Perineal fistula is an anal malformation in which the anal opening is located anterior to the center of the sphincter. In females, the anal opening is located somewhere between the location of the normal sphincter and the female genitalia in the area known as the perineum or perineal body. The anterior mislocation of the orifice could be minimal (a few millimeters) (Fig. 8.1) or severe, becoming borderline with a malformation called vestibular fistula (Fig. 8.2). When the anal orifice is located at the junction of both labia majora, the malformation sometimes receives the French name “fourchette malformation” (Fig. 8.3), which is considered a defect intermediate between the vestibular and perineal area. Yet, most anorectal malformations in females can be clearly differentiated between perineal and vestibular. This is, perhaps, the anorectal defect subjected to more controversies, both in semantics and treatments. In female patients, some surgeons use different terms to refer to this condition, including “ectopic anus” and “anterior displacement of the anus” [1–13]. We prefer the term perineal fistula for the following reasons:

These facts make us believe that this is not a real anus. For similar reasons, we believe that in order to call a malformation “anterior anus,” it would be necessary for the patient to have a non-stenotic orifice, with normal anal canal, and surrounded 360° by a sphincter mechanism (as electrically demonstrated). If we accept this, as the definition of an anterior anus, then we must say that we have never seen that specific type of defect. The fact that we have not seen such defect does not mean that it does not exist, but it certainly means that it must be extremely rare. In addition, we believe that in the event of seeing a case suffering from such condition, we would be very hesitant to operate.

Perineal fistula is one of the most common anorectal defects. Our series includes 90 males and 84 females, occupying the second place in frequency in males after the rectourethral fistulas (bulbar and prostatic) together and the third place in females after vestibular fistula and cloacas. However, we have reasons to believe that the perineal fistula is perhaps one of the two most frequent defects in females. Most likely, the majority of perineal fistula cases are not referred to us, probably because they are considered easy to repair. Ours is a referral center, and we receive mainly complex and (or) complicated patients from other institutions. That may be the reason to explain the elevated number of cloacas that we have, as well as the rather low number of cases with perineal fistula. We conclude that the relative frequency of presentation of these malformations in our series is not representative of the frequency in the general population.

Perineal fistulas are the most benign of all anorectal defects in terms of functional prognosis for bowel control. In fact, in our experience, 100 % of the patients operated by us have bowel control provided the sacrum is normal. The majority of patients have a good sacrum, but there are exceptions, as we will be discussing below.

The chances for these patients to have bowel control are 100 % provided they receive a good operation. Ironically, the incidence of constipation in these patients is the highest of the entire spectrum of anorectal malformations!! In fact, we observed that the higher the malformation, the poorer the prognosis for bowel control, but the better the prognosis for constipation, or the other way around, the lower and more benign the malformation, the highest chances of bowel control, but also the highest possibilities of suffering severe constipation. The reason for this is unknown. Interestingly, higher malformations require much more perirectal dissection in order to bring the rectum down to the perineum. This dissection means that we divide the vessels and the nerves that surround the rectum in order to mobilize it down. In other words, higher rectums require more denervation, yet they have less constipation!! Patients with perineal fistulas require a minimal degree of mobilization and therefore denervation, and yet they have the worst degree of constipation.

Another important characteristic of this particular defect is that there is a group of patients with perineal fistulas that run in families. It is well documented in the literature that about 1 % of all patients with anorectal malformations have a sibling with an anorectal malformation [14]. In other words, traditionally, when the parents ask about the risk of having a second child with an anorectal malformation, the standard answer from geneticists, pediatricians, and us is 1 %. Yet, a deeper and more thoughtful analysis of the question reveals that, actually, we have never seen a family with two cloacas. In contrast, we have several families that have two or more siblings with perineal fistula frequently associated to a presacral mass and sacral defect. The familiar characteristic of this condition has been published many times [15–31]. Some other members of the family may have the sacral defect and the presacral mass and not the perineal fistula. For this reason, in a patient with perineal fistula, it is mandatory to document the integrity of the sacrum with an AP x-ray film of the sacrum to rule out a sacral defect because of the high incidence of sacral defects and presacral masses associated to perineal fistulas. Once we document a case of perineal fistula with a presacral mass, we have to screen the other members of the family for the same defect. This is extremely important because we have seen patients that were diagnosed as having a perineal fistula received an operation focused only in the anal defect, and the patients were left with a presacral mass and sometimes with very negative consequences. In addition, having diagnosed a sacral defect with a presacral mass changes completely the functional prognosis for these patients. This, we believe, it is extremely important to diagnose, to discuss with the parents, and to adjust their expectations in terms of future functional prognosis. In addition, as will be described later, this complex triad requires a specific therapeutic strategy.

The association of anorectal malformation, sacral defect, and presacral mass is well known [32–61] and is frequently called Currarino triad [38].

Unfortunately, there is a group of patients who were born with perineal fistula, as previously mentioned, a defect with an excellent functional prognosis, and yet, they end up suffering from fecal incontinence after several therapeutic misadventures and catastrophic events. Those are totally preventable problems consecutive to the lack of knowledge of the management of these patients.

