Colorectal

The answer

The main differential diagnosis is;

A foreign body, such as a bullett or something retained in the abdomen at the time of the previous operation (broken instrument).
A swallowed foreign body, which has lodged in the wall of the bowel, in a diverticulum, or perforated through the bowel wall.
A peritoneal stone
A faecolith in a diverticulum

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A Kidney stone is unlikely, the density is too low and lateral. Similary a stone in the ureter would not be this lateral.

A gall stone is unlikely, the postion is too lateral. Only 10 - 20 % of gall stones are calcified. They are not usually as dense as this.

Diverticula can occur in the right colon, there is a condition termed isolated caecal diverticulum that probably has a diffent aetiology to the usual colonic diverticulae.

Colo-Rectal

The answer

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