Labor, induction

Oxytocin is the most commonly used agent for labor induction after cervical ripening. 

Oxytocin may be given by intravenous infusion (e.g., labor induction), intramuscular injection (e.g., control of postpartum bleeding), or as a nasal spray (e.g., to promote milk ejection). 

Misoprostol (Cytotec) is a prostaglandin Ej analogue that is being evaluated as a cervical ripening agent. It also is used in the treatment and prevention of peptic ulcer disease (see Chapter 40). Clinical trials show that misoprostol is an effective agent for both cervical ripening and labor induction. It appears to be as effective as dinoprostone and is much less expensive. 

Answer In this case, the decision to induce labor is appropriate. In caring for patients, physicians must decide who are appropriate patients for labor induction. The median length of human pregnancy is 40 weeks (when using the woman s menstrual period to date the pregnancy). Pregnancy is considered to be full-term from the 37 0/7 weeks to 41 6/7 weeks. 

Maymon R, Haimovich L, Shulman A, Pomeranz M, Holtzinger M, Bahary C. Third-trimester uterine rupture after prostaglandin E2 use for labor induction. J Reprod... 

Cervical laceration associated with misoprostol has been reported in a 33-year-old woman who received four doses of vaginal misoprostol (total dose 100 micrograms) for labor induction. Uterine rupture has occurred during induction of labor with misoprostol, usually in women who have had a previous cesarean section (22,23). Uterine dehiscence occurred in one and uterine rupture in three of 48 women with prior cesarean sections treated with intravaginal misoprostol 50 micrograms for cervical ripening (24). In comparison, uterine rupture occurred in one of 89 women who had an oxytocin infusion and none of 24 patients who received intravaginal alprostadil. 

Wing DA, Lovett K, Paul RH. Disruption of prior uterine incision following misoprostol for labor induction in women with previous cesarean delivery. Obstet Gynecol 1998 91(5 Pt 2) 828-30. 

Mathews JE, Mathai M, George A. Uterine rupture in a multiparous woman during labor induction with oral misoprostol. Int J Gynaecol Obstet 2000 68(l) 43-4. 

Wing DA, Guberman C, Fassett M. A randomized comparison of oral mifepristone to intravenous oxytocin for labor induction in women with prelabor rupture of membranes beyond 36 weeks gestation. Am J Obst Gynecol 2005 192 445-51. 

Wolf, S.B., et al. 2005. Sublingual misoprostol for labor induction A randomized clinical trial. Obstet Gynecol 105 365. 

Cervical laceration associated with misoprostol has been reported in a 33-year-old woman who received four doses of vaginal misoprostol (total dose 100 micrograms) for labor induction. Uterine rupture has occurred during... 

Cervical ripening is also accomplished in nonpharmacologic ways such as slow dilation of the cervix with an intracervical Foley catheter balloon or with laminaria tents. The laminaria are composed of seaweed and, as they absorb the fluid from the vagina and surrounding tissues, slowly expand over time. They are used more commonly in preparing the cervix for abortion than induction of labor. Acupuncture also has been cited in both cervical ripening and labor induction. 

Once the cervix has been ripened, or in patients who present with a favorable, soft cervix, labor induction can proceed with IV oxytocin (Pitocin ). This is a synthesized form of the same peptide composed of nine amino acids that is synthesized by the hypothalamus and secreted by the posterior pituitary. Although it will cause contractions beyond the late second trimester of pregnancy, these contractions do not always lead to labor. Labor also can be initiated or augmented by rupture of the amniotic and chorionic membranes, which is thought to up-regulate oxytocin receptors on the uterus and release prostaglandins. Nipple stimulation causes the increased release of oxytocin from the posterior pituitary and can be used to initiate corrtractions as well. 

A 34-year-old woman presents for labor induction. Her history is of two prior vaginal deliveries, and examination shows that her cervix is dilated 3 cm and 75% effaced. Which of the following would be the best agent for labor induction ... 

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