Use of Perineocaliper® (Duchateau SA, Liège, Belgium). A: position of anal margin 2 cm higher than the ischial tuberosities (value = + 2 cm) at rest and in gynecological position (with thighs flexed to 90 degrees). B: during Valsalva's maneuver (red arrow) the anal margin is 1 cm below the ischial tuberosities (value = - 1 cm). View from the top as during clinical measurement. In this case, perineal descent = 3 cm (difference between A and B). 1 = anal margin. 2 = ischial tuberosity. 3 = level of the ischial tuberosities = reference or zero level.
Beco BMC Surgery 2008 8:13 doi:10.1186/1471-2482-8-13