BACKGROUND: Low anterior resection syndrome (LARS) is common following surgery for mid and low rectal cancer. Transanal total mesorectal excision (TaTME) involves intraoperative stretching of the anal sphincter while an anal single port is placed, which can potentially further disturb anorectal function. The aim of our study was to systematically assess anal function after TaTME using anorectal manometry and questionnaires.

METHODS: Patients who had TaTME for rectal cancer at our institution were prospectively assessed by means of anorectal manometry and the standard LARS score. The primary endpoint was the resting pressure to assess internal sphincter damage and the secondary endpoints were squeeze pressure to assess external anal sphincter and analysis of correlation between LARS score and these two manometry parameters. Patients who had laparoscopic TME (LaTME) served as a control group.

RESULTS: Out of 81 patients invited to participate 48 accepted. There were 36 in theTaTMEgroup, and 12 in the LaTMEgroup. The mean follow-up time from the index operation date to the assessment date was 41.34 months (± SD 24.834). The mean resting pressure did not differ significantly between the groups (36.44 mmHg ± 18.514 and 36.58 mmHg ± 13.318 in the TaTME and LaTME groups, respectively, p = 0.981). The mean squeeze pressure was also comparable (125.00 mmHg ± 66.141 and 111.83 mmHg ± 51.111 in the TaTME and LaTME groups, respectively, p = 0.533). The mean LARS score was comparable and showed comparable results. The analysis of correlation between LARS score and manometry parameters showed no significant associations between resting or squeeze pressure and L:ARS score.

CONCLUSIONS: Following TME surgery, the resting and squeeze pressures of the anal sphincter measured by manometry were generally decreased, with no differences between the transanal and laparoscopic approaches.