AUTHOR INFORMATION

Section 1 of 12

Authored by Sandy Craig, MD, Associate Program Director, Adjunct Assistant Professor, Department of Emergency Medicine, University of North Carolina at Chapel Hill, Carolinas Medical Center

Sandy Craig, MD, is a member of the following medical societies: Alpha Omega Alpha, and Society for Academic Emergency Medicine

Edited by David S Howes, MD, Residency Program Director, Professor of Medicine, Section of Emergency Medicine, University of Chicago/Pritzker School of Medicine; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Richard Sinert, DO, Associate Professor of Emergency Medicine, Clinical Assistant Professor of Medicine, State University of New York College of Medicine; Consulting Staff, Department of Emergency Medicine, Kings County Hospital Center; John Halamka, MD, Chief Information Officer, CareGroup Healthcare System, Assistant Professor of Medicine, Department of Emergency Medicine, Beth Israel Deaconess Medical Center; Assistant Professor of Medicine, Harvard Medical School; and Robert E O'Connor, MD, MPH, Director of Education and Research, Department of Emergency Medicine, Christiana Care Health System; Professor of Emergency Medicine, Thomas Jefferson University

Author's Email:	Sandy Craig, MD
Editor's Email:	David S Howes, MD

eMedicine Journal, November 30 2006, VOLUME 7, Number 11

INTRODUCTION

Section 2 of 12

Background: Acute passage of a kidney stone from the renal pelvis through the ureter gives rise to pain at times so excruciating that it has been likened to the discomfort of childbirth. The often sudden, extremely painful episode of renal colic prompts more than 450,000 visits to EDs annually and places emergency physicians on the front line of management of acute nephrolithiasis. ED management is focused on excluding other serious diagnoses and providing adequate pain relief.

Pathophysiology: Most calculi arise in the kidney when urine becomes supersaturated with a salt that is capable of forming solid crystals. Symptoms arise as these calculi become impacted within the ureter as they pass toward the urinary bladder.

Frequency:

• In the US: The lifetime prevalence of nephrolithiasis is approximately 12% for men and 7% for women in the United States. Recurrence rates after the first stone episode are 14%, 35%, and 52% at 1, 5, and 10 years, respectively. An increased incidence has been noted in the southeastern United States, prompting the term "stone belt" for this region of the country.

• Internationally: Incidence is lower in nonindustrialized countries.

Mortality/Morbidity:

• Approximately 80-85% of stones pass spontaneously.

• Approximately 20% of patients require hospital admission because of unrelenting pain, inability to retain enteral fluids, proximal urinary tract infection (UTI), or inability to pass the stone.

• A ureteral stone associated with obstruction and upper UTI is a true urologic emergency. Complications include perinephric abscess, urosepsis, and death. Immediate involvement of the urologist is essential.

Race:

• White males are affected 3-4 times more often than African American males.

• African Americans have a higher incidence of infected ureteral calculi than whites.

Sex:

• The male-to-female ratio is approximately 3:1.

• Female patients have a higher incidence of infected hydronephrosis.

Age: Peak onset of symptomatic nephrolithiasis is in the third and fourth decades of life.

• Beware of the patient older than 60 years with an apparent first kidney stone. Consider the possibility of symptomatic abdominal aortic aneurysm (AAA) in the older patient, and rule out this possibility before pursuing the diagnosis of nephrolithiasis. Use bedside ultrasonography if the patient’s condition is potentially unstable. CT scan is a reasonable alternative in the patient in stable condition.

• Nephrolithiasis in children is rare; approximately 5-10 children aged 10 months to 16 years are seen annually for the condition at a typical US pediatric referral center.

CLINICAL

Section 3 of 12

History: Most calculi originate within the kidney and proceed distally, creating various degrees of urinary obstruction as they become lodged in narrow areas, including the ureteropelvic junction, pelvic brim, and ureterovesical junction. Location and quality of pain are related to position of the stone within the urinary tract. Severity of pain is related to the degree of obstruction, presence of ureteral spasm, and presence of any associated infection.

• Stones obstructing the ureteropelvic junction may present with mild-to-severe deep flank pain without radiation to the groin, due to distension of the renal capsule.

• Stones impacted within the ureter cause abrupt, severe, colicky pain in the flank and ipsilateral lower abdomen with radiation to the testicles or the vulvar area. Intense nausea, with or without vomiting, usually is present.

• Stones lodged at the ureterovesical junction also may cause irritative voiding symptoms, such as urinary frequency and dysuria.

• Calculi that have entered the bladder are usually asymptomatic and are passed relatively easily during urination.

• Rarely, a patient reports positional urinary retention (obstruction precipitated by standing, relieved by recumbency), which is due to the ball-valve effect of a large stone located at the bladder outlet.

Physical: The classic patient with renal colic is writhing in pain, pacing about, and unable to lie still, in contrast to a patient with peritoneal irritation, who remains motionless to minimize discomfort.

• Fever is not part of the presentation of uncomplicated nephrolithiasis. If present, suspect infected hydronephrosis, pyonephrosis, or perinephric abscess.

• The most common finding in ureterolithiasis is flank tenderness due to the dilation and spasm of the ureter from transient obstruction as the stone passes from the kidney to the bladder.

• Abdominal examination usually is unremarkable. Bowel sounds may be hypoactive, a reflection of mild ileus, which is not uncommon in patients with severe, acute pain.

• In patients older than 60 years with no prior history of renal stones, the emergency physician should look carefully for physical signs of AAA (see Aneurysm, Abdominal).

• Testicles may be painful but should not be very tender and should appear normal.

Causes: The formation of the 4 basic chemical types of renal calculi is associated with more than 20 underlying etiologies. Stone analysis, together with serum and 24-hour urine metabolic evaluation, can identify an etiology in more than 95% of patients. Specific therapy can result in a remission rate of more than 80% and can decrease the individual recurrence rate by 90%. Therefore, emergency physicians should stress the importance of urologic follow-up, especially in patients with recurrent stones, solitary kidneys, or previous kidney or stone surgery and in all children.

• Calcium stones (75%): Calcium oxalate, calcium phosphate, and calcium urate are associated with the following disorders:

• Hyperparathyroidism - Treated surgically or with orthophosphates if the patient is not a surgical candidate

• Increased gut absorption of calcium - The most common identifiable cause of hypercalciuria, treated with calcium binders or thiazides plus potassium citrate

• Renal calcium leak - Treated with thiazide diuretics

• Renal phosphate leak - Treated with oral phosphate supplements

• Hyperuricosuria - Treated with allopurinol, low purine diet, or alkalinizing agents such as potassium citrate

• Hyperoxaluria - Treated with dietary modification, oxalate binders, vitamin B-6, or orthophosphates

• Hypocitraturia - Treated with potassium citrate

• Hypomagnesuria - Treated with magnesium supplements

• Struvite (magnesium ammonium phosphate) stones (15%)

• Struvite stones are associated with chronic UTI with gram-negative rods capable of splitting urea into ammonium, which combines with phosphate and magnesium.

