If you’re seeing what looks like stool, brown debris, or dark particles in your urine, you likely have an abnormal connection between your bowel and your bladder called a fistula. This passage allows intestinal contents to leak directly into the bladder and come out when you urinate. The medical term for this is fecaluria, and it is not normal. It requires medical evaluation because it won’t resolve on its own and can lead to serious infections.
What a Bowel-to-Bladder Fistula Is
A fistula is a tunnel that forms between two organs that aren’t supposed to be connected. When one develops between the colon and the bladder (called a colovesical fistula), stool, gas, and bacteria from the intestines can pass into the bladder. This means you may notice fecal material in your urine, air bubbles when you pee, urine that smells unusually foul, or dark debris floating in the toilet bowl.
You might also pass gas through your urethra, which can feel like bubbles during urination. This symptom, called pneumaturia, is one of the hallmark signs. Many people with this condition also develop repeated urinary tract infections because gut bacteria are constantly entering the bladder.
The Most Common Causes
Over two-thirds of bowel-to-bladder fistulas are caused by complicated diverticulitis. Diverticulitis happens when small pouches in the colon wall become inflamed or infected. In severe cases, the inflammation erodes through the colon and into the neighboring bladder, creating a fistula. This is by far the most frequent scenario.
The second most common cause is cancer, accounting for 10% to 20% of cases. Colon adenocarcinoma is the typical culprit, though tumors in other pelvic organs can also grow into the bladder wall. In some cases, a fistula is actually the first sign that a cancer exists. Crohn’s disease is the third most common cause, responsible for 5% to 7% of cases, typically after years of chronic intestinal inflammation.
Less common causes include prior pelvic surgery, radiation therapy, abdominal trauma, and tuberculosis.
Symptoms Beyond Fecal Matter in Urine
Fecaluria is the most alarming symptom, but it’s often not the first one people notice. The full picture tends to include:
- Recurrent urinary tract infections that keep coming back despite antibiotic treatment
- Air bubbles in urine (pneumaturia), especially noticeable at the start or end of urination
- Foul-smelling or cloudy urine that doesn’t improve with hydration
- Pain above the pubic bone, sometimes with a feeling of pressure or urgency
- Blood in the urine
- Frequent, painful urination with a sense of incomplete emptying
This cluster of symptoms is sometimes called Gouverneur syndrome: suprapubic pain, urinary frequency, painful urination, and straining. Because the symptoms overlap with common UTIs and prostate problems, misdiagnosis is a real issue. One published case describes a patient bounced between clinics and misdiagnosed with conditions ranging from ulcerative colitis to a psychiatric illness before the fistula was identified.
How It Gets Diagnosed
A CT scan is the first and most useful test. It can detect the fistula tract itself, identify the underlying cause (diverticulitis, tumor, or Crohn’s), spot inflammation outside the bowel, and help plan surgery. Its diagnostic accuracy ranges from 60% to 100% depending on the size and location of the fistula.
Other tests are less reliable on their own. Cystoscopy (a camera inserted into the bladder) fails to find the fistula in more than half of patients, often showing only swelling near the tract. Colonoscopy detects the bowel side of the fistula in fewer than 10% of cases. Barium enema, an older imaging method, catches only 20% to 35% of fistulas.
One surprisingly effective test is the poppy seed test. You swallow about 50 milligrams of poppy seeds and then collect your urine over the next 24 to 48 hours. If seeds appear in your urine, the connection between bowel and bladder is confirmed. This simple test has a detection rate of 95% to 100%, outperforming CT, colonoscopy, and cystoscopy. Some facilities use a similar approach with activated charcoal: if your urine turns black after swallowing charcoal, the fistula is confirmed.
Why It Needs Treatment
A bowel-to-bladder fistula doesn’t heal on its own. As long as the connection exists, bacteria from the colon keep entering the urinary tract. What starts as recurring UTIs can progress to urosepsis, a life-threatening bloodstream infection that originates in the urinary system. Left untreated, repeated infections can cause kidney damage and, in severe cases, kidney failure.
What Surgery Looks Like
Surgery is the standard treatment. The goal is to remove the diseased section of bowel, close the fistula, and restore normal anatomy. For diverticulitis-related fistulas, this typically means removing the affected portion of the sigmoid colon and reconnecting the healthy ends. In most cases, the bladder wall heals on its own once the fistula is divided, without needing a separate repair.
The procedure can be done as open surgery or laparoscopically. Laparoscopic surgery is increasingly common, though the inflammation and scar tissue around the fistula can make it technically challenging. If the tissues are severely inflamed or fragile, surgeons may create a temporary ostomy (a small opening in the abdomen where stool is collected in a bag) to let everything heal before reconnecting the bowel. This is usually reversed in a later procedure.
When cancer is the underlying cause, surgery is more extensive. The tumor and surrounding tissue need to be removed in one piece, and the approach is designed to avoid disturbing the tumor during the operation.
Recovery from fistula repair varies depending on the surgical approach and the underlying cause. Open surgery generally requires a longer hospital stay and slower return to normal activity than laparoscopic procedures. Either way, you’ll have a urinary catheter in place for a period after surgery while the bladder heals, and your bowel function will take days to weeks to normalize. Most people see complete resolution of their urinary symptoms once the fistula is repaired.