[The coronal anatomy of the pelvis at rest and under straining]

Twenty-five subjects with no pelvic floor dysfunctions at defecography were examined with direct coronal CT scans of the pelvis at rest and on straining. Three compartments with different characteristics were delimited by two planes-the anterior one being tangent to the ischiatic foramen and the posterior one to the ischial tuberosities. At rest, the average length of the levator ani muscle and the surface of the supralevator space were significantly lower posteriorly than in the other two compartments (48.3 mm +/- 7.9; 48.8 mm +/- 7; 42.6 mm +/- 9.4, p < 0.05 and 70.6 cm2 +/- 7.5; 66.9 cm2 +/- 11.2; 27.2 cm2 +/- 4.8, p < 0.01, respectively). On straining, maximum muscle lengthening occurred posteriorly, as indicated by similar average values (63.7 mm +/- 12.7; 63.3 mm +/- 9.5 and 60.5 mm +/- 14) and the corresponding increase (+12.5%) in the supralevator space occurred in the middle compartment (73.8 cm2 +/- 7.6; 75.3 cm2 +/- 11.6 and 30.2 cm2 +/- 5.2). To conclude, our method proved reliable enough (intra- and interobserver correlation index > 80%) and promising for future clinical applications and studies of pelvic floor dysfunctions.