• Usual organisms include Proteus, Pseudomonas, and Klebsiella species. Escherichia coli is not capable of splitting urea and, therefore, is not associated with struvite stones.

• UTI does not resolve until stone is removed entirely.

• Urine pH is typically greater than 7.

• Uric acid stones (6%): These are associated with urine pH less than 5.5, high purine intake (eg, organ meats, legumes, fish, meat extracts, gravies), or malignancy (ie, rapid cell turnover). Approximately 25% of patients with uric acid stone have gout.

• Cystine stones (2%)

• Cystine stones arise because of an intrinsic metabolic defect resulting in failure of renal tubular reabsorption of cystine, ornithine, lysine, and arginine.

• Urine becomes supersaturated with cystine with resultant crystal deposition.

• These are treated with low-methionine diet (unpleasant), binders such as penicillamine or a-mercaptopropionylglycine, large urinary volumes, or alkalinizing agents.

• Drug-induced stone disease: A number of medications or their metabolites can precipitate in urine causing stone formation. These include indinavir; guaifenesin; triamterene; silicate (overuse of antacids containing magnesium silicate); and sulfa drugs including sulfasalazine, sulfadiazine, acetylsulfamethoxazole, acetylsulfasoxazole, and acetylsulfaguanidine.

DIFFERENTIALS

Section 4 of 12

Aneurysm, Abdominal
Aneurysm, Thoracic
Appendicitis, Acute
Back Pain, Mechanical
Cholecystitis and Biliary Colic
Cholelithiasis
Constipation
Dissection, Aortic
Diverticular Disease
Epididymitis
Foreign Bodies, Gastrointestinal
Foreign Bodies, Rectum
Gastritis and Peptic Ulcer Disease
Glomerulonephritis, Acute
Herpes Zoster
Inflammatory Bowel Disease
Lumbar (Intervertebral) Disk Disorders
Obstruction, Large Bowel
Obstruction, Small Bowel
Pancreatitis
Pediatrics, Urinary Tract Infections and Pyelonephritis
Pelvic Inflammatory Disease
Pneumonia, Bacterial
Pneumothorax, Tension and Traumatic
Pregnancy, Ectopic
Pregnancy, Urinary Tract Infections
Testicular Torsion
Torsion of the Appendices and Epididymis
Transplants, Renal
Urinary Obstruction
Urinary Tract Infection, Female
Urinary Tract Infection, Male

Other Problems to be Considered:

Pyonephrosis
Renal vein thrombosis
Renal artery embolus

WORKUP

Section 5 of 12

Lab Studies:

• Urinalysis

• One retrospective study found that 67% of patients with ureterolithiasis had more than 5 RBC per high power field (hpf) and 89% of patients had more than 0 RBC/hpf on urine microscopic examination (Bove, 1999). In addition, 94.5% have hematuria if screened with microscopy plus urine dipstick testing (Press, 1995).

• Degree of hematuria is not predictive of stone size or likelihood of passage.

• No literature exists to support the theory that ureterolithiasis without hematuria is indicative of complete ureteral obstruction.

• Pyuria (>5 WBC/hpf on a centrifuged specimen) in a patient with ureterolithiasis should prompt a careful search for signs of infected hydronephrosis. Obtain a complete blood count (CBC), creatinine, and urine culture. Treatment with antibiotics is indicated in patients with ureterolithiasis and pyuria. Admission to the hospital is mandatory if the patient has any signs of infected hydronephrosis (fever, elevated WBC count, elevated creatinine), or if follow-up within 24 hours is not reliably available.

• A urine pH greater than 7 suggests presence of urea-splitting organisms, such as Proteus, Pseudomonas, or Klebsiella species, and struvite stones.

• A urine pH less than 5 suggests uric acid stones.

• Electrolytes

• Serum creatinine level is the major predictor of contrast-induced nephrotoxicity.

• If creatinine level is greater than 2 mg/dL, use diagnostic techniques that do not require an infusion of contrast, such as ultrasonography or helical CT scan.

• Hypokalemia and decreased serum bicarbonate suggest underlying distal (type 1) renal tubular acidosis, which is associated with formation of calcium phosphate stones.

Imaging Studies:

• Most authors recommend diagnostic imaging to confirm the diagnosis in first-time episodes of ureterolithiasis, when the diagnosis is unclear, or if associated proximal UTI is suspected.

• Kidney, ureter, and bladder (KUB) radiograph

• Multiple studies show that the KUB has low sensitivity and specificity for the presence of ureterolithiasis and adds nothing to the emergent clinical impression. At follow-up, the urologist may find the KUB to be helpful in determining the exact size and shape of the stone, in establishing a baseline for follow-up studies, and for visualization of the surgical orientation.

• KUB can be used to monitor passage of a previously documented opaque stone.

• Computed tomography (CT): CT scan has been thought historically to play no role in diagnosis of ureterolithiasis because of the need for many cuts to define stones as small as 1-2 mm in diameter. Since 1996, helical CT scanners have been able to acquire images with greatly reduced examination time and with little motion artifact. Noncontrast helical CT has become the criterion standard imaging study in the ED diagnosis of ureterolithiasis (see Image 1).

• Numerous studies have demonstrated that CT has a sensitivity of 95-100% and superior specificity and accuracy compared with the historic criterion standard, intravenous pyelogram (IVP).

• Other advantages of helical CT include rapid ( <5 min) acquisition time, avoidance of intravenous (IV) contrast, and potential for diagnosis of other pathology including AAA, pancreatitis, appendicitis, ovarian disorders, diverticular disease, and biliary tract disorders. The cost of the study varies among institutions and averages approximately $619.

• Principal disadvantages are that helical CT gives no information on renal function or degree of urinary obstruction.

• Indinavir stones are not visualized well by helical CT scan.

• Intravenous pyelogram: Prior to the advent of helical CT, IVP was the test of choice in diagnosing ureterolithiasis. IVP is widely available and fairly inexpensive ($486, varies among institutions) but less sensitive than noncontrast helical CT. IVP remains the test of choice in patients with suspected indinavir stones.

• Contrast is administered intravenously at a dose of 1 mL/kg, and KUB films are taken immediately and at 1, 5, 10, and 15 minutes until contrast fills both distal ureters (see Image 2). Look for direct visualization of stone within the ureter, unilateral ureteral dilation, delayed appearance of the nephrogram phase, lack of normal peristalsis pattern of the ureter, or perirenal contrast extravasation. Degree of obstruction is graded based on delay in appearance of the nephrogram.

• Anaphylaxis to ionic contrast agents (eg, Renografin, Conray) occurs in 1-2 patients per 1000 IVP studies. Risk of recurrence is approximately 15% if reexposed to ionic agents but falls to 5% when nonionic agents are used. Risk of anaphylaxis can be reduced further by pretreatment with a combination of H1- and H2-blockers and steroids, but studies showing the benefit of pretreatment began pretreatment more than 12 hours prior to study. Risk of nephrotoxicity is not clearly reduced with use of nonionic agents. Indications for use of nonionic contrast agents vary among institutions but consistently include history of prior mild to moderately severe reaction to ionic contrast, asthma, multiple allergies, or severe cardiac disease.

