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Induction and Augmentation of labor
LABOR INDUCTION ......e...........e......e....e. 503
PREINDUCTION CERVICAL RIPENING ..e....e.....e.... 505
PHARMACOLOGICAL TECHNIQUESe. . . . . . . . . . . . . . . . 506
MECHANICAL TECHNIQUES .e........e....e...e..e... 507
METHODS OF INDUCTION AND AUGMENTATION . .. 508
PROSTAGLANDIN E, .. .......... ......... .... 508
OXYTOCIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 509
AMNIOTOMY FOR INDUCTION AND AUGMENTATION . 511
In other cases, if inteerence becomes imperative, the introduction of a bougie into the uterus, or the employment of a smal Champetier de Ribes rubber bag acts as an eective uterine irritant and brings about complete dilatation.
-J.
No efective means of labor induction were available when Williams wrote the first edition of this book. Labor augmentation methods were largely inefective, and manual cervical dilation was performed as a last resort. Contrast with today, when several pharmacological agents permit labor induction or augmentation, and ironically the use of a "bougie" has come back into vogue.
Induction implies stimulation of contractions before the spontaneous onset of labor, with or without ruptured membranes. When the cervix is closed and unefaced, labor induction will often commence with cervical ripening, a process that generally employs prostaglandins to soften and open the cervix.
Augmentation refers to enhancement of spontaneous contractions that are considered inadequate because of failed cervical dilation and fetal descent-inertia uteri-as described by Williams (1903).
In the United States, the incidence ofilabor induction rose 2.5-fold from 9.5 percent in 1991 to 23.8 percent in 2015 (Martin, 2017). he incidence varies between practices. At Parkland Hospital, approximately 35 percent of labors are induced or augmented. By comparison, at the University of Alabama at Birmingham Hospital, labor is induced in approximately 20 percent of women, and another 35 percent are given oxytocin for augmentation-a total of 55 percent. This chapter discusses indications for labor induction and augmentation and various techniques to efect preinduction cervical ripening.
Induction is indicated when the beneits to either mother or fetus outweigh those of pregnancy continuation. The more common indications include membrane rupture without labor, gestational hypertension, oligohydramnios, nonreassuring fetal status, postterm pregnancy, and various maternal medical conditions such as chronic hypertension and diabetes (American College of Obstetricians and Gynecologists, 20i16).
Methods to induce or augment labor are contraindicated by most conditions that preclude spontaneous labor or delivelY. The few maternal contraindications are related to prior uterine incision type, contracted or distorted pelvic anatomy, abnormally implanted placentas, and uncommon conditions such as active genital herpes infection or cervical cancer. Fetal factors include appreciable macrosomia, severe hydrocephalus, malpresentation, or nonreassuring fetal status.