A pathophysiological study using anorectal manometry on patients with or without soiling 5 years or more after low anterior resection for lower rectal cancer.

BACKGROUND/AIMS: Physiological assessments of the anorectum in patients with soiling 5 years or more after low anterior resection (LAR) are still inconclusive. The purpose of this study is to clarify the significance of anorectal functions in patients with soiling 5 years or more after LAR for lowerrectal cancer.

METHODOLOGY: Thirty-eight patients after LAR for lower rectal cancer were manometrically studied and compared with 30 healthy volunteers as controls (group C; 19 men and 11 women, aged 44 to 76 with a mean age of 65.5 years). Patients after LAR were divided into 2 groups [group A; 20 patients without soiling (13 men and 7 women, aged 47 to 75 years with a mean age of 62.1 years), group B; 18 patients with soiling (12 men and 6 women, aged 51 to 77 years with a mean age of 64.8 years)]. The mean follow-up time from LAR was 67.2months (range 60-84 months). Anorectal manometry was performed on all patients in order to assess: Anal sphincter pressure at rest (ASPR; mmHg), Maximum anal sphincter pressure during voluntary contraction (MASPVC; mmHg), Minimum rectal sensory threshold volume (MRSTV; mL), Maximum rectal tolelated threshold volume (MRTTV; mL), Rectal compliance (RC; mL/mmHg), Rectoanal inhibitory reflex (RAIR), and Rectal pressure (RP; mmHg).

RESULTS: The distance from the dentate line (DL) to the level of anastomosis in group B (2.2 cm) was significantly shorter than that in group A (4.1 cm) (p<0.05). ASPR in group B was significantly lower than that in groups A and C (p<0.05, p<0.01, respectively). MASPVC in group B was significantly lower than groups A and C (p<0.05, p<0.01, respectively). There were no significant differences of MRSTV among groups. MRTTV in group B was significantly lower than that in groups A and C (p<0.01, p<0.05, respectively). RC in group B was significantly lower than that in groups A and C (p<0.05, p<0.01, respectively). The frequency rate of positive RAIR in group B was significantly lower than that in groups A and C p<0.05, p<0.01, respectively). RP in group B was significantly higher than that in groups A and C (p<0.01, respectively).

CONCLUSIONS: These findings support the hypothesis that soiling after LAR may be due to analsphincter and rectal dysfunctions. Increase of the RP also may cause soiling in patients after LAR. According to our studies, a length of remaining rectum 4 cm or more from the DL may be necessary to prevent soiling after LAR.