Clinical History
The occurrence of an enterovesical fistula is most commonly seen, secondary to diverticulitis. A colovesical fistula formation most frequently occurs between the sigmoid colon and the dome of the
bladder. Plain films showing the presence of air within the urinary bladder provide supportive evidence. A definitive diagnosis is achieved with a CT scan, with the point of fistula formation often
being demonstrated.
Imaging Findings
A 75-year-old female presented with a 3-week history of dysuria, altered bowel habits and abdominal pain. She also had symptoms of weight loss and lethargy. A clinical examination was done, and it
revealed a distended abdomen with increased bowel sounds throughout. No hernias could be detected clinically. An erect chest radiograph was taken, which demonstrated the presence of multiple
metastatic lesions but no free air was found under the diaphragm. The abdominal radiograph demonstrated the presence of air within the bladder and the distended loops of the small bowel (Fig. 1). A
CT scan of the abdomen and the pelvis was performed with an intravenous contrast. Fig. 2 clearly demonstrates the presence of air within the urinary bladder, which is indicative of a colovesical
fistula. The point of the fistula can be most clearly identified on the sagittal image (Fig. 3). A small bowel obstruction is also clearly demonstrated. There is also a thickening of the sigmoid,
consistent with an indication of sigmoid carcinoma (Fig. 4). Metastatic liver disease and chest metastases can also be identified (Fig. 5). As the patient represented a significant surgical risk, due
to the possibility of an associated comorbidity, she was treated conservatively.
Discussion
A colovesical fistula is the commonest form of a vesico-enteric fistula and is most frequently located between the sigmoid colon and the dome of the bladder. Diverticulitis accounts for 50%–70%
of cases of vesico-enteric fistula, with malignancy, Crohn's disease, radiotherapy and trauma accounting for the remainder. Pneumaturia, faecaluria and recurrent urinary tract infections are the most
common presenting symptoms. A cystoscopy has a sensitivity of 89% for the diagnosis of vesicocolic fistula and this is regarded as the first line investigation. A computed tomography scan has a
sensitivity ranging between 40% and100%. A barium enema is also useful, with a sensitivity of 20%–62.5%. In addition to documenting the fistula, a CT scan provides important intra-luminal and
extra-luminal pathological findings, which are helpful for planning subsequent surgery. A CT scan should be included in the evaluation of patients with suspected vesicocolic fistula. The treatment of
choice is primary resection of the colon with anastomosis, performed as a one stage procedure involving either a simple closure, use of an omental flap, or resection and closure of the bladder
defect. In those not fit enough for surgery, supportive measures including the administration of intravenous antibiotics are the preferred option.
Differential Diagnosis List
Vesicocolic fistula secondary to sigmoid carcinoma.
Final Diagnosis
Vesicocolic fistula secondary to sigmoid carcinoma.
