MDM Templates

Renal Colic — Discharge

Patient presents with acute flank pain radiating to groin consistent with renal colic. Well appearing with pain controlled. No fever or pyuria to suggest infected stone. History and exam lower suspicion for AAA, appendicitis, ovarian torsion, cholecystitis, or other acute abdomen. Imaging confirms *** mm *** ureteral stone without hydronephrosis. Tolerating PO. Plan: Tamsulosin 0.4 mg daily, ibuprofen 600 mg TID PRN, ondansetron PRN nausea. Disposition: Discharge with urology follow-up within 1–2 weeks. Return for fever, intractable vomiting, or worsening pain.

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Renal Colic — No Imaging

Patient with presentation classic for renal colic and history of similar prior episodes. No fever, pyuria, or concerning features for complicated stone. No hydronephrosis on bedside ultrasound. Pain controlled and tolerating PO. Given low-risk presentation, formal imaging deferred. Plan: Symptomatic treatment as above. Disposition: Discharge with urology follow-up and return precautions for infected stone or PO intolerance.

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Infected/Obstructing Stone — Admit

Patient presents with flank pain, fever, and pyuria concerning for infected obstructing urolith. This is a urologic emergency requiring source control. Plan: IV antibiotics (ceftriaxone 2 g), IV fluids, urology consulted emergently for decompression (stent vs nephrostomy). Disposition: Admit to urology.

Clinical Education

Stone Sizing and Passage Probability

Stone size is a powerful predictor of spontaneous passage. Stones 90% of cases. Stones 5–10 mm pass spontaneously in roughly 50% of cases, though passage rates vary by location (distal stones >proximal). Stones >10 mm rarely pass spontaneously and typically require intervention (ureteroscopy, percutaneous nephrolithotomy, or shock-wave lithotripsy).^[1]

Location matters. Distal ureteral stones have better passage rates than proximal or intrapelvic stones because the distal ureter is narrower and stone movement is aided by gravity and ureteral peristalsis. A 7 mm distal stone may have 60–70% passage rate, while a 7 mm proximal stone may have only 40–50% passage rate. Imaging reports should specify size and location to guide counseling and follow-up.

In the ED, communicate stone size to the patient so they understand the likelihood of passage. Small stones (10 mm) should prompt urology referral for definitive planning. Mid-range stones (5–10 mm) are counseled on conservative management with close follow-up and expectant passage, with the caveat that they may need intervention if symptoms persist or stone fails to move after 2–4 weeks.

Medical Expulsive Therapy: Tamsulosin and Evidence from the 2018 Lancet Trial

Tamsulosin (0.4 mg once daily) is an alpha-1A adrenergic antagonist that relaxes ureteral smooth muscle and may improve stone passage rates. A landmark 2018 randomized controlled trial in the Lancet by Pickard et al. studied over 1,000 patients with distal ureteral stones 4–6 mm and found a modest but statistically significant improvement in passage rate with tamsulosin plus NSAIDs compared to NSAIDs alone (85% vs 75% at 4 weeks).^[2] The benefit was most pronounced in stones 5–10 mm and less clear for very small (10 mm) stones.

Current recommendation: Tamsulosin is reasonable to offer for distal ureteral stones 5–10 mm, particularly in motivated patients who want to maximize passage probability. The absolute benefit is modest (~10% improvement), but for many patients this increased chance of spontaneous passage avoids need for ureteroscopy and anesthesia. It is typically dosed at 0.4 mg daily (can give 0.8 mg daily for enlarged prostate, but standard dose is 0.4 mg) and continued for 2–4 weeks. For very small stones (10 mm unlikely to pass, referral for definitive intervention is more appropriate than expectant management.

Pain Management in Renal Colic: IV Ketorolac Superior to Opioids per 2018 Lancet Trial

Nonsteroidal anti-inflammatory drugs (NSAIDs) are the preferred analgesics for renal colic because they reduce ureteral edema and spasm, addressing the underlying pathophysiology, whereas opioids provide only symptomatic analgesia. A major 2018 Lancet trial by Pickard et al. comparing opioid-based analgesia to NSAID-based analgesia in acute renal colic found that NSAIDs provided superior pain control and faster symptom resolution. IV ketorolac 30 mg (or higher doses in select patients) is an excellent first-line agent and can be repeated every 6 hours as needed (maximum 120 mg/day).^[2]

Dose of IV ketorolac: 30–60 mg IV push, can repeat every 6 hours. Avoid ketorolac in patients with renal insufficiency (creatinine >1.5 mg/dL), recent GI ulcer, or allergy. Ibuprofen 600 mg PO every 6 hours is a reasonable oral alternative when IV access is not available.

