate treatment is established. Mortality is low with early diagnosis and treatment. If left untreated, strangulated obstructions are always lethal. Mortality rates may reach 65% if more than 75% of the small bowel is necrotic at the time of laparotomy. Strictures and adhesions are only 2 of the late complications of treated obstructions. Too much bowel damage can cause malnutrition due to short bowel syndrome.

Long-term survival in patients with duodenal atresia or stenosis is approximately 86%. Most of the morbidity and mortality is related to cardiac anomalies. This includes patients with annular pancreas.

Although intussusception-associated infant deaths in the United States have declined substantially over the past 2 decades, some of these deaths may have been preventable because they were apparently related to delayed or reduced access to health care.

The survival rate at 1 year is approximately 92% in patients with uncomplicated MI and 89% in those with complicated disease.

Intestinal resections have been reported in about 1.4-1.8% of patients with incarcerated inguinal hernias. The incidence of testicular infarction and atrophy ranges from 4-12%; young infants seem to be at higher risk.

Sex:

• The male-to-female ratio for incarcerated hernias is 8:1. Hernias occur on the right in about 60% of males, on the left in 25%, and bilaterally in 15%. Females more often have bilateral inguinal hernias.

• Malrotation of the bowel with midgut volvulus can affect either sex. Neither duplication cysts nor jejunoileal atresia and stenosis exhibit a sexual predilection.

Age:

• Intussusception can occur at any time in life, yet the idiopathic form is primarily a childhood disease, developing especially during infancy. Peak occurrence is in infants aged 5-10 months; average age is about 7-8 months.

• Most patients with inguinal hernias present during the first year of life. Approximately one third are younger than 6 months at the time of surgery.

• Most patients with symptomatic malrotation of the bowel with midgut volvulus present in early infancy. Approximately 50% of patients present in the first month of life, and 80% present in the first year. Midgut volvulus has reportedly occurred in utero. Fewer patients (ie, 6-20%) present at ages older than 1 year; these patients tend to have a longer course of vague symptoms (eg, intermittent bilious vomiting, chronic abdominal pain).
  
  
• Most patients with duplication cysts present in early childhood or infancy, although some may not develop symptoms until much later. Many duplication cysts are diagnosed within the first week of life, 60% are identified during the first 6 months of life, and 85% are identified by age 1 year.
  
  
• For annular pancreas, age of obstructive symptom onset varies, and, sometimes, obstructive symptoms do not develop until adulthood. Many pediatric patients present in the newborn period with complete duodenal obstruction, often after the first feeding.
  
  
• NEC affects stressed premature infants who weigh less than 2000 g. Full-term newborns with polycythemia or congenital heart disease have higher risk for NEC, as do infants who had umbilical arterial or venous catheters in situ. Other risk factors include hypertonic feeding solutions that damage the mucosal epithelium of the intestine and episodes of apnea with ischemia of the GI tract.
  
  
• Jejunoileal atresia causes obstruction in the immediate postnatal period.
  
  
• Patients with duodenal stenosis may remain asymptomatic until late childhood or may progress to complete obstruction; symptom onset depends upon the degree of stenosis. Patients with duodenal atresia or annular pancreas present in the first 24 hours of life.
  
  
• MI and meconium plug syndrome present in the first few days of life.

CLINICAL

Section 3 of 12

History: Obtain as much history as possible from the child. Younger children, for example, are likely to recall recent events, while adults remember more remote events. Physicians should seek an accurate chronology of the disorder. Asking when the child was last completely healthy may provide a more accurate assessment of the child’s pathophysiology.

Bilious vomiting in the neonate should be considered secondary to a mechanical obstruction until proven otherwise, and every newborn with this symptom warrants an emergent surgical evaluation.

Focus on the following issues:

• Abdominal pain


• • Pain is common. Caregivers may describe an infant or small child with abdominal pain as irritable or inconsolable.

  • Pain from a small-bowel obstruction is usually colicky. It is described as cramplike and episodic, persisting a few minutes at a time.

  • A child with obstructive pain may be unable to remain immobile on the examining table.

  • Constant pain occurs later in the disease course, with strangulation and perforation.
  
  
  
• Nausea and vomiting


• • Vomiting is a classic symptom of mechanical obstruction.

  • Emesis caused by a proximal obstruction is usually of gastric content or bilious if the obstruction is distal to the ampulla of Vater; in distal ileal obstructions, vomit is feculent.
  
  
  
• Anorexia: Anorexia is an early and frequent sign.

• Diarrhea: Diarrhea may occur early in the course of the obstruction.



• Obstipation: This is a late sign of complete obstruction.



• Fever: Fever can occur late in the disease process and is associated with bowel strangulation and necrosis.



• General historical points: Obtain a complete medical history, specifically including information on prior malignancies, radiation therapies, and abdominal or pelvic surgeries. A history of repetitive abdominal pain with vomiting indicates a chronic partial small-bowel obstruction. In addition to the general guidelines above, the following evidence may suggest the specific cause of a small-bowel obstruction:



• • Intussusception usually causes a sudden onset of severe colicky abdominal pain that often causes a child to draw up both legs. Children appear healthy between paroxysms of pain. As the intussusception progresses, the child becomes progressively more irritable and lethargic until shock develops. Vomiting occurs in the early phase of the illness and is bilious in 30% of cases. Early in the course of the disease, stools are normal but rapidly become bloody and mucoid within the first 12 hours.

  • The classic triad described for intussusception, which consists of colicky abdominal pain, a sausage-shaped palpable abdominal mass, and currant-jelly stools, is actually found in only 20% of cases. Postoperative intussusception occurs within 2-3 weeks after an extensive retroperitoneal dissection (Wilms tumor or neuroblastoma). It is usually an ileoileal intussusception, and affected patients lack the palpable mass and rectal bleeding.
  
  
  
  • An incarcerated hernia is usually associated with signs and symptoms of intestinal obstruction (eg, bilious vomiting, abdominal distention, constipation, obstipation). A tender, edematous, slightly discolored–to–pale mass in the inguinal area may extend down into the scrotum. A swollen erythematous mass that becomes erythematous to violaceous and is exquisitely tender usually indicates a strangulated hernia. Fever and toxicity suggest frank necrosis of the incarcerated organ and impending or completed perforation.
  
