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Urinary tract imaging: haematuria, stones, infection, trauma and the transplanted kidney

Macroscopic haematuria in an adult is investigated with CT urography and cystoscopy, renal colic with low-dose non-contrast CT, and in trauma CT with a delayed phase grades the injury by AAST — and an obstructed infected kidney is an emergency for drainage.

לקריאה בעברית

Why it matters in the exam

Macroscopic haematuria in an adult — high risk of malignancy: CT urography (unenhanced, nephrographic and excretory phases) and cystoscopy. Urothelial carcinoma appears as a filling defect in the excretory phase and can be multifocal. Renal colic: low-dose non-contrast CT — almost all stones are dense on CT (exception: indinavir stones); a uric acid stone is radiolucent on a plain film but visible on CT. In pregnancy and young patients — US first. An obstructed kidney with fever or sepsis — urgent drainage by nephrostomy or stent, not antibiotics alone.

Infection: uncomplicated pyelonephritis needs no imaging; CT when there is no response to treatment within 72 hours — wedge-shaped areas of reduced enhancement and a "striated nephrogram". Emphysematous pyelonephritis — gas in the renal parenchyma, mainly in poorly controlled diabetes; life-threatening. Xanthogranulomatous pyelonephritis — a staghorn stone, an enlarged kidney with dilated calyces ("bear paw"). Trauma: blunt mechanism is more common. AAST 2018: I — contusion or subcapsular haematoma; II — laceration up to 1 cm without collecting system; III — laceration above 1 cm without collecting system, or contained vascular injury; IV — collecting system laceration with urine leak, segmental artery or vein injury, or active bleeding beyond Gerota's fascia; V — shattered kidney or hilar avulsion. Ureteric injury — mainly iatrogenic in pelvic surgery. Bladder: extraperitoneal rupture (the commonest, with pelvic fracture) is managed with a catheter; intraperitoneal rupture (at the dome, in a full bladder) is managed surgically; the diagnosis is by CT cystography with retrograde filling of at least 300 mL.

Renal artery stenosis: in adults — ostial atherosclerosis; in a young woman and also in children — fibromuscular dysplasia of the mid-distal segment ("string of beads"). Doppler: high peak velocity at the stenosis and a "tardus parvus" waveform distally; CTA or MRA for diagnosis. Transplanted kidney: early — acute rejection, ATN, renal vein thrombosis (reversed diastolic flow in the artery) and arterial thrombosis, urine leak; after weeks to months — lymphocele (the commonest collection causing hydronephrosis) and anastomotic arterial stenosis (the commonest vascular complication). Renal vein thrombosis in a native kidney — an enlarged kidney without venous flow. The commonest renal anomaly — a duplex collecting system; horseshoe kidney — the commonest fusion anomaly.

Key points

• Macroscopic haematuria — CT urography and cystoscopy.
• Renal colic — low-dose non-contrast CT.
• Obstruction with infection — urgent drainage.
• AAST IV — collecting system or segmental vessel.
• Extraperitoneal — catheter; intraperitoneal — surgery.

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Sources

• AUA/SUFU Guideline on Microhematuria, 2020, amended 2025 — Risk-based evaluation
• ACR Appropriateness Criteria: Hematuria, 2020 — CT urography
• AAST Kidney Injury Scale, 2018 revision — Grades I–V

Sources are given for further reading; the text is written afresh and not copied from them.

Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.

See also: Imaging in urology: ultrasound, CT, MRI and scintigraphy