• Disadvantages of IVP include radiation exposure and risk of nephrotoxicity or anaphylactoid reaction to contrast agent. IVP is relatively contraindicated in pregnant or dehydrated patients or if serum creatinine level exceeds 2 mg/dL. IVP is absolutely contraindicated in patients with a history of severe contrast-induced anaphylaxis. False-negative results usually occur with stones located at the ureterovesical junction.

• Ultrasonography: This is a good imaging modality in patients who are pregnant or to rule out the presence of an AAA in patients older than 60 years with a first or atypical presentation of nephrolithiasis.

• A handful of small studies have found sensitivities of 65-100% (see Images 3-4). Ultrasonography has been found to be less accurate in diagnosis of ureteral stones than IVP or helical CT. Diagnostic criteria include direct visualization of the stone, hydroureter more than 6 mm in diameter, and perirenal urinoma suggesting calyceal rupture. The cost is approximately $440.

• Advantages include lack of radiation exposure and ability to complete the study at the bedside in patients who are potentially in unstable condition.

• Disadvantages include inferior sensitivity, lack of universal availability, dependence on operator expertise, and inability to accurately estimate the degree of urinary obstruction.

• A urine-filled bladder provides an excellent acoustic window for ultrasound imaging; sonograms occasionally may demonstrate a stone at the ureterovesical junction that is not seen on helical CT or IVP.

• Future studies may utilize 2-dimensional ultrasonography in combination with color Doppler analysis of the ureteral jets to enhance sensitivity of ultrasonography in patients with ureteral colic.

• Magnetic resonance imaging: MRI can be used to detect ureteral stones. One study of 40 consecutive patients with acute flank pain found sensitivity of 54-58% and specificity of 100% using breath-hold heavily T2-weighted sequences (Sudah, 2001). Sensitivity and specificity increased to 96.2-100% and 100%, respectively, using gadolinium-enhanced 3-D FLASH MR urography. Although MRI does not play a major role in the diagnosis of ureteral stones, lack of radiation makes MRI a good choice in pregnant women who have nondiagnostic findings from a sonogram.

Procedures:

• Occasionally, a patient may require urinary catheterization to relieve retention due to extreme pain or an obstructing bladder neck stone.

TREATMENT

Section 6 of 12

Emergency Department Care:

• Intravenous access should be obtained to facilitate delivery of analgesic and antiemetic medications.

• Intravenous hydration is controversial.

• Some authorities believe that intravenous fluids hasten passage of the stone through the urogenital system. Others express concern that additional hydrostatic pressure exacerbates the pain of renal colic.

• No data exist to support either theory. Intravenous hydration should be given to patients with clinical signs of dehydration or to those with a borderline serum creatinine level who must undergo IVP.

• Analgesia should be provided promptly.

• The pain of renal colic is mediated by prostaglandin E2. Nonsteroidal anti-inflammatory drugs inhibit formation of this mediator, and ketorolac (the only parenteral NSAID approved by the FDA) has been proven in multiple studies to be as effective as opioid analgesics, with fewer adverse effects.

• Opioid analgesics can be added in cases of incomplete pain control.

• Antiemetics should be administered as needed.

• Medical expulsive therapy

• Multiple prospective randomized controlled studies (Dellabella, 2003; Dellabella, 2005; Porpiglia, 2004) have demonstrated that patients treated with oral alpha-blockers have an increased rate of spontaneous stone passage and a decreased time to stone passage. The best studied of these is tamsulosin, 0.4 mg administered daily.

• Calcium channel blockers in combination with oral steroids have also proven efficacious in multiple studies. The most common regimen is 30-mg slow-release nifedipine daily plus oral corticosteroid such as prednisolone.

• Strain urine for stone collection.

Consultations:

• Consult a urologist immediately in cases of ureterolithiasis with proximal UTI. Infected hydronephrosis is a true urologic emergency and requires hospital admission, intravenous antibiotics, and immediate drainage of the infected hydronephrosis via percutaneous nephrostomy or ureteral stent placement.

• Urologic consultation is also appropriate in patients who are unable to tolerate oral fluids and medications and in those with unrelenting pain, renal failure, renal transplant, a solitary functioning kidney, and history of prior stones that required invasive intervention.

MEDICATION

Section 7 of 12

Pain of renal colic is mediated locally primarily by prostaglandin E2. Ureteral obstruction stimulates synthesis of prostaglandin E2 in the renal medulla, which increases ureteral contractility and renal blood flow, leading to increased ureteral pressures and painful renal colic.

Drug Category: Narcotic analgesics -- These agents act at the CNS mu receptors and are the standard of care for treatment of renal colic. They are inexpensive and proven effective. Disadvantages include sedation, respiratory depression, smooth muscle spasm, and potential for abuse and addiction.

Drug Name	Butorphanol (Stadol) -- Mixed agonist-antagonist narcotic with central analgesic effects for moderately severe to severe pain. Causes less smooth muscle spasm and respiratory depression than morphine or meperidine. Weigh these advantages against increased cost of butorphanol.
Adult Dose	0.5-2.9 mg IV q3-4h prn 1-4 mg IM q3-4h prn
Pediatric Dose	Not established
Contraindications	Documented hypersensitivity
Interactions	Guanabenz, MAOIs, CNS depressants, phenothiazines, barbiturates, and skeletal muscle relaxants increase toxicity
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Caution in hepatic or renal insufficiency, respiratory limitations (bronchial asthma, obstructive respiratory conditions, cyanosis); may increase CSF pressure and cardiac overload; causes respiratory depression

Drug Category: Nonsteroidal anti-inflammatory drugs (NSAIDs) -- These agents inhibit synthesis of prostaglandin E2 and are at least as effective as narcotic analgesics in numerous randomized controlled trials. NSAIDs cause less nausea and less sedation than narcotic analgesics, do not cause respiratory depression, and have no abuse potential. Principal disadvantage is cost. Potential adverse effects on renal function, GI mucosa, and platelet aggregation do not appear clinically important when used for short-term pain relief.

Drug Name	Ketorolac (Toradol) -- Inhibits prostaglandin synthesis by decreasing activity of enzyme cyclooxygenase, which, in turn, decreases formation of prostaglandin precursors. Only NSAID approved for IV or IM use in adults in United States. Single IM dose of 30 mg provides pain relief comparable to meperidine 100 mg IM with fewer adverse effects. Also can be administered IV. Onset of analgesic action is evident within 10 min of IM administration. Efficacy of PO formulation for outpatient treatment of renal colic has not yet been studied.
Adult Dose	30-60 mg IM initial, followed by 15-30 mg q6h prn; not to exceed 5 d of treatment
Pediatric Dose	Not established
Contraindications	Documented hypersensitivity; peptic ulcer disease; recent GI bleeding or perforation; renal insufficiency; high risk of bleeding Do not administer into CNS
Interactions	Aspirin increases risk of inducing serious NSAID-related adverse effects; probenecid may increase concentrations and, possibly, toxicity; may decrease effects of hydralazine, captopril, and beta-blockers; may decrease diuretic effects of furosemide and thiazides; may increase PT in patients taking anticoagulants—monitor PT closely and instruct patients to watch for signs of bleeding; may increase risk of methotrexate toxicity; may increase phenytoin levels
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Category D in third trimester of pregnancy; acute renal insufficiency, hyperkalemia, hyponatremia, interstitial nephritis, and renal papillary necrosis may occur; increases risk of acute renal failure in patients with preexisting renal disease or compromised renal perfusion; low WBC counts (rare) usually return to normal during ongoing therapy; discontinue therapy if persistent leukopenia, granulocytopenia, or thrombocytopenia occur

Drug Category: Antiemetics -- Patients with acute renal colic frequently experience intense nausea and/or vomiting. Effective pain control often is accompanied by resolution of nausea and vomiting, but some patients may require antiemetics in addition to analgesics. Various antiemetic medications are used, including phenothiazines and butyrophenones.

