What is the most common cause of colovesicular fistula leading to pneumaturia?

• A. Crohn's disease
• B. Diverticulitis
• C. Transplant rejection
• D. Systemic infection

Answer: (B)

A colovesicular fistula is an abnormal connection between the colon and the bladder. Pneumaturia, or the presence of air in the urine, often indicates the presence of a fistula due to bowel gas escaping into the urinary tract. Among the potential causes of a colovesicular fistula, diverticulitis is particularly noteworthy.

Diverticulitis, which involves inflammation and infection of diverticula in the colon, is a common condition that can lead to the development of a colovesicular fistula. When diverticula become inflamed, they can erode through the bladder wall, creating a pathway for gas and stool to enter the urinary tract, resulting in pneumaturia. This process occurs due to the proximity of the sigmoid colon to the bladder.

While other options like Crohn's disease could also lead to fistula formation, diverticulitis is statistically the most prevalent cause in the general population, especially in older adults. This is critical because diverticulitis is a common gastrointestinal condition that often leads to complications, including fistula formation, making it a key focus when evaluating pneumaturia's underlying causes.