Evaluations of pelvic floor muscle in infants with rectovestibular fistula

Abstract

Objective To evaluate the morphology of pelvic muscle in infants with rectovestibular fistula. Methods A total of 20 infants with rectovestibular fistula aged 3-5 months received the examinations of radiology, barium enema and pelvic floor magnetic resonance imaging(MRI). The follow-up period was 1 year. Two infants were complicated by tethord cord syndrome. Three infants were complicated by dilations of rectum and sigmoid colon. There were 10 girls aged 3-6 months in control group. Results In control group, no difference existed between the thickness of bilateral external anal sphincter[left:(1.58±0.12)mm, right:(1.57±0.14)mm], puborectalis[left:(1.47±0.13)mm, right:(1.45±0.09)mm], ani levator[left:(1.75±0.18)mm, right:(1.72±0.22)mm]. The thickness of bilateral external anal sphincter[left:(1.32±0.39)mm, right:(1.21±0.35)mm], puborectalis[left:(1.18±0.33) mm, right:(1.06±0.35) mm] in infants with rectovestibular fistula were thinner than those in control group. The thickness of bilateral ani levator(left: 1.53±0.37 mm, right: 1.53±0.29 mm)in infants with rectovestibular fistula showed no difference from control group. Spearman's rank correlation analysis indicated sacral ratio(0.69±0.15) had no correlation with the thickness of external anal sphincter(left: r=0.361, P=0.118; right: r=0.150, P=0.527), puborectalis(left: r=-0.032, P=0.893; right: r=0.096, P=0.689)and ani levator(left: r=-0.082, P=0.732; right: r=-0.034, P=0.852). And the postoperative complications included difficult defecation(n=4), tethord cord syndrome(n=1) and dilations of rectum and sigmoid colon(n=3). Conclusions External anal sphincter, puborectalis and ani levator are bilaterally symmetric in healthy infants. Ani levator is normal in infants with rectovestibular fistula. External anal sphincter and puborectalis are weaker, but there is no dysfunction of defecation. The developments of external anal sphincter, puborectalis and ani levator have no correlation with sacral ratio. Key words: Congenital abnormalities; Rectum; Fistula