Drug Name	Metoclopramide (Reglan) -- Only antiemetic that has been studied specifically in treatment of renal colic. In 2 small double-blinded studies, provided relief of nausea and pain relief equal to that of narcotic analgesics. Antiemetic effect due to blockade of dopaminergic receptors in chemoreceptor trigger zone in CNS. Does not possess antipsychotic or tranquilizing activity and is less sedating than other central dopamine antagonists. Onset of action is 1-3 min after IV injection and 10-15 min after IM injection.
Adult Dose	10 mg IV/IM; repeat q4-6h prn
Pediatric Dose	0.1-0.2 mg IV; repeat q6-8h prn
Contraindications	Documented hypersensitivity; pheochromocytoma; GI hemorrhage, obstruction, or perforation; history of seizure disorders
Interactions	Accelerated gastric emptying may increase rate or extent of absorption of drugs such as acetaminophen, aspirin, diazepam, lithium, and tetracycline; as a central dopamine antagonist, may diminish effectiveness of dopamine agonists such as amantadine, bromocriptine, levodopa, or pergolide
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Caution in history of mental illness or Parkinson disease; children and adolescents more likely to experience extrapyramidal side effects; elderly persons more likely to experience drowsiness

Drug Category: Antibiotics -- Infected hydronephrosis mandates IV antibiotic therapy in addition to urgent drainage via percutaneous nephrostomy or urethral stent placement. Aerobic gram-negative enteric organisms, including E coli and Klebsiella, Proteus, Enterobacter, and Citrobacter species, are typical pathogens. Enterococcal infection occasionally is seen in patients recently on antibiotics. Candida albicans sometimes is responsible in diabetic or immunosuppressed patients. Initial empiric antibiotic therapy should cover common bacterial pathogens.

Drug Name	Ampicillin (Omnipen) plus gentamicin (Garamycin) -- Ampicillin is beta-lactam aminopenicillin antibiotic. Non–penicillinase-producing staphylococci and most streptococci are susceptible. Ampicillin is effective against E coli and Proteus and Enterococcus species, but most Klebsiella, Serratia, Acinetobacter, indole-positive Proteus, and Pseudomonas species and Bacteroides fragilis are resistant. Gentamicin is aminoglycoside antibiotic, which is active against Staphylococcus aureus and Enterobacteriaceae organisms including E coli and Proteus, Klebsiella, Serratia, Enterobacter, and Citrobacter species. Pseudomonas aeruginosa is usually sensitive, although its sensitivity varies somewhat. When used in combination with ampicillin, gentamicin also effective against Enterococcus faecalis.
Adult Dose	Ampicillin: 150-200 mg/kg/d IV in equally divided doses q3-4h; dosages can be increased, but not to exceed 14 g/d Gentamicin (patients with normal renal function): 3-6 mg/kg/d IV administered in 2-3 divided doses; monitor at least a trough level drawn on third or fourth dose (0.5 h before dosing); may draw peak level 0.5 h after 30-min infusion
Pediatric Dose	Ampicillin: 100-200 mg/kg/d IV in equally divided doses q4-6h; not to exceed 12 g/d Gentamicin: 2.5 mg/kg IV q8h
Contraindications	Documented hypersensitivity; non–dialysis-dependent renal insufficiency
Interactions	Ampicillin - Probenecid and disulfiram elevate ampicillin levels; allopurinol decreases ampicillin effects and has additive effects on ampicillin rash; may decrease effects of oral contraceptives Gentamicin - Other aminoglycosides, cephalosporins, penicillins, and amphotericin B may increase nephrotoxicity; enhances effects of neuromuscular blocking agents, thus prolonged respiratory depression may occur; loop diuretics may increase auditory toxicity of aminoglycosides—irreversible hearing loss of varying degrees may occur (monitor regularly)
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Narrow therapeutic index (not intended for long-term therapy); caution in renal failure (not on dialysis), myasthenia gravis, hypocalcemia, and conditions that depress neuromuscular transmission; adjust dose in renal impairment; evaluate rash and differentiate from hypersensitivity reaction; patients who develop diarrhea during or after therapy should be evaluated for pseudomembranous colitis; ampicillin excreted via kidneys, and dosing interval should be adjusted as follows: CrCl <50 mL/min: Adjust dosing interval CrCl 10-50 mL/min: Extend dosing interval to q6-12h CrCl <10 mL/min: Extend dosing interval to q12-16h Gentamicin also excreted via kidneys, and following reduction in dose and dosing frequency necessary in patients with renal insufficiency: CrCl >70 mL/min: Multiply maintenance dose by 0.85 and administer IV q8-12h CrCl 50-69 mL/min: Multiply maintenance dose by 0.85 and administer IV q12h CrCl 25-49 mL/min: Multiply maintenance dose by 0.85 and administer IV q24h CrCl <25 mL/min: Multiply maintenance dose by 0.85 and administer IV

Drug Name	Ticarcillin and clavulanic acid (Timentin) -- Ticarcillin is extended-spectrum penicillin, beta-lactam antibiotic. Clavulanic acid is beta-lactamase inhibitor that, in combination with ticarcillin, extends spectrum of ticarcillin to include many beta-lactamase–producing bacteria. Timentin active against most staphylococci and streptococci and gram-negative organisms including E coli, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Neisseria gonorrhoeae, and Pseudomonas and Providencia species. Anaerobic spectrum includes Peptococcus and Peptostreptococcus species, Clostridium perfringens, Clostridium tetani, and Bacteroides species, including many strains of B fragilis. Timentin not effective against Enterococcus species or methicillin-resistant staphylococci. Timentin excreted via urinary tract.
Adult Dose	<60 kg: 200-300 mg/kg/d (based on ticarcillin content) IV divided q4-6h >60 kg: 3.1g IV infused over 30 min q4-6h Hemodialysis: 2 g IV q12h supplemented with 3.1 g after each dialysis session
Pediatric Dose	200-300 mg/kg/d (based on ticarcillin content) IV in divided doses q6h; not to exceed 18-24 g/d
Contraindications	Documented hypersensitivity; severe pneumonia; bacteremia; pericarditis; emphysema; meningitis Purulent or septic arthritis should not be treated with oral penicillin during acute stage
Interactions	Tetracyclines may decrease effects; high concentrations may physically inactivate aminoglycosides if administered in same IV line; synergistic effects with aminoglycosides; probenecid may increase levels; can inhibit renal tubular excretion of methotrexate—do not coadminister
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Perform CBCs prior to initiation of therapy and at least weekly during therapy; monitor for liver function abnormalities by measuring AST and ALT during therapy; caution in patients with hepatic insufficiencies; perform urinalysis and BUN and creatinine determinations during therapy and adjust dose if values become elevated; monitor blood levels to avoid possible neurotoxic reactions; may cause pseudomembranous colitis; after loading dose of 3.1 g, administer maintenance dose using renal function kinetics as follows: CrCl >60 mL/min: No dosage adjustment needed CrCl 30-60 mL/min: 2 g IV q4h CrCl 10-30 mL/min: 2 g IV q8h CrCl <10 mL/min: 2 g IV q12h CrCl <10 mL/min with hepatic failure: 2 g IV q24h

