Endourology and Stone Disease
Diagnosis
Non-contrast CT is the standard for suspected stone disease, giving stone size, location, Hounsfield units, and obstruction. Size predicts spontaneous passage: under 5 mm usually passes, 5–10 mm is intermediate, and over 10 mm rarely passes. Ultrasound is preferred in pregnancy and children.
Acute management
An obstructing stone with fever or sepsis is a urologic emergency requiring decompression by ureteral stent or percutaneous nephrostomy; definitive stone treatment waits until the infection is controlled. Medical expulsive therapy may be offered for distal ureteral stones with adequate analgesia.
Definitive treatment
Ureteroscopy suits distal and mid-ureteral stones; ESWL suits proximal stones under 2 cm with normal renal function. ESWL is contraindicated in pregnancy, coagulopathy, untreated infection, and distal obstruction. PCNL is first-line for staghorn calculi and stones over 2 cm, with a nephrostomy tube or stent and careful attention to bleeding and post-operative fever.
Metabolic evaluation
Struvite stones arise from urease-producing organisms and require complete removal. Uric acid stones are radiolucent and dissolve with urinary alkalinisation. Cystine stones reflect cystinuria. High-risk patients merit 24-hour urine testing.
Traps
Treating the stone rather than decompressing a septic obstructed system; assuming every radiolucent stone is uric acid; forgetting that ESWL fails in dependent or hard stones; ignoring residual fragments that seed recurrence.
Worked example
A 6 mm distal ureteral stone in an afebrile patient with controlled pain and no obstruction-related renal impairment can be observed with analgesia and expulsive therapy for four to six weeks before intervention.