♦ A decision-making algorithm for the initial management of females is shown in Fig. 21-3. Perineal inspection usually provides more information in girls than in boys. The principle of waiting 20 to 24 hours before making a decision is again valuable.

♦ The presence of a single perineal orifice is pathognomonic for a cloaca. Because of their complexity, these defects are dealt with in a separate chapter.

♦ Perineal inspection may reveal the presence of a vestibular fistula (Fig. 21-4, in prone position), which is the most common condition in girls. In cases with rectovestibular fistula, the rectal orifice is located within the vestibule and outside the hymen. A true rectovaginal fistula is an extremely rare anomaly.

♦ These patients can undergo a primary repair via a posterior sagittal approach, either in the newborn period or following a period of dilatations, provided that the surgeon has adequate experience and that a meticulous technique is used. Our preference is to perform the repair during the newborn period. A colostomy followed by the definitive repair is an acceptable and safe approach. These fistulas are usually large enough to decompress the gastrointestinal tract. Occasionally the fistula is too narrow, and the patient will suffer from abdominal distention. In these patients the fistula may first be dilated to facilitate emptying the rectum. The defect is then repaired with a limited posterior sagittal operation.

♦ Patients with vestibular fistula are the ones most often referred after a failed attempt at a primary repair without a colostomy. Patients with vestibular fistula are usually continent after a successful operation. Infection or dehiscence may damage the continence mechanism and change the final functional prognosis.

♦ The presence of a rectoperineal (cutaneous) fistula is the simplest defect in the spectrum of female malformations. These patients can be treated with a minimal posterior sagittal anoplasty without a colostomy during the neonatal period.

♦ Most girls with imperforate anus (95%) have a fistula. Sometimes, after 20 to 24 hours of observation, the neonate’s abdomen may become distended without any evidence of meconium passing through the genitalia. In such a case, the infant probably has imperforate anus without fistula. The neonate should have a cross-table lateral film as described previously.

Figure 21-3

Figure 21-4

High-Pressure Distal Colostography

♦ Before the definitive repair, distal colostography is performed. It is the most valuable and accurate diagnostic study for anorectal malformations. Water-soluble contrast medium is instilled into the distal stoma, which fills the distal intestine and enables demonstration of the location of the blind rectum and the precise location of a rectourinary fistula. The rectum is surrounded by striated muscle, which keeps it collapsed and prevents filling of its most distal part. This may give the erroneous impression of a very high defect and may prevent demonstration of a rectourinary fistula. To avoid this problem, the contrast medium must be injected with hydrostatic pressure under fluoroscopic control. The use of a Foley catheter is recommended; it is passed through the distal stoma, the balloon is inflated (2 to 5 mL), and it is pulled back as far as possible to occlude the stoma during the injection of the contrast medium. This maneuver permits exertion of enough hydrostatic pressure (syringe manual injection) to overcome the muscle tone of the striated muscle mechanism, fill the rectum, and demonstrate the urinary fistula when present.

♦ In cases of rectourethral fistula (prostatic and bulbar), the surgeon will know preoperatively precisely where to find the rectum. In cases of rectobladder neck fistulas, the surgeon will not expect to find the rectum through the posterior sagittal approach and so avoids a blind perineal dissection. In this latter case, the surgeon can prepare the patient for an additional laparoscopy or laparotomy to mobilize a very high rectum.

Step 3: Operative Steps

Males

Perineal (Cutaneous) Fistula

♦ This type of defect is also known as a low imperforate anus. The rectum is located within most of the sphincter mechanism, but only the lowest part is anteriorly displaced.

♦ Sometimes the fistula follows a subepithelial midline tract opening along the midline perineal raphe, scrotum, or penis. The perineal findings in this kind of defect include a prominent skin tag, below which an instrument can be passed, known as a “bucket-handle” malformation (Fig. 21-5, in prone position), a black or white, ribbon-like, midline structure that represents a subepithelial fistula filled with meconium or mucus or a very well-formed anal dimple suggesting the presence of a very low defect. The diagnosis is established by perineal inspection. No further investigations are required.

Figure 21-5

Rectourethral Fistula

♦ This is the most common defect in boys. The rectum may communicate with the lower part of the urethra (bulbar urethra) (Fig. 21-6) or with the upper urethra (prostatic urethra). Immediately above the fistula site, the rectum and urethra share a common wall with no plane of dissection.

♦ This anatomic fact has important technical and surgical implications. The rectum is surrounded laterally and posteriorly by the levator muscle mechanism. Between the end of the rectum and the perineal skin, there is a portion of striated voluntary muscle called the muscle complex. The contraction of the levator muscle pushes the rectum forward. The contraction of the muscle complex elevates the skin of the anal dimple. At the level of the skin, and located on both sides of the midline, there is a group of voluntary muscle fibers called parasagittal fibers.