Drug Name	Ciprofloxacin (Cipro) -- Reasonable alternative for treating infected hydronephrosis in penicillin-allergic patients. Fluoroquinolones active against aerobic gram-negative organisms and generally effective against aerobic gram-positive organisms, though some resistance has been noted in S aureus and Streptococcus pneumoniae. Not effective against anaerobes. Variably effective against E faecalis, though ampicillin and gentamicin likely to be more effective.
Adult Dose	400 mg IV q8-12h
Pediatric Dose	<18 years: Not recommended; if quinolone therapy clearly indicated, may be used in dose of 15-20 mg/kg/d IV divided q12h >18 years: Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	Antacids, iron salts, and zinc salts may reduce serum levels; administer antacids 2-4 h before or after; cimetidine may interfere with metabolism; reduces therapeutic effects of phenytoin; probenecid may increase serum concentrations; may increase toxicity of theophylline, caffeine, cyclosporine, and digoxin (monitor digoxin levels); may increase effects of anticoagulants (monitor PT)
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	In prolonged therapy, perform periodic evaluations of organ system functions (eg, renal, hepatic, hematopoietic); adjust dose in renal function impairment; superinfections may occur with prolonged or repeated antibiotic therapy; associated with tendon rupture and should be discontinued in any patient who develops tendonitis; may lower seizure threshold and should be used cautiously in patients with seizures or cerebral atherosclerotic disease

Drug Name	Levofloxacin (Levaquin) -- Reasonable alternative for treating infected hydronephrosis in penicillin-allergic patients. Fluoroquinolones active against aerobic gram-negative organisms and generally effective against aerobic gram-positive organisms, though some resistance has been noted in S aureus and S pneumoniae. Not effective against anaerobes. Variably effective against E faecalis, though ampicillin and gentamicin likely to be more effective.
Adult Dose	250 mg IV over 60 min qd for 10 d
Pediatric Dose	<18 years: Not recommended >18 years: Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	Antacids, iron salts, and zinc salts may reduce serum levels; administer antacids 2-4 h before or after; cimetidine may interfere with metabolism; reduces therapeutic effects of phenytoin; probenecid may increase serum concentrations; may increase toxicity of theophylline, caffeine, cyclosporine, and digoxin (monitor digoxin levels); may increase effects of anticoagulants (monitor PT)
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	In prolonged therapy, perform periodic evaluations of organ system functions (eg, renal, hepatic, hematopoietic); adjust dose in renal function impairment; superinfections may occur with prolonged or repeated antibiotic therapy; associated with tendon rupture and should be discontinued in any patient who develops tendonitis; may lower seizure threshold and should be used cautiously in patients with seizures or cerebral atherosclerotic disease

Drug Name	Ofloxacin (Floxin) -- Reasonable alternative for treating infected hydronephrosis in penicillin-allergic patients. Active against aerobic gram-negative organisms and generally effective against aerobic gram-positive organisms, though some resistance has been noted in S aureus and S pneumoniae. Not effective against anaerobes. Variably effective against E faecalis, though ampicillin and gentamicin likely to be more effective.
Adult Dose	200 mg IV over 60 min q12h
Pediatric Dose	<18 years: Not recommended >18 years: Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	Antacids, iron salts, and zinc salts may reduce serum levels; administer antacids 2-4 h before or after taking; cimetidine may interfere with metabolism; reduces therapeutic effects of phenytoin; probenecid may increase serum concentrations; may increase toxicity of theophylline, caffeine, cyclosporine, and digoxin (monitor digoxin levels); may increase effects of anticoagulants (monitor PT)
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	In prolonged therapy, perform periodic evaluations of organ system functions (eg, renal, hepatic, hematopoietic); adjust dose in renal function impairment; superinfections may occur with prolonged or repeated antibiotic therapy; associated with tendon rupture and should be discontinued in any patient who develops tendonitis; may lower seizure threshold and should be used cautiously in patients with seizures or cerebral atherosclerotic disease

Drug Category: Corticosteroids -- These agents are strong anti-inflammatory drugs that reduce ureteral inflammation. They also have profound metabolic and immunosuppressive effects.

Drug Name	Prednisolone (Econopred, Pediapred, Delta-Cortef, Articulose-50, AK-Pred) -- In combination with nifedipine or tamsulosin, proven to facilitate spontaneous passage of a ureteral stone in several small prospective studies. Only a short course of therapy (5-10 d) should be administered.
Adult Dose	25 mg PO qd
Pediatric Dose	0.1-2 mg/kg/d PO qd
Contraindications	Documented hypersensitivity; viral, fungal, tubercular skin, and connective tissue infections; peptic ulcer disease; hepatic dysfunction; GI disease
Interactions	Decreases effects of salicylates and toxoids (for immunizations); phenytoin, carbamazepine, barbiturates, and rifampin decrease effects of corticosteroids
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Caution in hyperthyroidism, osteoporosis, cirrhosis, nonspecific ulcerative colitis, peptic ulcer, diabetes, and myasthenia gravis

Drug Category: Calcium channel blockers -- These agents are smooth muscle relaxants that, in combination with prednisolone, facilitate ureteral stone passage in several small prospective studies.

Drug Name	Nifedipine (Procardia) -- Sustained-release (SR) formulation simplifies treatment and encourages compliance. Only short-term therapy (5-10 d) should be considered for this indication.
Adult Dose	30 mg SR PO qd
Pediatric Dose	Not established
Contraindications	Documented hypersensitivity
Interactions	Caution with coadministration of any agent that can lower BP, including beta-blockers and opioids; H2 blockers (cimetidine) may increase toxicity
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	May cause lower extremity edema; allergic hepatitis has occurred (rare)

Drug Category: Alpha-adrenergic blockers -- These agents promote smooth muscle relaxation and, in combination with prednisolone, facilitate spontaneous passage of a ureteral stone.