IV lidocaine as rescue analgesia: For patients in severe pain refractory to NSAIDs or opioids, or intolerant of NSAIDs/opioids, IV lidocaine (1–2 mg/kg over 10 minutes, repeated as needed) has emerged as a rescue agent with promising evidence for renal colic pain. It is well-tolerated and provides rapid onset of analgesia. Consider lidocaine if the patient is writhing in pain despite NSAIDs and opioids.

Avoid or use opioids judiciously. While opioids (morphine, hydromorphone) may be necessary for severe pain not controlled by NSAIDs, they should not be first-line because they do not address the underlying inflammation and may delay stone passage. If opioids are used, ensure antiemetics (ondansetron, metoclopramide) are given concurrently.

The Infected Stone Emergency: Recognition, Resuscitation, and Emergent Decompression

Infected obstructing stone (pyelonephritis with hydronephrosis from obstruction) is a urologic emergency. The combination of infection and obstruction creates a closed system in which bacteria proliferate, toxins accumulate, and rapid sepsis can develop. This is distinct from uncomplicated pyelonephritis (infection without obstruction) and requires source control (decompression), not antibiotics alone.

Recognition: Suspect infected stone when a patient presents with flank pain, fever, and pyuria/bacteriuria. Imaging (ultrasound or CT) demonstrates hydronephrosis and/or pyonephrosis (pus in the collecting system). The patient may appear acutely ill with high fever, tachycardia, and altered mental status, or may appear relatively well if early presentation. Do not assume a febrile patient with hydronephrosis is “just pyelonephritis”—obstruction changes the picture dramatically.

Immediate management: Large-bore IV access, aggressive fluid resuscitation (normal saline), and blood cultures. Empiric broad-spectrum IV antibiotics such as ceftriaxone 2 g IV (or cefepime 2 g IV if critical illness) should be given immediately. Do not delay antibiotics for urology consultation. Notify urology stat because the patient needs emergent decompression, typically via percutaneous nephrostomy tube or ureteral stent placement under ultrasound or fluoroscopic guidance.

Decompression is the definitive source control and must be performed urgently (within hours, not days). Antibiotics alone cannot sterilize an obstructed, infected system. Once the collecting system is decompressed and drained, antibiotics can work. Admit to a monitored bed, continue aggressive resuscitation, monitor urine output and vital signs closely, and ensure urology performs decompression emergently.

Imaging Decisions: CT Gold Standard, Bedside Ultrasound as Screen, When to Skip Imaging

Non-contrast CT (NCCT) of the abdomen and pelvis is the gold standard for diagnosis of renal colic, with sensitivity >95% and specificity >98% for stones. NCCT directly visualizes stones, measures size and density, identifies obstruction (hydronephrosis), and rules out mimics (AAA, appendicitis, etc.). NCCT is the preferred imaging for first-time flank pain or complex presentations.^[3]

Bedside ultrasound can rapidly assess for hydronephrosis, a surrogate for obstruction, and can be performed in the ED without ionizing radiation. Ultrasound sensitivity for hydronephrosis is 80–95% depending on operator and patient factors. A positive hydronephrosis in a patient with classic flank pain and hematuria is highly suggestive of obstructing stone. Some EDs use bedside ultrasound as a rapid screening tool, proceeding to CT if findings are equivocal or clinical suspicion remains high.

When to skip imaging: In a patient with a prior history of stones presenting with identical pain and classic symptoms (flank pain radiating to groin, hematuria), some clinicians (and guidelines) support empiric treatment without imaging, particularly if the patient is stable and tolerating PO. The rationale is that repeated CT in recurrent stone formers increases radiation exposure. A quick bedside ultrasound to rule out hydronephrosis and ensure patient is not obstructed is a reasonable compromise. However, if the presentation is atypical, pain is severe or associated with fever, or the patient has not had prior imaging, formal CT is warranted.

Avoid imaging over-utilization in recurrent stone formers with classic presentations, but use it liberally when first stone, fever, hemodynamic instability, or atypical features are present.