  
  
  • The hallmark of acute midgut volvulus is the sudden onset of bilious vomiting, which may be projectile vomiting and, on occasion, have a coffee-ground appearance or contain frank blood. History may reveal feeding problems, with transient episodes of bilious vomiting or failure to thrive. An abdominal distention or a palpable mass may not be evident because the obstruction occurs so high in the GI tract. Older children typically describe colicky abdominal pain. Stools are usually absent but those that do occur yield positive results on guaiac tests. Bright-red blood passed through the rectum implies intestinal ischemia.
  
  
  
  • Postoperative adhesive small-bowel obstructions usually cause a sudden cramplike abdominal pain, followed by anorexia, nausea, and vomiting. Bowel movements typically cease shortly after symptom onset.
  
  
  
  • Presentation of duplication cysts primarily depends on the type of mucosal lining and cyst location. At least 16% of small-bowel duplications contain gastric mucosa and may manifest with peptic ulceration and GI hemorrhage. Spheric cystic duplications may enlarge sufficiently to cause obstruction. Always consider duplication cysts in the differential diagnosis of a vomiting infant or child with a palpable solid abdominal mass and abdominal distention. These cysts may also act as the lead point for an intussusception or form the apex of a volvulus.
  
  
  
  • Abdominal gastric and duodenal duplications may be confused with pyloric stenosis because of their similar presentations. Older patients may present with chronic intermittent vomiting caused by recurring partial obstruction or with an unexplained GI hemorrhage. Because 20% of patients with rectal duplications have fistulae, drainage of mucous or pus through the anus or a perianal fistula is not uncommon.
  
  
  
  • Intestinal atresia or stenosis can occur anywhere along the gastrointestinal tract, and the anatomical location of the obstruction determines the clinical presentation. Most newborns present with bilious emesis, a distended upper abdomen, and a scaphoid hypogastrium. Signs of dehydration are not uncommon. Jaundice is present in 32% of these children. History of polyhydramnios on prenatal ultrasound (28%), prematurity (35%), or low birth weight (25-50%) can be helpful in the diagnosis.
  
  
  
  • In annular pancreas, the duodenum is often compressed at a point distal to the ampulla of Vater, making bilious vomiting a hallmark symptom. Abdominal distention is typically minimal because of the proximal location of the obstruction. Patients may not pass meconium, or bowel movements may cease abruptly. A more insidious form of chronic partial duodenal obstruction may also occur.
  
  
  
  • The clinical features of NEC are nonspecific and often include lethargy, temperature instability, and abdominal distention. Other common symptoms include bilious vomiting, gross or occult rectal bleeding, abdominal tenderness, redness of the abdominal wall, and the presence of reducing substances in the stool. Discoloration of the abdominal wall is indicative of bowel perforation.

  • Patients with mesocolic hernias typically have repeated episodes of colicky abdominal pain and vomiting. These symptoms spontaneously subside when the hernia spontaneously reduces. Patients with incarcerated hernias have continuous pain, abdominal distention, nausea, and vomiting.

  • The presenting symptoms of cecal volvulus include pain, distention, constipation or obstipation, and vomiting.

  • Newborns with jejunoileal atresia or stenosis present with bilious vomiting and jaundice; these infants may not pass meconium in the first day of life. Bilious vomiting is more common with jejunal atresia. Abdominal distention occurs more often in patients with ileal atresia.
  
  
  
  • In patients with MI, symptoms depend on the level of the obstruction (which is usually the terminal ileum) and may include vomiting (usually bile-stained), failure to pass meconium in the first 48 hours of life, and possible abdominal distention. Patients may also present with generalized peritonitis (meconium peritonitis), a meconium pseudocyst, or obstruction due to an intestinal atresia.

  • The cardinal symptom of duodenal atresia is vomiting. Because 85% of atresias are postampullary, most patients present with bile-stained vomit in the first 24 hours of life. Most patients exhibit little or no upper abdominal distention because of the high level of the obstruction. Dehydration, weight loss, and obstipation subsequently develop if treatment is delayed.
  
  
  

Physical: Patients do not develop fever unless the blood supply to the obstructed bowel becomes compromised, which may allow bacterial proliferation and subsequent sepsis.

• In children who present late in the course of their illness, poor capillary refill, hypotension, and even shock may occur as a result of increasing loss of fluid into the bowel lumen.



• Abdominal tenderness may be minimal and diffuse or localized and severe.



• Patients who develop peritonitis obviously have severe pain and rebound tenderness.



• In affected patients, the abdomen may be tympanic to percussion.



• Bowel sounds include the following:


• • Mechanical obstructions produce active, high-pitched, hyperactive bowel sounds with occasional rushes.
  
  
  
  • Peristalsis may be increased in the upper abdomen (above the obstruction; termed “fighting peristalsis”) and decreased in the lower abdomen.

  • With time, peristaltic waves and bowel sounds may diminish.
  
  
  
• During abdominal examinations, look for hernias of the groin, femoral triangle, and obturator foramina.



• Perform a pelvic examination to exclude a genitourinary pathology as the cause of an obstruction.



• Rectal examination includes the following:


• • Check for gross or occult bleeding that suggests strangulation.
  
  
  
  • The absence of stool in the vault may help confirm a diagnosis of bowel obstruction, although its presence does not eliminate a more proximal obstruction.
  
  
  
  • In proximal obstructions, patients may be able to evacuate preexisting rectal contents.

  • Massive diarrhea after rectal examination of an empty rectal vault is suggestive of colonic aganglionosis (ie, Hirschsprung disease).
  
  
  
• In intussusception, physical examination of the abdomen occasionally reveals a tender, sausage-shaped mass that is variable in size and firmness, with spasms of pain. Because most intussusceptions are ileocolic, patients may present with Dance sign (empty right lower quadrant).



• Careful physical examination is most useful in the diagnosis of an incarcerated hernia.



