What is the most common cause of pneumaturia?

The Most Common Cause of Pneumaturia

Diverticular disease is the most common cause of pneumaturia, accounting for approximately 65-88% of enterovesical fistulas that lead to this symptom. 1, 2

Understanding Pneumaturia

Pneumaturia refers to the passage of gas in the urine and is considered a pathognomonic sign of an abnormal communication between the intestine and the urinary tract, known as an enterovesical fistula (EVF). This condition represents a challenging clinical entity that requires prompt diagnosis and appropriate management.

Clinical Presentation of Enterovesical Fistulas

Patients with enterovesical fistulas typically present with:

• Pneumaturia (68-80% of cases) 3, 2
• Fecaluria (28-41% of cases) 3, 2
• Recurrent urinary tract infections (32-47% of cases) 3, 2
• Dysuria (64% of cases) 3

Etiology of Pneumaturia

The most common causes of enterovesical fistulas leading to pneumaturia include:

1. Diverticular disease (65-88%) - By far the most common cause 1, 2
2. Colorectal carcinoma (16-20%) 3, 4
3. Crohn's disease (7-9%) 3, 2
4. Radiation enteritis (rare)
5. Bladder carcinoma (5%) 4
6. Other causes (trauma, iatrogenic injury, etc.)

Diagnostic Approach

The diagnosis of enterovesical fistulas can be challenging and often delayed. The most useful diagnostic tests include:

• Cystoscopy - Highest diagnostic yield (74-79%) 3, 4
• CT scan of abdomen/pelvis - Diagnostic yield of 52-80% 3, 2
• Colonoscopy - Useful for identifying the intestinal component 2

Management

While conservative management with antibiotics may be attempted in selected patients, surgical intervention is required in approximately 90-97% of cases 3, 2. The surgical approach typically involves:

• Resection of the affected bowel segment
• Primary anastomosis with or without temporary ostomy
• Bladder repair (if necessary)

Laparoscopic approaches have recently shown promising results with good outcomes and lower morbidity.

Gender Distribution

Interestingly, enterovesical fistulas occur more commonly in men than women, with a male-to-female ratio of approximately 2.4:1 4. This may be related to the protective effect of the uterus and adnexa in women, which can prevent direct communication between the colon and bladder.

Key Points to Remember

• Pneumaturia is pathognomonic for enterovesical fistulas
• Diverticular disease is the predominant cause
• The classic triad of pneumaturia, fecaluria, and recurrent UTIs should prompt investigation for an enterovesical fistula
• Surgical management is usually required and has good outcomes with low recurrence rates

Understanding the common causes of pneumaturia is essential for appropriate diagnosis and management of this condition, with diverticular disease being the most frequent etiology.