What Is a Rectoperineal Fistula and How Is It Treated?

A rectoperineal fistula is an abnormal tunnel connecting the rectum to the skin of the perineum, the soft tissue area between the genitals and the anus. In most cases it is present from birth as a form of anorectal malformation, making it one of the conditions newborn screening is designed to catch. Although it sits on the milder end of the anorectal malformation spectrum, the word “mild” can be misleading: without surgical repair, the fistula causes chronic stool leakage, skin breakdown, and recurring infections that affect quality of life for years.

Why It Happens

The majority of rectoperineal fistulas are congenital, meaning a baby is born with one. During early fetal development, a tissue partition called the urorectal septum is supposed to divide the shared hindgut tube into a urinary tract in front and a rectal tract behind. When that partition develops abnormally, the rectum can end up connecting to structures it should not, including the urinary tract, the genital tract, or the perineal skin. A rectoperineal fistula is the result when the abnormal opening lands on the perineum itself.¹ In these babies the true anus may be absent or displaced forward, and stool exits partly or entirely through the fistula tract.

Less commonly, a rectoperineal fistula can develop later in life. In adults it sometimes appears as a complication after pelvic surgery, after childbirth injuries, or following failed repairs of nearby fistulas such as rectovaginal fistulas. One single-center series of women who underwent gracilis muscle flap repair for failed rectovaginal fistula closures documented a delayed rectoperineal fistula as one of the postoperative complications.² Chronic perianal abscesses and Crohn’s disease can also produce fistula tracts that reach the perineal skin, though these are typically classified separately from the congenital form.

Telling It Apart from a Normal Anus or Other Anomalies

Newborn exams can be surprisingly tricky in this area. A group of specialists from the ARM-Net Consortium worked to clarify the definitions because clinicians were confusing several related but distinct diagnoses. Their consensus defined a perineal fistula as an anus that is located abnormally forward on the perineum and is not completely surrounded by the sphincter muscle complex. The opening can look nearly normal-sized or it can be narrowed, which they further classify as “non-stenotic” or “stenotic.”³

This matters because the treatment path changes depending on the diagnosis. An anterior anus with a normal sphincter complex may not need surgery at all, while a true perineal fistula nearly always does. A congenital anal stenosis, where the anus is in the right place but simply too narrow, calls for dilations rather than reconstruction. Misidentifying one condition as another can lead to unnecessary or insufficient surgery, so the physical exam findings and imaging need to match up before the surgical team commits to a plan.

How It Is Diagnosed

In newborns the diagnosis usually starts at the bedside. The examining doctor notices that the baby has no normal-appearing anus, or that meconium (the first stool) is appearing from an abnormal opening on the perineum. In some cases a thin membrane of skin called a “bucket-handle” partially covers the fistula, which can delay recognition by a few hours or even days.

Imaging confirms the anatomy before surgery. In pediatric patients, a distal colostogram, where contrast dye is injected through a temporary colostomy, is the gold standard for mapping where the fistula connects. In adults with acquired fistulas, MRI has become the preferred tool. A meta-analysis of fistula imaging found that MRI had a combined sensitivity of about 87% for detecting fistula tracts, with somewhat better specificity than endoanal ultrasound.⁴ For congenital rectoperineal fistulas in infants, though, the anatomy is usually clear enough from the physical exam and the colostogram that MRI is reserved for complex cases.

Surgical Repair in Children

Surgery is the definitive treatment. The goal is to separate the rectum from its abnormal perineal opening, mobilize the bowel so it sits within the sphincter muscle complex, and create a new, properly positioned anus. Several approaches exist, and which one a surgeon chooses depends on the child’s anatomy, the surgeon’s experience, and the available resources.

The posterior sagittal anorectoplasty, commonly known as PSARP, has been the dominant technique since it was popularized in the 1980s. The surgeon makes an incision along the midline of the buttocks, splits the muscle complex under direct vision, identifies the fistula, divides it, and places the rectum inside the muscle funnel. This approach provides excellent visualization of the anatomy. A newer variation called posterior rectal advancement anoplasty avoids splitting the full muscle complex and instead advances the rectal wall forward through a smaller dissection. Early reports describe children returning to feeding sooner and being discharged faster, with no need for a temporary stoma.⁵

The anterior sagittal anorectoplasty, or ASARP, approaches the fistula from the front rather than the back. A comparative study of these two approaches in girls with low anorectal malformations found that ASARP was associated with shorter hospital stays, fewer wound infections, and fewer complications overall. PSARP patients had longer hospitalizations and more days on intravenous nutrition.⁶ Another prospective study comparing the two techniques in girls found that cosmetic satisfaction scores were higher after ASARP, while long-term bowel function scores were similar between the two approaches once children were followed for several years.⁷

For families, this can mean that the choice of approach is less about which one “works better” and more about the individual surgeon’s comfort, the specific anatomy of the child, and local institutional factors. In resource-limited settings, the shorter hospital stay and lower complication profile of ASARP can be a practical advantage.

