Autopsy Study of Calretinin Immunohistochemistry in the Anorectal Canal in Young Infants and Potential Implications for Rectal Biopsy Approach in the Neonatal Period.

BACKGROUND: Absent submucosal ganglion cells in biopsies 1-3 cm above the pectinate line establishes the pathologic diagnosis of Hirschsprung Disease (HD). Calretinin stains both ganglion cells and their mucosal neurites and has gained importance in HD diagnosis. Absent calretinin positive mucosal neurites in biopsies at the appropriate level above the pectinate line is highly specific for HD. Whether this applies to lower biopsies is uncertain. To address this, we studied anorectal canal autopsy specimens from infants. METHODS: We performed an autopsy study of infant anorectal canal specimens to describe calretinin staining in this region. Calretinin staining was correlated with histologic and gross landmarks. RESULTS: In all 15 non-HD specimens, calretinin positive mucosal neurites were present in glandular mucosa up to the anorectal line where neurites rapidly diminished. Age range was preterm 26 weeks to 3 months. CONCLUSIONS: Calretinin positive mucosal neurites are present in glandular mucosa up to the anorectal line in young infants. This is potentially important regarding neonatal HD biopsy level and diagnosis. Positive calretinin staining at the anorectal line favors normal innervation making HD unlikely. Absent calretinin positive neurites in glandular mucosa is worrisome for HD in young infants, regardless of location.

How best to expose the entire surgical anal canal in the operative field during transanal pull-through for Hirschsprung's disease: a crucial step that determines success.

PURPOSE: During transanal pull-through (TAPT) for Hirschsprung's disease (HD), exposing the entire surgical anal canal (SAC) including the squamo-columnar junction, or anorectal line (ARL) is a crucial step for minimizing problematic postoperative bowel function. We present a hint for exposing the entire SAC. METHOD: Histologically, the ARL represents the junction of proximal unilayer columnar colorectal mucosa with distal stratified squamous epithelium and is the proximal limit of the SAC. It is an obvious landmark; proximal mucosa is vivid pink and distal mucosa is more whitish. We use the Lone Star (LS) self-retaining retractor system to expose the ARL. Before we attach the LS hooks to the anal sinuses on the dentate line full-circle, we place 3/0 sutures at 0, 3, 6, and 9 o'clock around the anus to expose the anal sinuses. If the patient's buttocks cannot be positioned as described or the patient is too high on the table, the LS ring does not sit well, resulting only in dilatation and lengthening of the SAC without prolapse. By hanging the patient's buttocks 5 cm over the end of the table, the LS ring sits snugly and the ARL and entire SAC prolapse to the anal verge. RESULTS: Good positioning, as described, greatly facilitated dissection in 61/68 TAPT cases, while poor exposure hindered treatment in 7/68. CONCLUSION: Thorough exposure of the entire SAC, which is crucial for adequate TAPT, is greatly facilitated by patient positioning.

Sensory innervation of the anal canal and anorectal line in Hirschsprung's disease: histological evidence from mouse models.

AIM: We used non-Hirschsprung's disease (HD) Sox10-Venus Transgenic mice (non-HDSV-mice), an endothelin receptor-B knockout mouse model of HD (HD-mice), and C57B6C3 wild controls (C-mice) to identify the correlation between the anorectal line (ARL) and successful transanal pull-through (TAPT). METHODS: In non-HDSV-mice, intestinal neural crest-derived cells can be visualized with Venus,-a green fluorescent protein-without histochemical staining. We exposed the anal canal in each non-HDSV-mouse and marked the ARL directly with red ink. Specimens of anus and rectum from HD- and C-mice were immunostained with sensory nerve markers substance P and calcitonin gene related peptide (CGRP) and Hematoxylin and Eosin. RESULTS: Stereoscopic microscopy confirmed a squamous-columnar epithelial junction corresponding to the red ink in non-HDSV-mice. Fluorescence microscopy showed intense Venus expression proximal to the ARL and little enteric nerve expression distally. Substance P and CGRP expression were strong in the basal layer of the anal transitional zone (ATZ) in both HD- and C-mice; i.e., distal sensory innervation was normal in HD-mice. CONCLUSIONS: The ARL delineated a distinct demarcation in sensory innervation that is normal even in HD-mice. Thus, the initial incision during TAPT should be based on the ARL because it is readily identifiable and intimately involved with bowel function.

