What is the best course of treatment for an adult patient presenting with renal colic, likely caused by a kidney stone, and experiencing severe pain?

Treatment of Renal Colic

Administer intramuscular diclofenac 75 mg immediately as first-line therapy to achieve pain relief within 30 minutes. 1, 2, 3

Immediate Assessment and Triage

Time-sensitive evaluation: Patients presenting with acute renal colic require medical assessment within 30 minutes of presentation. 1 If this cannot be achieved in primary care, activate paramedical services to provide analgesia and transport to an emergency department. 1

Diagnostic criteria: The diagnosis centers on abrupt onset of severe unilateral flank pain radiating to the groin or genitals. 1 While urinalysis showing hematuria supports the diagnosis (present in >80% of cases), its absence does not exclude renal colic. 1, 4

Critical exclusions before treatment:

• Rule out leaking abdominal aortic aneurysm, especially in patients over 60 years 1
• Exclude ruptured ectopic pregnancy in women of reproductive age 1
• Assess vital signs to identify shock or fever requiring immediate hospital admission 1, 4

First-Line Analgesia: NSAIDs

NSAIDs are superior to opioids for renal colic because they reduce the need for additional analgesia and have fewer side effects. 2, 3 The evidence strongly supports this approach across multiple high-quality guidelines.

Specific NSAID regimen:

• Diclofenac 75 mg intramuscular injection is the preferred agent and route 1, 2, 3
• Oral and rectal routes are unreliable in the acute setting 1, 3
• Alternative NSAIDs include ibuprofen or metamizole, though diclofenac has the strongest evidence 3

Target: Complete or acceptable pain control within 30 minutes, maintained for at least 6 hours. 1, 2

Second-Line Treatment: Opioids

Use opioids only when NSAIDs are contraindicated due to renal impairment, cardiovascular disease, gastrointestinal bleeding history, or pregnancy. 2, 3

Opioid selection:

• Avoid pethidine due to highest rates of vomiting and need for additional analgesia 2, 3
• Prefer hydromorphone, pentazocine, or tramadol 2, 3
• In renal impairment, use fentanyl exclusively as it does not accumulate active metabolites 2, 3
• Never use morphine, codeine, or tramadol in renal failure 2

Dosing caution: Start with lower doses in elderly patients and those with renal impairment, titrating carefully to prevent confusion and respiratory depression. 5

Failure of Initial Treatment

If pain is not controlled within 60 minutes of appropriate analgesia, immediately admit the patient to hospital. 1, 2, 4, 3 This is non-negotiable and requires no further consultation in primary care. 1

Urgent Hospital Admission Criteria

Immediate admission required for:

• Fever or signs of systemic infection (sepsis in obstructed kidney is a urologic emergency) 1, 4
• Shock or hemodynamic instability 1, 4
• Anuria in an obstructed kidney 2, 3
• Failure to respond to analgesia within 60 minutes 1, 2, 4

Urgent decompression via percutaneous nephrostomy or ureteral stenting is required for sepsis and/or anuria in an obstructed kidney. 2, 3

Adjunctive Medical Therapy

Medical expulsive therapy with alpha-blockers (tamsulosin) is strongly recommended for stones >5 mm in the distal ureter to facilitate spontaneous passage. 2, 3, 5 Tamsulosin increases spontaneous stone passage rates by approximately 50% and is well-tolerated in elderly patients. 5

Follow-Up Protocol

Telephone follow-up 1 hour after initial assessment to reassess pain control and determine need for hospital admission. 1, 2

Imaging within 7 days: All patients with suspected renal colic require renal imaging (ultrasound or CT urography) within 7 days to identify the stone and determine management. 1

Urology referral within 14 days if a stone is identified on imaging. 1, 6

Home Management Instructions

For patients with adequate pain control:

• Maintain higher fluid intake 1
• Strain urine to capture stone for analysis 1, 7
• Provide limited supply of oral or rectal NSAIDs for recurrent pain 1
• Approximately 90% of stones causing renal colic pass spontaneously 1, 7

Critical Pitfalls to Avoid

NSAID safety concerns:

• NSAIDs may impair renal function in patients with low GFR; use lowest effective dose and monitor carefully 3
• Increased cardiovascular and gastrointestinal risks in elderly patients with comorbidities 3
• Screen for contraindications including renal failure, peptic ulcer disease, and cardiovascular disease 5

Opioid-related errors:

• Never use standard opioid dosing in renal failure 2
• Avoid morphine, codeine, or tramadol as first-line agents in renal impairment 2
• Monitor for respiratory depression and confusion, especially in elderly patients 5

Diagnostic errors:

• Absence of hematuria does not exclude renal colic 4
• Elderly patients may have atypical presentations with minimal fever despite serious infection 4
• Do not delay analgesia while awaiting imaging 4