Drug Name	Tamsulosin (Flomax) -- Alpha-adrenergic blocker specifically targeted to alpha1-receptors. Has advantage of relatively less orthostatic hypotension and requires no gradual up-titration from initial introductory dosage. Inhibits postsynaptic alpha-adrenergic receptors, resulting in vasodilation of veins and arterioles and decrease in total peripheral resistance and blood pressure. Improves irritative and obstructive voiding symptoms. Only short-term therapy (5-10 d) should be considered for this indication.
Adult Dose	0.4 mg PO qd
Pediatric Dose	Not established
Contraindications	Documented hypersensitivity
Interactions	Cimetidine may significantly increase plasma concentrations; may increase toxicity of warfarin
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Not for use as antihypertensive drug; may cause orthostasis; avoid situations that may result in injuries if syncope occurs; exclude presence of carcinoma or cancer before initiating treatment; adverse effects include increased rate of retrograde ejaculation and rhinitis

FOLLOW-UP

Section 8 of 12

Further Inpatient Care:

• Admission rate for patients with acute renal colic is approximately 20%. Three absolute indications for admission are (1) infected hydronephrosis (2) unrelenting pain or vomiting despite analgesics and antiemetics, and (3) dehydration.

• Infected hydronephrosis is defined as UTI proximal to an obstructing stone. Infected hydronephrosis mandates admission for antibiotics and prompt drainage. Midstream urine culture and sensitivity was a poor predictor of infected hydronephrosis in one series, and findings were positive for hydronephrosis in only 30% of cases.

• The clinical presentation of infected hydronephrosis is variable. Pyuria (>5 WBC/hpf) is almost always present but not diagnostic of proximal infection. In one small series of 23 patients with infected hydronephrosis, the temperature was higher than 38°C in 15 patients, the peripheral WBC count was more than 10 X 10⁹/L in 13 patients, and the creatinine level was greater than 1.3 mg/dL in 12 patients (St Lezin, 1992). Renal ultrasonography or helical CT may distinguish pyonephrosis from simple hydronephrosis by demonstrating a fluid-fluid level in the renal pelvis (urine on top of purulent debris). In 2 small studies, the ultrasonographic sensitivity for pyonephrosis was found to be 62-67%. CT sensitivity for pyonephrosis has not been reliably determined (Jeffrey, 1985; Schneider, 1989). The emergency physician must maintain a high index of suspicion. Antibiotics should cover E coli and Staphylococcus, Enterobacter, Proteus, and Klebsiella species.

• Patients with complete obstruction, perinephric urine extravasation, a solitary kidney, renal transplant, renal failure, or pregnancy, and those with a poor social support system, also should be considered for admission, especially if rapid urologic follow-up is not reliably available.

• A stone less than 4 mm in diameter has an 80% chance of spontaneous passage; this falls to 20% for stones larger than 8 mm in diameter. The urologist may choose to admit a patient with a ureteral stone larger than 6 mm because of low likelihood of spontaneous passage.

• About 15-20% of patients require invasive intervention due to stone size, continued obstruction, infection, or intractable pain. Several techniques are available to the urologist when the stone fails to pass spontaneously.

• Extracorporeal shock wave lithotripsy (ESWL) utilizes an underwater energy wave focused on the stone to shatter it into passable fragments. Approximately 70% of stones can be treated with ESWL alone. This technique is especially suitable for stones that are smaller than 2.5 cm and lodged above the iliac crest. Anesthesia or sedation is required. ESWL is contraindicated in pregnancy, untreatable bleeding disorders, patients weighing more than 300 lb, tightly impacted or cystine stones, or in cases of ureteral obstruction distal to the stone.

• Ureteroscopy is especially suitable for removal of stones lodged below the iliac crest. Stones smaller than 5 mm in diameter generally are retrieved using a stone basket, while tightly impacted stones or those larger than 5 mm are manipulated proximally for ESWL or are fragmented using an endoscopic direct-contact fragmentation device.

• Percutaneous nephrolithotomy involves entering the renal pelvis percutaneously using the Seldinger technique after ultrasonography or fluoroscopic localization. Renal calyces, pelvis, and proximal ureter can be examined and stones extracted with or without prior fragmentation. This technique is especially useful for stones larger than 2.5 cm in diameter, hard or cystine stones, staghorn calculi, lower calyceal stones, stones associated with obstruction, or in cases of ESWL failure or contraindication. A percutaneous nephrostomy can be used as an emergency procedure to relieve obstruction in a high-risk patient in whom other treatments are not feasible.

• Open nephrostomy rarely is used since the development of ESWL and endoscopic and percutaneous techniques. Open nephrostomy now constitutes only 1-2% of all interventions. Disadvantages include longer hospitalization, longer convalescence, and increased requirements for blood transfusion.

Further Outpatient Care:

• Patients who do not meet admission criteria may be discharged from the ED in anticipation that the stone will pass spontaneously at home.

• Arrange for follow-up with a urologist in 2-3 days. Patients should be told to return immediately for fever, uncontrolled pain, or vomiting.

• Patients should be discharged with a urine strainer and encouraged to submit any recovered calculi to a urologist for chemical analysis.

• Follow-up for patients with first-time incidence of stones should consist of stone analysis and abbreviated metabolic evaluation to rule out hyperparathyroidism, renal tubular acidosis, and chronic infection with urea-splitting bacteria.

• Patients with recurrent ureterolithiasis should undergo a more thorough metabolic evaluation. Patients with recurrent stones who undergo thorough metabolic evaluation and specific therapy enjoy a remission rate in excess of 80% and can decrease the rate of stone formation by 90%. A stone chemical analysis together with serum and appropriate 24-hour urine metabolic tests can identify the etiology in more than 95% of patients. A typical 24-hour urine determination should include urinary volume, pH, specific gravity, calcium, citrate, magnesium, oxalate, phosphate, and uric acid. Most common findings are hypercalciuria, hyperuricosuria, hyperoxaluria, hypocitraturia, and low urinary volume. Therefore, the emergency physician should encourage urologic follow-up.

In/Out Patient Meds:

• Discharge on an oral analgesic and an antiemetic if needed. No studies exist that demonstrate superiority of one oral analgesic over another. Typical choices include agents such as hydrocodone, oxycodone, meperidine, or oral anti-inflammatory agents.

• Medical therapies to aid in passage of a stone have been studied. A handful of small, randomized controlled prospective studies show that outpatient treatment with sustained-release nifedipine 30 mg/d plus prednisolone 25 mg/d or tamsulosin 0.4 mg/d plus prednisolone decreases the time to spontaneous passage of the stone; increases the overall spontaneous expulsion rate; and decreases the need for analgesics, hospitalization, and endoscopic intervention (Dellabella, 2003; Dellabella, 2005; Porpiglia, 2004).

Deterrence/Prevention:

• Patients with recurrent nephrolithiasis traditionally have been instructed to drink 8 glasses of fluid daily to maintain adequate hydration and decrease chance of urinary supersaturation with stone-forming salts.

• Recent prospective studies suggest that daily consumption of coffee, tea, beer, or wine decreases risk of stone formation, while daily consumption of apple or grapefruit juice increases risk of stone formation (Finkielstein, 2006).

