title: Smooth muscle enfoldment internal sphincter construction after intersphincteric resection for rectal cancer.
abstract: OBJECTIVE
  To assess smooth muscle enfoldment and internal sphincter construction (SMESC) for improvement of continence after intersphincteric resection (ISR) for rectal cancer.
  
  
  METHODS
  Twenty-four Bama miniature pigs were randomly divided into a conventional ISR group and experimental SMESC group, with 12 pigs in each group. The proximal sigmoid colon was anastomosed directly to the anus in the ISR group. In the SMESC group, internal sphincter construction was performed. At 12 weeks before and after surgery, rectal resting pressure and anal canal length were assessed. Three-dimensional ultrasound was used to determine the thickness of the internal sphincter. After the animals were sacrificed, the rectum and anus were resected and pathological examinations were performed to evaluate the differences in sphincter thickness and muscle fibers.
  
  
  RESULTS
  All 24 animals in the SMESC group and the ISR group survived the surgery. Twelve weeks post-surgery, the rectal resting pressure, length of the anal high-pressure zone and the postoperative internal sphincter thickness for the ISR group were significantly lower than for the SMESC group. There was a thickened area (about 2 cm) above the anastomotic stoma among animals from the SMESC group; in addition, the smooth muscles were significantly enlarged and enfolded when compared to the ISR group.
  
  
  CONCLUSIONS
  This animal model study shows that the SMESC procedure achieved acceptable reconstruction of the internal anal neo-sphincter (IAN/S), without increasing surgical risk. However, the findings in this experimental animal model must be confirmed by clinical trials to determine the safety and efficacy of this procedure in clinical practice.
authors.affiliation: National center of colorectal surgery, the third affiliated Hospital of Nanjing University of Traditional Chinese Medicine, Nanjing, Jiangsu, China.
authors.forename: Heiying
authors.initials: H
authors.lastname: Jin
authors.affiliation: National center of colorectal surgery, the third affiliated Hospital of Nanjing University of Traditional Chinese Medicine, Nanjing, Jiangsu, China.
authors.forename: Bei
authors.initials: B
authors.lastname: Zhang
authors.affiliation: National center of colorectal surgery, the third affiliated Hospital of Nanjing University of Traditional Chinese Medicine, Nanjing, Jiangsu, China.
authors.forename: Hang
authors.initials: H
authors.lastname: Yao
authors.affiliation: National center of colorectal surgery, the third affiliated Hospital of Nanjing University of Traditional Chinese Medicine, Nanjing, Jiangsu, China.
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Du
authors.affiliation: National center of colorectal surgery, the third affiliated Hospital of Nanjing University of Traditional Chinese Medicine, Nanjing, Jiangsu, China.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Wang
authors.affiliation: National center of colorectal surgery, the third affiliated Hospital of Nanjing University of Traditional Chinese Medicine, Nanjing, Jiangsu, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Leng
mesh_terms: D001003:Anal Canal / Q000601:surgery*; D000818:Animals; D013505:Digestive System Surgical Procedures; D004195:Disease Models, Animal; D005242:Fecal Incontinence / Q000601:surgery; D005260:Female; D008297:Male; D008365:Manometry; D009130:Muscle, Smooth / Q000473:pathology*; D011312:Pressure; D019651:Plastic Surgery Procedures; D012004:Rectal Neoplasms / Q000503:physiopathology / Q000601:surgery*; D013552:Swine; D013556:Swine, Miniature