What is the initial medical management for a patient presenting with renal colic?

Medical Management of Renal Colic

Administer intramuscular diclofenac 75 mg immediately as first-line therapy to achieve pain relief within 30 minutes, and if pain persists after 60 minutes, arrange immediate hospital admission. 1

Immediate Assessment (Within 30 Minutes)

Critical initial evaluation must include:

• Vital signs assessment (pulse, blood pressure, temperature) to exclude shock and systemic infection 1, 2
• Abdominal examination to rule out peritonitis and other acute conditions 1
• Age-specific red flags: In patients >60 years, consider leaking abdominal aortic aneurysm; in women with delayed menses, consider ectopic pregnancy 1, 2

Immediate hospital admission is required for:

• Fever or signs of systemic infection (suggests obstructive pyelonephritis—a surgical emergency) 2, 3
• Shock or hemodynamic instability 2, 3
• Anuria or acute kidney injury with obstruction 3

First-Line Analgesic Treatment

NSAIDs are superior to opioids for renal colic because they reduce the need for additional analgesia and have fewer adverse effects (vomiting occurs in ~6% with NSAIDs vs ~20% with opioids). 4, 5

Preferred regimen:

• Intramuscular diclofenac 75 mg (Grade A recommendation) 1, 4
• Oral and rectal routes are unreliable in acute settings 4
• Alternative NSAIDs include ibuprofen or metamizole, though diclofenac has the strongest evidence 4, 6

Critical timing: Pain relief should occur within 30 minutes; if not controlled within 60 minutes, immediate hospital admission is mandatory. 1, 2

Second-Line Treatment (When NSAIDs Contraindicated)

Use opioids only when NSAIDs cannot be given due to:

• Renal impairment or acute kidney injury 4, 3
• Cardiovascular disease 4
• History of gastrointestinal bleeding 4
• Pregnancy 4, 5

Preferred opioid regimen:

• Morphine sulfate plus cyclizine (antiemetic) 1
• In renal impairment, use fentanyl (does not accumulate active metabolites); avoid morphine, codeine, or tramadol 4, 3
• Avoid pethidine (highest rate of vomiting and need for additional analgesia) 4

Combination therapy: Adding morphine to NSAIDs provides additional benefit in ~10% of patients when monotherapy fails. 5

Home Management Protocol

Approximately 90% of stones pass spontaneously, making outpatient management appropriate for most patients without red flags. 2

Patient instructions:

• Maintain high fluid intake 1
• Strain all urine through a tea strainer or gauze to catch any passed calculus for analysis 1, 2
• Consider limited supply of oral/rectal NSAIDs for recurrent pain (though concerns exist about drug misuse) 1

Mandatory follow-up:

• Telephone call 1 hour after initial assessment to verify pain control 1
• Imaging within 7 days to identify calculus size and location 1
• Urgent urology consultation within 1 week if intervention needed 1

Medical Expulsive Therapy

For stones >5 mm in the distal ureter, prescribe tamsulosin (alpha-blocker) to facilitate spontaneous passage—this increases stone passage rate by approximately 50%. 4, 7

Critical Pitfalls to Avoid

• Never delay analgesia while waiting for diagnostic tests 2
• Do not discharge before ensuring adequate pain control for at least 6 hours 2
• Missing obstructive pyelonephritis (infected obstructed kidney) is life-threatening and requires urgent decompression via percutaneous nephrostomy or ureteral stenting 2, 4, 3
• NSAIDs may worsen renal function in patients with low GFR, dehydration, heart failure, or concurrent nephrotoxic drugs—use lowest effective dose and monitor carefully 4, 8
• NSAIDs increase cardiovascular and gastrointestinal risks, particularly in elderly patients with comorbidities 4, 8
• Avoid NSAIDs after 20 weeks gestation due to risk of fetal renal dysfunction and oligohydramnios; avoid entirely after 30 weeks due to premature ductus arteriosus closure 8

Special Populations

Pregnant women: Morphine carries lower risk than NSAIDs; avoid NSAIDs entirely after 20 weeks gestation. 8, 5

Elderly patients: Screen for NSAID contraindications (renal failure, peptic ulcer disease); if opioids needed, use downward-adjusted doses with monitoring for confusion and respiratory depression. 7

Acute kidney injury: Avoid NSAIDs; use fentanyl if opioid needed; urgent imaging to assess for obstruction requiring decompression. 4, 3