What is the initial treatment for a patient with renal colic?

Initial Treatment for Renal Colic

NSAIDs, specifically intramuscular diclofenac 75 mg, are the first-line treatment for renal colic and should be administered immediately to achieve pain relief within 30 minutes. 1, 2

First-Line Analgesic Approach

• Administer NSAIDs as the primary analgesic because they reduce the need for additional analgesia compared to opioids and provide superior pain control 1
• Intramuscular diclofenac 75 mg is the preferred agent and route due to rapid onset and reliability, with oral and rectal routes being unreliable in acute settings 2, 3
• Alternative NSAIDs include ibuprofen and metamizole, though diclofenac has the strongest evidence base 1
• NSAIDs are significantly more effective than placebo in reducing pain by 50% within the first hour (RR 2.28,95% CI 1.47-3.51) 4
• Intramuscular diclofenac is more effective than intravenous morphine in achieving at least 50% pain reduction at 30 minutes (68% vs 61%, OR 1.35, p=0.0187) 5

Second-Line Treatment When NSAIDs Are Contraindicated

• Use opioids only when NSAIDs cannot be given due to contraindications such as renal impairment, cardiovascular disease, gastrointestinal bleeding history, or pregnancy 1, 2
• Combine the opioid with an antiemetic (morphine sulfate plus cyclizine) because opioids cause vomiting in approximately 20% of patients versus 6% with NSAIDs 6, 7
• Avoid pethidine as it has the highest rate of vomiting and need for additional analgesia; prefer hydromorphine, pentazocine, or tramadol 1
• In renal impairment, use fentanyl because it does not accumulate active metabolites, and avoid morphine, codeine, or tramadol 6

Critical Monitoring and Failure Criteria

• If pain is not controlled within 60 minutes of appropriate analgesia, immediate hospital admission is required 2, 3, 6
• Follow up via telephone one hour after initial assessment to ensure adequate pain control 3, 6
• Complete or acceptable pain control must be maintained for at least six hours before considering discharge 3
• Abrupt recurrence of severe pain warrants immediate hospital admission 3, 6

Red Flags Requiring Urgent Intervention

• Sepsis and/or anuria in an obstructed kidney requires urgent decompression via percutaneous nephrostomy or ureteral stenting 1
• Immediate hospital admission is mandatory for: shock or hemodynamic instability, fever or signs of systemic infection, failure to respond to analgesia within 60 minutes 2, 6
• Collect urine for antibiogram testing before and after decompression, and administer antibiotics immediately in septic patients 1

Adjunctive Therapies

• Medical expulsive therapy with alpha-blockers (tamsulosin) is strongly recommended for stones >5 mm in the distal ureter to facilitate spontaneous passage 1
• The combination of NSAIDs plus antispasmodics is not superior to NSAIDs alone and does not provide additional benefit 1, 4
• Instruct patients to drink plenty of fluids and void into a container to catch any passed stones 3

Important Caveats and Pitfalls

• NSAIDs may impact renal function in patients with low glomerular filtration rate, so use the lowest effective dose and monitor carefully 1
• NSAIDs increase cardiovascular and gastrointestinal risks, particularly in elderly patients with comorbidities 1, 8
• Never delay analgesia while waiting for diagnostic tests as this is a common and harmful pitfall 3, 6
• Absence of hematuria does not exclude renal colic, as hematuria is present in only >80% of cases 2
• Consider alternative diagnoses in patients over 60 years (leaking abdominal aortic aneurysm) or women with delayed menses (ectopic pregnancy) 3