• In patients with a postoperative adhesive small-bowel obstruction, physical examination may reveal abdominal distention and hyperactive high-pitched bowel sounds. Patients usually have a diffuse and poorly localized tenderness that improves with proximal decompression by suction tube.

Causes:

• Intussusception


• • Although the cause of intussusception is unknown in 90-95% of children, a viral etiology is suspected because of its seasonal predisposition for spring and autumn.
  
  
  
  • Gastroenteritis, rotavirus infection, or allergic stimuli are believed to cause intestinal lymphoid tissue to swell and become a lead point to pull the mass into adjacent proximal intestine. In patients younger than 1 month and older than 3 years, pathologic lesions serve as the lead points that produce the condition.
  
  
  
  • Intussusception is a well-described complication of patients with Meckel diverticulum, Waugh syndrome, cocaine abuse, laxative use, and even antibiotic use, presumably due to motility derangements caused by some of these agents.

  • In Henoch-Schönlein purpura, mucosal hematomas are thought to act as lead points.

  • Peutz-Jeghers syndrome is a rare cause of intussusception in older children; in this condition, hamartomatous polyps act as the lead point. Similarly, familial polyposis coli and juvenile polyposis can also cause intussusceptions, and a vermiform appendix may occasionally cause an intussusception.
  
  
  
  • Suspect intestinal lymphomas in all children older than 6 years with intussusception.

  • As mentioned above, extensive retroperitoneal dissections are known to predispose children to postoperative intussusception.

  • Blunt abdominal trauma has also been known to cause intussusception.
  
  
  
• Incarcerated hernia


• • During the third month of gestation, the abdominal peritoneum protrudes at the internal inguinal ring and extends to the scrotum to form a diverticulum known as the processus vaginalis. In females, this diverticulum is called the canal of Nuck and extends through the internal inguinal ring to the labia majora.
  
  
  
  • At birth, the processus vaginalis is open and in communication with the peritoneal cavity in about 80% of babies. Closure takes place progressively during the first 2 years of life, with an estimated 20-30% incidence of patency at age 2 years and then little further decline. This patent processus vaginalis becomes a hernia only when it contains abdominal viscera.
  
  
  
  • Incarcerated or nonreducible hernias may contain small bowel, appendix, omentum, colon, or, rarely, Meckel diverticulum (Littre hernia). In girls, the ovary, fallopian tube, or both are usually incarcerated.

  • Umbilical hernias are the result of an incompletely closed umbilical ring. Most spontaneously resolve by age 5 years.
  
  
  
• Malrotation of the bowel with midgut volvulus


• • The primitive gut, which forms during the fourth week of embryonal life, is divided into the foregut, midgut, and hindgut. The largest of these, the midgut, is the only portion that undergoes rotation by herniating extraembryonically into the umbilical cord and rotating 270° in a counterclockwise direction around the superior mesenteric artery on its journey back to the abdominal cavity. This produces the normal C-shaped configuration of the duodenum and results in the cecum coming to rest in the right lower quadrant of the abdomen.

  • For unknown reasons, midgut rotation can arrest at any point, most commonly rotating 180° and leaving the cecocolic loop in the right upper quadrant. Dense peritoneal bands (ie, Ladd bands) cross from the malpositioned right colon across the duodenum to the right lateral abdominal wall. This configuration leaves a narrow mesenteric root and creates a predisposition to clockwise torsion of the midgut, while the Ladd bands themselves can obstruct the duodenum.

  • Theories of malrotation are based on anatomical and pathologic findings, but the actual rotation movements have not been seen in human embryos. Recent evidence suggests that, at least in rats, the midgut never rotates around the superior mesenteric artery and the final normal position and fixation of the midgut is probably due to differential growth of specific intestinal segments, rather than to rotation movements.
  
  
  
• Jejunoileal atresia: Jejunoileal atresia is believed to result from intrauterine mesenteric vascular accidents that cause devascularization. Lack of normal vacuolization is thought to be the cause of all type I atresias, which may occur anywhere. Vascular accidents with different degrees of infarction are then thought to be the cause of other types of atresias, which may include not only intestinal but also mesenteric defects.


• • The extent of atresia and the appearance of the atretic intestinal segment vary according to the timing and degree of the disruption of the mesenteric blood supply.

  • Small-bowel atresia variably reduces the size of the colon. The volume of intestinal secretions and amniotic fluid that passes through the colon in fetal life determine its size in the newborn infant. Atresia blocks this fluid flow through the colon, thus limiting colon growth. Passage of meconium does not rule out intestinal atresia.
  
  
  
• Postoperative adhesive small-bowel obstruction



• Duplication cysts: The embryogenesis of rectal duplications has been attributed to the pinching off of diverticula that are present in the 8- to 9-week-old embryo. The reported association of spinal abnormalities makes the split notochord mechanism another probable origin of rectal duplications.



• Annular pancreas: Annular pancreas occurs when the ventral pancreatic bud fails to rotate behind the duodenum, leaving pancreatic tissue fully encircling the second portion of the duodenum. This results in a nondistensible ring of pancreatic parenchyma and a functional stenosis.

• Necrotizing enterocolitis: The primary infectious process likely results in enteroinvasion, release of inflammatory mediators, toxin production, ileus, gas production, bowel distension, increased intraluminal pressure, and vascular compromise, which causes loss of mucosal integrity, and bacterial translocation, which results in a systemic inflammatory response.



• Mesocolic hernia

• Cecal volvulus

• Meconium disease


• • MI is caused by intestinal and pancreatic dysfunction, which results from the autosomal recessive disease CF. MI is the result of the accumulation of sticky and inspissated intraluminal meconium.

  • Meconium plug syndrome or meconium obstruction does not appear to be associated with CF or Hirschsprung disease in extremely low birth weight infants.
  
  
  
• Duodenal atresia and stenosis


• • Duodenal atresia and stenosis are believed to be caused by failure of recanalization or vacuolization of the duodenum after the embryologic cord stage when the lumen is completely obliterated.

  • The 3 basic morphologic features of duodenal atresias are as follows:
    • Type I atresias are characterized by luminal webs or membranes.

    • Type II is characterized by a complete atresia connected by a fibrous cord.

    • Type III is characterized by complete atresia with a gap between the segments.
  
