title: Morphologic changes of the anal sphincter musculature during and after temporary stool deviation.
abstract: OBJECTIVE
  Temporary stool deviation, using a stoma, is a well-known surgical principle to protect low colorectal or coloanal anastomoses. The purpose of this study was to evaluate any morphologic changes with regard to the anal sphincter muscles during and after temporary ileostomy.
  
  
  METHODS
  Forty-four patients with rectal carcinomas were studied prospectively. All patients underwent low anterior resection. Reconstruction was performed using either a coloanal pouch or a straight end-to-end anastomosis. A protective stoma was fashioned in all 44 patients (ileostomy n=41; colostomy n=3). Stoma closure was carried out after a median of 85 days (41-330 days). Using a standard protocol, anal-sphincter thickness [m. puborectalis, external anal sphincter (EAS) and internal anal (IAS) sphincter] was assessed by means of endoanal ultrasonography preoperatively, at the time of stoma closure, and every 3 months thereafter for 1 year.
  
  
  RESULTS
  The diameter of the puborectal muscle decreased from a median preoperative value of 6.3 mm to 5.7 mm at the time of stoma closure (P=0.03). After 3 months, 6.2 mm was measured. This value remained stable for the complete follow-up period. Similar results were recorded for the EAS. The IAS thickness remained stable throughout the study period, measuring between 2.1 mm and 2.4 mm.
  
  
  CONCLUSIONS
  Temporary stool deviation does lead to morphologic changes of the anal sphincter. While the smooth muscle remains unchanged, the striated counterpart undergoes atrophic transformation. However, after passage reconstruction, i.e., stoma closure, a rapid regeneration of the voluntary muscles is observed.
authors.affiliation: Department of Surgery, University School of Medicine Würzburg, Germany. m.sailer@mail.uni-wuerzburg.de
authors.forename: M
authors.initials: M
authors.lastname: Sailer
authors.forename: M
authors.initials: M
authors.lastname: Fein
authors.forename: K H
authors.initials: KH
authors.lastname: Fuchs
authors.forename: D
authors.initials: D
authors.lastname: Bussen
authors.forename: C
authors.initials: C
authors.lastname: Grun
authors.forename: A
authors.initials: A
authors.lastname: Thiede
mesh_terms: D000368:Aged; D001003:Anal Canal / Q000000981:diagnostic imaging / Q000473:pathology*; D019160:Endosonography; D005260:Female; D006801:Humans; D007081:Ileostomy; D008297:Male; D011446:Prospective Studies; D012004:Rectal Neoplasms / Q000601:surgery*; D013997:Time Factors