♦ Patients with rectourethral bulbar fistulas usually have a normal sacrum and a “good-looking” perineum consisting of a prominent midline groove.

♦ Patients with rectoprostatic fistulas tend to have a more abnormal sacrum, underdeveloped sphincter mechanism, and a flat perineum. The sphincter (anal dimple) is often located close to the scrotum. Exceptions to these rules exist. Neonates with rectourethral fistulas may pass meconium through the urethra but usually not until after 20 hours of life.

Figure 21-6

Females

Perineal (Cutaneous) Fistula

♦ This defect is like the perineal fistula described for boys. The rectum and vagina are well separated. There is an intact sphincteric mechanism, and therefore the prognosis is excellent.

Vestibular Fistula

♦ This is the most common defect seen in girls (see Figs. 21-4 and 21-7]. It has an excellent functional prognosis. Unfortunately this is also the most common type to suffer a failed repair.

♦ The rectum opens in the vestibule of the female genitalia immediately posterior to the hymen. The most pertinent anatomic characteristic of this defect is that immediately above the fistula site the rectum and vagina share a thin common wall. These patients usually have good muscles and a normal sacrum. The diagnosis is established by perineal inspection. These patients are not uncommonly mislabeled as having rectovaginal fistula.

Figure 21-7

Imperforate Anus Without Fistula and Rectal Atresia

♦ These two defects in girls have similar anatomic characteristics and prognostic implications as those described in boys.

Colostomy

♦ A descending colostomy with separated stomas is ideal. Transverse colostomies have several disadvantages. The mechanical preparation of the distal colon before the definitive repair is much more difficult, and, in the case of a large rectourethral fistula or rectobladder fistula, the patient often passes urine into the colon, where it remains and is absorbed, leading to metabolic acidosis. Also, during distal colostography, it is more difficult to distend the distal rectum and define the anatomy. Patients with transverse colostomies are more likely to develop a megarectosigmoid.

♦ Loop colostomies often permit the passage of stool from the proximal stoma into the distal intestine, which can cause urinary tract infections and impaction of stool in the distal rectal pouch that translates into severe constipation later in life. Colostomy prolapse is more common with loop colostomies and in colostomies created in a mobile portion of the colon. The incidence of prolapse in descending colostomies is almost zero, owing to the fact that the proximal stoma is opened immediately distal to the fixed descending colon. A colostomy created too distally in the area of the rectosigmoid colon may interfere with mobilization of the rectum during the pull-through procedure.

♦ During the opening of the colostomy, the distal colon must be irrigated to remove all the meconium so as to prevent the formation of a megasigmoid. The colostomy is constructed through a left lower quadrant oblique or transverse incision. The proximal stoma is exteriorized through the upper and lateral part of the incision, and the mucous fistula is placed in the medial or lower part of the incision. The mucous fistula is made very small to prevent prolapse. The stomas should be separated enough to allow the use of a stoma bag that covers only the functional stoma.

Definitive Repair

Incision

♦ All anorectal malformations can be corrected by the posterior sagittal approach. The size of the incision depends on the specific defect. The patient is placed in the prone position with the pelvis elevated. An electric stimulator is used to elicit muscle contraction during the operation as a guide to remain exactly in the midline. An incision from the coccyx to the anal sphincter is used for rectoprostatic fistulas. Smaller incisions (limited posterior sagittal anorectoplasty) are adequate for defects such as vestibular fistula. Perineal fistulas require a small posterior sagittal incision (minimal posterior sagittal anoplasty). The anatomic relationship of the rectum to the genitourinary structures is complex, and separation of the rectum from these structures represents the most risky part of the procedure. About 90% of male defects can be repaired from a posterior sagittal approach without entering the abdomen.

Perineal (Cutaneous) Fistulas

♦ The repair of these defects consists of a small anoplasty with minimal mobilization of the rectum, sufficient for it to be transposed and placed within the limits of the sphincter mechanism. This is a meticulous operation that can be done during the neonatal period without a colostomy. The most common complication is a urethral injury, which can be avoided by placing a urethral catheter and taking particular care during the dissection of the anterior rectal wall. These patients, both boys and girls, have an excellent prognosis but have problems with bowel control under only two circumstances: if they are subjected to an inadequate surgical technique or if they are not treated adequately to prevent constipation, fecal impaction, and overflow pseudoincontinence.

Rectourethral Fistula

♦ A Foley catheter is inserted. To avoid passing the catheter into the rectum rather than the bladder, it must be intentionally directed anteriorly by the use of a Coudé catheter. Occasionally the catheter must be positioned intraoperatively, under direct vision, once the fistula is visualized.

