Management of Ruptured Membranes at Term

Amy Marowitz, CNM; Heather Hunter, SNM

Disclosures

J Midwifery Womens Health. 2004;49(6) 

Case Presentation

A healthy 32-year-old gravida 1 para 0 at 38 4/7 weeks' gestation was admitted to labor and delivery at 5 PM in labor. Her history and prenatal course were uncomplicated. She had a negative group B streptococcus culture at 36 weeks. She began contracting at 7 AM and was seen for evaluation at 8 AM. At that time, contractions were every 5 to 6 minutes and perceived as moderately uncomfortable. Her cervix was closed and thick. Membranes were intact. At 5 PM she returned with every 4- to 5-minute contractions, complaining of extreme back pain. Her cervix was unchanged from the first exam. Membranes ruptured shortly after this vaginal examination and she was admitted.

A posterior position was confirmed at the next vaginal examination. The labor proceeded slowly, and a healthy baby girl was born the next day at 6:20 PM. Apgars were 7 and 9. Total duration of ruptured membranes was approximately 25 hours. Total length of active labor was approximately 19 hours. Maternal temperature and other vital signs and the fetal heart rate were normal throughout labor. Nine vaginal examinations were performed between rupture of membranes and complete dilation. Only 1 of these examinations was performed during the first 12 hours of rupture. No antibiotics were given during labor. The baby had a complete blood count shortly after birth due to duration of membrane rupture and received a septic workup and antibiotics due to a high white count. Mother and baby were discharged on day 3 after culture results were found to be negative.

Management of Ruptured Membranes in Women at Term

The management of labor at term when membranes have spontaneously ruptured can be confusing. Questions arise about appropriate management for both prelabor rupture of membranes and spontaneous rupture of membranes after labor has begun. These questions are primarily related to concerns about infection. Maternal infection may occur during labor (chorioamnionitis) or after birth (postpartum endometritis). Ruptured membranes are known to be a risk factor for subsequent maternal and neonatal infection. However, infection can also be an etiologic factor that causes prelabor rupture of membranes. Thus, the risk of clinical infection in the mother or newborn may be greater when the membranes rupture prior to the onset of labor.

Some factors commonly considered in forming a management plan for women with ruptured membranes include 1) duration of ruptured membranes, 2) the necessity of induction or augmentation of labor after a particular duration of rupture, 3) the frequency of vaginal examinations, 4) group B streptococcus colonization status, and 5) the routine use of antibiotics. Practice routines are often not evidence-based.

Management of Prelabor Rupture of Membranes at Term

Studies on management of prelabor rupture of membranes have focused primarily on comparing the incidence of infection in women who undergo immediate induction versus expectant management on risk of infection following different durations of rupture. Kappy and colleagues compared outcomes following induction and expectant management with term premature rupture of membranes (PROM).[1,2] They found no difference in infection rates between the two groups and a higher rate of cesarean sections in the induced group. More recently, Hannah and colleagues[3] conducted a large, multicenter randomized trial, the TERMPROM study, which compared immediate induction to expectant management for up to 4 days following diagnosis of term PROM. In this trial, maternal infection occurred more frequently in women managed expectantly. The rate of neonatal infection and cesarean sections was the same.[3]

Risk Factors for Infection

Increasing duration of time following rupture of the membranes is clearly a risk factor for infection. Research conducted in the 1960s showed that perinatal morbidity and mortality increased significantly if birth did not occur within 24 hours of rupture.[4,5] The design flaws in this early research led subsequent researchers to question these findings. These flaws include the inclusion of term and preterm babies who have significantly different risks for infection, not eliminating women with other medical and obstetric complications, and inconsistently and/or inaccurately defining maternal and neonatal infection.[6] Research on factors that are true risks for chorioamnionitis, postpartum endometritis, and neonatal infection suggest that the risk of infection gradually increases with increasing duration of rupture.[7,8,9,10] However, some of these studies have identified the difficulty in separating the risk of the duration of ruptured membranes from other factors also known to increase the risk for subsequent infection.[11]

Despite a lack of evidence, there is a widespread impression among providers that when duration of rupture of membranes exceeds 24 hours, there is increased danger to mother and baby. Birth within 24 hours is a common management goal when the membranes are ruptured. This may lead to use of oxytocin and associated practices such as internal monitors and more frequent vaginal examinations, which are in themselves independent risk factors for infection.

