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CDHB

Renal Colic

History

• Pain: severe loin to groin radiation (50% of patients giving this history however will not have a kidney stone).

Examination

• If there is a high fever >38°C + significant renal tenderness, infection may be present.

Differential Diagnosis

The following must be excluded in anyone with suspected renal colic, especially the elderly:

• Aortic and iliac aneurysms.
• Testicular torsion.
• Pyelonephritis.
• Peritonitis, including appendicitis and diverticulitis.
• Biliary colic.
• Clot colic usually secondary to malignancy in kidney.

Investigations

• MSU: haematuria is present in only 85% of patients with renal colic.
• CBC + diff (the white cell count is often raised even when there is no infection), creatinine, electrolytes, calcium, phosphate, uric acid.
• Blood cultures if patient is febrile.
• CT urogram and plain X-ray (KUB) for kidney, ureter and bladder.

Management

• IV access for analgesia + fluids.
• Adequate analgesia, opiates usually required.

  Note: Patients with infection and obstructed kidneys may develop urosepsis. Use gentamicin, initial dose 3-5 mg/kg IV. If further doses are required, see the gentamicin/tobramycin dosing guidelines in the PML.

Further Investigation

In the young, healthy patient in whom the diagnosis of renal colic is clinically not in question, the pain has completely settled and there is no suspicion of any complication, there is no need to obtain immediate diagnostic imaging but it should be arranged as an outpatient. If pain is severe and ongoing, the diagnosis is in doubt, another condition is suspected, or if the patient is elderly, some diagnostic imaging is essential.

1. CT urogram:
   • Is the first line of imaging.
   • Advantages: sensitivity 95-97% and specificity 96-98% in detection of renal stones.
2. Plain X-ray KUB:
   • 90% of renal stones are radio-opaque but the sensitivity is only up to 52-58% and the specificity 69-74%. Negative predictive value is only 23%.
   • In patients in whom the diagnosis is already established, plain X-ray is useful in following the passage of a radio-opaque stone.
3. Ultrasound:
   • When CT is contraindicated (e.g., pregnancy).
   • Will detect larger (>5mm) stones, particularly in the proximal and distal ureter but only poorly visualizes midureteric stones.
   • Very sensitive for hydronephrosis (98%) but 22% of hydronephroses detected on ultrasound do not represent obstruction.
   • Advantages: non-invasive, no contrast, no radiation, no side effects. Can give clues to other pathology (such as AAA).

Subsequent Management

• The majority of patients do not need admission and will pass a stone.
• The decision to admit the patient must be taken by the Urology on-call team concerned.

Admission is required in the following situations:

• Fever >38°C, or septic, as may require a nephrostomy.
• Severe ongoing pain that does not settle with IV opioids and NSAIDs.
• Recurrent attacks of colic with repeated visits to the Emergency Department.
• Any ureteric stone in a solitary kidney.
• Creatinine >200 micromol/L.
• Admission may be required in other circumstances. Discuss with Urology on-call team.

When discharged:

• Send a referral to the Urology Outpatient Clinic.
• If the stone is 5 mm or less at the vesico-ureteric junction and becomes asymptomatic then no follow up is required.
• If the stone is >7 mm, the patient will be booked directly for semi-urgent surgery.
• Other stones will be followed in outpatients in 4 weeks.
• In all cases send the referral to Urology and a letter will be sent to GP and patient with advice and instructions.
• Advise patient to return if they develop a fever or become unwell.
• Give the patient a prescription for diclofenac unless there is a contraindication to this drug.
• Routine prescription of an alpha blocker (doxazosin 2 - 4 mg/day - but consider a lower dose in elderly patients) assists passage of ureteric calculi.

Topic Code: 3709