Hyaluronidase modifies the biomechanical properties of the rat cervix and shortens the duration of labor independent of myometrial contractility.

Abstract

To investigate the effect of intracervical hyaluronidase on the biomechanical properties of the cervix and on uterine contractility. Sprague-Dawley rats (n = 33, term day 22) were injected with hyaluronidase (100 IU) or saline solution on day 18 of gestation (n = 8-9/group). On day 21, labor was induced with mifepristone (8 mg/rat). Injection-to-delivery times were recorded. Biomechanical properties of the cervix were assessed using stretch-tension analysis. Myometrial contractility was investigated in response to hyaluronidase (0.2-200 IU/mL), oxytocin (10(-10)M to 10(-5)M), and potassium chloride (60 mM). Delivery times were shorter in the hyaluronidase group (P = .03). Cervices of the treated animals showed higher measures of elasticity and plasticity (P = .02 for both). Myometrial sensitivity to hyaluronidase, oxytocin, or potassium chloride was not affected by the cervical application of hyaluronidase (P > .05 for all). Cervical hyaluronidase treatment shortens labor and alters the biomechanical properties of the cervix, independent of the myometrium.