An anticoagulated patient with falling haemoglobin and flank pain: CT finds the haematoma, its compartment, the hematocrit level, active extravasation and the source — iliopsoas, rectus sheath, renal or adrenal — which decides embolisation.
Orient first
- Spontaneous retroperitoneal haematoma is most often anticoagulation-related, arising in the iliopsoas or rectus sheath.
- A haematoma centred on the kidney or adrenal suggests an underlying tumour (angiomyolipoma, renal cell carcinoma) or vasculitis — Wunderlich syndrome.
- Active extravasation on the arterial phase that grows or changes shape on the delayed phase marks the bleeding vessel for the interventional radiologist.
Acquire the study
- Unenhanced CT, CT angiography (arterial phase) and a portal venous or delayed phase; 1 mm reconstructions with coronal reformats.
The manoeuvre
- Unenhanced series: hyperdense clot (sentinel clot, highest attenuation near the source) and hematocrit level.
- Compartment: anterior pararenal, perirenal, posterior pararenal, iliopsoas or rectus sheath — measure the haematoma in three planes (cm).
- Arterial phase: extravasation (attenuation similar to the aorta) that increases on the delayed phase; name the likely feeding vessel (lumbar, iliolumbar, inferior epigastric).
- Source: renal or adrenal mass, aneurysm, abnormal vessels.
What confirms it
- Retroperitoneal haematoma with a defined compartment, with or without active extravasation.
What licenses you to exclude it
- No active extravasation on a triphasic study does not exclude intermittent bleeding; say so if the patient remains unstable.
The classic misread
- Missing the underlying renal tumour inside a perirenal haematoma — recommend follow-up imaging once the blood resorbs.