OB DILEMMAS: Is this induction necessary?
3 cases, 3 evidence-based choices
Limitations. In some women it is impossible to place the catheter into the cervical canal because of discomfort or unfavorable position or consistency of the cervix. Also, the catheter may increase the risk of infection or cause disruption of a low-lying placenta.
Combined pharmacologic and mechanical methods?
Although the combination would appear to have greater potential for success, it has not proven to be more effective.7
Sequential cervical ripening on an outpatient basis also has been suggested, but further studies are needed before it can be recommended.18
After G.C. is counseled about the risks of postterm pregnancy, as well as the risk of cesarean delivery with induction of labor, she decides to proceed with labor induction. Cervical ripening with misoprostol is begun. After 2 doses, the patient is dilated 4 cm, and oxytocin is initiated along with artificial rupture of membranes. Labor ultimately arrests at 7 cm dilation, and a healthy male infant is delivered by cesarean.
CASE 2: Mild preeclampsia at 37 weeks
M.A. is a 35-year-old gravida 4 para 2012, who complains of a headache at 37 5/7 weeks’ gestation. Her blood pressure is 157/97, and she has 1+ proteinuria on dipstick urinalysis. Her laboratory tests are unremarkable, including normal serum creatinine, liver function tests, and platelets.
The fetus appears to be appropriately grown with normal amniotic fluid. Antepartum fetal heart rate testing is reactive and reassuring. The patient is having intermittent, mild uterine contractions, and her cervix is dilated 3 cm. She is given acetaminophen for the headache, which brings relief.
You diagnose mild preeclampsia at term, for which induction of labor is clearly indicated. However, M.A.’s pregnancy history is notable for a term vaginal delivery followed by a low transverse cesarean section for a term breech infant after a failed external cephalic version. She strongly desires vaginal delivery.
Do you accede to her wish for a trial of labor?
Critical questions
Is her pregnancy history favorable?
No. This patient’s previous deliveries have a bearing on the current pregnancy.15 Specifically, the patient should have had no more than 1 low transverse cesarean delivery, no other uterine scars, no previous uterine rupture, and she should have a clinically adequate pelvis.
Are facilities and staff adequate?
Obviously the answer to this question is unique to the site. It is necessary to have immediate availability of the obstetrician throughout active labor, and to have adequate personnel to perform an emergency cesarean if necessary.
If these criteria are met, is induction of labor appropriate?
Perhaps. Recent data suggest that women with a uterine scar who undergo induction with prostaglandins have a risk of uterine rupture 5 times that of women who enter spontaneous labor (24.5 per 1,000 versus 5.2 per 1,000).16 For this reason, do not use prostaglandins for labor induction in women with viable gestations who have a prior low transverse incision.
Oxytocin. Augmentation of labor with oxytocin does not appear to increase the risk of rupture, compared with spontaneous labor.14 Induction of labor with oxytocin has been associated with a slightly higher risk of uterine rupture, compared with spontaneous labor, although both types of labor have a rupture rate under 1%.14
Our recommendations
If M.A. still desires a trial of labor after she has been counseled about the risks and benefits of vaginal birth after cesarean delivery, induction should be considered. She has a reasonable likelihood of success, because she has given birth vaginally in the past, her previous cesarean delivery was for a nonrecurring indication (breech presentation), and she does not require any cervical ripening agents, as this has occurred naturally.15
Amniotomy may help reduce time to delivery
One option for induction of labor is amniotomy with oxytocin augmentation as needed. Amniotomy, or the artificial rupture of membranes, has been shown to be an effective method of labor induction in women with a favorable cervix.19
The combination of amniotomy and oxytocin administration is particularly effective, resulting in a shorter induction to delivery time, compared with women undergoing oxytocin induction alone.20
Sweeping or stripping the fetal membranes
Digital separation of the chorioamniotic membrane from the walls of the cervix and lower uterine segment during sterile vaginal examination could also be incorporated into M.A.’s induction process.21
Membrane sweeping causes the release of endogenous prostaglandins and can lead to labor without the need for induction agents or amniotomy. Although membrane sweeping is generally performed without admission to the hospital, M.A. would require hospitalization because of her diagnosis of preeclampsia.
If the cervix is unfavorable
If this patient had an unfavorable cervix, would induction of labor be contraindicated? Certainly the use of prostaglandins for preinduction cervical ripening would be contraindicated, given the existing evidence, although use of a transcervical Foley catheter would be acceptable.13-16 Published studies suggest that transcervical Foley catheter induction does not appreciably increase the risk of uterine rupture, although these studies have relatively small sample sizes and are not randomized.22,23
