submitted by Christina Brown, M.D.
- Most common cause of renal colic
- Stone composition:
- 80%: Calcium stones (calcium oxalate > calcium phosphate)
- 5% uric acid
- Others: Magnesium ammonium phosphate (struvite), cystine
- Associated with infections caused by urea-splitting organisms (eg, Pseudomonas, Proteus, Klebsiella) along with an alkalotic urine
- 90% of urinary calculi are radiopaque.
Epidemiology and Etiology
- 1% of the population
- Twice as common in men as women
- Theories on stone formation:
- Urinary supersaturation of solute followed by crystal precipitation
- Decrease in the normal urinary proteins inhibiting crystal growth
- Urinary stasis from a physical anomaly, catheter placement, neurogenic bladder, or the presence of a foreign body
- Rare in children
- When present, indication of an overt metabolic or genetic disorder
- Painless hematuria common presentation (up to 30%)
Causes of stone formation:
- Metabolic abnormalities (50%)
- Urologic abnormalities (20%)
- Infection (15%)
- Sudden onset of severe pain in the costovertebral angle, flank, and/or lateral abdomen
- Colicky or constant pain: Patient cannot find a comfortable position
- Hematuria: Gross hematuria in 1/3 of patients
- Microscopic hematuria present in >80%
- Gross hematuria
- Absent urinary blood in 10–30%
- No correlation between the amount of hematuria and the degree of urinary obstruction
- WBC/bacteria suggests infection
Imaging – CT:
- Helical CT has replaced IV pyelogram (IVP) as test of choice.
- Detects calculi as small as 1 mm in diameter
- Advantages over IVP:
- Performed rapidly
- Does not require IV contrast media
- Detects other non-urologic causes of symptoms, such as abdominal aortic aneurysms (AAAs)
- 1st-time diagnosis
- Persistent pain
- Clinical confusion with pyelonephritis
- unilateral hydronephrosis suggests possible obstructive stone
- no radiation involved, but does not eval for non-urologic causes of symptoms
- Initiate IV crystalloid infusion with 1 L of normal saline infused over 30–60 min followed by 200–500 mL/hr.
- Bolus volume compromised patients with 500-mL increments until urine output adequate
- Analgesics (morphine, ketorolac):
- Combination of IV NSAIDS and opioids decrease ED stay.
- Antiemetics (prochlorperazine, ondansetron, droperidol, hydroxyzine)
- α-Blockers (tamsulosin) or calcium-channel blockers (nifedipine) have been shown to decrease time to spontaneous stone passage:
- Most efficacious for stones <5 mm in diameter
- Tamsulosin and nifedipine equally effective
- prescribe on discharge.
- Obstruction in the presence of infection mandates immediate urologic intervention.
- Intractable pain with refractory nausea and vomiting
- Severe volume depletion
- Urinary extravasation
- Hypercalcemic crisis
- Solitary kidney and complete obstruction
- Relative admission indications (discuss with urologist):
- High-grade obstruction
- Renal insufficiency
- Intrinsic renal disease
- Stones of size <5 mm usually pass spontaneously; those >8 mm rarely do.
- Normal vital signs
- No evidence of concomitant urinary tract infection
- Adequate analgesia
- Able to tolerate PO fluids to maintain hydration status
PEARLS AND PITFALLS
- Do not miss a vascular catastrophe mimicking as renal colic.
- Aggressive pain management and hydration promote passage of stones
- The absence of hematuria does not exclude the diagnosis of acute renal colic.
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2. Hollingsworth J M, Rogers M A, and Kaufman S R et al.: Medical therapy to facilitate stone passage: A meta-analysis. Lancet. 2006; 368:1171–1179.
3. Marx J A, Hockberger R S, and Walls R M: eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 7th ed.St. Louis, MO:Mosby;2009.