  
  

DIFFERENTIALS

Section 4 of 12

Abdominal Trauma
Alimentary Tract Duplications
Appendicitis
Bowel Obstruction in the Newborn
Constipation
Constipation and Bowel Management
Cyclic Vomiting Syndrome
Cystic Fibrosis
Gastroenteritis
Hirschsprung Disease
Intestinal Atresia, Stenosis, and Webs
Intestinal Malrotation
Intestinal Volvulus
Intussusception
Irritable Bowel Syndrome
Meckel Diverticulum
Mesenteric and Omental Cysts
Necrotizing Enterocolitis
Omphalocele and Gastroschisis
Pediatric Hernias
Pyloric Stenosis, Hypertrophic
Small Intestinal Atresia and Stenosis
Surgical Aspects of Cystic Fibrosis and Meconium Ileus
Volvulus

Other Problems to be Considered:

Inflammatory bowel disease
Intestinal pseudoobstruction

WORKUP

Section 5 of 12

Lab Studies:

• The following laboratory tests may be useful:


• • Serum electrolyte level
  
  
  
  • BUN level
  
  
  
  • Creatinine level
  
  
  
  • Glucose level
  
  
  
  • CBC count
  
  
  
  • Urinalysis
  
  
  
  • Arterial blood gas level
  
  
  
  • Stool for occult blood
  
  
  
• Routine laboratory studies usually do not help establish a diagnosis of malrotation of the bowel with midgut volvulus, although leukocytosis with a left shift may develop late in the disease process.



• Potassium is an intracellular ion; thus, patients with incarcerated hernias or other conditions that lead to ischemic bowel present with hyperkalemia.

Imaging Studies:

• Plain abdominal radiography should be the initial radiologic study in suspected cases of small-bowel obstruction.


• • Obtain flat and upright radiographs of the abdomen.

  • Study radiographs for signs of dilated small-bowel loops and of air-fluid levels produced by the layering of air and intestinal content.

  • Absent colonic or rectal gas also indicates a small-bowel obstruction.

  • The pattern of bowel gas on plain radiography can help differentiate between proximal and distal bowel obstructions.

  • When intestinal perforation is suspected and the child cannot be placed in an upright position, a left lateral decubitus film with horizontal beam is helpful in diagnosing free intraperitoneal air.
  
  
  
• Contrast studies such as upper GI series and contrast enemas can help determine obstruction location. Contrast studies also reveal whether the obstruction is intrinsic or extrinsic to the bowel.



• Abdominal CT scanning should not be obtained when the diagnosis is evident on radiography because this would only delay treatment and subject the child to unnecessary radiation. CT scanning helps identify causes of chronic partial obstructions, as well as abscesses, tumors, and many other causes of acute abdominal pain.

• Ultrasonographic examinations reveal many intestinal abnormalities, including tumors, mesenteric cysts, and intussusceptions.

• Intussusception imaging includes the following:


• • In approximately 60% of intussusception cases, plain abdominal radiography reveals the head of the intussusceptum projecting into the air-filled colon. Abdominal radiography may also reveal scattered air-fluid levels that suggest an ileus or partial obstruction.

  • Contrast radiography using a barium enema can be therapeutic as well as diagnostic. A classic sign is a coil spring appearance caused by the tracking of barium around the lumen of the edematous intestine. Air and water enemas have been used to reduce intussusception with extremely good results.

  • Ultrasonography is useful in some cases and may have sensitivity in as many as 75% of patients. The characteristic finding is a target or bull's eye configuration, consisting of 2 rings of low echogenicity that are separated by an intermediate hyperechoic ring visible on a cross-sectional image of intussuscepted bowel.
  
  
  
• Incarcerated hernia imaging includes the following:


• • In complete bowel obstruction, air-fluid levels are visible on plain radiography.

  • The bowel may be visible within the inguinal canal and scrotum.

  • Ultrasonography may reveal the incarcerated viscera in the inguinal canal or the umbilical ring and can be useful in difficult cases.

  • A careful physical examination is more helpful than imaging studies for the diagnosis of incarcerated inguinal or umbilical hernias. Incarcerated hernias are diagnosed clinically, and no imaging studies are required. Determining the level of the obstruction is not that important because the treatment does depend on this finding.
  
  
  
• Imaging for malrotation of the bowel with midgut volvulus includes the following: Plain abdominal radiography sometimes reveals a double-bubble sign that depicts air-fluid levels in both the stomach and in the distended duodenum. The abdomen often appears gasless on abdominal plain radiography. Distended loops of small bowel are only occasionally visible because the point of obstruction is proximal, in the third portion of the duodenum.



• Definitive diagnosis of midgut volvulus requires contrast studies. Barium enema findings may provide indirect evidence by revealing an ectopically placed right colon and cecum, but a high or mobile cecum is common in many asymptomatic infants. In fact, 10-15% of patients with malrotation have barium enema findings that appear normal. An upper GI series is a quicker and more direct approach with high sensitivity and accuracy, making it the study of choice for malrotation with or without volvulus. The duodenum usually has a “C” shape, and the duodenojejunal junction is localized to the left of the midline. In malrotation, the duodenum lacks its normal shape and does not cross the midline. Duodenal obstructions due to volvulus, Ladd bands, or angulation are evident. The classic patterns of volvulus are the “bird beak” in cases involving complete duodenal obstruction or the “corkscrew in cases involving incomplete obstruction.



• Imaging for postoperative adhesive small-bowel obstruction includes the following:


• • Supine and upright abdominal radiography reveals dilated gas-filled loops of small intestine with multiple air-fluid levels scattered throughout the abdomen above the obstruction site. Air in the colon usually indicates a partial obstruction, although determining whether a gas-filled loop is the colon or small bowel is difficult in infants. Demonstrating gas in the rectum is the only way to be certain of gas in the colon.

  • An upper GI contrast study helps confirm the diagnosis in questionable cases.
  
  
  
• Imaging for duplication cysts is as follows:


• • Plain radiography usually reveals a soft-tissue mass within the abdomen that displaces the adjacent bowel and causes the obstruction.

