Comparison of Anorectal Manometry Testing in Left Lateral and Lithotomy Positions

Objectives Anorectal manometry (ARM) is typically performed in left lateral position, but many practitioners are more familiar with the lithotomy position. We aimed to evaluate agreement between ARM performed in left lateral and lithotomy positions and patient preference for testing position. Methods We performed a prospective comparison study of left lateral versus lithotomy position for women undergoing ARM for the evaluation of fecal incontinence. Women were randomly assigned to undergo testing in either left lateral position first followed by lithotomy position, or vice versa. Women then completed a survey assessing preference of position. We performed Bland-Altman analysis to measure the level of agreement between anorectal measurements obtained in the 2 positions. Results Twenty-one women were enrolled (mean age, 65 ± 2.2 years). We noted an acceptable level of agreement between anal pressure values obtained in left lateral versus lithotomy positions: anal resting pressure (mean difference, 0.9 mm Hg; 95% limits of agreement, 30.2 and -28.5) and anal squeeze pressure (mean difference, 1.8 mm Hg; 95% limits of agreement, 54.3 and -50.7). The level of agreement for sensory values was outside the predetermined clinical acceptability range. Most women (17/21 [81%]) reported a "good"or "very good"experience in both positions. Conclusions Anorectal manometry testing in the 2 positions can be used interchangeably for anal resting and squeeze pressures, but not for anorectal sensation. This modification can be introduced into clinical practice to accommodate the preference of women and practitioners who favor lithotomy position.