Nephrolithiasis (Renal Colic) — ED Evaluation & Treatment

Key Points

• Infection plus an obstructed urinary system is a urologic emergency requiring drainage and antibiotics.
• NSAIDs are first-line analgesia for uncomplicated renal colic when not contraindicated.
• Do not force fluids to accelerate stone passage.
• Noncontrast CT is most sensitive; ultrasound reduces radiation and is preferred in pregnancy.
• Tamsulosin provides the clearest expulsive benefit for selected distal ureteral stones around 5 to 10 mm.
• Stone size and location predict spontaneous passage more reliably than pain intensity.
• A solitary kidney, bilateral obstruction, or rising creatinine lowers the threshold for urgent urologic intervention.
• Recurrent stone formers should receive stone analysis and metabolic prevention evaluation.

Algorithm

1. Assess pain, fever, hemodynamics, urine output, solitary-kidney status, pregnancy, and signs of infection.
2. Obtain urinalysis, creatinine, pregnancy test when relevant, and imaging selected by radiation risk and diagnostic uncertainty.
3. If obstruction with infection or sepsis is present, start antibiotics and arrange emergent decompression.
4. For uncomplicated colic, treat with NSAID-based analgesia and antiemetic therapy.
5. Estimate passage probability from stone size and location and consider tamsulosin for an appropriate distal ureteral stone.
6. Discharge only when pain and nausea are controlled, renal function is acceptable, and follow-up is reliable.
7. Refer for ureteroscopy or lithotripsy when the stone is unlikely to pass, symptoms remain uncontrolled, or obstruction persists.
8. After recovery, analyze the stone and institute recurrence prevention for high-risk or recurrent disease.

Clinical Synopsis & Reasoning

Classic ureteral colic produces sudden severe flank pain radiating toward the groin, with restlessness, nausea, vomiting, and microscopic or gross hematuria. Pain severity does not correlate reliably with stone size or degree of obstruction. Fever, rigors, hypotension, pyuria, or toxic appearance in a patient with obstruction suggests infected hydronephrosis and requires emergency drainage rather than outpatient stone therapy. Examine for abdominal tenderness, peritonitis, testicular or pelvic pathology, and vascular emergencies such as ruptured abdominal aortic aneurysm. Urinalysis assesses hematuria and infection; absence of hematuria does not exclude a stone. Pregnancy testing influences imaging and medication selection. Noncontrast CT identifies stone size, location, hydronephrosis, and alternative diagnoses. Ultrasound can demonstrate hydronephrosis and some stones but is less sensitive for ureteral calculi. Stone size and location predict passage: small distal ureteral stones pass most often, while stones larger than 10 mm are much less likely to pass. Recurrent stone formers need metabolic prevention evaluation rather than repeated episode-only treatment.

Treatment Strategy & Disposition

Use an NSAID such as ketorolac or ibuprofen as first-line analgesia when kidney function, GI bleeding risk, pregnancy status, and allergy permit; add opioid analgesia for refractory pain. Antiemetics support oral tolerance. Alpha-blocker medical expulsive therapy with tamsulosin can be offered for selected ureteral stones, with greatest evidence of benefit for distal stones approximately 5 to 10 mm. Encourage normal hydration but do not force large IV or oral fluid volumes to push a stone because this does not accelerate passage and can worsen pain. Urgent urologic decompression with ureteral stent or percutaneous nephrostomy is required for obstruction plus infection or sepsis. Decompression is also urgent with threatened renal function in a solitary kidney, bilateral obstruction, or other high-risk physiology. Persistent uncontrolled pain or vomiting, worsening kidney function, or a stone unlikely to pass warrants early intervention. Definitive options include ureteroscopy and shock-wave lithotripsy based on anatomy and stone characteristics. Send a passed or removed stone for analysis, and provide metabolic evaluation for recurrent, bilateral, unusual, or high-risk stone disease.

Epidemiology / Risk Factors

• Kidney stones are common and recurrence rates are substantial over a lifetime.
• Calcium oxalate is the most common stone composition.
• Low urine volume, high sodium intake, dietary and metabolic factors, obesity, gout, bowel disease, and some medications increase risk.
• Family history and early age of onset can suggest inherited predisposition.
• Climate and dehydration contribute to geographic and seasonal variation in stone presentations.

Investigations

Likelihood of Passage by Size (Approx.)

Pharmacology

Prognosis / Complications

• Most stones smaller than 5 mm pass spontaneously, especially when distal.
• Passage becomes less likely as stone size increases, particularly above 10 mm.
• Renal function usually returns after short uncomplicated unilateral obstruction, but prolonged or infected obstruction can cause permanent injury.
• Septic obstructed systems can deteriorate rapidly and carry significant mortality without drainage.
• Long-term recurrence can be reduced through high urine volume and cause-specific dietary or pharmacologic prevention.

Patient Education / Counseling

• Strain urine when practical so a passed stone can be analyzed.
• Drink enough over the long term to produce a high urine volume, but do not force excessive fluids during an acute obstructed colic episode.
• Return immediately for fever, chills, fainting, inability to urinate, uncontrolled vomiting, or worsening pain.
• If prescribed tamsulosin, discuss dizziness and orthostatic symptoms.
• For recurrence prevention, reduce excess sodium, maintain normal dietary calcium unless specifically advised otherwise, and follow the metabolic plan based on stone type and 24-hour urine findings.

Notes

Renal colic is usually an analgesia-and-follow-up problem, but a small subset is a source-control emergency. Fever or sepsis in an obstructed urinary tract should immediately shift the plan from pain control and medical expulsive therapy to antibiotics plus urgent drainage. In uncomplicated disease, NSAIDs, selective use of tamsulosin, and realistic estimates of passage based on size and location avoid unnecessary procedures. The episode should also trigger prevention in recurrent stone formers, because long-term urine chemistry and diet matter more than repeated emergency treatment.

References

1. American Urological Association Kidney Stone Guidelines — Link