title: A Retrospective Cohort Study of Total Colonic Aganglionosis: Is the Appendix a Reliable Diagnostic Tool?
abstract: BACKGROUND
  Hirschsprung's disease (HD) is characterized by a lack of ganglion cells in the myenteric and submucosal plexus, associated with increased numbers of acetyl cholinesterase (AChE) positive nerve fibres. In approximately 10% of patients with HD the entire colon will be affected; a condition known as Total Colonic Aganglionosis (TCA). Aganglionosis of the appendix has long been considered to be an important finding in a patient in whom TCA is suspected, but its reliability for diagnosis has seldom been discussed. The aim of our study was to assess the reliability of the appendix as a histological specimen for the diagnosis of TCA, and to evaluate the long-term outcome of TCA.
  
  
  METHODS
  A retrospective cohort study was performed of all pathological specimens of patients with confirmed HD in our institution between March 2006 and April 2016.
  
  
  RESULTS
  Out of a total of 91 patients identified, 15 patients also had histopathological analysis of the appendix. Nine of these cases were confirmed as having TCA. The remaining 6 patients had HD involving the rest of the bowel up to the ascending colon, with normal ganglion present in the caecum. The appendix was removed in all the 15 cases. All 9 patients with confirmed TCA had aganglionosis of the appendix as well. The remaining 6 cases of short and long segment HD not involving the caecum, demonstrated normal ganglion cells within the appendix.
  
  
  CONCLUSIONS
  Aganglionosis of the appendix is a reliable tool in the diagnosis of TCA. The authors recommend that at the time of levelling biopsies, if aganglionosis extends to the mid-transverse colon, an ileostomy be performed and appendix sent for definitive confirmation of TCA. However, at the time of definitive surgery, a frozen section of pull-through segment of bowel is recommended to confirm the presence of ganglion cells.
authors.affiliation: Department of Paediatric Surgery, Our Lady's Children's Hospital, Dublin, Ireland.
authors.forename: T
authors.initials: T
authors.lastname: O'Hare
authors.affiliation: Department of Histopathology, Our Lady's Children's Hospital, Dublin, Ireland.
authors.forename: M
authors.initials: M
authors.lastname: McDermott
authors.affiliation: Department of Histopathology, Our Lady's Children's Hospital, Dublin, Ireland.
authors.forename: M
authors.initials: M
authors.lastname: O'Sullivan
authors.affiliation: School of Postgraduate Studies, Faculty of Medicine and Health Sciences, Royal College of Surgeons in Ireland, Dublin, Ireland.
authors.forename: P
authors.initials: P
authors.lastname: Dicker
authors.affiliation: Department of Paediatric Surgery, Our Lady's Children's Hospital, Dublin, Ireland.
authors.forename: B
authors.initials: B
authors.lastname: Antao
keywords: Appendix; Hirschsprung's disease; Histology; Rectal suction biopsy; Total colonic aganglionosis