Rectourethral Fistula: Causes, Signs, and Treatment

A rectourethral fistula is an abnormal tunnel connecting the rectum to the urethra, allowing stool, gas, or urine to pass between the two in ways the body was never designed for. Most cases in adults develop after treatment for prostate cancer, whether from surgery or radiation, though trauma, inflammatory bowel disease, and other pelvic conditions can also be responsible. The condition is rare enough that no standardized treatment protocol exists, yet the physical and emotional toll on those affected is significant, and the surgical options available today can close the fistula in the majority of cases.

How Rectourethral Fistulas Develop

The vast majority of rectourethral fistulas in adults are acquired rather than something a person is born with. The most common cause is injury during or after prostate cancer treatment. Radical prostatectomy, the surgical removal of the prostate gland, carries a small but real risk: studies report a prevalence of roughly 0.03% across various surgical series.¹ That number sounds tiny, but given how many prostatectomies are performed worldwide each year, a steady stream of men end up dealing with this complication.

Radiation therapy for prostate cancer is the other major culprit. The mechanism is different from surgical injury. Radiation damages the tiny blood vessels in the tissue between the rectum and urethra, causing ongoing inflammation, scarring, and thinning of the tissue over time. Acute mucosal damage gives way to chronic fibrosis, and the weakened tissue can eventually break down into ulcers, perforations, and ultimately a fistula connecting the two structures.² This process can unfold months or even years after radiation treatment ends, which is why some patients are blindsided by symptoms long after they thought their cancer treatment was behind them.

Less common causes include Crohn’s disease, pelvic trauma such as straddle injuries or penetrating wounds, infection, and pelvic malignancy itself.³ Other prostate procedures like transurethral resection and high-intensity focused ultrasound have also been reported as causes, though they account for a much smaller share of cases than radical prostatectomy or radiation.⁴

Congenital Rectourethral Fistulas in Newborns

Not every rectourethral fistula stems from a medical procedure gone wrong. Some boys are born with one as part of a group of birth defects called anorectal malformations, which occur in roughly 1 in 5,000 births.⁵ In these cases, the connection between the rectum and urethra forms during fetal development because the structures that should have separated did not fully do so. These malformations vary widely in severity and anatomy, and each child’s treatment is individualized based on the specific defect.

Surgical repair in children typically uses a posterior sagittal approach, meaning the surgeon accesses the fistula through an incision between the buttocks. Long-term follow-up after these repairs is generally encouraging.⁶ However, children born with anorectal malformations often face ongoing challenges with bowel control and, in some cases, urinary function that extend well into adulthood. Psychosocial concerns are also real: repeated medical interventions, continence issues, and worries about hygiene and body image can take a toll on self-esteem. Starting bowel management programs early helps reduce fecal incontinence and the social stigma that comes with it.⁷

Recognizing the Symptoms

The hallmark signs of a rectourethral fistula are hard to miss once you know what to look for, but they can initially be mistaken for other conditions. The most common symptoms are passing gas through the urethra during urination (pneumaturia), stool or fecal-tinged material appearing in the urine (fecaluria), and urine leaking from the rectum, which patients sometimes interpret as watery diarrhea.⁴ Recurrent urinary tract infections are another red flag, since bacteria from the bowel gain easy access to the urinary system through the fistula.

Some patients notice only one or two of these symptoms initially, particularly if the fistula is small. The condition worsens without treatment as the abnormal connection rarely heals on its own, and ongoing contamination of the urinary tract can lead to serious infections. Anyone who has had prostate cancer treatment and develops unexplained urinary symptoms, especially gas in the urine or fecal-looking material when urinating, should bring it up with their doctor without delay.

How the Diagnosis Is Confirmed

Doctors typically suspect a rectourethral fistula based on the symptoms and the patient’s history of prostate treatment, but imaging is needed to confirm the diagnosis, pinpoint the fistula’s exact location, and determine its size. A contrast study called a cystogram, where dye is introduced into the bladder and X-rays or CT scans are taken, is one common approach. CT imaging with detailed reconstructions can reveal whether the fistula involves just the urethra or extends to the bladder, which makes a significant difference in treatment planning.⁸ MRI provides excellent soft-tissue detail and is helpful for assessing the surrounding tissue quality, particularly whether radiation damage has compromised the area. Endoscopy of the rectum and urethra allows direct visualization of the fistula openings from both sides.

Accurate preoperative evaluation is critical because fistula size, surrounding tissue health, the presence of urethral narrowing, and whether the patient has received radiation all influence which surgical approach has the best chance of success.⁹ Surgeons also need to know whether the cancer has been controlled, since repairing a fistula while active cancer remains is a different proposition altogether.

Why Most Fistulas Need Surgery

A rectourethral fistula closing on its own is rare. Most cases require reconstructive surgery, and the literature describes more than 40 different surgical approaches, reflecting just how varied these fistulas can be in size, location, and tissue quality.⁹ In occasional situations, particularly when the fistula is very small and involves only the urethra with no bladder involvement, conservative management with prolonged catheter drainage may allow healing. One case report documented successful closure simply by resting the urethra with a catheter left in place for a month.⁸ But these conservative successes are the exception, not the rule.

Before definitive repair, most patients undergo a temporary colostomy, which diverts stool away from the fistula site to reduce contamination and give the area the best chance of healing after surgery. A urinary catheter is also placed to divert urine. These diversions are generally temporary and reversed after the fistula repair has healed, though reversal timelines vary.

