How should a patient with suspected renal colic be evaluated and treated in an urgent‑care setting?

Management of Kidney Stones in Urgent Care

Administer intramuscular diclofenac 75 mg immediately for pain relief, assess the patient within 30 minutes for red flags requiring hospital admission, and arrange fast-track imaging within 7 days for those managed as outpatients. 1, 2

Immediate Assessment (Within 30 Minutes)

Clinical Diagnosis

• Confirm abrupt onset of severe unilateral flank pain radiating to groin or genitals, typically accompanied by nausea, vomiting, and hematuria 2
• Assess vital signs including pulse, blood pressure, and temperature to exclude shock and systemic infection 1, 2
• Examine the abdomen to exclude peritonitis and other acute conditions 1

Critical Red Flags Requiring Immediate Hospital Admission

• Fever or signs of systemic infection (suggests obstructive pyelonephritis—a surgical emergency) 1, 2, 3
• Shock or hemodynamic instability 4, 2
• Failed pain control after 1 hour of analgesia 1, 2, 5
• Age >60 years (consider leaking abdominal aortic aneurysm) 1, 2, 5
• Women with delayed menses (consider ectopic pregnancy) 1, 2, 5
• Solitary kidney 5
• Diagnostic uncertainty 5

Pain Management Protocol

First-Line Treatment

• Give intramuscular diclofenac 75 mg immediately to provide pain relief within 30 minutes (Grade A recommendation) 1, 2, 5, 3
• NSAIDs are superior to opiates as they reduce ureteric spasm in addition to providing analgesia 3
• Do not delay analgesia while waiting for diagnostic tests 4, 2

If NSAIDs Contraindicated

• Use morphine sulfate plus cyclizine (opiate with antiemetic) 4
• Avoid morphine, codeine, or tramadol in renal failure due to accumulation of active metabolites 4

Failed Analgesia

• If pain is not controlled within 60 minutes, immediately admit to hospital by phone without further consultation 1, 2, 5

Diagnostic Workup

Urinalysis

• Hematuria is present in >80% of renal colic cases and supports the diagnosis 4
• However, absence of hematuria does not exclude the diagnosis 4
• Symptoms plus positive dipstick for hematuria have 84% sensitivity and 99% specificity 3

Imaging Strategy

• Ultrasound should be considered as the primary imaging technique for most patients—it is non-invasive, non-expensive, and avoids radiation 6, 7
• Ultrasound achieves accurate diagnosis in most cases through direct stone visualization or indirect findings (asymmetry of ureteric jet, increased resistive index, color Doppler twinkling artifact) 6
• Non-contrast CT is the gold standard for diagnostic accuracy (sensitivity 93.1%, specificity 96.6%) but should be reserved for specific scenarios requiring definitive imaging 5, 8, 7
• Multispecialty consensus supports ultrasound or no further imaging in many clinical scenarios, with reduced-radiation CT employed only when necessary 7

Home Management Criteria

Appropriate for Outpatient Management

• Approximately 90% of stones pass spontaneously, making home management appropriate for most patients 2, 3
• Patients must have adequate pain control and no red flags 1, 2
• Do not discharge before ensuring adequate pain control for at least 6 hours 4, 2

Patient Instructions

• Maintain high fluid intake (>2 L/day) and strain urine through a sieve to catch any passed calculus for analysis 1, 2, 5, 3
• Reduce salt intake (ideally <2g/day) and animal protein in diet to reduce stone formation 3
• Provide limited supplies of oral or rectal analgesia for self-administration if pain recurs 1

Follow-Up Protocol

• Telephone follow-up 1 hour after initial assessment to ensure adequate pain control 1, 5
• Arrange fast-track renal imaging within 7 days of symptom onset 1, 5, 3
• Urgent urology consultation within 1 week if imaging shows intervention is needed 1, 5

Urgent Urology Referral Criteria (Within 1 Week)

• Stone size >5 mm (less likely to pass spontaneously) 5
• Proximal ureter or renal pelvis location 5
• Recurrent severe pain after initial relief 5
• High-grade obstruction or severe hydronephrosis on imaging 5

Special Considerations

Obstructive Uropathy with Infection

• If imaging confirms urinary obstruction with infection, urgent decompression via percutaneous nephrostomy or ureteral stenting is required 4
• This represents obstructive pyelonephritis—a true surgical emergency 2, 9

Acute Kidney Injury

• NSAIDs may be contraindicated in AKI—use alternative analgesia 4
• The combination of AKI and groin pain strongly suggests obstructive uropathy requiring urgent evaluation 4

Common Pitfalls to Avoid

• Never delay analgesia while waiting for diagnostic tests 4, 2
• Missing obstructive pyelonephritis (infected obstructed kidney)—always check for fever and systemic signs 4, 2
• Failing to arrange appropriate follow-up imaging to confirm stone passage 5
• Missing alternative diagnoses in atypical presentations (AAA in elderly, ectopic pregnancy in women of childbearing age) 1, 2, 5
• Discharging patients before adequate pain control is achieved 4, 2