Factors other than duration of rupture are known to increase risk of infection when membranes are ruptured. One strongly predictive factor is the number of vaginal examinations.[8,9,10,11] The authors of the term PROM study point out that the number of vaginal examinations was more predictive of maternal infection than duration of membrane rupture.[9] Other factors that may impact infection rates in term pregnancies are 1) maternal group B streptococcus status; 2) use of internal monitoring; 3) mode of delivery; 4) presence of meconium in the amniotic fluid; 5) time between rupture of membranes; and 6) onset of labor, length of labor, and mode of delivery.[8,9,10,11,12]

Timing of Antibiotic Treatment

Another vexing question regarding management of ruptured membranes is the routine use of antibiotics. The overuse of antibiotics is not a trivial issue. Antibiotic resistance is a growing public health concern. Specific to this issue is the increasing occurrence of non-group B streptococcus, ampicillin-resistant neonatal sepsis after intrapartum antibiotic use.[13] The Centers for Disease Control and Prevention have provided clear recommendations regarding ruptured membranes at term and group B streptococcus.[13] "At the time of labor or rupture of membranes, intrapartum chemoprophylaxis should be given to all pregnant women identified as GBS carriers."[13] If her group B streptococcus status is unknown, antibiotics for group B streptococcus prevention are recommended when the membranes have been ruptured for 18 hours. If she is group B streptococcus negative and does not have symptoms of chorioamnionitis, she does not need antibiotics for group B streptococcus prevention, regardless of the duration of rupture.[13]

It is not clear if antibiotics should be given routinely for prevention of chorioamnionitis, postpartum endometritis, and neonatal infections that are caused by organisms other than group B streptococcus. The issue is not addressed in the 2003 ACOG Practice Bulletin on Prophylactic Antibiotics in Labor and Delivery[14]; nor is it mentioned in recent revisions of the standard obstetric texts: William's Obstetrics and Obstetrics: Normal and Problem Pregnancies by Gabbe et al.[15,16] In the recent Cochrane Review on the use of antibiotics in women with prelabor rupture of membranes, Flenady and King conclude that "... although antibiotics for women with term (PROM) was shown to reduce maternal (infection), with the low rate of maternal infection in the control population, it does not seem justifiable to expose all women with term PROM to antibiotics when treatment can be restricted to those who develop clinical indications for antibiotic treatment."[17]

In practice however, many providers routinely give antibiotics to women with PROM at term. In addition, many women receive antibiotics when membranes rupture after labor has begun, if their providers feel that the duration of rupture is too long. The timing of and stated reason for using antibiotics varies and is generally based more on tradition than evidence. Eighteen hours after rupture is a common time for antibiotics, regardless of group B streptococcus status or whether the rupture occurred before labor. It is likely that this time frame arose from recommendations that group B streptococcus prophylaxis be given at this point if the group B streptococcus status is unknown. A policy of routine antibiotics for all women for group B streptococcus prevention after 18 hours of rupture is not evidence-based and not recommended if group B streptococcus status is known to be negative.

Conclusion

In the case presented here, the woman had spontaneous rupture of membranes early in labor and a long labor, both of which are often seen in women whose fetuses are in a posterior position. The duration of rupture and length of labor were both risk factors for infection. The number of vaginal examinations was probably a risk factor for infection as well, although the timing of most of the examinations in the last 7 of the 19 hours of labor may have reduced that risk. Not using internal fetal monitors or intrauterine pressure catheters may have reduced the risk of infection. Antibiotics were not given, which is consistent with current recommendations. Because the benefit of routine antibiotics for prevention of maternal infection with organisms other than group B streptococcus is questionable, it was reasonable to defer their use in the absence of symptoms of infection. The management of the baby illustrates the need for awareness of pediatric policies in effect at one's institution.

In caring for women with ruptured membranes, there may be considerable pressure to intervene in an attempt to prevent infection and little support for avoiding interventions known to contribute to the risk. However, interventions such as frequent vaginal examinations and internal monitoring, which often accompany augmentation and/or induction, may actually increase the risk of infection and thus do more harm than good.

Antibiotics should be prescribed judiciously. Use of antibiotics for group B streptococcus prevention in women colonized with group B streptococcus is clearly indicated. Evidence supporting routine use with ruptured membranes to prevent infection is much weaker.

Induction in women with prelabor rupture at term may reduce the incidence of maternal infection. It is possible that limiting vaginal examinations and using antibiotic prophylaxis in group B streptococcus-positive women are as effective in reducing the risk of infection as immediate induction once membranes have ruptured. Augmenting labor when membranes rupture after labor begins to ensure birth in a particular time frame is not evidence-based.

Limiting vaginal examinations cannot be overemphasized. Women with prelabor rupture of membranes should not receive digital vaginal examinations until after labor begins and then only when the results are necessary to guide or alter management.

Almost 40 years ago, Shubeck et al. wrote that the clock of infection begins ticking with rupture of membranes.[18] Years of subsequent research have shown that there is truth to this simple statement but also that the etiology of infection in the presence of ruptured membranes is far more complex. There is no clear formula for determining the risk for a particular mother and baby. In most cases, infection is probably caused by multiple interrelated factors. Many questions regarding ruptured membranes and infection remain unanswered.

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