Comparison of rectal balloon expulsion test in seated and left lateral positions

Defecatory disorders can be diagnosed by rectal balloon expulsion (BE) and anorectal manometry, which are traditionally evaluated in the seated and left lateral (LL) positions, respectively. The aims of this study were to compare BE in the LL and seated positions and to compare anorectal manometric parameters to BE performed in the seated and LL positions.

220 women [healthy (62), chronic constipation (158)] had anorectal high-resolution manometry and BE, summarized by time required (seated position, normal ≤60 s) or external traction to facilitate expulsion (LL position, normal ≤100 g).

Balloon expulsion results in both positions were either concordant [normal (141) or abnormal (32)] or discordant [only LL abnormal (30), only seated abnormal (17)]. There was modest agreement [κ = 0.44 (95% CI 0.30-0.57)] between seated and LL BE. Compared with subjects with normal BE in both positions, anal pressure during simulated evacuation (SE) was higher, and the rectoanal gradient (rectal-anal pressure) during SE was more negative in the other 3 categories (i.e., abnormal LL only, abnormal seated only, and both abnormal). High anal pressure during SE (OR = 1.02, 95% CI 1.00-1.04) and high rectal sensory threshold for desire to defecate (OR = 1.01, 95% CI 1.00-1.02) were associated with increased risk of abnormal BE in both positions, whereas high rectal pressure during SE (OR = 0.96, 95% CI 0.93-0.98) was associated with lower risk.

There is modest agreement between rectal BE in LL and seated positions. In addition to abnormal seated BE, which is considered indicative of pelvic floor dysfunction, high resolution manometry findings suggest that even some patients with abnormal BE in the LL position have pelvic floor dysfunction.