Access the accompanying videos for this chapter online. Available on ExpertConsult.com .
Operative management for Hirschsprung disease (HD) involves removing the aganglionic bowel segment and reconstructing the intestinal tract by bringing normally innervated bowel down to the anus while preserving the anal sphincter mechanism and sensory innervation of the anal transitional zone to ensure good postoperative bowel function.
In 1995, the laparoscopic-assisted transanal pull-through (LTAPT) was described by Georgeson et al. In 1998, De La Torre-Mondragon reported a single-stage transanal endorectal pull-through without laparoscopy assistance (pure TAPT). Today, most centers opt to treat HD using either LTAPT or pure TAPT.
The anal canal between the dentate line (DL) and the anorectal line (ARL), otherwise known as the Hermann line, is the anal transitional zone. The upper border of the transitional zone is the ARL. Above the ARL, the rectum is lined with columnar epithelium, which is visually pinker than other areas, allowing the ARL to be identified accurately as a reliable landmark ( Fig. 14-1 ). The transanal dissection should commence just proximal to the ARL, leaving the ARL intact ( Fig. 14-2A ) and preserving the anal transitional zone between the DL and ARL. Preserving the anal transitional zone is crucial for normal anorectal sensation to ensure good bowel function following LTAPT or TAPT. By using the ARL as a surgical landmark, the transanal dissection can be standardized with reliable and reproducible results. In addition, the posterior aganglionic rectal muscle cuff above the ARL should be excised completely to prevent achalasia due to the aganglionic cuff.
In contrast, when the DL is used as the landmark for transanal dissection, this dissection may commence anywhere from 5 to 20 mm above the DL, depending on the surgeon’s subjective preference, resulting in a spectrum of outcomes that are largely unpredictable. If dissection is commenced too close to the DL, which would mean below the ARL ( Fig. 14-2B ), fecal incontinence will occur due to injury to the anal transitional zone. If dissection is commenced too far from the DL, which would mean above the ARL ( Fig. 14-2C ), constipation may ensue because a ring of aganglionic rectum is left, even though it may be short in length.
TAPT is composed of four key steps that must be performed exactingly to ensure a successful outcome: identification of normoganglionic colon, adequate colorectal dissection, anatomically accurate transanal dissection, and total excision of the posterior aganglionic rectal muscle cuff. There are advantages to using laparoscopy for TAPT: the presence of ganglion cells can be verified in the proximal bowel segment using laparoscopy-assisted colon suction biopsy ( Fig. 14-3 ). Also, the marginal arteries can be left intact because laparoscopic visualization allows the operation to progress without physically disrupting them, which in turn ensures that the blood supply to the distal end of the pull-through colon is fully preserved ( Fig. 14-4 ). Moreover, any tension on the feeding vessels of the pull-through colon or torsion on the pull-through colon can be visualized and treated appropriately ( Fig. 14-5 ).
In this chapter, the operative management of HD (excluding total colonic aganglionosis) will be described, focusing on a modified LTAPT procedure developed by one of the authors (AY) at Juntendo University School of Medicine in Tokyo, Japan (JLTAPT). The distinguishing features of the JLTAPT are (1) commencing transanal dissection just above the ARL and (2) complete excision of the posterior aganglionic rectal muscle cuff proximal to the ARL.
Indications and Preoperative Workup
The diagnosis of HD should be confirmed via a suction rectal biopsy. A full-thickness biopsy is needed if the suction rectal biopsy is inconclusive. However, the surgeon should be wary of an overzealous suction biopsy, especially in low-birth-weight babies, because rectal bleeding or perforation can occur. Finally, a contrast enema delineating the likely colonic transitional zone is useful for choosing the segment of colon for pull-through. However, the surgeon should be aware that the radiographic transition zone does not always correspond with the histologic transition zone.
When rectosigmoid dilatation is extreme, as often occurs due to fecal impaction in older children, an ileostomy or colostomy should be considered to reduce the risks of postoperative complications, such as intrapelvic abscess formation and coloanal anastomosis dehiscence due to infection.
A definitive contraindication to primary one-stage TAPT is failure of rectal tube colonic irrigation/decompression, which is often seen when the aganglionic colon extends proximal to the midtransverse colon. Laparoscopy is relatively contraindicated if there is a history of previous abdominal surgery (other than stoma surgery), if the patient has other conditions that may be negatively affected by a pneumoperitoneum (certain cardiac conditions), or if the patient has acute enterocolitis.
