Effect of posture on anorectal manometric measurements in female patients with fecal incontinence and rectoanal intussusception

PURPOSE: This study aimed to investigate the influence of erect position on anorectal manometry in patients with rectoanal intussusception (RAI). METHODS: This was a single center prospective observational study. Eighty female patients with fecal incontinence (FI) who underwent defecography between 1st January 2016 and 30th April 2022 were included. The effect of posture on commonly measured parameters during manometry was assessed in the left-lateral and erect positions. The severity of FI was assessed using FI Severity Index (FISI). RESULTS: Defecography showed that 30 patients had circumferential RAI (CRAI), and 50 had non-CRAI. There were no significant differences in age, parity, FI type, and FISI scores between the groups. However, FISI scores were significantly lower in 51 patients with passive FI than 12 patients with mixed FI type [21 (8–38) vs. 32 (8–43), P = 0.007]. Endo-anal ultrasound showed no significant difference in the incidence of sphincter defects between the groups. Maximum squeeze pressure was significantly lower in the erect position than in the left-lateral position in the CRAI patients [119 cm H(2)O (59‒454 cm H(2)O) vs. 145 cm H(2)O (65‒604 cm H(2)O), P = 0.006] however, this finding was not observed in the non-CRAI group and the subgroup of anterior RAI patients. In either group, maximum resting pressure, defecation desire volume, and maximum tolerated volume were significantly higher, while anal canal length was significantly shorter in the erect position than in the left-lateral position, respectively. CONCLUSION: Voluntary contraction in female FI patients with CRAI was suppressed in the erect position. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12876-022-02581-7.