Following the same pattern already observed in the entire spectrum of anorectal malformations, perineal fistulas have the lowest incidence of urologic-associated defects or functional disorders. According to our database, 18 % of female patients and 27 % male patients with perineal fistulas suffer from urologic problems. Absent kidney occurs in 2–4 % of the cases, vesicoureteral reflux in 3–5 %, hypospadias in 1 %, ectopic ureters in less than 1 %, vaginal septum in 2 %, hyposadias in 1 %, undescended testicle in 2 %, bifid scrotum in 8 %, and hydronephrosis in 6 %.

Vertebral anomalies also are less common in these defects as compared to the others. Hemivertebra occurs in less than 2–4 % of the cases, and sacral defects are very unusual. The sacra in these patients are usually normal except in those patients who are born with presacral mass and hemisacrum.

Patent ductus arteriosus occurs in less than 3 %, atrial septal defect in 2 %, ventricular septal defect in 1 %, tetralogy of Fallot in 1 %, and esophageal atresia in 1 %.

Tethered cord is present in 29 % of male patients and 13 % of female patients. This relatively high frequency of tethered cord is explained by the fact that patients with perineal fistula have a high frequency of association with sacral defects and presacral masses.

Since these defects represent the simplest of all anorectal malformations, the operation designed to repair these defects is also a limited, rather simple, yet meticulous operation. Operations to repair these defects are performed without a protective colostomy. The exceptions to this rule include cases of misdiagnosis. More specifically, some male patients are born with no anal opening; they rather have a tiny perineal orifice that goes unrecognized, and the surgeon erroneously believed that the patient had a “high” malformation and opens a non-indicated colostomy.

When the patients are born full term at our institution, with no serious associated defects, we operate on them without bowel preparation within the first 72 h of life. Unfortunately, however, patients frequently come to us weeks or months after they were born, and in that type of case, we feel it is safer to prepare the gastrointestinal tract with GoLYTELY as described in the chapter related to colonic preparation. In the case of a newborn operated in the first hours of life, we feed the patient usually 3–5 days after the operation. We believe that those babies operated early, without bowel preparation, have a better postoperative course and less chance of infection, perhaps due to the fact that the bacterial proliferation in the bowel is nil or very limited. However, in older patients, we are stricter in the protocol of management. We use GoLYTELY for total bowel preparation (see Chap.​ 7), insert a central line, and keep the patients 10 days with nothing by mouth.

During the newborn period, there are several therapeutic options for these patients. The first one is simple dilatation of the perineal orifice.

Dilatations usually help the patient to eliminate the stool and avoid abdominal distention. This treatment modality is preferred by many doctors all over the world, based on the fact that these patients will have bowel control with and without an operation. In fact, misadventure and catastrophic events in these patients occur when somebody performed the wrong type of operation or technically incorrect procedure that ended up in a series of complications that will be described later. Therefore, we can say that it is preferable for the patient to receive anal dilatations rather than a poor operation. The fact is that these patients will have bowel control with and without an operation. We explain that, by the fact that the mislocation of the anal orifice is only present in the lowest part of the rectum (Fig. 8.2), most of the rectum, however, is well located traversing within the funnel-like muscle structure and is only deviated in the lowest part. It is this type of case that exemplifies the fact that a perfect location of the anus, within the sphincter mechanism, is not a precondition to have bowel control. Bowel control then seems to depend on many other factors besides anal location.

Anal dilatations, from our point of view, are then indicated under specific circumstances. One of those could be a patient that has multiple serious associated defects and abdominal distention. Premature babies with severe cardiac conditions that are not in good condition to be taken to the operating room are also good candidates to receive anal dilatations. The protocol of dilatation should be as the one described here (Chap.​ 18). Another reason to do dilatations is the case in which the surgeon has no experience with performing a formal posterior sagittal anoplasty for these patients. In that case, the chances of hurting the patient are much less with anal dilatations than with an operation. The operation also could be done later. Anal dilatations in cases of perineal fistula are sometimes rather difficult and painful. The reason is that one has to dilate a congenital stricture type of anomaly. This is not the same as in cases of postoperative dilatations after a technically correct operation; in those cases usually the dilatations are uncomfortable, but not painful. Very painful dilatation usually means a congenital stricture or ischemia that occurred during the performance of an anoplasty.

The cutback operation is another therapeutic alternative for these patients. The indications are similar to the ones of the anal dilatation. In fact, it is a procedure that can be done with local anesthesia. Again, we do not think that it should be the final ideal operation for these patients, but it is certainly an alternative for patients who are extremely sick or in situations in which the surgeon does not have the necessary training to perform a formal posterior sagittal anoplasty. The cutback procedure consists of making an incision in the posterior rim of the anal opening and suturing the skin to the mucosa. In other words, it is a kind of Heineke-Mikulicz type of procedure. The cosmetic appearance after the cutback is less than optimal, yet this operation does not really hurt the sphincter mechanism or the innervation of the bowel, and therefore it is considered a good contemporizing preliminary operation, designed to facilitate the passing of stool and alleviate the abdominal distention.