Rectosigmoid diverticulitis complicated by colovesical fistula
Presentation
Afebrile adult patient complains of lower abdominal discomfort and dysuria, with some abnormal sensations during urination (like air coming out, as reported), for at least 2 weeks. There is also a history of intermittent constipation for a long time.
Patient Data
Diffuse irregular circumferential wall thickening affects a long segment of the colon, measuring at least 25 cm in length. This involvement includes the sigmoid, rectum, as well as the anal canal. The maximum wall thickness is observed in the lower part of the rectum, measuring about 1.6 cm, associated with marked adjacent fatty stranding. This fat stranding becomes more prominent in the upper part of the rectum and the distal part of the sigmoid, mainly surrounding multiple air-containing outpouchings arising from the wall of the rectosigmoid part (complicated diverticulitis).
There is evidence of a small gas locule between the anterior wall of the rectosigmoid part of the colon and the posterior superior wall of the urinary bladder. This area shows inflammatory wall thickening and is filled with an intraluminal air-fluid level with a loss of the fatty plane between the posterior wall of the urinary bladder and rectosigmoid junction at this level. This raises the possibility of developing a fistulous tract between the rectosigmoid junction and the urinary bladder (colovesical fistula).
Multiple oval-shaped lymph nodes are noted at para-aortic and bilateral iliac regions, with the largest measuring 17 x 8 mm in the left para-aortic region.
Circumferential atheromatous plaque affects the distal part of the aorta, causing less than 20% stenosis. It is associated with complete occlusion of the left common iliac artery and the absence of contrast flow for a segment of about 4.4 cm. Additionally, there is a calcified plaque in its posterior wall measuring about 1.8 x 0.2 cm, with refilling of the artery with contrast just before the bifurcation, continuing to the left internal iliac artery and external iliac artery. The right common iliac artery shows a partially calcified atheromatous plaque, more prominent at its middle part, causing about 30% stenosis. Multiple interrupted calcified plaques are noted at both internal iliac arteries, more so on the left side.
No measurable free fluid collection is observed.
The prostate is enlarged with no obvious lesion (BPH).
Case Discussion
The above findings suggest an inflammatory process involving the anorectal and sigmoid part of the colon, with complicated diverticulitis and a suspicious colovesical fistula. The possibility of an inflammatory process on top of neoplastic change should be excluded, and histopathological correlation is still pending.
In this case, there is no history of urinary bladder catheterization procedures. Additionally, the presence of a significant air-fluid level in the urinary bladder, associated with adjacent colonic diverticulitis, as well as questionable wall thickening involving the anorectal and sigmoid part of the colon and some loss of the fat plane in between the anterior wall of the rectosigmoid junction and the superior posterior wall of the urinary bladder, with the presence of a small air locule in between, strongly suggests the development of a colovesical fistula.
Colovesical fistula (CVF) is considered one of the most common complications of diverticular disease, inflammatory bowel disease like Crohn's disease, and cancer. Pneumaturia is one of the most common symptoms of CVF, present in about 90% of patients. CT scan provides a sensitivity of about 90% in the diagnosis of CVF.
Surgery is the first-line treatment for such a case, with antibiotic cover before the surgical procedure, as in this case, along with close follow-up and a surgical plan accordingly.
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