Diverticulitis can cause a urinary tract infection (UTI), but only through a specific and serious complication called a colovesical fistula. This abnormal connection allows bacteria from the colon to directly enter the sterile environment of the bladder. The vast majority of diverticulitis cases do not lead to a UTI; the connection requires advanced inflammation and tissue erosion to create a pathway between the two organs.
Understanding Diverticulitis and Urinary Tract Infections
Diverticulitis involves the inflammation or infection of small pouches, known as diverticula, that form in the wall of the large intestine. These pouches are most commonly found in the sigmoid colon, the lower section of the large bowel located near the bladder. When fecal matter or bacteria become trapped in these pouches, it leads to acute inflammation and infection.
A urinary tract infection (UTI) is a microbial infection, most often caused by bacteria, affecting any part of the urinary system. UTIs typically occur when bacteria from the digestive tract enter the urethra and travel upward to the bladder, causing an infection called cystitis. The bladder is normally a sterile environment.
The Mechanism of Bacterial Transfer
The direct link between diverticulitis and a UTI is the development of a colovesical fistula, an abnormal passage connecting the inflamed colon to the bladder. This complication results from severe, complicated diverticulitis, often leading to a localized abscess near the colon wall. Diverticular disease is the most common cause of these fistulas, accounting for over two-thirds of cases.
As the infection and inflammation intensify, the diseased tissue adheres to the nearby bladder wall. Persistent inflammation and erosion eventually break down the separating tissue layers, creating an open channel. This pathway allows the high bacterial load and contents of the colon, including enteric bacteria like E. coli, to contaminate the bladder. The transfer of colonic bacteria results in a persistent and complicated UTI that is difficult to clear because the fistula creates a continuous source of infection.
Recognizing Symptoms of the Specific Complication
Symptoms indicating a colovesical fistula are distinct from a standard UTI. A hallmark sign is pneumaturia, the passage of gas or air bubbles while urinating, which occurs because the fistula allows gas produced by colonic bacteria to enter the bladder.
Another highly specific symptom is fecaluria, the presence of fecal matter in the urine, which may appear brownish or cloudy. Patients also typically experience recurrent UTIs that do not respond permanently to antibiotics, since the source of contamination remains open. These symptoms are often accompanied by general urinary complaints such as painful urination (dysuria) and increased urinary frequency. The presence of air or stool in the urine clearly distinguishes a fistula-related problem from an uncomplicated bladder infection and should prompt immediate investigation.
Diagnosis and Treatment of the Connection
Confirming a colovesical fistula requires specific diagnostic imaging to visualize the abnormal tract. A computed tomography (CT) scan of the abdomen and pelvis is the initial and preferred test, often performed with contrast material. The scan can reveal air within the bladder, thickening of the bladder wall, and inflammation surrounding the colon.
Other tests may be employed to confirm the diagnosis and determine the underlying cause. A cystoscopy involves inserting a thin, lighted tube into the bladder to visually inspect the lining for the fistula opening. A colonoscopy is also necessary to rule out other causes, such as colorectal cancer or Crohn’s disease.
The definitive treatment for a colovesical fistula resulting from diverticulitis is surgical intervention. The primary goal is to remove the diseased section of the colon containing the fistula, known as a sigmoid colectomy or colon resection. The opening in the bladder is then closed and repaired.
Antibiotics manage the ongoing UTI but only provide temporary relief, as they do not close the source of the infection. Surgical repair is necessary to permanently stop the flow of bacteria and is often performed in a single stage, leading to a high success rate and resolution of the recurrent UTI.