• Hemorrhage in the RP or posterior abd wall mm; high attenuation poorly marginated collection that initially accumulates near site of bleeding and can spread throughout RP and even into thigh, genitals, abd walls, and peritoneum.

• Look for associated findings to locate cause:

  • Coagulopathy/AC: high density collection w/ cellular-fluid level (hemotocrit sign) +/-bleeding into several spaces

    • Relatively common finding in hospitalized and chronically ill patients, especially those on systemic AC. 

  • Trauma: pelvic fx, spine trauma, renal/adrenal, and vascular injury

  • Ruptured AAA: large eccentric aneurysm; draped aorta, disrupted calcs with periarotic hematoma +/- active extravasation contiguous w aorta.

  • Active bleeding: linear, flame-shaped density, isodense to vessels

  • Sentinal clot sign: high attenuation (60-80 HU) layering along organ of origin.

  • Chronic hematoma: lower density (20-40 HU) w rim enhancement. 

  • Spontaneous perirenal hemorrhage: consider underlying tumor, vasculitis, or coagulopathy.

Source of bleeding is most often venous, but arterial (particularly aortic) bleeding has a much more ominous prognosis and must be ruled out.

Though NECT is sufficient to diagnose RP hemorrhage, if there is concern for active bleeding requiring intervention, need to get multiphase CTA.

TX

• Coagulopathic bleeds: most are self-limited, require no intervention beyond stopping medicine and supportive care such as infusion of blood products.

• Active bleeds: angiographic embolization.

• Surgery: ruptured aneurysm, tumor, trauma, presence of severe motor dysfunction or abd compartment syndrome.