Premature Rupture of the Membranes

Premature rupture of the fetal membranes is one of the most common problems in obstetrics, complicating approximately 5% to 10% of term pregnancies and up to 30% of preterm deliveries Gestational age and patient demographics are considerations in selecting management in a particular patient

Premature rupture of the membranes (PROM) is usually defined as rupture at any time before the onset of contractions. preterm premature rupture of the membranes (PPROM) refers to PROM prior to 37 weeks gestation

Incidence The incidence of PROM ranges from about 5% to 10% of all deliveries, and PPROM occurs in approximately 1% of all pregnancies Approximately 70% of cases of PROM occur in pregnancies at term, but in referral centers, more than 50% of cases may occur in preterm pregnancies. PROM is the clinically recognized precipitating cause of about one third of all preterm births. Despite some progress in prolonging the latent period after PPROM and possible prevention of recurrence (such as by the use of progesterone or by treating bacterial vaginosis), PPROM remains a leading contributor to the overall problem of premature birth

Etiology With term PROM, the cause may be physiologic weakening of the membranes cervical incompetence Polyhydramnios risk factors for PPROM were previous PPROM, positive fetal fibronectin at 23 weeks, and short cervix (<25 mm) at 23 weeks subclinical infection

amniotic fluid is obtained by amniocentesis in cases of PPROM, positive cultures are found in approximately 30% if the specimen is properly handled for aerobes, anaerobes, and genital mycoplasmas.

Complications and Consequences of Premature Rupture of the Membranes Onset of Labor Effect of Tocolytic Drugs Respiratory Distress Syndrome, Infections, and Other Complications

Onset of Labor At term, the onset of labor occurs within 24 hours after membrane rupture in 80% to 90% of patients. Among patients with PROM prior to term, latent periods occur longer. There is an inverse relationship between gestational age and the proportion of patients with latent periods longer than 3 days. For pregnancies between 25 and 32 weeks, 33% had latent periods longer than 3 days, whereas for pregnancies of 33 to 34 and 35 to 36 weeks, the corresponding values were 16.0% and 4.5%, respectively

Effect of Tocolytic Drugs The value of tocolytics in PPROM remains controversial if tocolytics are used, such as during transfer to a tertiary care center or obtaining benefits of corticosteroids, the course of tocolytics should be limited to less than 48 hours

Respiratory Distress Syndrome, Infections, and Other Complications The risks of PROM generally have been viewed as those of infection versus those of prematurity Subclinical infection based on positive amniotic fluid culture or histologic inflammation of the cord or membranes is seen much more often, in up to 80% at very early gestational ages with PPROM

Endometritis develops in up to 29%. Abruption after PROM is reported in 4.0% to 6.3% of cases, several-fold higher than the rate of 0.5% to 1.0% in the general population. Pulmonary hypoplasia is a serious fetal complication occurring in PPROM)very early PPROM, especially when this occurs in the presence of prolonged PROM and with severe oligohydramnios. There is nearly a 100% probability of lethal pulmonary hypoplasia when PROM occurs before 23 weeks and when there is severe oligohydramnios. When PPROM occurs less than 25 weeks with severe oligohydramnios lasting more than 14 days, the likelihood of lethal pulmonary hypoplasia is estimated to be 80%. At the other extreme, when PPROM occurs at more than 25 weeks and when there is either no severe oligohydramnios or severe oligohydramnios for less than 5 days, then the predicted probability of lethal pulmonary hypoplasia is only 2%. These data provide important information for counseling patients with midtrimester PROM

Recurrence The reported recurrence rate for PPROM is up to 32% for patients who had PPROM in an index pregnancy. Based on these data, the risk of recurrence is considerable, prompting patient education and close follow-up in subsequent pregnancies. Progesterone therapy appears effective in reducing the risk of recurrent preterm birth due to PROM or preterm labor. Some studies have shown a decrease in recurrent preterm births due to PROM by treating bacterial vaginosis

Diagnosis to reveal amniotic fluid egressing from the vagina. The differential diagnosis : loss of the mucus plug, vaginal discharge associated with infection, and urinary loss. If the patient is not going to be delivered immediately, then a digital examination should be deferred as examination may introduce bacteria into the uterus and shorten the latent phase. A sterile speculum exam may demonstrate pooling of fluid in the posterior vaginal vault. Direct observation of fluid leaking from the cervical os confirms ruptured membranes.

Nitrazine Test The normal pH of the vagina is between 4.0 and 4.7 in pregnancy pH of the amniotic fluid is 7.1 to 7.3. Nitrazine paper changes to a dark blue from yellow with a pH above 6.5. Nitrazine paper to diagnose amniotic fluid in the vagina has an overall accuracy of approximately 93%, but false-positive results can result from blood, semen, alkaline urine, bacterial vaginosis, and trichomoniasis.

