Comparative study of functional outcomes between ultra-low anterior resection and inter-sphincteric resection: a propensity matched analysis.

Background: Comparative bowel functional outcomes between ultralow anterior resections (ULAR) and inter-sphincteric resection (ISR) for similar tumour and patient characteristics is not known.

Methods: Single centre study of low rectal caners (<5cm from anal verge) with 1:1 propensity matching of age, sex, body mass index, prior radiation, and surgical approach (open vs. minimally invasive) was performed for the ULAR and ISR groups. Primary outcome measure was Wexner Incontinence scores and Low Anterior Resection Syndrome (LARS) score at a single time point after stoma reversal.

Results: Seventy-two matched patients were included. Median Wexner scores were five and eight for the ULAR and ISR cohorts (p = 0.006). Major incontinence (Wexner >11) was found in 5.6% versus 33% after ULAR and ISR, respectively. Major LARS (score > 29) was demonstrated in 11% versus 25% in ULAR versus ISR (p = 0.293). Majority in both groups has no LARS (score < 20), that is, 72.2% versus 63.9% in ULAR against ISR. Besides these, stool fragmentation (p < 0.001), nocturnal defecation (p < 0.001) and use of anti-diarrhoeal medications (p = 0.023) were significantly more after ISR.

Conclusions: Bowel continence was relatively inferior after ISR as compared to an ULAR for low rectal cancers in matched cohorts. Major LARS in ISR was twice as prevalent without statistical differences.