Urogenital Hiatus Closure: Facts, Fallacies, and Why a Unified Theory of Hiatal Failure is Needed.

An enlarged urogenital hiatus is as important as apical support or fascial attachment failures in the development of prolapse and is strongly related to operative failure, yet we lack a conceptual model for factors responsible for hiatal failure. For a conceptual model to be valid, it cannot be proven false by empirical observation. We present six clinical observations with which future model development must be consistent. (1) Perineal body damage alone does not explain an enlarged urogenital hiatus. Three women have complete 4th degree lacerations but small hiatuses. (2) Levator damage is not a sole causal factor. One woman has bilateral levator avulsion but a normal hiatus, while another has intact muscles and an enlarged hiatus. (3) Hiatal assessment during straining is incomplete. Two women with similar straining urogenital hiatuses of 6-7 cm have respective 1.5 cm and 7 cm resting hiatuses. (4) Urogenital hiatus measurements during straining are confounded by Valsalva effort strength. Urogenital hiatus size increases by 30%, 51%, and 181% in one woman depending on straining strength. (5) Hiatal closure during pelvic muscle contraction differs widely. One woman can close her hiatus from 3.5 cm to 1.5 cm, while another shows no reduction despite evidence of contraction. (6) Prolapse/hiatus interactions occur with advancing age. One woman experiences progressive hiatal enlargement over 31 years. Our clinical observations reveal the complexity of the multiple factors involved in hiatal failure and support the need for a unified disease model consistent with these factors on which to base future research.