Whether a Stoma Is Needed

One of the first questions parents ask is whether their baby will need a colostomy, a temporary opening in the abdomen that diverts stool into a bag. For rectoperineal fistulas specifically, the answer is often no. Because the fistula sits on the perineal skin rather than deep inside the pelvis, many surgeons feel comfortable doing a single-stage repair without diverting the stool first. The posterior rectal advancement technique, for instance, has been performed successfully in newborns without any stoma.⁸

That said, some children do end up with a temporary colostomy, especially if the diagnosis was delayed, if the fistula anatomy is more complex than expected, or if there are associated anomalies that require staged procedures. A colostomy is not a failure of care; it is a safety measure that lets the surgical site heal without being contaminated by stool. When it is used, it is typically reversed a few months later once the repair has fully healed.

Postoperative Dilations and Preventing Stricture

After the new anus is created, scar tissue can gradually narrow the opening. To prevent this, most pediatric surgery centers follow a structured dilation program. Parents are taught to pass a smooth, calibrated dilator through the new anus on a schedule, usually starting a couple of weeks after surgery and continuing for months. The size of the dilator is gradually increased over time.

A study examining stricture rates after anorectal malformation repair found that post-operative narrowing can be avoided when surgeons preserve adequate blood supply to the pulled-through bowel, avoid tension at the site where the bowel meets the skin, and when families adhere to the dilation protocol.⁹ The dilation process can be stressful for families, but skipping it or stopping early is one of the most common reasons children later need additional surgery for narrowing.

Long-Term Bowel Function

Rectoperineal fistulas generally have the best functional outlook among all anorectal malformations, but “best” does not mean “perfect.” The most common long-term issue is constipation. One study followed 30 patients with rectoperineal fistulas who were treated with a limited posterior sagittal approach and found that constipation rates dropped from about 77% before surgery to 30% afterward.¹⁰ That is a substantial improvement, but it also means roughly a third of patients still dealt with constipation after repair.

Constipation in these children is not the same as ordinary constipation from a low-fiber diet. It stems from the anatomy itself: the rectum may not have normal nerve supply, the muscle complex may not fully envelop the bowel, and the sensation that signals “time to go” may be dulled. Many children manage well with a daily laxative regimen and dietary adjustments. A smaller number require a bowel management program, which involves daily enemas tailored to the child’s specific anatomy, to stay clean and avoid accidents. For most children with repaired rectoperineal fistulas, fecal continence is achievable, but it sometimes requires years of active management to reach that point.

When Reoperation Is Necessary

Not every initial repair goes perfectly. A large review of reoperations at a major referral center found that the most common reasons children came back for additional surgery included stricture or acquired narrowing of the rectum, a rectum that had been placed outside the muscle complex (a “mislocated” rectum), and recurrent or persistent fistulas.¹¹ The analysis traced these complications back to specific technical errors during the first surgery: dissection in the wrong tissue plane, inadequate mobilization of the bowel leading to a tense connection, damage to the rectal blood supply, and errors in diagnosis because a proper contrast study was not performed beforehand.

The reoperation rate is not specific to rectoperineal fistulas alone; that study included the full range of anorectal malformations, many of which are far more complex. Still, it underscores why families are often referred to specialized pediatric colorectal centers rather than having the repair done at a general hospital. Surgeon experience with these relatively uncommon anomalies matters.

Rectoperineal Fistulas in Adults

When a rectoperineal fistula occurs in an adult, the surgical problem is different. The anatomy is fully developed, but the tissue has often been scarred by prior failed repairs or by the process that created the fistula in the first place, whether that was an obstetric injury, a perianal abscess, or a complication of pelvic radiation. Recurrence after initial repair is a common frustration.

