CT Interpretation: Abdomen/Pelvis

As with the systematic approach preferred for the evaluation and management of other processes explored on this site, a similarly structured method for the interpretation of imaging commonly obtained in the emergency department may afford the same benefits – namely, the timely identification of pathology while avoiding costly missed diagnoses. In this post, I propose an approach to the interpretation of computed tomography of the abdomen and pelvis.

Aorta Down

Thoracic Aorta

Thoracic Aorta

Start with the descending thoracic aorta

Abdominal Aorta

Abdominal Aorta

Follow the abdominal aorta down including its branches (celiac, SMA, paired renal arteries, IMA)

Aortic Bifurcation

Aortic Bifurcation

Continue to the bifurcation of the abdominal aorta to the left and right common iliac arteries

Veins Up

Femoral Veins

Femoral Veins

Start with the left and right femoral veins

Inferior Vena Cava

Inferior Vena Cava

Follow the inferior vena cava up

Infrahepatic IVC

Infrahepatic IVC

The inferior vena cava gains contrast from the renal veins

Right Atrium

Right Atrium

The inferior vena cava empties into the right atrium

Solid Organs Down

Heart and Pericardium

Heart and Pericardium

Evaluate for the presence of a pericardial effusion or cardiomegaly

Spleen

Spleen

Heterogenous contrast-enhancement is normal

Pancreas

Pancreas

The tail of the pancreas lies in the hilum of the spleen

Liver

Liver

Evaluate the intrahepatic bile ducts for dilation or pneumobilia, portal venous system for gas, and liver parenchyma for vascular abnormalities or abscesses

Gallbladder

Gallbladder

Evaluate for radioopaque stones, pericholecystic fluid or surrounding fat stranding

Adrenal

Adrenal

A wishbone-shaped structure superior to the kidneys

Kidney and Ureter

Kidney and Ureter

Evaluate for hydronephrosis or hydroureter

Bladder

Bladder

Continue down into the pelvis; in a female patient the evaluation should include the uterus and adnexa

Rectum Up

Rectum

Rectum

Having reached the inferior-most portion of the image following solid organs, move upward again from the rectum

Sigmoid

Sigmoid

Evaluate the sigmoid colon for diverticulitis

Transverse

Transverse

Continue following the sigmoid colon up the descending colon to the transverse colon and the hepatic flexure

Cecum

Cecum

Continue down the ascending colon to the cecum

Appendix

Appendix

At the cecum, attempt to identify a small tubular structure (the appendix) - evaluate for periappendiceal fat stranding, perforation or abscess

Esophagus Down

Esophagus

Esophagus

Start at the esophagus, evaluate for perforation or hernia

Stomach

Stomach

Continue to the stomach and duodenum

Small Bowel

Small Bowel

Evaluate the small bowel for obstruction (dilation, air-fluid levels)

Tissue-specific Windows

Lung Window

Lung Window

Switch to lung window to evaluate the lung parenchyma and continue through the abdomen to identify intraperitoneal free air

Bone Window

Bone Window

Use the bone window to identify fractures or lytic lesions

Try It Yourself

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CT Abdomen/Pelvis Interpretation

  • Cystic lesion in the inferior right lobe of the liver most consistent with hepatic abscess.
  • Multiple calcified gallstones in the gallbladder.