Abdominal and pelvic trauma on CT: liver, spleen, kidneys and shock bowel
- Finding
After a blow or a wound to the belly, a stable patient gets a contrast CT; an unstable one goes from a positive FAST to the operating room.
What it is
In abdominal trauma the first question is whether the patient is haemodynamically stable. An unstable patient with free fluid on FAST goes to the operating room, not the scanner. A stable patient after blunt trauma gets CT of the abdomen and pelvis with intravenous contrast, usually in the portal venous phase, often with an arterial phase and, if the kidneys or bladder may be injured, a delayed phase; oral contrast is not needed. CT shows solid-organ injuries (lacerations, haematomas, active bleeding), blood in the peritoneum, injuries to bowel, mesentery, pancreas and diaphragm, and fractures of the spine and pelvis. The spleen and liver are the organs most often injured by blunt force, and most stable patients with these injuries are now managed without surgery, sometimes with angioembolisation. Signs of hypovolaemic shock on CT (the hypoperfusion complex or shock bowel) warn that the patient is about to deteriorate.
What it looks like
- Laceration: a linear or branching low-density band through the organ.
- Subcapsular haematoma: a crescent of fluid under the capsule that flattens the organ edge; intraparenchymal haematoma is a rounded collection inside it.
- Active extravasation: a blush of contrast as dense as the arteries that grows or changes shape on later phases.
- Pseudoaneurysm: a contrast blush that keeps the same shape and fades in step with the blood pool on later phases.
- Sentinel clot: the densest clot lies next to the bleeding organ, pointing to the source.
- Shock bowel: diffuse small-bowel wall thickening with intense mucosal enhancement, a flat, narrow inferior vena cava, a small aorta and bright adrenals.
- Kidney: perirenal haematoma, lacerations and, on delayed images, contrast leaking from the collecting system.
Why it looks that way
- Torn tissue does not enhance and fills with blood, which is darker than enhancing parenchyma in the portal venous phase.
- A bleeding artery pours contrast out of the vessel, so the blush spreads; a pseudoaneurysm is contained, so it stays the same.
- In shock, blood is shunted away from the gut and the veins collapse, giving the pattern of the hypoperfusion complex.
| Patient | First study | Next |
|---|---|---|
| Blunt, unstable | FAST at the bedside | Positive: operating room. Negative: look for other sources of bleeding |
| Blunt, stable | CT abdomen and pelvis with IV contrast | Admit and observe; angioembolisation if active bleeding |
| Gunshot, unstable or peritonitis | None; straight to surgery | Laparotomy |
| Stab, stable, no peritonitis | Exam, local wound exploration, FAST | CT; serial examinations |
Differential and pitfalls
- Do not send an unstable patient to CT; FAST and the surgeon decide.
- Free fluid without a solid-organ injury, especially in a man, suggests bowel or mesenteric injury and needs close follow-up.
- A seat-belt bruise across the abdomen goes with bowel and mesenteric injury and with flexion-distraction (Chance) fractures of the lumbar spine.
- Pancreatic and bowel injuries can look subtle on the first CT; repeat imaging or re-examination if pain persists.
- Penetrating trauma: gunshot wounds often go straight to laparotomy; stable stab wounds may be managed with exam, local wound exploration and CT.
Next step
- Unstable with a positive FAST: resuscitate and call the trauma surgeon for laparotomy.
- Stable after blunt trauma: CT of the abdomen and pelvis with intravenous contrast (with chest CT if the mechanism suggests it).
- Active extravasation or pseudoaneurysm in a solid organ or the pelvis: call interventional radiology for angioembolisation and the surgeon.
- Haematuria with a pelvic fracture: ask for a CT cystogram or delayed images to look for bladder injury.
- Signs of shock bowel: alert the team immediately; the patient may be about to collapse.
Test yourself
Think of the answer, then tap the question to see it.
What should happen to an unstable blunt trauma patient with free fluid on FAST?
Resuscitation and immediate laparotomy; the patient should not be taken to the CT scanner.
How can active extravasation be told apart from a pseudoaneurysm on multiphase CT?
Active extravasation is a blush that grows and changes shape on later phases; a pseudoaneurysm keeps its shape and fades like the blood pool.
What are the CT features of the hypoperfusion complex (shock bowel)?
Thick small-bowel wall with bright mucosal enhancement, fluid-filled loops, a flat narrow inferior vena cava, a small aorta and intensely enhancing adrenals.
Why is free fluid without a solid-organ injury worrying after blunt trauma?
It may be the only sign of bowel or mesenteric injury, which CT can show poorly at first, so the patient needs close observation or repeat imaging.
Connections
Educational content; it does not replace a radiologist's report and is not a clinical instruction. Each study is ordered on the patient's assessment and your institution's protocols.
Sources: Blunt Abdominal Trauma (StatPearls (NCBI Bookshelf), 2023); Liver Trauma (StatPearls (NCBI Bookshelf), 2026); Penetrating Abdominal Trauma (StatPearls (NCBI Bookshelf), 2025); Focused Assessment With Sonography for Trauma (StatPearls (NCBI Bookshelf), 2023).
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Representative model, for educational purposes only.