♦ The skin is opened through a midsagittal incision, and the parasagittal fibers and muscle complex are divided exactly in the midline by use of fine-needle cautery. The fibers of the muscle complex run perpendicular and medial to the parasagittal fibers. The crossing of the muscle complex fibers with the parasagittal fibers represents the anterior and posterior limits of the new anus, and these limits can be seen most clearly with the use of an electrical stimulator. The levator muscle, which lies deep in the incision, is then divided in the midline. The higher the malformation, the deeper the levator muscle. Levator muscle and muscle complex are in continuum toward the center of the sphincter at the anal dimple.

♦ When all muscle structures have been divided, the rectum can be seen (Fig. 21-8). In cases of rectourethral bulbar fistulas, the rectum is prominent, and it almost bulges into the wound. In cases of rectoprostatic fistulas, the rectum is located much higher, just under the coccyx. In cases of rectobladder neck fistulas, the rectum is not visible through this approach, and searching for it risks injury to other structures.

♦ Two silk sutures are placed in the posterior rectal wall on both sides of the midline. The rectum is opened between the sutures, and the incision in the rectum is continued distally, exactly in the midline, down to the fistula site. Temporary silk sutures are placed on the edges of the open posterior rectal wall for traction (Fig. 21-9).

♦ The anterior rectal wall immediately above the fistula is a thin structure. No plane of separation lies between the rectum and urethra in that area. A plane of separation must be created in the common wall. Multiple 6/0 silk sutures are placed through the rectal mucosa immediately above the fistula in a semicircumferential fashion (Fig. 21-9). The rectum is then separated from the urethra, creating a submucosal plane for approximately 5 to 10 mm above the fistula site. During this delicate dissection, it is helpful to dissect the rectum laterally, very close to the rectal wall, until both dissections (lateral and medial) meet, separating the rectum completely from the urinary tract. Once the rectum is fully separated, a circumferential perirectal dissection is performed to gain enough rectal length to reach the perineum. The rectum is surrounded by a conspicuous whitish fascia, and the dissection must be performed between this fascia and the rectal wall to avoid damage to the innervation of the bladder and genitalia.

♦ In cases of a fistula opening into the bulbar urethra, the dissection necessary to pull the rectum down to the perineum is minimal, whereas in cases of prostatic fistula the perirectal dissection is considerable. In both cases, enough rectal length must be gained to perform a comfortable, tension-free anastomosis between the rectum and the skin. As traction is exerted on the mobilized rectum, grooves can be seen in the rectal wall, demonstrating the tension lines that hold the rectum. These indentations are nerves and vessels that must be divided. Patients with higher malformations that require more dissection might be expected to suffer from more severe constipation. However, patients with lower defects treated with this approach suffer more constipation than patients with higher defects.

♦ Once the rectum has been fully mobilized, a decision must be made concerning the need for tailoring of the rectum. The size of the rectum can be evaluated and compared with the available space. If necessary, the rectum can be tapered by removing part of the posterior wall. The rectal wall is reconstructed with two layers of interrupted, long-lasting, absorbable sutures. The anterior rectal wall is often damaged to some degree as a consequence of the separation between rectum and urethra. To reinforce this wall, both smooth muscle layers can be sutured together. The urethral fistula is sutured with long-term, absorbable sutures.

♦ Tapering of the rectum must always be done on the posterior rectal wall. The part of the intestine that will be adjacent to the closed urethral fistula must be normal rectal wall to avoid a recurrent rectourethral fistula.

♦ The rectum is placed in front of the levator muscle and within the limits of the muscle complex (Fig. 21-10). The electrical stimulator is helpful in identifying the limits of the muscle structures. The anterior and posterior limits of the sphincter are temporarily marked with silk sutures. In cases where the incision is extended anteriorly beyond the limits of the sphincter, it is necessary to repair the anterior perineum with interrupted long-term, absorbable sutures to bring together both anterior limits of the sphincter. Long-lasting absorbable sutures are placed on the posterior edge of the levator muscle. The posterior limit of the muscle complex must also be reapproximated behind the rectum. These sutures should include part of the rectal wall to anchor it and thereby help to avoid rectal prolapse.

♦ The anoplasty is performed with 16 interrupted, long-lasting, absorbable sutures. These anoplasty sutures are placed under slight tension so that once cut, the anus retracts slightly. The wound is then closed, bringing together corresponding sphincteric structures in the midline. The Foley catheter is left in place for 7 days. The patient receives broad-spectrum antibiotics for 2 days.

Figure 21-8

Figure 21-9

Figure 21-10

Rectobladder Neck Fistula

♦ For the repair of rectobladder neck fistulas, the entire lower part of the patient’s body from chest down is included in the sterile field so that the surgeon can work simultaneously in the abdomen and the perineum. The initial approach is by laparoscopy or laparotomy; the distal rectum is dissected and the fistula to the bladder neck ligated.