Complications:

• Infected hydronephrosis is the most deadly complication because the presence of infection adjacent to the highly vascular renal parenchyma places the patient at risk for rapidly progressive sepsis and death.

• Calyceal rupture with perinephric urine extravasation due to high intracaliceal pressures occasionally is seen and usually is treated conservatively.

• Complete ureteral obstruction may occur in patients with tightly impacted stones. This is best diagnosed via IVP and is not discernible on noncontrast CT scan. Patients with 2 healthy kidneys can tolerate several days of complete unilateral ureteral obstruction without long-term effects on the obstructed kidney. If a patient with complete obstruction is well hydrated and pain and vomiting are well controlled, the patient can be discharged from the ED with urologic follow-up within 1-2 days.

Prognosis:

• Approximately 80% of ureteral stones pass spontaneously without hospitalization or invasive intervention.

• Approximately 20% of patients require hospitalization due to dehydration, continued pain or vomiting, or inability to pass the stone spontaneously.

• Recurrence rates after an initial episode of ureterolithiasis are 14%, 35%, and 52% at 1, 5, and 10 years, respectively. Risk of recurrence can be reduced drastically by specific medical therapy based on analysis of the stone and serum and urine metabolic profiles.

Patient Education:

• For excellent patient education resources, visit eMedicine's Kidneys and Urinary System Center. Also, see eMedicine's patient education articles Blood in the Urine and Kidney Stones.

MISCELLANEOUS

Section 9 of 12

Medical/Legal Pitfalls:

• Failure to diagnose or delay in diagnosing symptomatic AAA: Pain of a leaking abdominal aortic aneurysm often is misdiagnosed initially as renal colic.

• In one series of 134 patients with symptomatic AAA presenting to the ED, the following statistics were reported (Borrero, 1988):

• Eighteen percent had an initial misdiagnosis of nephrolithiasis.

• All were older than 60 years of age and none had a prior history of renal calculi.

• Eighty percent had a pulsatile mass noted by at least one examiner.

• Forty-three percent had microhematuria on urinalysis.

• Delay of diagnosis of AAA in the ED was associated with higher mortality and morbidity rates than in the group who received the correct diagnosis promptly.

• Failure to diagnose UTI proximal to a ureteral stone and to seek urgent urologic intervention in these patients

TEST QUESTIONS

Section 10 of 12

CME Question 1: A 40-year-old woman presents with severe flank pain and vomiting. A catheterized urine specimen shows 50-100 RBC, 30-40 WBC, and a few bacteria. Intravenous pyelogram (IVP) reveals a 2-mm stone in the area of the right ureterovesical junction with mild right hydronephrosis. Upon returning to the ED, repeat vital signs reveal a temperature of 101°F. What is the most critical treatment for this patient?

A: Admit for intravenous antibiotics in addition to analgesics.
B: If pain and vomiting are well controlled in the ED, send a urine culture and discharge on oral antibiotics and analgesics.
C: Obtain a CBC and consult a urologist if the WBC count is elevated.
D: Consult a urologist and recommend immediate drainage of suspected infected hydronephrosis.
E: Admit for serial creatinine measurements and observe for other signs of adverse reaction to ionic contrast.

The correct answer is D: In patients with ureterolithiasis and fever, the ED physician should suspect infected hydronephrosis, pyonephrosis, or a perinephric abscess, all of which mandate admission and urgent drainage. A normal WBC count does not exclude the possibility of proximal infection.

CME Question 2: In patients older than 60 years who present with flank pain suggestive of a first-time kidney stone, what is the first priority?

A: Ensure adequate pain control and be sure creatinine level is less than 2 mg/dL before allowing the patient to undergo intravenous pyelogram.
B: Consider the possibility of abdominal aortic aneurysm and rule out this diagnosis before pursuing the diagnosis of ureterolithiasis.
C: Obtain urinalysis and proceed with evaluation for ureterolithiasis if hematuria is present.
D: Intravenous pyelogram is relatively contraindicated in elderly patients; choose an alternate diagnostic imaging test.
E: Involve a urologist immediately, since all elderly patients with nephrolithiasis should be admitted to the hospital.

The correct answer is B: Nephrolithiasis typically begins in the third and fourth decade. Elderly patients with flank pain and no history of stones should be evaluated first for the presence of abdominal aortic aneurysm, regardless of the presence of hematuria. Intravenous pyelogram is not contraindicated in elderly patients.

Pearl Question 1 (T/F): Patients with infected hydronephrosis are best managed by obtaining urine culture, starting oral antibiotics, and ensuring close urologic follow-up.

The correct answer is False: Infected hydronephrosis is a urologic emergency and must be treated with immediate intravenous antibiotics and drainage of the infected hydronephrosis.

Pearl Question 2 (T/F): Urine pH greater than 7 in a patient with nephrolithiasis is suggestive of chronic urinary tract infection with urea-splitting organisms.

The correct answer is True: Urinary tract infection with urea-splitting organisms such as Proteus, Pseudomonas, or Klebsiella species are associated with urinary pH greater than 7.

Pearl Question 3 (T/F): Prior anaphylactoid reaction to intravenous contrast material is the best predictor of contrast-associated nephropathy.

The correct answer is False: Elevated serum creatinine level is the best predictor of contrast-associated nephropathy.

Pearl Question 4 (T/F): In patients with acute ureterolithiasis, absence of hematuria suggests complete ureteral obstruction.

The correct answer is False: Approximately 5-15% of all patients with acute ureterolithiasis have no hematuria on dipstick and microscopic examination of the urine. Absence of hematuria has not been shown to be evidence of complete ureteral obstruction.

PICTURES

Section 11 of 12

Caption: Picture 1. Noncontrast helical CT scan of the abdomen demonstrating a stone at the right ureterovesical junction.
	View Full Size Image
	eMedicine Zoom View (Interactive!)
Picture Type: CT
Caption: Picture 2. Intravenous pyelogram (IVP) demonstrating dilation of the right renal collecting system and right ureter consistent with right ureterovesical stone.
	View Full Size Image
	eMedicine Zoom View (Interactive!)
Picture Type: X-RAY
Caption: Picture 3. Renal sonogram showing a dilated renal collecting system consistent with ureteral obstruction.
	View Full Size Image
	eMedicine Zoom View (Interactive!)
Picture Type: Image
Caption: Picture 4. Transabdominal sonogram revealing a ureteral stone at the ureterovesical junction.
	View Full Size Image
	eMedicine Zoom View (Interactive!)
Picture Type: Image