The Transperineal Approach With Gracilis Flap

Among the many surgical techniques described, the transperineal approach with a gracilis muscle flap interposition has emerged as the most commonly used method for complex rectourethral fistulas. A systematic review covering more than 500 patients found that this technique was the dominant approach across the studies analyzed.¹⁰ The operation is performed through an incision in the perineum, the area between the scrotum and the anus. The surgeon separates the rectum from the urethra, closes each defect individually, and then swings a gracilis muscle from the inner thigh into the space between them to serve as a barrier of healthy, well-vascularized tissue.

Success rates with this technique are consistently high. One series of 21 patients reported a 95% success rate for fistula closure.¹¹ Another series found that all patients achieved successful closure at a mean follow-up of roughly two years, with no recurrences.¹² An earlier study of 12 gracilis transpositions reported that 10 out of 12 flaps (about 83%) resulted in complete healing on the first attempt, with the remaining two needing additional procedures before achieving full closure. All patients eventually had their diverting colostomies reversed.¹³

A smaller transperineal series of seven patients with a mean fistula size of about 2.8 centimeters reported no recurrences at roughly 11 months of follow-up. Three of those patients had their colostomies reversed, one was awaiting reversal, and three had permanent colostomies related to the complexity of their situation.¹⁴

Why Radiation History Changes the Picture

Whether a patient has received pelvic radiation is arguably the single most important factor in predicting how the repair will go. Radiation-damaged tissue has compromised blood supply, is prone to scarring and poor healing, and is more likely to develop concurrent problems such as urethral narrowing. A large comparative study of 74 patients found that all non-irradiated fistulas were successfully closed with a single procedure, compared to 84% of radiation-related or ablation-related fistulas. Concurrent urethral strictures were present in about 28% of the radiated group versus 11% of the non-radiated group.¹⁵

Irradiated patients also tend to need more complex operations. One study found that those with radiation-related fistulas frequently required gracilis flap interposition (38%) or even full pelvic exenteration (19%), while non-irradiated patients were more likely to be treated with a simpler transanal approach.¹⁶ A history of radiation and preexisting urinary incontinence have both been identified as factors associated with fistula recurrence after repair.¹⁷ The systematic review of over 500 patients echoed these findings, noting that irradiated patients consistently had higher complication rates, worse healing, and more frequently required additional operations or permanent urinary diversion.¹⁰

Robotic and Minimally Invasive Repair

Although open transperineal surgery remains the workhorse for rectourethral fistula repair, robotic-assisted and laparoscopic approaches are being explored at specialized centers. A series of 15 patients treated with either robotic or laparoscopic repair reported no recurrences at 12 months of follow-up, with a median hospital stay of four days and no intraoperative complications.¹⁸ In two patients who developed fistulas after focal prostate cancer treatment, robotic-assisted repair combined with salvage prostatectomy and omental flap placement achieved successful closure confirmed at follow-up.¹⁹

These approaches offer the potential benefits of smaller incisions, less pain, and faster recovery, though the numbers are still too small to draw firm comparisons with traditional open repair. The available evidence is encouraging, but robotic fistula repair remains a niche procedure performed mainly at high-volume centers with surgeons experienced in complex pelvic reconstruction. For now, the choice between open and minimally invasive repair depends heavily on the surgeon’s expertise and the specifics of the fistula.

Life After Repair

Closing the fistula is the primary goal, but the story does not end there. Even after successful repair, many patients deal with ongoing urinary or bowel symptoms. One study of men who underwent transperineal repair with gracilis flap and were followed for an average of nearly four years found that about 80% had some degree of urinary incontinence, though this was mostly mild and occasional. About half reported perineal pain, and roughly 43% had some issue related to the muscle flap donor site. Still, 80% said the surgery had positively impacted their life, and not a single patient said they would have chosen permanent urinary diversion instead.²⁰

A separate quality-of-life study painted a similar picture. About 75% of patients reported some urinary incontinence, though only a small fraction described it as constant. Fecal outcomes were generally better than urinary ones. Colostomy reversal typically happened around four months after the repair.²¹ These results are worth putting in context: the patients entering fistula repair have already been through cancer treatment and are dealing with a complication that profoundly disrupts daily life. By that standard, eliminating the fistula and achieving functional bowel and bladder control, even if imperfect, represents a meaningful improvement.

Mild numbness along the inner thigh where the gracilis muscle was harvested is a known side effect, reported in a minority of patients, but it tends to be well-tolerated and does not interfere with walking or leg function.¹³ More serious complications such as recurrent fistula, wound infection, or bladder neck contracture occur in a small percentage of cases and may require additional procedures.

Finding the Right Surgeon

Because rectourethral fistulas are uncommon and the surgical options are varied, expertise matters enormously. The literature describes over 40 different approaches, ranging from simple transanal repairs to complex multi-stage reconstructions involving tissue flaps, bowel grafts, and urinary diversion. No single technique works for every patient, and the best approach depends on fistula size, location, tissue quality, radiation history, and whether there are concurrent problems like urethral strictures or bladder neck scarring.⁹

If you or someone you know is facing this diagnosis, seeking out a surgeon or center that handles these cases regularly is worth the effort, even if it means traveling. High-volume centers tend to have multidisciplinary teams involving urologists, colorectal surgeons, and sometimes plastic surgeons who work together on the reconstruction. The difference between a first-time repair and a redo operation after a failed attempt is significant: tissue quality deteriorates with each intervention, and success rates are generally lower for revision surgery. Getting it right the first time, with the right team, makes a real difference in outcomes.