Intensive preoperative bowel preparation is necessary to prevent postoperative infection. Patients without stomas may continue normal oral intake until 2 to 3 days before operative pull-through. Parents familiar with glycerin enema administration can use daily glycerin enemas with or without colorectal irrigation with normal saline to decompress the colorectum. Once the patient is admitted to the hospital, prior to the operation, oral intake is limited to clear fluids only, and intravenous fluid replacement is important. Bowel irrigations with normal saline are performed once or twice daily and magnesium citrate is administered (1 g/kg) until there is no fecal residue. An aminoglycoside antibiotic (100 mg/kg/day) is given orally the day before operation. Broad-spectrum antibiotics such as ceftazidime (120 mg/kg/day) and isepamicin sulfate (8 mg/kg/day) are given intravenously once the patient is anesthetized.
Peripheral intravenous nutrition including amino acid and intravenous fat emulsion supplementation is highly recommended because the period a patient will be nothing by mouth or clear water only, both pre- and postoperatively, will generally be 4 days. If necessary, more intensively managed nutritional support using intravenous hyperalimentation through a central venous catheter may be required.
Operative Technique (JLTAPT)
Patient/Surgeon Positioning
After induction of general endotracheal anesthesia, the patient is positioned at the end of the operating table in the supine position. Skin antisepsis is performed. For infants, the trunk and buttocks are prepared extensively, followed by the legs circumferentially to the tips of the toes, and sterile stockings are placed on both legs.
The operating surgeon and an assistant initially stand on the patient’s right side. (After laparoscopic dissection of the colorectum is completed, the operating surgeon moves to the end of the table to perform the transanal dissection.) A monitor is positioned on the left side of the patient, beyond the patient’s feet. The scrub nurse stands at the right lower end of the operating table. The operating table is placed in the Trendelenburg position during the operation. A urinary catheter is inserted to decompress the bladder.
Port Placement
A 5-mm cannula is inserted through the umbilicus using an open technique and the pneumoperitoneum is established with carbon dioxide to a pressure of 10 mm Hg. Three additional 5-mm ports are introduced in the right upper and lower quadrants and in the left upper quadrant, respectively ( Fig. 14-6 ). The telescope is inserted through either the umbilical or right upper quadrant cannula. The port in the right upper or lower quadrant (whichever is not being used for the operating surgeon’s right hand) can be used for retracting the colon.
Laparoscopic-Assisted Colon Suction Biopsy
A laparoscopic-assisted suction biopsy can be performed in any infant or child of any size with rectosigmoid HD (see Fig. 14-3 ) as the sigmoid colon can be mobilized readily to allow the tip of the suction biopsy device to reach the planned biopsy site. Fortunately, 80% of HD cases are rectosigmoid in location, and a laparoscopic-assisted suction biopsy is safe, simple, and quick compared to a full-thickness biopsy.
After identification of the region of caliber change in the colon, the suction biopsy device is inserted into the anus by the assistant surgeon, ensuring that the tissue sampling mechanism is orientated correctly. After the suction biopsy has been performed, the operating surgeon places a metal laparoscopic vessel clip or suture at the biopsy site as a marker. The biopsy specimen is sent for immediate histologic assessment. If ganglion cells are not seen, the biopsy is repeated more proximally. It is essential that nerve bundles are absent in biopsy specimens to prevent using a segment of colon that is histologically transitional for the pull-through.
Laparoscopic Colorectal Dissection
If the suction colon biopsy shows normal ganglion cells without nerve bundles, the operating surgeon starts mobilizing the aganglionic rectum. The operating surgeon should confirm the location of the ureters and the vas deferens (in males) during this rectal dissection. Dissection of the mesorectum should follow the rectal wall closely to avoid injuring the hypogastric nerves (associated with ejaculation) and the pelvic splanchnic nerves (associated with erection and excretory function). When dissecting the rectum anteriorly, the dissection should being slightly distal to the peritoneal reflection to prevent injury to nerves supplying the bladder and urinary tract ( Fig. 14-7 ). When dissecting the rectum posteriorly and laterally, the dissection proceeds distally but stops cephalad to the external sphincter muscles in order not to injure them ( Fig. 14-8 ). By doing so, the blood supply to the rectum is almost completely disrupted, and bleeding is much less when excising the posterior aganglionic rectal muscle cuff. Without posterior and lateral dissection of the rectum proximal to the external anal sphincters, the posterior aganglionic rectal muscle cuff will retain attachments preventing nice eversion that should ensue naturally as far as just proximal to the level of the anorectal line transanally; thus, complete excision of the posterior aganglionic rectal cuff is unlikely, resulting in aganglionic rectal cuff remaining posteriorly.
