Size of the urogenital hiatus in the levator ani muscles in normal women and women with pelvic organ prolapse

Objective: Compare urogenital hiatus size in normal women and women with pelvic organ prolapse. Methods: The sagittal and transverse urogenital hiatus diameters were measured and hiatus area calculated in 300 women whose support was scored using a modified Baden system. Results: In women with normal support and without prior surgery, hiatus area was 5.4 cm(2) (+/- 1.71 standard deviation [SD], n = 197). In women with uncorrected clinical prolapse (grade 2-3), the area of the hiatus was enlarged (9.6 cm(2) +/- 3.97, (n = 34, P < .05) and became larger with progressive prolapse (grade 0, 5.4 cm(2) +/- 1.71, n = 197; grade 1, 7.3 cm(2) +/- 1.91, n = 27; grade 2, 8.3 cm(2) +/- 2.45, n = 18; grade 3, 11.0 cm(2) +/- 4.90, n = 16). When matched for age and parity, prolapse patients had a Larger hiatus than normal women. Women with recurrent prolapse had a larger hiatus than cured women (13.3 cm(2) +/- 3.86 n = 8 compared with 8.1 cm(2) +/- 2.44 n = 16 P < .05) or women with recurrence after one operation (8.9 cm(2) +/- 1.77 n = 18 P < .05). Hiatus size in patients surgically cured (8.3 cm(2) +/- 2.44, n = 16) did not return to normal (5.4 cm(2) +/- 1.71, n = 197, P < .05). Increasing area of the hiatus was correlated with an increase in anterior-posterior diameter (r(2) = 0.9, P < .05), was less attributable to increased transverse diameter (r(2) = 0.6, P < .05), and was not related to thickness of the perineal body (r(2) = 0.0, P > .05). Conclusion: Increasing pelvic organ prolapse is associated with increasing urogenital hiatus size; the hiatus is larger after several failed operations than after successful surgery or single failure. (C) 1998 by The American College of Obstetricians and Gynecologists.