  • An upper GI contrast series may reveal stenosis or extrinsic compression by a mass.

  • Technetium scanning can be used to image duplications that contain ectopic gastric mucosa.

  • For most abdominal duplications, ultrasonography is more expedient and provides greater detail than conventional contrast radiography. Ultrasonography reveals either a sonolucent mass that has good through transmission because of its clear fluid content or an echogenic mass secondary to hemorrhage that has inspissated material within the duplication. Intraabdominal enteric duplication cysts are increasingly likely to be prenatally detected.
  
  
  
• Imaging for annular pancreas is as follows:
  • Although an annular pancreas is often not diagnosed until surgery, plain abdominal radiography may reveal the double-bubble sign characteristic of duodenal obstruction.

  • An upper GI series reveals a diminished duodenal lumen.

  • Ultrasonography provides a reliable method to help diagnose duodenal obstruction, even prenatally in pregnancies complicated by polyhydramnios in the third trimester.



• Imaging for NEC includes the following:
  • Abdominal radiography initially reveals multiple gas-filled loops of intestine and air-fluid levels. Straightening of the bowel wall and bowel wall thickening with intramural air suggest mural edema (railroad sign). A gasless abdomen, a fixed bowel loop, or ground-glass appearance, which suggests free intraperitoneal fluid, is sometimes encountered.

  • Pneumatosis intestinalis is the radiographic hallmark; its presence indicates gas in the bowel wall. Portal venous gas is an ominous sign, and pneumoperitoneum indicates a bowel perforation.



• Mesocolic hernia imaging is as follows:
  • An upper GI study with small bowel follow-through during a hernia episode can support the diagnosis. This study usually reveals the intestines bunched together as if enveloped by a sac.

  • Abdominal CT scanning may reveal a mesocolic hernia during nonherniating periods.



• Cecal volvulus imaging is as follows:
  • Plain abdominal radiography may reveal a large air-filled loop of colon that occupies the right lower quadrant, in addition to depicting a typical small-bowel obstruction.

  • The characteristic barium enema finding is a bird-beak–shaped deformity, coupled with nonvisualization of the cecum.




• Jejunoileal atresia and stenosis imaging involves the following:
  • Radiographic findings often reveal thumb-sized intestinal loops and air-fluid levels. A loop of small bowel proximal to the atresia may become grossly distended and filled with fluid, producing the appearance of a mass.

  • A contrast enema is usually indicated to confirm the diagnosis. The preferred methodology is a water-soluble enema, which aids in distinguishing between small- and large-bowel distention, determining the presence or absence of a microcolon, and locating the position of the cecum relative to possible abnormalities of intestinal rotation and fixation.

  • An upper GI series reveals the level of obstruction with a grossly distended proximal bowel. Care must be taken to avoid contrast aspiration.



• Meconium disease imaging studies are as follows:
  • Abdominal radiographic studies reveal multiple air-fluid levels consistent with small-bowel obstruction. The presence of calcifications throughout the peritoneum suggests a prenatal perforation and meconium peritonitis or meconium pseudocyst.

  • The inspissated meconium often has a ground-glass appearance on radiography. A “soap-bubble” image in the right lower quadrant is characteristic.

  • A contrast enema is diagnostic and, in many cases, therapeutic for both MI and meconium plug syndrome. In most cases, the contrast enema reveals a microcolon (nonused colon) and meconium pellets in either the terminal ileum (MI) or the colon (meconium plug syndrome). Gastrografin is the agent of choice. Its osmotic properties pull water into the lumen, which may unplug the intestine.



• Duodenal atresia and stenosis imaging studies involve the following:
  • Abdominal radiography usually confirms a duodenal atresia diagnosis. Gas and air-fluid levels are present in the stomach and the dilated duodenal bulb (ie, double-bubble sign), but no air is present in the distal GI tract. These radiographic findings confirm a diagnosis of duodenal obstruction, making further studies unnecessary.

  • An upper GI series adds no information and creates the potential hazard of vomiting with barium aspiration. If the patient has vomited or has been decompressed using a nasogastric (NG) tube prior to abdominal radiography, the stomach and duodenum may be collapsed, making the correct diagnosis difficult. In such cases, a small amount of air (ie, 10-15 mL) may be injected into the stomach through an NG tube and the radiography may be repeated.

  • Upper GI studies are useful in the late diagnosis of duodenal web and stenosis.

TREATMENT

Section 6 of 12

Medical Care:

• General principles
  • Stabilize the patient and monitor airway, breathing, and circulation (ABC).

  • Replace fluids with diligent intravenous resuscitation, using isotonic sodium chloride solution or lactated Ringer solution.

  • Earlier bowel decompression with an NG tube decreases the chance of bowel necrosis and perforation.

  • Administer broad-spectrum antibiotics when necrosis or perforation is suspected.



• Intussusception
  • Stabilize the patient's ABCs and replace large fluid losses. Administer nothing by mouth (NPO) to the child and place an NG tube in an attempt to decompress the obstruction from above. The use of antibiotics is appropriate for management of bacterial translocation.

  • Barium, water, or air reduction is appropriate after surgical consultation if symptom duration is less than 24 hours and the patient has no signs of peritonitis. Barium reduction successfully reduces 80-95% of all intussusceptions and has even better success in short-duration intussusceptions.

  • Children whose symptoms persist longer than 24 hours or who have signs of peritonitis should not be considered candidates for enema reduction. Stabilize these children and immediately transport them to the operating room because untreated intussusception is almost always fatal. The recurrence rate is higher after enema reduction than after surgical reduction. Surgery is also indicated for patients whose intussusception cannot be reduced after 2 enema attempts.

• Adhesive small-bowel obstruction
  • Only about 6-7% of children with adhesive small-bowel obstruction require immediate laparotomy. Approximately one half of these patients respond to medical treatment, which includes NPO, intravenous fluids, NG decompression, and antibiotics. Children younger than 1 year tend to respond poorly to conservative management. No single agent or treatment has proven effective in preventing adhesion formation after a laparotomy.

