My friend got back to me, and, as it turns out, prelabor rupture of membranes (PROM) at term (37 weeks gestation or more) was not part of her paper. So here’s my version: If you want the info supporting expectant management up to 1998, you can look at the mini reviews in Thinking Woman’s Guide to a Better Birth on pp 230-231 under the headings “Waiting for labor onset for at least 24 hours after membrane rupture is safe provided there are no symptoms of infection, the mother tests negative for group B strep, and no vaginal exams are done” and “Inducing with oxytocin shortly after membrane rupture may greatly increase the odds of c-section compared with awaiting labor.” To summarize what I found, the major rationale for inducing labor is to avert neonatal infections. With respect to that issue:
· Multiple vaginal examinations in combination with length of time since rupture increase the risk of neonatal infection. Avoid vaginal examinations and invasive monitoring, and time doesn’t matter.
· Neonatal infections related to length of time and vaginal examinations is particularly a problem for women testing positive for Group B strep but who do not receive prophylactic antibiotics. This was the finding of Hannah et al. 1996, the biggest by far of the RCTs of induction vs. expectant management. Many of the trials of induction versus watchful waiting for some period antedate the routine use of prophylactic antibiotics in such women, so infection rates cannot be generalized to current practice. (The CDC guidelines for GBS+ women, by the way, says nothing about inducing labor with PROM at term and recommends against inducing with preterm PROM in GBS+ women.)
· Inducing shortly after membrane rupture as opposed to waiting longer may increase the cesarean rate. Some studies report a substantial increase while others don’t.
I am working on a new edition of my first book, Obstetric Myths Versus Research Realities, but I haven’t gotten to the induction chapters yet, so I don’t have any thorough evaluation of the research since 1998. However, I have the 2006 Cochrane systematic review on PROM at term. I don’t want to rely on it overmuch because systematic reviews are only as good as the studies that go into them, AKA, “garbage in, garbage out,” and they are only as good as the reviewers are free medical model biases. I’m not ready yet to get the studies included in this review and evaluate them. Nonetheless, even taken at face value, the review has useful information for your cause. To begin with—and this is key for your case—expectant management in all of the component studies lasted at least 24 hrs, not 12! Therefore, even if the conclusions of the review are sound, they do not form a basis for inducing at 12 hrs.
Here are the review’s results pasted in from its abstract:
Main results
Twelve trials (total of 6814 women) were included. Planned management was generally induction with oxytocin or prostaglandin, with one trial using homoeopathic caulophyllum. Overall, no differences were detected for mode of birth between planned and expectant groups: relative risk (RR) of caesarean section 0.94, 95% confidence interval (CI) 0.82 to 1.08 (12 trials, 6814 women); RR of operative vaginal birth 0.98, 95% 0.84 to 1.16 (7 trials, 5511 women). Significantly fewer women in the planned compared with expectant management groups had chorioamnionitis (RR 0.74, 95% CI 0.56 to 0.97; 9 trials, 6611 women) or endometritis (RR 0.30, 95% CI 0.12 to 0.74; 4 trials, 445 women). No difference was seen for neonatal infection (RR 0.83, 95% CI 0.61 to 1.12; 9 trials, 6406 infants). However, fewer infants under planned management went to neonatal intensive or special care compared with expectant management (RR 0.72, 95% CI 0.57 to 0.92, number needed to treat 20; 5 trials, 5679 infants). In a single trial, significantly more women with planned management viewed their care more positively than those expectantly managed (RR of \nothing liked" 0.45, 95% CI 0.37 to 0.54; 5031 women).
Looking at the review’s conclusions:
· Inducing did not reduce cesarean and instrumental vaginal delivery rates. It didn’t raise them either, as the studies I looked at tended to show, but the shorter the time between rupture and induction, the more likely to see a higher cesarean surgery rate, and as I said, all studies in this review waited at least 24 hrs. Induction at 12 hrs post rupture could show a very different picture.
· More women had chorioamnionitis, but the indicator commonly used for this diagnosis is maternal fever in labor. As we now know, length of time with an epidural increases the likelihood of fever independent of infection, so I wouldn’t pay too much attention to this.
· More women had endometritis, uterine inflammation, as well, but the absolute difference was 1%, meaning that 1 more woman in every 100 would have endometritis with expectant management of 24 hrs or more.
· No difference was seen for neonatal infection, the key rationale for inducing.
· A difference was seen in NICU admission, but there may be more to this. Without looking at the component studies, I can’t tell you if that finding is because babies had more severe infections or there was some other policy-related factors, such as the mother running a fever in labor. The pooled NICU admission rate is 11% in the induction group, which seems incredibly high, suggesting that something may be determining NICU admission rates besides serious infections. Also, Hannah 1996 is the 500 lb gorilla in all these metaanalyses because of its size, and Hannah only reported an excess newborn infection rate in women testing GBS+. GBS is a serious infection in newborns, so that might explain the increase in NICU admissions.
· Women were more satisfied with being induced. This came from the Hannah trial. Most women were kept in the hospital in the expectant management arm. They might have felt quite differently had they been sent home. Also, if you knew you were in a trial to see if induction reduced newborn infection rates, mightn’t you be likely to be quite anxious and dissatisfied if you ended up in the “let’s wait it out” group?
The review did not find an association between infection and vaginal exams, but I’d have to look at the studies because that’s not what I found. It could be that women being induced had enough internal monitoring and length of time with multiple vaginal exams to mask differences from the expectantly managed group.
In summary, there may be an argument for inducing at 24 hrs post rupture, but there isn’t one for inducing at 12 hrs, not even in GBS+ women. In fact, for this population, you wouldn’t want to start an induction under any circumstances until the woman has 4 hrs of IV antibiotics on board in case her labor takes off like gangbusters. An argument can also be made for avoiding vaginal exams, at least until active labor, and internal monitoring on the basis of the precautionary principle if nothing else. However the hospital, according to the research of which I am aware, hasn’t a leg to stand on for inducing at 12 hrs.
-- Henci |