Ferning Test The diagnosis of PROM also may be confirmed by observing arborization or ferning‌ of dried amniotic fluid on a slide. This method has an overall accuracy of diagnosis of PROM of approximately 96%. False positives occur with contamination by semen or cervical mucus. False negatives can result from a dry swab, contamination with blood at a 1:1 dilution, or not allowing sufficient time for the fluid to dry on the slide. Amniotic fluid arborization is unaffected by meconium at any concentration and is unaffected by pH alteration.

Ultrasound examination has been used widely, since oligohydramnios suggests PROM, but there have been no evaluations of its sensitivity and specificity. Fetal fibronectin showed an excellent sensitivity (98.2%) but a low specificity, leading to speculation that fetal fibronectin in cervicovaginal secretions may be a marker for impending labor, even without frank rupture of the membranes.

When the diagnosis of ruptured membranes is unclear by these tests, a transabdominal dye injection is sometimes performed. Indigo carmine blue (1 mL diluted in 9 mL of sterile normal saline solution) is injected into the amniotic fluid, and a sponge is placed into the vagina and inspected 30 minutes later for the dye. Methylene blue should not be used because of reported methemoglobinemia in the fetus. This test is invasive, and the accuracy of diagnosis is not established

Fetal Maturity Determination of the fetal age and maturity status is useful in developing a treatment plan Amniotic fluid may be collected by amniocentesis or by collection from the vaginal pool. Vaginal pool collection is less accurate for lecithin:sphingomyelin (L:S) ratio determination. Whereas phosphatidylglycerol (PG) production by vaginal bacteria has been described, there has been an excellent correlation between PG detection in amniotic fluid obtained vaginally and transabdominally.

Cervical Status sterile speculum exam can evaluate the degree of cervical dilation and can exclude the possibility of a fetal extremity or umbilical cord prolapsing through the cervix. Endovaginal ultrasound may be used safely in patients with PPROM, as it does not increase the risk of infection.

Infection When the diagnosis of PROM is made, a rectovaginal culture should be taken for GBS, and appropriate antibiotics (usually intravenous penicillin G) for prevention of GBS infection should be given pending culture results.

All patients with PPROM should be evaluated for possible evidence of chorioamnionitis. Physical exam includes maternal or fetal tachycardia; uterine tenderness; and detection of a purulent, foul-smelling discharge. Temperature elevation is often a late sign of chorioamnionitis, especially in PPROM

Amniocentesis may be performed to evaluate for an intrauterine infection, if there are equivocal clinical signs of infection Because of the high likelihood of subclinical infection and the association of intrauterine infection with cerebral palsy, there is a growing enthusiasm for early detection of subclinical infection. Analyses of amniotic fluid for possible infection include Gram stain, glucose concentration, and culture. Gram stain does not identify colonization with genital mycoplasmas. A low amniotic fluid glucose predicts a positive amniotic fluid culture When the glucose is greater than 20 mg/dL, the likelihood of a positive culture is less than 5%; when glucose is less than 5 mg/dL, the likelihood of a positive culture approaches 90%. Elevated interleukin 6 (IL-6) in amniotic fluid may be the most sensitive predictor of intrauterine infection. A biophysical profile of 6 points or less has been shown in several studies to correlate with intrauterine infection. Most newborns who are delivered after clinical chorioamnionitis do not show clinical infection, possibly because of common use of empiric antibiotic therapy

Treatment Considerations Management :four different phases of pregnancy. second trimester, neonatal survival is nil, leading numerous investigators to adopt a policy of expectant management or induction. Early in the third trimester, neonatal survival rises markedly, but there is still considerable morbidity associated with delivery at this gestational age. In the mid third trimester, neonatal survival is high, but there is still considerable morbidity, whereas in the late third trimester (at or near term), neonatal mortality and morbidity are low.

Use of Steroids Antenatal steroids in PPROM reduce the risk of RDS in randomized clinical trials, but the effect was less than with intact membranes. Strong evidence suggests reduced neonatal mortality and IVH with use in PPROM. Corticosteroid use is appropriate in the absence of chorioamnionitis in fetuses <30 to 32 week.

Effect of Latent Period and Vaginal Examination upon Incidence of Amnionitis women with digital examination after PROM had a significantly shorter latent period (2.1 آ± 4.0 vs. 11.3 آ± 13.4 days; P < .001), more maternal infection (44% vs. 33%; P = .09), and more positive amniotic fluid cultures (11/25 [44%] vs. 10/63 [16%]; P < .05). routine vaginal examination should be avoided until labor develops in patients with PPROM

Use of Prophylactic Antibiotics two indications for prophylactic antibiotics prevention of perinatal GBS infection antibiotic prophylaxis has been based on the hypothesis that infection is either the triggering cause of PPROM or that infection ensuing after PPROM triggers the labor rationale for prophylactic antibiotics has been to delay delivery after PPROM rather than to prevent clinically evident infection.

Determination of Fetal Lung Maturity Presence of either PG or an L:S ratio of more than two in amniotic fluid collected vaginally has been reported to be a good predictor of pulmonary maturity.