BIBLIOGRAPHY

Section 12 of 12

• Barrett BJ, Parfrey PS, McDonald JR, et al: Nonionic low-osmolality versus ionic high-osmolality contrast material for intravenous use in patients perceived to be at high risk: randomized trial. Radiology 1992 Apr; 183(1): 105-10[Medline].
• Borrero E, Queral LA: Symptomatic abdominal aortic aneurysm misdiagnosed as nephroureterolithiasis. Ann Vasc Surg 1988 Apr; 2(2): 145-9[Medline].
• Boulay I, Holtz P, Foley WD, et al: Ureteral calculi: diagnostic efficacy of helical CT and implications for treatment of patients. AJR Am J Roentgenol 1999 Jun; 172(6): 1485-90[Medline].
• Bove P, Kaplan D, Dalrymple N, et al: Reexamining the value of hematuria testing in patients with acute flank pain. J Urol 1999 Sep; 162(3 Pt 1): 685-7[Medline].
• Catalano O, De Sena G, Nunziata A: The color Doppler US evaluation of the ureteral jet in patients with urinary colic. Radiol Med (Torino) 1998 Jun; 95(6): 614-7[Medline].
• Chandhoke PS: Metabolic abnormalities and the medical management of calcium oxalate nephrolithiasis. Minerva Urol Nefrol 2005 Mar; 57(1): 9-16[Medline].
• Chen MY, Zagoria RJ: Can noncontrast helical computed tomography replace intravenous urography for evaluation of patients with acute urinary tract colic? J Emerg Med 1999 Mar-Apr; 17(2): 299-303[Medline].
• Dellabella M, Milanese G, Muzzonigro G: Efficacy of tamsulosin in the medical management of juxtavesical ureteral stones. J Urol 2003 Dec; 170(6 Pt 1): 2202-5[Medline].
• Dellabella M, Milanese G, Muzzonigro G: Randomized trial of the efficacy of tamsulosin, nifedipine and phloroglucinol in medical expulsive therapy for distal ureteral calculi. J Urol 2005 Jul; 174(1): 167-72[Medline].
• Dretler SP: The physiologic approach to the medical management of stone disease. Urol Clin North Am 1998 Nov; 25(4): 613-23, ix[Medline].
• Erwin BC, Carroll BA, Sommer FG: Renal colic: the role of ultrasound in initial evaluation. Radiology 1984 Jul; 152(1): 147-50[Medline].
• Finkielstein VA, Goldfarb DS: Strategies for preventing calcium oxalate stones. CMAJ 2006 May 9; 174(10): 1407-9[Medline].
• Fultz PJ, Hampton WR, Totterman SM: Computed tomography of pyonephrosis. Abdom Imaging 1993; 18(1): 82-7[Medline].
• Hill MC, Rich JI, Mardiat JG, Finder CA: Sonography vs. excretory urography in acute flank pain. AJR Am J Roentgenol 1985 Jun; 144(6): 1235-8[Medline].
• Jeffrey RB, Laing FC, Wing VW: Sensitivity of sonography in pyonephrosis: a reevaluation. AJR Am J Roentgenol 1985 Jan; 144(1): 71-3[Medline].
• Labrecque M, Dostaler LP, Rousselle R, et al: Efficacy of nonsteroidal anti-inflammatory drugs in the treatment of acute renal colic. A meta-analysis. Arch Intern Med 1994 Jun 27; 154(12): 1381-7[Medline].
• Laing FC, Jeffrey RB Jr, Wing VW: Ultrasound versus excretory urography in evaluating acute flank pain. Radiology 1985 Mar; 154(3): 613-6[Medline].
• Larkin GL, Peacock WF 4th, Pearl SM, et al: Efficacy of ketorolac tromethamine versus meperidine in the ED treatment of acute renal colic. Am J Emerg Med 1999 Jan; 17(1): 6-10[Medline].
• Mariappan P, Loong CW: Midstream urine culture and sensitivity test is a poor predictor of infected urine proximal to the obstructing ureteral stone or infected stones: a prospective clinical study. J Urol 2004 Jun; 171(6 Pt 1): 2142-5[Medline].
• Miller OF, Rineer SK, Reichard SR, et al: Prospective comparison of unenhanced spiral computed tomography and intravenous urogram in the evaluation of acute flank pain. Urology 1998 Dec; 52(6): 982-7[Medline].
• Mutgi A, Williams JW, Nettleman M: Renal colic: utility of the plain abdominal roentgenogram. Arch Intern Med 1991 Aug; 151(8): 1589-92[Medline].
• Pak CY, Resnick MI: Medical therapy and new approaches to management of urolithiasis. Urol Clin North Am 2000 May; 27(2): 243-53[Medline].
• Porpiglia F, Ghignone G, Fiori C, et al: Nifedipine versus tamsulosin for the management of lower ureteral stones. J Urol 2004 Aug; 172(2): 568-71[Medline].
• Press SM, Smith AD: Incidence of negative hematuria in patients with acute urinary lithiasis presenting to the emergency room with flank pain. Urology 1995 May; 45(5): 753-7[Medline].
• Ramakumar S, Segura JW: Renal calculi. Percutaneous management. Urol Clin North Am 2000 Nov; 27(4): 617-22[Medline].
• Ramakumar S, Patterson DE, LeRoy AJ, et al: Prediction of stone composition from plain radiographs: a prospective study. J Endourol 1999 Jul-Aug; 13(6): 397-401[Medline].
• Russinko PJ, Agarwal S, Choi MJ, Kelty PJ: Obstructive nephropathy secondary to sulfasalazine calculi. Urology 2003 Oct; 62(4): 748[Medline].
• Schneider K, Helmig FJ, Eife R: Pyonephrosis in childhood--is ultrasound sufficient for diagnosis?. Pediatr Radiol 1989; 19(5): 302-7[Medline].
• Sinclair D, Wilson S, Toi A, Greenspan L: The evaluation of suspected renal colic: ultrasound scan versus excretory urography. Ann Emerg Med 1989 May; 18(5): 556-9[Medline].
• Smith RC, Verga M, McCarthy S, Rosenfield AT: Diagnosis of acute flank pain: value of unenhanced helical CT. AJR Am J Roentgenol 1996 Jan; 166(1): 97-101[Medline].
• St Lezin M, Hofmann R, Stoller ML: Pyonephrosis: diagnosis and treatment. Br J Urol 1992 Oct; 70(4): 360-3[Medline].
• Sudah M, Vanninen R, Partanen K, et al: MR urography in evaluation of acute flank pain: T2-weighted sequences and gadolinium-enhanced three-dimensional FLASH compared with urography. Fast low-angle shot. AJR Am J Roentgenol 2001 Jan; 176(1): 105-12[Medline].
• Thomas A, Woodard C, Rovner ES, Wein AJ: Urologic complications of nonurologic medications. Urol Clin North Am 2003 Feb; 30(1): 123-31[Medline].
• Whelan C, Schwartz BF: Bilateral guaifenesin ureteral calculi. Urology 2004 Jan; 63(1): 175-6[Medline].
• Wu TT, Lee YH, Tzeng WS, et al: The role of C-reactive protein and erythrocyte sedimentation rate in the diagnosis of infected hydronephrosis and pyonephrosis. J Urol 1994 Jul; 152(1): 26-8[Medline].

eMedicine Journals > Emergency Medicine > Genitourinary > Renal Calculi

Please email us with any comments you have on our new chapter format.

Author Information | Introduction | Clinical | Differentials | Workup | Treatment | Medication | Follow-up | Miscellaneous | Test Questions | Pictures | Bibliography