Rectourethral Fistulas

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Imperforate anus with rectourethral fistula is the most frequent defect in male patients [10]. The fistula may be located at the lower part of the urethra (bul-bar urethra; Fig. 20.3) or the upper urethra (prostatic urethra) (Fig. 20.4). Immediately above the fistula site, the rectum and urethra share a common wall, an anatomic fact with significant technical and surgical implications. The rectum is usually distended and surrounded laterally and posteriorly by the levator ani muscle. Between the rectum and the perineal skin, a portion of striated voluntary muscle, called the muscle complex, is present. Contraction of these muscle fibers elevates the skin of the anal dimple. At the level of the skin, a group of voluntary muscle fibers, called parasagittal fibers, are located on both sides of the midline.

Lower urethral (bulbar) fistulas are usually associated with good-quality muscles, a well-developed sacrum, a prominent midline groove, and a prominent anal dimple. Higher urethral (prostatic) fistulas are more frequently associated with poor-quality muscles, an abnormally developed sacrum, a flat perineum with a poor midline groove, and a barely visible anal dimple. Of course, exceptions to these rules exist.

A Foley catheter is inserted through the urethra. About 20% of the time, this catheter goes into the rectum rather than the bladder. Under these circumstances, the surgeon can attempt catheterizing again using a catheter guide, or can relocate the catheter into the bladder under direct visualization during the operation. The incision is performed as previously described (Fig. 20.1); the parasagittal fibers, muscle complex, and levator muscle fibers are completely divided. Sometimes, the coccyx can be split in the mid-line with a cautery, particularly in those cases of rec-toprostatic fistula in which the surgeon requires more exposure in the upper part of the incision. The higher the malformation, the deeper the levator muscle is located. When the entire sphincter mechanism has been divided, the surgeon expects to find the rectum.

It is at this point in the operation that the importance of a good high-pressure distal colostogram cannot be overstated. If the radiologic image shows the presence of a rectourethral bulbar fistula, the surgeon can expect that the rectum will be found just below the levator, and there is no way to injure the urinary tract because the rectum extends all the way down to the area of the bulbar urethra. On the other hand, if the preoperative image of the distal colostogram

Rectourethral Fistula Bulbar

Fig. 20.3 Rectourethrobulbar fistula ([15], with permission)

Rectoperineal Fistula

Fig. 20.4 Rectourethroprostatic fistula ([15], with permission)

Fig. 20.3 Rectourethrobulbar fistula ([15], with permission)

Fig. 20.4 Rectourethroprostatic fistula ([15], with permission)

Rias Stulas Coxis
Fig. 20.5 Dividing the muscle complex and levator muscle. The rectum is exposed ([15], with permission)

shows a rectoprostatic fistula, the surgeon must be particularly careful and look for the rectum near the coccyx. Looking for the rectum lower than that exposes the patient to the risk of urinary tract injury. Also, if the high-pressure distal colostogram discloses the presence of a rectobladder-neck fistula, the surgeon should not even look for the rectum posterior sagittally because it is not there, and during a blind search, injury to the genitourinary tract could occur. In patients with rectourethrobulbar fistula, the rectum actually bulges through the incision when one completes division of the entire sphincter mechanism (Fig. 20.5).

Silk stitches are placed in the posterior rectal wall on both sides of the midline. The rectum is opened in the midline and the incised distally, exactly in the midline, down to the fistula site. Temporary silk stitches are placed on the edges of the opened posterior rectal wall. When the fistula site is visualized, a final silk stitch is placed in the fistula orifice itself.

The anterior rectal wall above the fistula is a thin structure. It is actually a common wall with no plane of separation between the urinary tract and the rec tum. Therefore, a plane of separation must be created in that common wall. For this, multiple 6-0 silk traction stitches are placed in the rectal mucosa immediately above the fistula site. The rectum is then separated from the urethra, creating a submucosal plane for approximately 5-10 mm above the fistula site (Fig. 20.6). This dissection is the source of the most serious complications during this repair. Creating a lateral plan first makes the anterior dissection easier.

