Posterior Sagittal Anorectoplasty (PSARP) for Imperforate Anus

0. Preparation

After anesthesia, a Foley urinary catheter is placed. A coudé catheter helps avoid a recto-urethral fistula. If the fistula is large or the urinary tract is hard to access, cystoscopy may be needed.

The prone, slightly jack-knifed position (with a roll under the hips) improves visualization during the dissection of the rectum’s anterior wall from the vagina or urinary system. Proper placement of the rectum and marking the anoplasty site with a pen or sutures and using a muscle stimulator for orientation helps ensure accuracy.

1. Posterior Sagittal Incision

The procedure starts with a posterior sagittal incision.

Traction sutures are placed around any visible fistula. The incision is made around the fistula and extended posteriorly toward the coccyx, with the length varying based on exposure needed.

Without a fistula, the posterior sagittal incision starts below the coccyx and extends to the perineal body, keeping the dissection in the midline.

Muscle complex fibers run perpendicular to the incision. Uniform traction and frequent muscle stimulation ensure midline dissection. Protrusion of unilateral ischiorectal fat indicates deviation from the midline.

2. Traction Sutures on the Rectum

Dissection continues in the midline, separating the levators until the white fascia of the rectum is reached. Traction sutures are placed in the rectum’s inferior aspect, and the rectum retracted up into the field with sutures.

3. Open the Rectum

Once the rectum has been identified, it is opened along longitudinally and anteriorly toward the level of the fistula. The fistula can be identified with gentle probing with a lacrimal duct probe to confirm its location. The fistula is divided and the rectum dissected free. Traction sutures are placed circumferentially in the rectal mucosa above the fistula to aid in separating the urethra from the rectum. Excessive bleeding during the anterior dissection suggests entry into the spongiosum tissue around the urethra.

4. Separating Urethra from the Rectum

In males, the urinary and reproductive systems can share a wall with the rectum’s anterior side. In females, the vagina often shares this wall with the rectum. The lower the fistula, the longer this common wall. This wall must be divided to the peritoneal cavity level to ensure the rectum can reach the perineum without tension. There is no natural plane between these tissues; it is created with even traction and careful dissection, staying close to the rectal wall to avoid nerve injury and not entering the rectum. Dissection begins laterally on both sides. Once enough colon is mobilized, the anterior dissection starts. The fistula is marked with a stitch and retracted downward as the rectum’s anterior wall is carefully separated from the urethra’s posterior wall.

5. Mobilize the Rectum

The rectum must be circumferentially freed to reach the perineum without tension. The vascular supply along the rectum is freed posteriorly, staying close to the rectal wall.

6. Lateral Dissection

The rectum’s lateral attachments are freed, ensuring the dissection plane stays on the rectal wall to avoid injury.

7. Mobilized Rectrum

The rectum freed along the length to the level of the peritoneum.

Glistening white perirectal fascia indicates a too-wide rectal dissection, which potentially causes a neurogenic bladder. To ensure proper mobilization and prevent injury, this fascia and the extrinsic blood supply of the rectum should be removed. The distal rectum remains well-perfused due to its robust intramural blood supply. Adequate blood supply and a tension-free anastomosis help prevent complications like stricture and dehiscence.

Once mobilized, the rectum is relocated posteriorly. The sphincters are identified with a muscle stimulator to guide the next steps. The rectum is placed anterior to the levators, which are reapproximated with multiple interrupted absorbable stitches. The perineal body is recreated with multiple layers of interrupted absorbable sutures and skin sutures.

8. Recreate the perineal Body

Before the anoplasty, the perineal body should be closed in layers behind the urethral closure to ensure healthy, vascularized tissue is placed between the urethra and rectum.

The posterior aspect of the muscle complex is reapproximated behind the rectum, incorporating the rectal wall with each stitch to help prevent prolapse. The posterior soft tissue is also closed with interrupted absorbable sutures.

9. Rectopexy

To prevent prolapse, a rectopexy is performed by attaching the rectum to the posterior muscle complex as the incision is closed.

10. Split the Fistula/Rectum

After creating the perineal body and closing the posterior incision, the anoplasty is completed. The fistula and rectum are then opened vertically in the midline.

11. Redundant Rectum Resection

To avoid mucosal prolapse, the redundant rectum should be resected back to the skin level. It’s easiest to do this one half at a time, securing the tissue superiorly and inferiorly before resecting.

12. Anoplasty

The anal opening should be fully encircled by the sphincter complex before creating the anoplasty. The colon is divided in half and sequentially anastomosed to the skin with sixteen full-thickness, long-lasting absorbable sutures. A size-appropriate Hegar dilator should be passed into the anastomosis to ensure it passes freely.

The circumference of the rectum is secured to the skin within the sphincter complex. After completing the anoplasty, the perineal body is closed anteriorly, the posterior sagittal incision is closed posteriorly, and the anoplasty is completed in between. The anus puckers inward once all sutures are cut.^19.20,21,22