Pneumoperitoneum from perforated diverticulitis

Case contributed by Dr Foroogh Jafari Mousavi


Presents with abdominal pain and presyncope post two loose bowel motions. Abdominal guarding and percussion tenderness. Lactate 4.0.

Patient Data

Age: 68
Gender: Male

Lateral: crescent-shaped locule of free air under the diaphragm, anteriorly. Note marked lucency of this locule  compared to air in the GI tract posteriorly that can help differentiating free air form intra-luminal air. 

Frontal: linear lucency under left hemi-diaphragm in keeping with free air. 

There is significant thickening of the proximal sigmoid colon which contains numerous diverticula; marked fat stranding in the left iliac fossa adjacent to the sigmoid colon and free fluid in rectovesical pouch. The findings are in keeping with diverticulitis.

Multiple locules of free gas are seen in the left iliac fossa, adjacent to the sigmoid colon in keeping with perforation. In addition, there are multiple locules of gas of various sizes below the diaphragm and adjacent to anterior abdominal wall.

 Gastrostomy/PEG tube is in-situ. The gallbladder contains a calcified calculus in the fundus.

Case Discussion

Typically free air under the diaphragm has a linear shape but in this case it has a crescent shape and could be misinterpreted as intraluminal on lateral film. 

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Case information

rID: 39472
Case created: 6th Sep 2015
Last edited: 21st Aug 2017
Inclusion in quiz mode: Included

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