Maternal Dystocia: Causes and treatment

Maternal dystocia includes defects of the birth canal and defects of the expulsive forces. Defects of the birth canal would be due to the pelvic constriction, failure of cervical dilation, incomplete relaxation of the caudal vagina and vulva and other physical abnormalities causing obstruction such as remnants of the paramesonephric ducts. The expulsive force of labour is due to a combination of myometrial contractions and straining induced by the contraction of the abdominal muscles with a closed glottis. Because the abdominal muscles do not come into play until the myometrium has forced the fetus and fetal membranes into the pelvic canal and stimulated the pelvic sensory nerve receptors, it is logical to consider first the expulsive deficiencies that may arise in the myometrium. These may occur spontaneously or dependently and are called, respectively, primary and secondary uterine inertia.