Seated Anorectal Manometry Better Predicts Balloon Expulsion Success: AJG |June 2026
Clinical knowledge base written and curated by GastroAGI Team from primary medical literatureLast updated June 1, 2026
- Dyssynergic defecation is commonly evaluated using anorectal manometry, traditionally performed in the left lateral decubitus position.
- However, defecation normally occurs in the seated position, raising questions about whether conventional testing accurately reflects real-world anorectal function.
- This study evaluated 384 adults undergoing high-resolution anorectal manometry and compared bear-down patterns in both lateral and seated positions.
- A small but clinically important subgroup of patients demonstrated dyssynergic patterns in the lateral position that normalised when tested while seated.
- Approximately 4% of patients showed normalisation of dyssynergia in the seated position.
- These patients had a dramatically higher likelihood of successfully completing the balloon expulsion test (BET), one of the most important physiological markers of normal evacuation.
- Normalisation in the seated position was strongly associated with successful balloon expulsion within one minute.
- The findings suggest that some patients may be incorrectly classified as having dyssynergic defecation when assessed only in the traditional lateral position.
- Seated testing may better reproduce physiological defecation mechanics and pelvic floor behaviour.
- This has important implications for diagnostic accuracy, particularly when anorectal manometry findings and balloon expulsion test results appear discordant.
- Incorporating seated assessment into routine anorectal physiology testing may improve identification of clinically relevant evacuation disorders.
- The study supports a growing movement toward more physiologic testing conditions during anorectal function evaluation.
Bottom line: High-resolution anorectal manometry performed in the seated position may provide a more accurate assessment of defecatory function than traditional lateral testing, with normalisation of dyssynergic patterns strongly predicting successful balloon expulsion.
