What is renal colic and how is it managed in adults with a history of kidney stones or urinary tract issues?

Renal Colic: Definition and Management

What is Renal Colic?

Renal colic is severe, sudden-onset unilateral flank pain radiating to the groin or genitals, caused by acute obstruction of the urinary tract from a kidney stone. 1, 2 The pain results from increased hydrostatic pressure in the urinary system above the obstruction, triggering ureteral spasm and distension. 3

Clinical Presentation

• Pain characteristics: Abrupt onset of severe unilateral flank pain that radiates from loin to groin or external genitalia 1, 2
• Associated symptoms: Nausea, vomiting (present in 50% of cases), hematuria, dysuria, and urinary frequency 3, 4
• Hematuria: Present in over 80% of cases on urinalysis, though absence does not exclude the diagnosis 1

Immediate Assessment and Red Flags

Critical Initial Evaluation (Within 30 Minutes)

All patients presenting with suspected renal colic require medical assessment within 30 minutes of presentation. 1, 2 This assessment must include:

• Vital signs: Check pulse, blood pressure, and temperature to exclude shock and systemic infection 1, 2
• Abdominal examination: Establish site of maximal tenderness and exclude peritonitis 1
• Urinalysis: Test for hematuria if specimen can be obtained (supports diagnosis but not mandatory) 1

Immediate Hospital Admission Required For:

• Fever or signs of systemic infection (suggests obstructive pyelonephritis—a surgical emergency requiring urgent decompression) 1, 5, 2
• Shock or hemodynamic instability 1, 2
• Anuria in an obstructed kidney (requires urgent percutaneous nephrostomy or ureteral stenting) 5
• Age >60 years (must exclude leaking abdominal aortic aneurysm) 1, 2
• Women with delayed menses (must exclude ectopic pregnancy) 6, 2

Acute Pain Management

First-Line Treatment

Administer intramuscular diclofenac 75 mg as the primary analgesic, targeting pain relief within 30 minutes. 1, 5, 6, 2 NSAIDs are superior to opioids because they:

• Directly interfere with the pathophysiology of renal colic by reducing prostaglandin-mediated ureteral spasm 7
• Reduce the need for additional analgesia compared to opioids 5
• Provide superior pain control 5

The intramuscular route is preferred because oral and rectal administration are unreliable in acute settings. 1, 5, 6

Second-Line Treatment (When NSAIDs Contraindicated)

Use opioids combined with an antiemetic only when NSAIDs cannot be given. 1, 5, 6 Contraindications to NSAIDs include:

• Renal impairment (NSAIDs may worsen glomerular filtration rate) 5
• Cardiovascular disease 5
• History of gastrointestinal bleeding 5
• Pregnancy 5

Recommended opioid regimen: Morphine sulfate plus cyclizine 1, 6

In renal impairment specifically: Use fentanyl (does not accumulate active metabolites); avoid morphine, codeine, or tramadol 5, 6

Critical Monitoring

If pain is not controlled within 60 minutes of appropriate analgesia, arrange immediate hospital admission by telephone. 1, 5, 6, 2 Do not wait for a second visit—telephone follow-up is sufficient. 6

Maintain pain control for at least 6 hours before considering discharge. 1, 6, 2

Adjunctive Therapy for Stone Passage

For stones >5 mm in the distal ureter, prescribe alpha-blockers (tamsulosin) as medical expulsive therapy to facilitate spontaneous passage. 5 Approximately 90% of stones pass spontaneously, making conservative management appropriate for most patients. 2

Home Management Instructions

For patients suitable for outpatient management:

• Maintain high fluid intake 2
• Strain urine to catch any passed calculus for stone analysis 2
• Return immediately if: Pain recurs abruptly, fever develops, or inability to void occurs 1, 6

Common Pitfalls to Avoid

• Never delay analgesia while waiting for diagnostic tests 6, 2
• Do not discharge before ensuring 6 hours of adequate pain control 6, 2
• Do not miss infected obstructed kidney (obstructive pyelonephritis)—this requires urgent decompression via percutaneous nephrostomy or ureteral stenting 5, 6, 2
• Avoid intensive hydration during acute colic—it is not currently recommended and may worsen pain 3, 7
• Use lowest effective NSAID dose in elderly patients due to increased cardiovascular and gastrointestinal risks 5

Long-Term Considerations

Recurrence risk is high: 40% at 5 years and 50% at 10 years. 3, 4 Patients with recurrent stones require metabolic evaluation and preventive strategies including dietary modification (increased fluid intake, reduced sodium and animal protein) and potentially pharmacologic therapy (thiazides, potassium citrate, or allopurinol depending on stone composition). 1, 4