The study included cases diagnosed as HD who were operated during the period 2008 through 2018. Cases of total colonic aganglionosis were excluded to be discussed in a separate report. Data retained by the author were retrospectively analyzed and included demographic data (sex, age at operation), investigations, operative details, and short-term outcomes. The study was conducted after internal review board approval.

The typical presentation included delayed passage of meconium, constipation, and abdominal distension, while some cases presented with neonatal intestinal obstruction and bilious vomiting. The diagnosis was usually confirmed by the typical findings in contrast enema studies, which has the additional benefit of determining the extent of aganglionic (spastic) bowel segment (Fig. 1). However, there is almost a consensus on the necessity of obtaining pre-operative histopathological evidence of HD, which requires a rectal biopsy. The latter may be performed as a bedside suction biopsy; however, only full-thickness rectal biopsy was available at our facility. Few cases, who were not doing well (e.g., bowel perforation), underwent exploration and leveling colostomy as an initial step before corrective surgery.

Fig. 1

Contrast enema of three different cases of “recto-sigmoid” Hirschsprung disease (a–c). Note the different lengths of the aganglionic (spastic) segment which is longest in c and shortest in a

Trans-anal endorectal pull-through (Soave’s procedure) [6]Position

The procedure was performed either in the prone or supine lithotomy position (Fig. 2) [7]. The former position may be preferred for a pure trans-anal procedure. However, for patients with colostomy or when expected to need additional laparotomy for mobilization of the colon from above, the supine position was definitely advantageous.

Fig. 2

Trans-anal endorectal pull-through (Soave’s procedure). The procedure can be performed either in the prone (a) or supine lithotomy position (b)

Anal retraction

Early during the study period, we used simple stitches to retract/open the anus allowing for trans-anal (endo-rectal) dissection (Fig. 2). Later, we shifted to using the Lone-Star retractor (when it became available, Fig. 3), which provided better exposure for trans-anal dissection compared to simple stitches. The latter was noticed to evert the anus rather than providing optimal retraction.

Fig. 3

Trans-anal endorectal pull-through (Soave’s procedure). a Note advancing the hooks of the Lone-Star retractor hiding the dentate line to protect the anal canal during the early beginning of dissection. b After submucosal injection of adrenaline/saline solution (1/200,000)

Trans-anal excision of aganglionic rectum

We start by submucosal injection of adrenaline/saline solution (1/200,000) in different quadrants above the dentate line (Fig. 3). This has the dual benefit of inducing hydro-dissection and minimizing bleeding. A circular mucosal incision is made 2 cm above the dentate line via a needle monopolar diathermy. Multiple stay sutures help to distribute the tension on the anal mucosa during traction. The first few centimeters of the rectum (3–7 cm) are excised via submucosal dissection before we shift to full-thickness excision (Fig. 4). The retained muscular cuff of the rectum is incised posteriorly; sometimes, we excise a strip of this muscle cuff. We continue to excise the abnormal/spastic bowel till we reach a healthy segment of the colon 7–10 cm above the characteristic “funnel” of the transitional zone. The latter was usually obvious at operation and well-consistent with the pre-operative imaging findings (Fig. 5) [8]. Intra-operative histopathological analysis (frozen section) to determine the level of the healthy proximal colonic segment for the pull-through was not our routine practice; however, this was occasionally essential and helpful when there was no consensus on the level of the transitional zone in the pre-operative imaging.

Fig. 4

Excised specimens in three different cases of Hirschsprung disease who underwent trans-anal endorectal pull-through (a–c). The first few centimeters of the rectum (3–7 cm) are excised via submucosal dissection before we shift to full-thickness excision. Note the variable length of submucosal dissection of the rectum (double arrowhead dotted line). Recently, there is a tendency to do less submucosal dissection in order to leave a shorter muscle cuff. d, e The contrast enema of cases a and c, respectively, are presented for comparing the operative findings with preoperative imaging. Note: contrast enema of case b was not available

Fig. 5

Trans-anal endorectal pull-through (Soave’s procedure) in two different cases of Hirschsprung disease. a, c The preoperative contrast enema showing the level of the transitional zone in the two cases. b, d The operative findings in the two cases, which proved to be well consistent with the preoperative imaging findings

Before turning to the final step of the procedure (colo-anal anastomosis), we had to straighten the retained rectal muscular cuff (make sure it is not rolled upon itself) to avoid postoperative obstruction. Also, it may be useful to add a layer of interrupted seromuscular stitches fixing the pulled-through colon/neorectum to the retained muscle cuff at a deeper level to the final colo-anal anastomosis.

Cases with colostomy or abdominal-assisted trans-anal pull-through

In the supine lithotomy position, we start by taking down the colostomy and/or mobilization of the colon making sure to preserve the marginal vessels to ensure reliable blood supply to the pulled-through colon. In addition to cases with colostomy, assistance via laparotomy was indicated for cases with long aganglionic segment and/or severely distended colon (Fig. 1c). The laparotomy incision was usually a left lower transverse (muscle splitting) incision. Alternatively, a lower midline incision may be used which has the advantage of easy extension to the upper abdomen as needed (e.g., mobilization of splenic flexure). In all cases, the laparotomy incision was used to ensure adequate mobilization of the colon, while the trans-anal part of the procedure was completed as previously described.

Early postoperative care

Usually, enteral feeding is resumed gradually on the 2nd or 3rd postoperative day. With the progression of feeding, abdominal distension is not uncommon; this is managed by temporarily withholding oral intake and maybe gentle insertion of a soft rectal tube. Most patients will have reached full oral intake to be discharged on the 7th to 10th postoperative day. Rectal examination should be performed routinely at follow-up visits (starting 2–3 weeks postoperatively) to check for possible narrowing at the colo-anal anastomosis.

Intermediate and long-term follow-up

Parents of operated cases were contacted via their registered phone numbers. They were informed about the study and were encouraged to visit the outpatient clinic to assess functional outcomes following corrective surgery.