Doctor

POSTERIOR SAGITTAL ANORECTOPLASTY
AND RECTAL FLAP
LUIS E. ZEA-SALAZAR
Department of Pediatric Surgery, Hospital del Niño "Francisco de Ycaza Bustamante," Guayaquil, Ecuador.
Abstract. A modification to the Posterior sagittal anorectoplasty technique, developed by A. Peña is described. A down based rectal flap makes it easier to reach the new anus, without dissecting the ventral side of therectal pouch, and uses the tissue otherwise thrown away in the necessary tapering.
Key words: Anorectal anomalies; Posterior sagittal anorectoplasty; Rectal flap.
Introduction
The posterior sagittal approach developed by A. Peña for the treatment of anorectal anomalies has proved to be the best way of exposure of the anatomy of the perineal region and has been used worldwide with excellentresults [1,2,4,7]. However as all other techniques, it implies some kind of tissue damage in the procedure of dissecting around the rectal pouch, with special concern to the external innervation of bowel and low urinary tract [2,7]. The operation discards a portion of rectal tissue in the necessary tapering of the pouch to make an adequate anal canal, that fits in the sometimes not well developed"muscular complex" [1,2,5].
In our hospital, we have modified Dr. Peña's technique, utilizing the excess of the pouch's wall in the form of a down based rectal flap. It allows us to reach the new anus site without mobilizing the ventral side of the terminal bowel; thus preserving intact it's innervation and vascularization.

FIGURE 1: Lost tissue in Peña"s technique

FIGURE 2: Gained tissuein author"s technique
Materials and method
From our preliminary theoretical considerations, we decided to use this technique on those patients with a high type of anomaly and without a fistula.
We perform the operation as described by Peña [1,2], but on reaching the terminal bowel pouch, we proceed to liberate only its dorsal wall. Dissection of the dorsal wall is taken as far up as possibleand necessary, taking into account the length of intestine needed to reach the new-anus.
Then we proceed to delineate the rectal flap, it's length being the same as the distance from the end of the pouch to the new anus, and it's width no less than one third and no more than one half of the circumference of the terminal intestine.
We start to cut the intestine's wall, with the electrocautery,in the middle of the flap's upper limit and then extend the incision to the sides through the hole thickness of the wall. We proceed on both sides toward the distal end. The lateral incisions are stopped about one centimeter before the end of the pouch.

FIGURE 3: Dorsal wall of rectum exposed and flap delimited.

FIGURE 4: Flap swung down.

FIGURE 5: Neo rectum formed over a rectal tube.The flap is swung downwards and the new anus is reached without tension.
We close the intestinal wall over a rectal tube of appropriate diameter for the age, with two layers of interrupted 4/0 sutures. The "muscular complex" is re-approximated over the intestinal tube and the operation completed as described by Peña.
Patients and results
Since 1990 we have used the technique on fivepatients, two girls and three boys. They all had a high type of anomaly without a fistula. Coincidentally all of them had a Down Syndrome.
PATIENTS | FILE | BIRTH | SEX | ASSOCIATED ANOMALIES | OPERATION |
CASE 1 | 091573 | 2/Oct./89 | fem. | Down Sind.V.S.D. | colostom. 3/Oct./89A.R.P.S.P. 15/Jun./90Colost. close 16/Nov./90 |
CASE 2 | 079170 | 7/May/88 | fem. | Down Sind. | colostm.9/May/88Laparot. 3/Sept./88A.R.P.S.P. 22/Oct./90Colostm.close 1/Jan/91 |
CASE 3 | 098250 | 5/May/90 | masc. | Down Sind.A.S.D | colostom. 7/May/90A.R.P.S.P. 2/Sept./91Colost. close 23/Jul./92 |
CASE 4 | 113004 | 12/Ene./92 | masc. | Down Sind. | colostom. 13/Ene./92A.R.P.S.P. 9/May./94 |
CASE 5 | 123755 | 25/Feb./93 | masc. | Down Sind. | colstom. 13/Ene./93A.R.P.S.P. 10/Jul./94 |
TABLE 1.- Patients...