The most likely cause
Five weeks after an attack of sigmoid diverticulitis, he reports cloudy urine and air bubbles at the end of urination, and he does not have diabetes. Pneumaturia (air in the urine) and cloudy urine after diverticulitis point to a colovesical fistula, in which the inflamed sigmoid colon erodes into the bladder and lets gas and stool enter the urine. The diagnosis is confirmed by CT, and the fistula usually needs elective surgical resection.
How the fistula forms
The sigmoid colon lies close to the dome of the bladder. In diverticulitis, inflammation can extend through the colonic wall and form a local abscess or adhesion against the bladder. Over time, this inflammatory process erodes through both walls and creates an abnormal tract. Because the colon contains gas and stool, these pass into the bladder, producing pneumaturia and fecaluria (stool particles, seen as cloudy or debris-filled urine). Recurrent urinary tract infections with mixed bowel organisms are another clue. Colovesical fistula is one of the recognized complications of diverticulitis, alongside abscess, perforation, obstruction, and bleeding. It is more common in men because in women the uterus lies between the sigmoid and the bladder.
Why the other options are less likely
An ileovesical fistula occurs mainly with Crohn's disease, which involves the small bowel; after sigmoid diverticulitis, the sigmoid colon is the source. A pericolic abscess pressing on the bladder may cause frequency or discomfort, but pressure alone does not put gas into the urine; gas requires a direct connection or gas-producing organisms. Gas-forming cystitis (emphysematous cystitis) is rare and occurs mostly in clients with diabetes, which he does not have. In this context, a colovesical fistula is far more likely.
| Finding | Suggests |
|---|
| Air in urine after diverticulitis | Colovesical fistula |
| Stool or debris in urine | Fecaluria from a bowel-bladder tract |
| Recurrent UTI with bowel organisms | Ongoing contamination through a fistula |
Nursing application
The nurse reports the findings, collects urine specimens as ordered, prepares the client for CT, and explains that elective resection of the diseased sigmoid with repair of the bladder is the usual treatment. The nurse also monitors for urinary infection and teaches the client to report fever or flank pain.
Exam takeaway
Key point Pneumaturia after diverticulitis equals colovesical fistula until proven otherwise. Link the sigmoid to the bladder, and Crohn's disease to the ileum.