Forty-Year Experience Alleviating Postoperative Hirschsprung-Associated Enterocolitis by Complete Full-Thickness Posterior Rectal Cuff Excision. The Anorectal Line Eliminates Problematic Anastomoses.

Introduction: A modified pull-through (PT) distinguished by complete full-thickness removal of the posterior rectal cuff, initially developed as an open procedure in 1980, has been performed with laparoscopic assistance since 1997. Postoperative bowel dysfunction improved when the anatomic landmark for PT surgery was revised from the dentate line (DL) to the anorectal (or Herrmann's) line (ARL) in 2007. A 40-year (1980-2019) review of 153 consecutive rectal/rectosigmoid type Hirschsprung's disease (HD) patients is presented. Methods: Data for postoperative bowel dysfunction and Hirschsprung-associated enterocolitis (HAEC) classified according to the American Pediatric Surgical Association (APSA) scale were obtained retrospectively. Results: PT was open (n = 43) and laparoscopic (n = 110). Dissection was DL (n = 57) and ARL (n = 96). Over 40 years, 5/153 patients (3.3%) had postoperative obstructive symptoms (POS), and 10/153 patients (6.5%) had 13 episodes of postoperative HAEC; APSA grades were: I (n = 4); II (n = 8); and III: (n = 1) presenting with explosive diarrhea (10/13; 76.9%), fever (10/13; 76.9%), abdominal distension (9/13; 69.2%), or bloody stools/shock (1/13 with grade III; 7.7%). The grade III case had histologically-proven transitional zone PT. Postoperative HAEC developed in 3/5 (60.0%) POS+ patients and 7/148 (4.7%) POS- patients (P = .002). Symptom duration and treatment were not correlated with APSA grades. Conclusions: Complete full-thickness posterior rectal cuff excision and using the ARL reduced postoperative HAEC significantly in this series. Despite being anatomically distinct, the DL is inadequate as a precise landmark for PT surgery because it lacks functional relevance. The APSA scale could benefit from timely review to improve its clinical and prognostic value.

Minimally Invasive Neonatal Surgery: Hirschsprung Disease.

Transanal pull-through (TAPT) is the procedure of choice for treating Hirschsprung disease and should be performed with laparoscopic assistance using the anorectal line (ARL) to ensure optimum postoperative bowel function (POBF). The dentate line (DL) has traditionally been used as the landmark for commencing dissection during TAPT, but we prefer the ARL because the DL is too subjective and can be associated with risk for injury to delicate sensory innervation required for normal defecation in the anal transition zone. An intact anal transition zone and total excision of the posterior rectal cuff are crucial for normal defecation. Objective assessment of POBF is essential for thorough follow-up and early detection of potential late complications that may arise.

Rectal mucosal dissection commencing directly on the anorectal line versus commencing above the dentate line in laparoscopy-assisted transanal pull-through for Hirschsprung's disease: Prospective medium-term follow-up.

BACKGROUND: In 2007, we began using the anorectal line (ARL) as the landmark for commencing rectal mucosal dissection (RMD) instead of the dentate line (DL) during laparoscopy-assisted transanal pull-through (L-TAPT) for Hirschsprung's disease (HD). We conducted a medium-term prospective comparison of postoperative fecal continence (POFC) between DL and ARL cases to follow our short-term study. METHODS: POFC is assessed by scoring frequency of motions, severity of staining, severity of perianal erosions, anal shape, requirement for medications, sensation of rectal fullness, and ability to distinguish flatus from stool on a scale of 0 to 2 (maximum: 14). RESULTS: Patient demographics were similar for ARL (2007-2014: n=33) and DL (1997-2006: n=41). There were no intraoperative complications and 2 cases of postoperative colitis in both ARL (6.1%) and DL (4.9%). Mean annual medium-term POFC scores for the 4-7 term of this study were consistently better in ARL: 9.7±1.4*, 10.1±1.6*, 10.6±1.6, and 11.3±1.4* in ARL and 8.6±1.5, 9.1±1.6, 9.8±1.9, 10.0±1.6 in DL (*: p<0.05). CONCLUSIONS: Medium-term POFC is better when the ARL is used as the landmark for RMD during L-TAPT for HD.