One case report described a 72-year-old woman with a recurrent rectoperineal fistula who had already undergone multiple procedures including endorectal advancement flap. Her surgical team ultimately used a perineal approach combined with a Martius flap (a blood-supply-carrying tissue flap harvested from the labia) and a house advancement flap. She recovered without complications, and her stool incontinence resolved within a month.¹² The case illustrates a broader principle: when simpler methods have failed, bringing in well-vascularized tissue from outside the scarred zone can improve healing. These are technically demanding surgeries that benefit from a surgeon experienced in complex perineal reconstruction.

Newer sphincter-sparing techniques are also being explored for complex anal fistulas in adults. Video-assisted anal fistula treatment, or VAAFT, uses an endoscope placed directly inside the fistula tract to visualize and destroy it from within. One study of 57 patients treated with VAAFT combined with an anal fistula plug reported a recurrence rate of about 10%, no severe complications, and preserved anal sphincter function in all patients.¹³ While that study focused on complex anal fistulas broadly rather than rectoperineal fistulas specifically, the approach represents the kind of minimally invasive philosophy that may increasingly apply to perineal fistula repairs as well.

Pain Management During and After Surgery

Anorectal surgery is painful, and the perineal location makes standard pain control strategies more challenging. A review of anesthesia practices across more than 100 pediatric anorectal malformation repairs found that regional anesthesia techniques, such as caudal blocks and epidurals, could substantially reduce or eliminate the need for opioid pain medication. Among children who underwent PSARP without an abdominal incision, nearly half required no opioids at all during their recovery when regional anesthesia was used. Children older than five who did need opioids required significantly higher weight-adjusted doses, which suggests that early repair, when it is anatomically feasible, may carry pain-management advantages beyond just fixing the anatomy sooner.¹⁴

For parents, this means it is worth asking the surgical team about the anesthesia plan before the operation. Regional blocks are not available at every center, and the specific technique chosen depends on the child’s age, weight, and the extent of the planned surgery. But when available, they can make the recovery period considerably more comfortable.

Pregnancy and Childbirth After Repair

Women who were born with anorectal malformations, including rectoperineal fistulas, eventually face questions about whether pregnancy is safe and how delivery should be managed. A study surveying women with repaired anorectal malformations found that among those who wanted to become pregnant, about two-thirds succeeded. Of the live births recorded, the vast majority, roughly 87%, were delivered by cesarean section.¹⁵

The high cesarean rate is not coincidental. Vaginal delivery puts enormous strain on the perineal muscles and the reconstructed anal canal, and obstetricians worry that a vaginal birth could damage the muscle complex that was painstakingly placed during the childhood repair. There is no universal rule, and some women with milder anomalies do deliver vaginally, but the conversation about delivery method should happen early in pregnancy with both the obstetrician and, ideally, the colorectal surgeon who understands the patient’s specific anatomy. A third of the women who attempted pregnancy in that study did not conceive, which may reflect associated urogenital anomalies that often accompany anorectal malformations rather than the fistula repair itself.

Associated Anomalies and the Bigger Picture

Rectoperineal fistulas rarely exist in isolation. Because the urorectal septum forms during the same developmental window as many other structures, babies born with anorectal malformations frequently have additional anomalies. The most commonly associated problems involve the spine (tethered cord, sacral abnormalities), the urinary tract (kidney anomalies, vesicoureteral reflux), the heart, and the esophagus. The VACTERL association, a non-random clustering of vertebral, anorectal, cardiac, tracheoesophageal, renal, and limb anomalies, is the classic pattern, though not every child has all components.

For rectoperineal fistulas specifically, associated anomalies tend to be less frequent and less severe than for higher forms of anorectal malformation like rectovesical or rectoprostatic fistulas. But “less frequent” does not mean absent. Standard workup after diagnosing any anorectal malformation includes a spinal ultrasound, a renal ultrasound, a cardiac echocardiogram, and a careful physical exam of the limbs and vertebral column. These screenings are done even if the perineal fistula itself looks straightforward, because catching a silent kidney problem or a tethered spinal cord early can prevent serious complications down the road.

The screening timeline matters, too. Spinal ultrasound is most useful before the vertebral bones fully calcify, which happens around three to four months of age. If that window is missed, an MRI becomes necessary to see the spinal cord clearly. Families who receive a late diagnosis or who are managing other aspects of the malformation may inadvertently miss the optimal screening window, so pediatric surgeons typically order all the associated-anomaly imaging at the time of the initial diagnosis rather than spacing it out.