Initiation of uterine contractions by purely mechanical stretching of the uterus at midpregnancy.
Purely mechanical stretching was applied to the uterus in normal midpregnancy by means of two No. 10 Nelaton catheters. Very gradual and steady onset of uterine contractions without hypertonia and hyperactivity were noted in all cases. All patients, in whom all possible afferent nerves of the uterus were blocked by continuous extradural and caudal anesthesia throughout the stretch treatment, also showed similar inauguration of uterine contractions. Uterine activity values indicated no significant difference between the nerve block and the non-nerve block groups (p = 0.68), but these values differed significantly with increasing time after stretching (p less than 0.001). All fetuses were delivered unaffected. The delivered placentas showed normal histologic integrity, and autoradiographic study proved the viability of the trophoblasts. It was concluded that the nerve and fetoplacental functions are probably not involved in the initiation of labor in this method.
D000029:Abortion, Legal / Q000379:methods*; D000767:Anesthesia, Epidural; D002404:Catheterization; D005260:Female; D006801:Humans; D007751:Labor, Induced / Q000379:methods*; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011453:Prostaglandins / Q000502:physiology; D013314:Stress, Mechanical; D014590:Uterine Contraction; D014599:Uterus / Q000502:physiology
D011453:Prostaglandins