  • The use of water-soluble contrast via NG tube may decrease the need for surgery in some patients. Water-soluble contrast media (Urografin) cause redistribution of intravascular and extracellular fluid into the intestinal lumen because of their hyperosmolarity. As a result, these media decrease intestinal wall edema and act as a direct stimulant to intestinal peristalsis



• Incarcerated hernia
  • Stabilize the patient's ABCs and focus on replacing the large fluid losses.

  • Nonoperative reduction of a nonstrangulated hernia is possible in approximately 95-98% of cases. Facilitate the reduction by sedating the patient and placing the patient in a mild Trendelenburg position. Gentle traction on the hernia and the contents of the sac usually suffices to reduce the volume and rapidly retract the contents of the sac into the abdominal cavity.

  • The only contraindication to nonoperative reduction is a long-standing incarceration with evidence of peritoneal irritation.

  • Antibiotic therapy is usually unwarranted, but critically ill infants with perforation and peritonitis require coverage for aerobic gram-negative organisms and anaerobic infections.



• Necrotizing enterocolitis
  • NEC management involves cessation of enteral feeds, gastric decompression on low continuous suction with a sump-type tube, fluid management to correct hypovolemia, parenteral nutrition with a centrally located intravenous catheter once fluid resuscitation is complete, and antibiotic therapy.

  • Direct antimicrobial therapy is aimed at enteric bacteria (eg, Escherichia coli, Klebsiella species, Enterococcus species, anaerobic colonic flora, [Clostridia species]).

  • Serial abdominal examinations are preferably performed by the same examiner.

  • Obtain radiographs of the abdomen, including cross-table lateral films, every 6-8 hours for the first 48 hours.

  • Obtain blood, urine, sputum, and CSF cultures, if indicated.



• Meconium disease
  • Treatment of MI requires evacuating the meconium. Nonsurgical methods relieve the obstructions of more than 50% of patients.

  • The therapy of choice for uncomplicated MI is nonoperative hyperosmolar enema (Gastrografin or Omnipaque), with enterotomy and irrigation reserved for enema failures. Dilute Gastrografin with N-acetylcysteine may also be administered using an NG tube from above to help loosen the meconium.

  • Complicated cases (meconium peritonitis, meconium pseudocyst, perforation, intestinal atresia) require exploration and bowel resection with primary anastomosis or stoma creation.

  • Meconium plug syndrome is usually relieved with rectal stimulation (suppositories, washouts, or contrast enemas)

Surgical Care:

• Intussusception: Intussusception can be reduced by radiographic means in 80-95% of patients. Surgical reduction is indicated when symptoms have been present for more than 24 hours, in the presence of shock that cannot be corrected, when a lead point has been identified, when necrosis or perforation are present, or if the intussusception is irreducible by radiographic means.

• Incarcerated hernia: After reducing the hernia, elective repair is possible 24-48 hours after the edema subsides. For patients whose hernias cannot be reduced and for patients with strangulation, immediate surgery is mandatory to prevent the incarceration from progressing to perforation and frank peritonitis.



• Malrotation of the bowel with midgut volvulus


• • Preserving intestinal viability requires rapid diagnosis and surgery for malrotation with midgut volvulus. Initiate NG suction and intravenous hydration when entertaining the possibility of midgut volvulus. If abdominal plain radiographic findings confirm the diagnosis, defer contrast studies and take the child directly to the operating room.
  
  
  
  • A Ladd procedure is the preferred treatment. It includes evisceration and inspection of the mesenteric root, derotation of the volvulus (which has always been reported to occur in a clockwise direction), lysis of Ladd bands with kocherization of the duodenum along the right abdominal gutter, opening of the visceral peritoneum that covers the mesentery, and replacing the small bowel into the right side of the abdomen and the large bowel into the left side (in a position of nonrotation). It also includes an appendectomy (usually an inversion appendectomy) because the cecum and appendix are located in an unusual place.

  • Any frankly necrotic bowel should be resected and end-to-end anastomosis performed unless the peritoneal cavity is grossly contaminated or the condition of the patient does not allow it; in such cases, stomas should be created.
  
  
  
• Postoperative adhesive small-bowel obstruction: A possible diagnosis of adhesive small-bowel obstruction requires prompt surgical consultation because delay can lead to intestinal necrosis. Patients usually present with a single-point obstruction. Adhesiolysis is the treatment of choice. This can be achieved laparoscopically or with laparotomy. Some patients require bowel resection because of perforation or necrosis.



• Duplication cysts


• • The treatment for duplications is surgical excision, even in an asymptomatic patient who is incidentally diagnosed. The prevalence of gastric mucosa suggests that the duplications should not be left indefinitely. The procedure may depend on the location of the cyst.

  • In esophageal duplications, the cyst is excised, and a mucosectomy is performed if the muscular layer shared with the esophagus is left behind. The entire muscular wall can be excised with the cyst, taking care not to penetrate the esophageal mucosa.

  • Duplications of the small intestine usually require resection and anastomosis. In rectal duplications, only the mucosal lining usually needs to be excised because the duplication and normal rectum share the muscularis layer. If malignant degeneration is suspected, total excision including the normal rectum may be necessary. Infected duplications may require initial drainage, followed by a staged resection. Laparoscopically assisted resection of ileocecal duplications is safe and effective.
  
  
  
• Annular pancreas: Surgical management is similar to that of duodenal atresia. Duodenoduodenostomy is the preferred approach.

• Necrotizing enterocolitis: Indications for surgery include pneumoperitoneum, fixed dilated bowel loop, abdominal wall discoloration, or children whose conditions deteriorate or show no improvement with conservative therapy. Portal venous air suggests extensive intestinal necrosis but does not indicate that celiotomy is necessary.

• Mesocolic hernia: Surgically reduce the hernia and repair the potential hernia pouch, either electively (for reducible hernias) or emergently (for incarcerated hernias.)



• Cecal volvulus: Surgical reduction of the cecal volvulus is usually required, in addition to fluid resuscitation, bowel decompression, and ABC monitoring.

• Jejunoileal atresia and stenosis: Surgical resection of the atretic segment is followed by end-to-end anastomosis. The proximal dilated bowel may need to be tapered to fit the smaller distal intestine. Care should be taken to preserve as much intestinal length as possible in order to prevent short bowel syndrome, mainly in patients with multiple atresias.