♦ In this very high defect, the rectobladder neck fistula is located approximately 2 cm below the peritoneal reflection, and the rectum communicates with the urinary tract in a T fashion, which means that there is no common wall between the distal part of the rectum and the urinary tract. This facilitates the dissection, which is minimal. The surgeon must be careful to avoid damage to the vas deferens, which runs close to the bowel. With a laparoscopic technique, separation of the rectum from the bladder neck is straightforward. Gaining adequate length, particularly with a high rectum, is challenging and must be meticulous so as to avoid devascularizing the distal rectum.

♦ The rectum is separated from the bladder neck, and the bladder end of the fistula is closed with interrupted absorbable sutures or ligated with an Endoloop.

♦ This is a very high defect, so mobilization of the rectum to reach the perineum requires special maneuvers. Ligation of the inferior mesenteric vessels as high as possible, close to their origin near the aorta, would mobilize the rectum but would probably compromise the blood supply of the rectum because the arcades that connect the middle colic vessels with the inferior mesenteric ones may have been interrupted at the time of the colostomy creation. An alternative is to ligate the most distal branches of the inferior mesenteric vessels close to the rectum. If this is done, the more proximal branches of the inferior mesenteric vessels must be left intact to guarantee a good blood supply to the rectum, a maneuver that is possible only because the rectum has an excellent intramural blood supply.

♦ Then the presacral space in front of the levator muscle and within the limits of the muscle complex and sphincter is defined via a small posterior sagittal incision. The patient’s legs can be lifted up for this part, with the patient remaining supine. This is where the rectum will subsequently be placed.

♦ If it is necessary to gain extra length, a plasty of the distal dilated portion of the rectum can also be performed. A combination of these maneuvers usually allows the rectum to reach the perineum, provided the colostomy does not interfere with the pull-through. Sometimes the mucous fistula must be taken down. This can be anticipated by the use of colostography, which demonstrates the precise length of intestine available from the colostomy to the end of the rectum. The rectum is tapered, if necessary, and then pulled down through the pelvis. The anoplasty is performed as previously described.

Imperforate Anus Without Fistula

♦ About 5% of patients have imperforate anus without a fistula. This is the most likely defect in patients with Down syndrome. In both boys and girls, the rectum lies about 2 cm from the perineal skin. Most of these patients have a very good sacrum and good muscles. The fact that these patients have no fistula does not necessarily mean that the repair is simpler; the rectum still must be carefully separated from the urethra because the two structures have a common wall. The remainder of the repair is performed as described for rectourethral fistula.

Rectal Atresia and Stenosis

♦ These defects are best repaired through a posterior sagittal approach. The entire sphincteric mechanism is divided in the midline. The upper rectal pouch is opened, as is the small distal anal canal. An end-to-end anastomosis is performed under direct vision, followed by a meticulous reconstruction of the muscle mechanism posterior to the rectum. The wound is closed following the principles already described.

♦ Multiple 6/0 silk sutures are placed at the edge of the fistula to exert uniform traction on the rectum to facilitate its dissection. The incision used to repair this defect is shorter than that used to repair rectourethral fistulas in boys, and it continues around the fistula into the vestibule in a racket-like fashion. The sphincteric mechanism is divided in the midline until the rectal wall is located. A characteristic whitish fascia covers the rectum posteriorly and must be divided. This helps to locate the plane of dissection during mobilization of the rectum. Once the rectal wall has been identified, a lateral dissection is performed from the posterior midline while placing traction on the fistula to make the plane of dissection more obvious. It is vital to be adjacent to the rectal wall and clean away the thin white fascia that envelops it. The surgeon must be in this key plane to be able to mobilize the rectum.

♦ Hemorrhoidal vessels are usually found on the lateral aspects of the rectum. The most delicate part of this dissection is the anterior rectal wall. The rectum and the vagina share a common wall, which is often very thin. This thin wall has no plane of separation, and the surgeon must make two walls out of one. This dissection is performed using a very fine needle cautery and suction, which allows each one of the little vessels that are encountered during the procedure to be meticulously cauterized. It is continued up to the point where rectum and vagina separate and have full-thickness walls. A nice areolar plane is reached, which demonstrates that the two structures are fully separated. The most common error in performing this operation is incomplete separation of the vagina and rectum, which may create a tense anastomosis between the rectum and the skin and may provoke dehiscence and recurrence of the fistula.

♦ Once the dissection has been completed, the electrical stimulator is used to determine the limits of the sphincteric mechanism (Fig. 21-11). The anterior limit of the sphincter is reapproximated as previously described. The levator muscle is usually not exposed and therefore does not have to be reconstructed. The muscle complex must be reconstructed posterior to the rectum, and the anoplasty is performed as previously described.