Management Premature Rupture of the Membranes at or Near Term Induction usually preferred, with oxytocin or prostaglandin preparations (especially with unripe cervix), either on admission or after a finite period of observation (up to 12 or even 24 hours). Prophylaxis for GBS with a positive screening culture at 35-37 weeks or with rupture of the membranes >18 hours in patients with unknown culture status

Premature Rupture of the Membranes at 32 to 33 Weeks Expectancy versus induction, especially if there is evidence of fetal lung maturity based on analysis of amniotic fluid collected by amniocentesis or from vaginal pool. Prophylaxis for GBS. Although broad-spectrum antibiotics have been used in some studies to prolong pregnancy in the gestational age bracket, there are concerns about selection pressure for resistant organisms and about masking fetal infection. Therefore, the author limits such broad-spectrum antibiotic use to earlier gestational ages. Do not use tocolytics. Because efficacy of corticosteroids is not established, the author does not use them in this gestational age bracket.

expectant management versus induction patients randomized to expectant management initially had significantly longer times to delivery than patients randomized to either of the induction arms (P <.001). the rate of clinically diagnosed chorioamnionitis was less in the patients randomized to induction initially (with significance achieved at P <.01 comparing arms 1 vs. 2). The distribution of postpartum infection was similar to that of chorioamnionitis. there was no significant difference in rates of neonatal infection or cesarean section. Patient satisfaction was significantly higher in the induction arms.

Premature Rupture of the Membranes at 25 to 32 Weeks Expectancy Prophylaxis for GBS Antibiotics for 7 days; no standard regimen has been established (ampicillin + erythromycin or erythromycin) or alternative regimens Corticosteroids Use of tocolytics remains controversial; if used, they should be limited to 48 hours

Premature Rupture of the Membranes <25 Weeks Induction vs. expectancy should be weighed, depending on gestational age and patient desires. There is no data on steroids, tocolytics, or antibiotics (prophylaxis for GBS or prolonging pregnancy). It is unlikely that tocolytics achieve any significant prolongation of pregnancy and may mask early evidence of infection. Therefore, they are not recommended. It is unlikely that corticosteroids provide any fetal benefit at this gestational age, and corticosteroids also may increase the risk of intrauterine infection. Therefore, corticosteroids should be reserved for gestational ages where benefit is more likely. A course of antibiotics for 7 days may prolong pregnancy and decrease complications, as in pregnancies with PPROM at 25 to 32 weeks. After a period of inpatient hospitalization, home management may be used for uncomplicated, selected patients.

Home Management of Premature Rupture of the Membranes PPROM with a previable pregnancy, management at home may be considered if there is no evidence of infection, abruption, or other maternal complications and if the mother is able to return to the hospital promptly in the event of complications PPROM with a viable pregnancy, the safety of management at home has not been evaluated thoroughly. One study found that few women were eligible. Because complications such as infection, abruption, and prolapse or delivery may develop rapidly, the author does not recommend home management once fetal viability has been achieved

Management of Clinically Evident Chorioamnionitis Begin intravenous, broad-spectrum antibiotics, based on the array of aerobic and anaerobic organisms isolated in amniotic fluid of cases of clinical chorioamnionitis. There is no place for expectant management in clinically overt chorioamnionitis. The route of delivery should be determined by standard obstetric considerations. Immediate cesarean delivery increases maternal morbidity and does not improve neonatal outcome. However, the cesarean delivery rate is high in pregnancies complicated by clinical chorioamnionitis because of poor progress in labor, nonreassuring fetal heart rate patterns, and malpresentation.

Preterm Premature Rupture of the Membranes and Clinical Herpes Simplex Virus Infection The risks of expectant management (ascending HSV infection and fetal–neonatal herpes) should be weighed against the risks of preterm delivery. Accordingly, where the risks of prematurity are great (such as less than 30 to 32 weeks), expectant management—usually with prophylactic use of acyclovir or another antiviral—may be used. In the few reported cases of this management, the clinical episode of HSV, which usually lasts for 3 to 5 days, has resolved before the onset of labor, and there have been no cases of neonatal HSV infection. When the risks of neonatal infection appear greater than the risks of prematurity (e.g., at greater than 32 weeks), then cesarean delivery should be carried out in the face of clinically evident maternal genital herpes infection.

Summary Points At or near term (34 weeks) induction usually is preferred; GBS prophylaxis is given with a positive screening culture at 35 to 37 weeks or with rupture of the membranes greater than 18 hours plus an unknown culture status. At 32 to 33 weeks, manage by either expectancy or by induction (especially with evidence of lung maturity). Give GBS prophylaxis. Do not use tocolytics; efficacy of corticosteroids is not clear at this gestational age. At 25 to 32 weeks, manage by expectancy. Give GBS prophylaxis and corticosteroids. The author gives antibiotics for 7 days to prolong pregnancy. No standard regimen is established. Ampicillin plus erythromycin is used most often. Use of tocolytics is controversial. At less than 25 weeks, manage by induction or expectancy, depending on gestational age and patient desires. The author does not use tocolytics or corticosteroids in this situation. A course of antibiotics for 7 days may prolong pregnancy, as it does at 25 to 32 weeks.