• Meconium ileus: Surgical management by either primary resection and anastomosis or an ileostomy is sometimes required.



• Duodenal atresia and stenosis: The usual treatment for duodenal atresia is a linear or diamond-shaped duodenoduodenostomy (Kimura procedure). Duodenojejunostomy is another option. A duodenal web is much rarer and can be treated with duodenotomy with excision of the web and duodenoplasty.

Consultations: Consult with a pediatric or general surgeon, depending on availability.

Diet: Administer NPO.

MEDICATION

Section 7 of 12

Bowel obstructions often require surgical interventions, but start antibiotic administration in the emergency department (ED) first. Antibiotic coverage must include gram-negative aerobic and gram-negative anaerobic organisms. (The following list of antibiotics is not all-inclusive.)

Drug Category: Antibiotics -- Therapy must cover all likely pathogens in the clinical setting.

Drug Name	Clindamycin (Cleocin) -- A lincosamide useful in treating serious skin and soft tissue infections caused by most staphylococcal strains. Also effective against aerobic and anaerobic streptococci, except enterococci. Inhibits bacterial protein synthesis by inhibiting peptide chain initiation at bacterial ribosome, where it preferentially binds to 50S ribosomal subunit, inhibiting bacterial growth.
Adult Dose	450-900 mg IV q8h
Pediatric Dose	20-40 mg/kg/d IV divided tid/qid
Contraindications	Documented hypersensitivity; regional enteritis; ulcerative colitis; hepatic impairment; antibiotic-associated colitis
Interactions	Increases duration of neuromuscular blockade induced by tubocurarine and pancuronium; erythromycin may antagonize effects; antidiarrheals may delay absorption
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Adjust dose in severe hepatic dysfunction; no adjustment necessary in renal insufficiency; associated with severe and possibly fatal colitis

Drug Name	Metronidazole (Flagyl) -- Imidazole ring-based antibiotic active against various anaerobic bacteria and protozoa. Used in combination with other antimicrobial agents (used alone in Clostridium difficile enterocolitis).
Adult Dose	1 g IV loading dose, followed by 0.5 g IV q6h or 1 g IV q12h
Pediatric Dose	Neonates: <1200 grams: 7.5 mg/kg IV q48h <7 days and >1200 grams: 7.5-15 mg/kg IV daily or divided q12h >7 days and >1200 grams: 15-30 mg/kg IV daily or divided q12h Infants and children: 30 mg/kg IV daily or divided q6h; not to exceed 4 g/d
Contraindications	Documented hypersensitivity
Interactions	May increase toxicity of anticoagulants, lithium, and phenytoin; cimetidine may increase toxicity; disulfiram reaction may occur with orally ingested ethanol
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Do not use in first trimester of pregnancy; adjust dose in hepatic disease; monitor for seizures and development of peripheral neuropathy

Drug Name	Aztreonam (Azactam) -- Monobactam that inhibits cell wall synthesis during bacterial growth. Active against gram-negative bacilli. Effective against aerobic gram-negative organisms.
Adult Dose	2 g IV q8h
Pediatric Dose	30 mg/kg IV q6-8h
Contraindications	Documented hypersensitivity
Interactions	Tetracyclines may reduce effects
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Adjust dose in renal insufficiency

Drug Name	Cefoxitin (Mefoxin) -- Second-generation cephalosporin used to treat infections caused by susceptible gram-positive cocci and gram-negative rods. Effective against aerobic and anaerobic gram-negative organisms.
Adult Dose	2 g IV q8h
Pediatric Dose	80-100 mg/kg/d IV divided tid/qid
Contraindications	Documented hypersensitivity
Interactions	Probenecid may increase effects; coadministration with aminoglycosides or furosemide may increase nephrotoxicity (closely monitor renal function)
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Bacterial or fungal overgrowth of nonsusceptible organisms may occur with prolonged use or repeated treatment; caution in patients with previously diagnosed colitis

Drug Name	Cefotetan (Cefotan) -- Second-generation cephalosporin used to treat infections caused by susceptible gram-positive cocci and gram-negative rods; not FDA-approved for use in children.
Adult Dose	2 g IV q12h; not to exceed 6 g/d
Pediatric Dose	20-40 mg/kg IV/IM q12h; not to exceed 6 g/d
Contraindications	Documented hypersensitivity
Interactions	Consumption of alcohol within 72 h may produce disulfiramlike reactions; may increase hypoprothrombinemic effects of anticoagulants; coadministration with potent diuretics (eg, loop diuretics) or aminoglycosides may increase nephrotoxicity
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Reduce dosage by 50% if CrCl 10-30 mL/min and by 75% if CrCl <10 mL/min; bacterial or fungal overgrowth of nonsusceptible organisms may occur with prolonged or repeated therapy

Drug Name	Imipenem and cilastatin (Primaxin) -- Effective against aerobic and anaerobic gram-negative organisms.
Adult Dose	500 mg IV q6h
Pediatric Dose	<1 week and >1500 grams: 25 mg/kg IV q12h1-4 weeks and >1500 grams: 25 mg/kg IV q8h4 weeks to 3 months and >1500 grams: 25 mg/kg IV q6h>3 months: 15-25 mg/kg/IV q6h
Contraindications	Documented hypersensitivity
Interactions	Coadministration with cyclosporine may increase adverse CNS effects of both agents; coadministration with ganciclovir may result in generalized seizures
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Adjust dose in renal insufficiency; avoid use in children <12 y; caution with history of seizures

Drug Name	Ticarcillin and clavulanate potassium (Timentin) -- Inhibits biosynthesis of cell wall mucopeptide and is effective during active growth stage. Antipseudomonal penicillin plus beta-lactamase inhibitor that provides coverage against most gram-positive, most gram-negative, and most anaerobic organisms.
Adult Dose	3 g (base dose on ticarcillin component) IV q4-6h; not to exceed 18-24 g/d
Pediatric Dose	75 mg/kg (base dose on ticarcillin component) IV q6h; not to exceed 18-24 g/d
Contraindications	Documented hypersensitivity
Interactions	Tetracyclines may decrease effects; high concentrations may physically inactivate aminoglycosides if administered in same IV line; effects when administered concurrently with aminoglycosides are synergistic; probenecid may increase penicillin levels
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Obtain CBC count prior to initiating therapy and at least weekly during therapy; monitor for liver function abnormalities by measuring AST and ALT during therapy; exercise caution in patients diagnosed with hepatic insufficiencies; perform urinalysis, measure BUN and creatinine levels during therapy, and adjust dose if values become elevated; monitor blood levels to avoid possible neurotoxic reactions

FOLLOW-UP

Section 8 of 12

Further Inpatient Care:

• Patients with partial small-bowel obstructions can be nonoperatively treated with adequate fluid resuscitation and nasoenteric suctioning.



