Retroperitoneum
Read Your Scan Editorial Team·Last updated
Written from published radiology references and reviewed for plain language. Not written or signed by a physician, and not a diagnosis. How we write these pages →
In plain language
The area at the back of the abdomen containing the kidneys, major vessels, and some lymph nodes.
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Where you'll see this
This wording turns up on Abdominal CT reports — CT imaging of the abdomen. An abdominal CT shows the liver, gallbladder, pancreas, spleen, kidneys, bowel, blood vessels, and lymph nodes in fine detail. Doctors order it for abdominal pain, to look into a suspected stone, infection, or blockage, or to check known findings. Because it is so detailed, it often notes small, harmless things by chance. The report describes what the images show; your doctor reads it together with your symptoms and other results.
Questions worth asking your doctor
- What was the main reason for this CT, and did it answer that question?
- Were any findings incidental, and do any of them need follow-up?
- If a stone or cyst was seen, does it need treatment or monitoring?
- Do the results change my current care or medications?
- Is there anything I can do about findings like fatty liver?
How common is this?
The retroperitoneum is the compartment at the back of the abdomen, behind the membrane that lines the abdominal cavity. It holds the kidneys, the adrenal glands, the aorta and the major veins, part of the pancreas and a portion of the bowel. The word appears on abdominal CT and MRI reports constantly, because organising the abdomen into compartments is how radiologists work through it.
When should I worry?
Naming the compartment is routine and carries no meaning on its own. Where it matters is that the location of a finding is a strong clue to what it is: something arising in the retroperitoneum has a different list of likely explanations from something in the peritoneal cavity in front of it, so the word helps narrow the possibilities rather than describing a problem. The specific phrase worth understanding is retroperitoneal bleeding, which is significant because the space can hold a large volume with few outward signs — but that would be reported explicitly and urgently, not left as an anatomical mention.
What happens next
Nothing follows from the anatomical term. What follows comes from whatever was described there. If a report mentions the retroperitoneum only in the course of listing what was examined, that is the radiologist recording that they looked — which is more useful to the referring doctor than silence.
Frequently asked questions
- What organs are in the retroperitoneum?
- The kidneys and adrenal glands, the aorta and inferior vena cava, most of the pancreas, the ureters and parts of the duodenum and colon. They sit behind the membrane lining the abdominal cavity rather than within it.
- Why does the report mention it if nothing is wrong?
- Because radiologists work through the abdomen compartment by compartment and record what they examined. Naming a region and describing it as normal is a positive statement that it was assessed.
- Why does the compartment matter for diagnosis?
- Because where something arises narrows what it is likely to be. A mass in the retroperitoneum has a different list of probable explanations from one in the cavity in front of it, so establishing the compartment is often the radiologist’s first step in characterising a finding.
Other words on the same report
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