Presentation
Recent extended right hemicolectomy for distal transverse colon cancer. Unwell post-operatively. Raised temperature and inflammatory markers. ?collection
Patient Data
Surgical drain with tip in left upper quadrant. Unremarkable ileocolic anastomosis. Small volume of free fluid. Fluid collection with enhancing margins in Pouch of Douglas. Well defined "collection" in lower abdomen/pelvis with multiple bubbles of gas dispersed throughout and multiple dense curvilinear structures within.
The urinary bladder has been catheterized. No small bowel dilatation. Bilateral lung basal atelectasis and pleural effusions. Diffuse hepatic steatosis.
Case Discussion
The collection in the lower abdomen/pelvis does not have the typical appearances of a post-operative abscess, particularly the pattern of gas distribution and the multiple dense curvilinear structures. The findings are, however, typical of a retained surgical swab, known as a gossypiboma. The swab contains dense linear strands which are seen as the curvilinear structures, and organization of a granulation membrane leads to formation of a collection that resembles an abscess. The dispersed bubbles of gas are trapped within the cotton mesh, whereas a typical abscess due to a leak from an anastomosis would have more air in the non-dependent portion. The findings were confirmed at re-operation and the 'mass' was removed.
Note that surgical hemostatic material is another item that is often confused for abscesses, particularly as both are seen in post-operative imaging of patients who have undergone complex procedures with a stormy post-operative course. The best diagnostic tool is being told that it has been used in the request, but other tips include identifying a geographic distribution of gas bubbles, polygonal shapes, and a relative lack of change over serial imaging studies.