Patient position during cinedefecography. Influence on perineal descent and other measurements

This study was undertaken to assess the reproducibility of cinedefecography measurements and abnormal findings between the left lateral decubitus and seated positions.

Prospective patient evaluation included all patients who had lateral radiographs of the pelvis taken at rest, during squeezing, and pushing in both positions. Anorectal angle, perineal descent, and puborectalis length measurements were calculated for each set of radiographs. Pelvic floor dynamics during evacuation were measured as the changes between rest and pushing. Abnormal findings included both increased dynamic and fixed perineal descent, nonrelaxing puborectalis, and premature evacuation.

One hundred five consecutive patients underwent cinedefecography. There were statistically significant differences between the positions with regard to anorectal angle (P < 0.0001), perineal descent (P = 0.0001), and puborectalis length (P = 0.0001). Dynamic changes of the anorectal angle, perineal descent, and puborectalis length were not significantly different (P > 0.05). However, 6 of 22 (27 percent) patients with fecal incontinence had premature evacuation severe enough to impede measurement only when seated (P = 0.05).

Because of the statistically significant differences between the two positions, centers should always employ the same position for a given diagnostic group.