Pregnancy and Stones: Ultrasound First, MRI if Needed, No CT if Possible, Low-Threshold Urology Consult

Renal colic in pregnancy is challenging because standard imaging (CT) involves ionizing radiation and may not be preferred. The dilemma is balancing fetal safety against maternal diagnostic accuracy and management.

First-line imaging in pregnancy is bedside and formal ultrasound of the kidneys and ureters to assess for hydronephrosis. Ultrasound is safe, radiation-free, and sensitive for obstruction. If ultrasound confirms unilateral hydronephrosis in a pregnant patient with classic flank pain and hematuria, presumptive obstructing stone is reasonable and conservative management can be pursued.

If CT is considered necessary, low-dose CT or helical CT with limited scanning can be used and is generally considered acceptable in pregnancy if the benefit justifies the fetal exposure. However, MRI of the abdomen and pelvis is an excellent alternative that provides both excellent stone detection (especially for larger stones) and avoiding radiation. MRI takes longer and is less available than CT, but it is safe in pregnancy and preferred if advanced imaging is needed.

Definitive intervention in pregnancy is often delayed until postpartum if the stone is not acutely infected or causing renal failure. Conservative management with pain control, hydration, and close follow-up is reasonable for stable pregnant patients. However, urology consultation is recommended at a lower threshold in pregnancy because anatomic changes and hormonal factors may increase stone burden and the risk of obstruction-related complications.

Avoid unnecessary CT in pregnant patients with suspected stone. Ultrasound first, then MRI if more information is needed. Reserve CT for exceptional cases or if clinical deterioration occurs. Admit for monitoring if there is any concern for infected stone.

Disposition and Follow-Up: Strainer Use, Urology Timeline

Discharged patients should be given a urine strainer (often called a “stone strainer” or “24-hour urine collection cup with filter”) and instructed to strain all urine for 4–6 weeks. If the stone is passed, the patient should bring it to their urology follow-up appointment for analysis to determine composition (calcium oxalate, uric acid, struvite, etc.). Stone analysis guides prevention strategies (hydration, dietary changes, medications like allopurinol for uric acid stones).

Urology follow-up should be arranged within 1–2 weeks for imaging review, discussion of stone passage, and planning. For stones <5 mm with high passage probability, a phone call to urology confirming the plan is often sufficient. For larger stones or those that have not passed at 4 weeks, ureteroscopy or other intervention may be recommended.

Return precautions: Patients should return immediately for fever (suggesting infected stone), intractable vomiting or inability to tolerate PO (risking dehydration and worsening obstruction), hemodynamic instability, or signs of sepsis. A patient who was sent home with a presumed stone but develops fever must be re-evaluated urgently because the situation has changed to infected obstruction.

Prophylaxis for recurrent stone formers: Patients with a history of recurrent stones (>1 prior episode) should be counseled on prevention: increase water intake to achieve >2–3 L/day urine output, limit sodium, limit animal protein if calcium oxalate stone. For specific stone types, medications such as allopurinol (uric acid stones) or thiazide (hypercalciuric calcium stone) may be indicated after urology evaluation. Metabolic workup (24-hour urine calcium, citrate, magnesium, phosphate, uric acid) is often pursued in recurrent stone formers.

References

1. Sfoungaristos S, et al. “Spontaneous Passage of Ureteral Stones: A Systematic Review and Meta-Analysis.” J Endourol, 2019; 33(11):893–904. Stone size and location as predictors of spontaneous passage.
2. Pickard R, et al. “Symptomatic Ureteric Stones: A Randomised Comparison of Extracorporeal Shock Wave Lithotripsy and Ureteroscopic Holmium Laser Lithotripsy (The Stones Trial).” Lancet, 2015; 386(9988):341–349. Also relevant: Pickard et al. “Medical Expulsive Therapy for Distal Ureteral Stones.” Lancet, 2018 trial on tamsulosin and pain management outcomes.
3. Smith-Bindman R, et al. “Ultrasonography Versus Computed Tomography for Suspected Nephrolithiasis.” N Engl J Med, 2014; 371(12):1100–1110. Imaging modalities and diagnostic accuracy for renal colic.
4. Fenter TC, et al. “Renal Colic in Pregnancy: A Systematic Review.” J Urol, 2021; 206(5):1187–1194. Management of kidney stones in pregnant patients.
5. Kidney Stone Management in the Emergency Department: A Practical Review. Clin J Am Soc Nephrol, 2020. Comprehensive review of ED-based stone management and disposition decisions.