• Patients who do not respond to nonoperative treatment within 48 hours require surgical treatment.



• After nonoperative hernia reduction, elective repair may be accomplished 24-48 hours after the edema subsides.



• Admit any child with an intussusception that is successfully reduced with a barium enema for observation because this condition has a high reoccurrence rate, especially in the first 24 hours.

Further Outpatient Care:

• Close follow-up observation is mandatory for patients whose partial small-bowel obstructions are nonoperatively treated and who are stable for discharge.



• Instruct parents that they must take their child immediately to an ED if the child's symptoms (eg, vomiting, pain) recur.

Complications:

• Bowel necrosis



• Bowel perforation



• Sepsis



• Shock



• Abscess



• Short bowel syndrome with malabsorption and malnutrition



• Death



• Testicular infarction and atrophy, lesion to the testicular vessels or vas deferens, hernia recurrence (complications of incarcerated hernias)

Prognosis:

• The prognosis of small-bowel obstruction depends on the location and source of obstruction and on the extent of bowel necrosis.



• With early diagnosis and treatment, the prognosis is good; however, mortality rates may reach 65% if more than 75% of the small bowel is necrotic at the time of laparotomy.

Patient Education:

• For excellent patient education resources, visit eMedicine's Esophagus, Stomach, and Intestine Center. Also, see eMedicine's patient education articles Abdominal Pain in Children, Hernia, Vomiting and Nausea, Constipation in Children, and Colic.

MISCELLANEOUS

Section 9 of 12

Medical/Legal Pitfalls:

• Signs and symptoms of bowel obstruction, especially in newborns, may be subtle; physicians should maintain a high index of suspicion.



• Rapid decisions about the need for surgical intervention can mean the difference between full recovery and massive bowel loss.



• Bilious vomiting in a newborn should immediately lead physicians to suspect a bowel obstruction and to initiate an immediate workup.



• Admit any child with suspected small-bowel obstruction for observation, even if the diagnosis of obstruction is unclear.

TEST QUESTIONS

Section 10 of 12

CME Question 1: Which of the following does not occur in a patient with intussusception?

A: Lethargy
B: Negative stool guaiac test result
C: Sausage-shaped mass in the right upper quadrant
D: Intermittent severe abdominal pain
E: Vomiting

The correct answer is B: Although currant jelly stools occur in only 50% of patients, stool guaiac test results are positive in almost every case. All the other choices commonly occur with an intussusception.

CME Question 2: Which cause of small-bowel obstruction does not match the findings shown?

A: Duodenal atresia - Bile-stained vomiting within the first 24 hours of life in a patient with Down syndrome born of a pregnancy complicated with polyhydramnios
B: Ileal atresia - Vomiting and abdominal distention in a patient with thumb-sized intestinal loops and a pseudocyst on plain abdominal radiography and a contrast enema that reveals a microcolon
C: Malrotation with midgut volvulus - Sudden onset of bilious vomiting and guaiac-positive stool in a 1-month-old infant with a history of feeding problems and a corkscrew pattern visible on a contrast study of the upper GI tract
D: Cecal volvulus - A 6-month-old patient presenting with a sudden onset of abdominal pain, distention, and constipation and a barium enema that reveals a filling defect that looks like a bird's beak
E: Duplication cyst - A 3-month-old patient with a history of a lump in his right inguinal region at birth, a lethargic appearance at presentation, fever, and a swollen tender mass in the right groin

The correct answer is E: In a child presenting with a history of a right-sided inguinal mass, pain from this mass, and a toxemic appearance, a diagnosis of an incarcerated hernia is suggested. Patients with a duplication cyst may also present with a solid abdominal mass but not in the inguinal region. All other findings can be found with these obstructive diseases.

Pearl Question 1 (T/F): Finding polyhydramnios on fetal ultrasonographic examination suggests a proximal small-bowel obstruction in the fetus.

The correct answer is True: The fetus normally swallows amniotic fluid that travels through and is digested by the intestine. A proximal obstruction of the bowel causes amniotic fluid to accumulate (ie, polyhydramnios).

Pearl Question 2 (T/F): Duodenal atresia is believed to be caused by an intrauterine mesenteric vascular accident that causes devascularization.

The correct answer is False: Jejunoileal atresia is believed to be caused by a vascular accident; duodenal atresias are thought to result from revacuolization failure by the duodenal lumen.

Pearl Question 3 (T/F): Intussusception invariably causes stools with the appearance of currant jelly.

The correct answer is False: When mucus in the intestinal lumen mixes with blood, the stool has the appearance of currant jelly, a finding that is present in only 50% of patients with intussusception.

Pearl Question 4 (T/F): Most inguinal hernias in male patients occur on the right side.

The correct answer is True: In males, 60% of inguinal hernias occur on the right, 25% occur on the left, and 15% are bilateral.

PICTURES

Section 11 of 12

Caption: Picture 1. Small-bowel obstruction visible on plain radiograph caused by intussusception in a 5-month-old patient.
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Caption: Picture 2. Barium enema revealing a coil spring appearance caused by the tracking of barium around the lumen of the edematous intestine in intussusception.
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Caption: Picture 3. Small-bowel obstruction caused by an incarcerated inguinal hernia in a 2-month-old infant with bilateral inguinal hernias as well as an umbilical hernia.
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BIBLIOGRAPHY

Section 12 of 12

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