The rectum is covered by a thin fascia that must be completely removed to be sure that one is working as close as possible to the rectal wall, to avoid denervation and injury to neighboring structures and to insure mobilization. Once the rectum is fully separated, a circumferential perirectal dissection is performed to gain enough rectal length to reach the perineum. In cases of rectourethrobulbar fistula, the dissection is rather minimal because only a short gap exists between the rectum and the perineum. In cases of rectoprostatic fistulas, the perirectal dissection is significant.

During this dissection, uniform traction is applied on the multiple silk stitches that were originally placed on the rectal edges and on the mucosa above the fistula. Uniform traction shows the rectal wall and identifies bands and vessels that hold the rectum in the pelvis. These bands must be carefully separated from the rectal wall and cauterized because they are vessels that tend to retract into the pelvis. The dissection should be performed as close as possible to the rectal wall without injuring the wall itself. Injury to the rectal wall can disrupt the intramural blood supply, upon which the pulled-through rectum depends.

The bands that are divided around the rectum are actually vessels and nerves. One would think that this denervation would provoke dysmotility, which leads to the problem of constipation in these patients. Thus, patients with higher malformations (which require

Muscle Recto UretralDistal Colostogram

Fig. 20.7 a The rectum is passed in front of the levator muscle. b Muscle complex sutures anchor the rectum ([15], with permission)

Fig. 20.7 a The rectum is passed in front of the levator muscle. b Muscle complex sutures anchor the rectum ([15], with permission)

more dissection) would be expected to suffer from more severe constipation. However, the opposite is true in that patients with lower defects suffer more severe constipation than patients with higher defects [10]. The explanation for the observed dysmotility remains elusive [12].

The circumferential dissection of the rectum continues until the surgeon feels that enough length has been gained to allow a tension-free rectoperineal anastomosis. At this point, the size of the rectum can be evaluated and compared with the available space. If necessary, the rectum can be tapered, removing part of the posterior wall. In such cases, the rectal wall is reconstructed with two layers of interrupted long-lasting absorbable stitches.

The anterior rectal wall is frequently damaged to some degree as a consequence of the mucosal separation between rectum and urethra. To reinforce this wall, both smooth muscle layers can be stitched together with interrupted 5-0 long-lasting absorbable stitches. The urethral fistula is sutured with the same material. The rectal tapering should never be performed anteriorly as this would leave a rectal suture line in front of the urethral fistula repair, and may lead to a recurrent fistula.

The limits of the sphincter mechanism are determined electrically and marked with temporary silk stitches at the skin level. Those limits are sometimes easily visible without electrical stimulation in patients with a good sphincter mechanism. The limits of the sphincter are represented by the crossing of the muscle complex (the voluntary muscle structure that runs from the levator all the way down to the skin parallel to the direction of the rectum) with the parasagit-

Minimal Sagittal Anoplasty
Fig. 20.8 Anoplasty ([15], with permission)

tal fibers (which run perpendicular and lateral to the muscle complex and parallel to the posterior sagittal incision.).

The perineal body is reconstructed, bringing together the anterior limits of the external sphincter, which was marked previously with the temporary silk stitches. The rectum must be placed in front of the levator and within the limits of the muscle complex (Fig. 20.7 a). Long-lasting 5-0 absorbable stitches 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 stitches must take part of the rectal wall to anchor it to avoid rectal prolapse (Fig. 20.7 b). An anoplasty is performed with 16 interrupted long-lasting absorbable stitches (Fig. 20.8). The ischiorectal fossa and the subcutaneous tissue are reapproximated and the wound is closed with a subcuticular absorbable monofilament.

All of these patients have a Foley catheter inserted prior to starting the operation. The patient receives broad-spectrum antibiotics for 24-48 h and can be fed postoperatively on the same day of surgery.

Repair of rectourethral fistulas has been performed laparoscopically [7] with separation of the fistula through the abdomen, and pull-through of the rectum through a minimized perineal incision. The preliminary experience shows that these procedures are feasible. It is unclear whether a laparoscopic approach for a rectourethral fistula is less invasive than the posterior sagittal approach. Prevention of prolapse is by a pelvic hitch rather than tacking of the posterior rectum via the posterior sagittal incision. Technical challenges with this approach include gaining adequate rectal length, and tapering an ectatic rectum if necessary.

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Constipation Prescription

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