SUMMARY:  

ACOG has released a guidance update on Prelabor Rupture of Membranes (PROM).  The use of ‘prelabor’ is in keeping with reVITALize terminology (see ‘Related ObG Topics’ below) and is defined as the ‘spontaneous rupture of membranes that occurs before the onset of labor’.

• Diagnosis
• PROM at < 24 Weeks
• Preterm PROM at 24w0d-33w6d
• Late Preterm, Early Term and Term PROM (≥ 34w0d)
• PROM-related Risks
• Additional Clinical Considerations
• PROM Following Amniocentesis
• Preterm PROM and Future Pregnancies

Diagnosis

• Most cases can be diagnosed based on history and physical examination 
• Avoid digital examination due to infection risk, unless delivery appears to be immediate  
• Speculum examination  
  • Visualization of amniotic fluid (AF) leaking through the cervix  
  • Vaginal pooling
  • Fern test of dried vaginal fluid seen under microscope
  • pH testing 
    • Normal: 4.5-6.0 
    • AF: 7.1-7.3 
    • False positives: Blood or semen, alkaline antiseptics or BV  
    • False negatives: Minimal remaining AF following rupture 
• If above inconclusive  
  • Ultrasound for AFV may be helpful but not diagnostic  
  • Fetal fibronectin is sensitive with high negative predictive value but positive result is not diagnostic
  • Amniotic protein tests have high sensitivity for PROM but false-positive rates may be as high as 19–30%
    • ACOG states that “These test kits should be considered ancillary to standard methods of diagnosis”

Note: In August 2018, the FDA sent a letter to health providers to be aware of rupture of membranes (ROM) test limitations, due to reports of adverse events. The FDA letter states that “health care providers may be over-relying on ROM test results when making critical patient management decisions, despite labeling instructions warning against this practice.” To promote awareness and aid in the proper use of the ROM test, the FDA letter states

The following limitations are typically stated in ROM device labeling

• A negative result does not assure the absence of membrane rupture
• False negatives may result if the amniotic sac has resealed or the position of the fetus has obstructed the rupture
• The presence of blood, meconium, anti-fungal creams or suppositories, baby powder, baby oil, or the use of lubricant with a vaginal exam may interfere with the device
• The test may not be accurate if sample collection and testing occurs after the timeframe recommended by the manufacturer
• To help protect patients and reduce the chance of adverse events, ROM tests should be part of an overall clinical assessment, which may include physical examination of the patient and testing to detect leaking amniotic fluid

• Conclusive test – dye instillation
  • Ultrasound guided dye with passage into the vagina and detected with tampon or pad stain  
  • Maternal urine may turn blue following instillation of indigo carmine
  • See ‘Related ObG Topics’ below for alternatives to indigo carmine  

PROM at < 24 Weeks

Clinical Considerations

• Survival with PROM ≥ 22 weeks is significantly higher (57.7%) than <22 weeks (14.4%)
  • Survival rates are likely overestimated
  • Combination of birthweight, gestational age and sex will impact morbidity/mortality
    • Individualize risks
• Maternal complications: infection | endometritis | abruption | retained placenta  
  • Maternal sepsis risk of 1%  
• Latency  
  • 40-50% will deliver within 1 week and 70-80% will deliver within 2-5 weeks  
• Pulmonary hypoplasia 
  • Will occur in approximately 10-20% of cases  
  • Insufficient data to recommend ultrasound for determination of lung volumes or function   
• Oligohydramnios can result in Potter’s deformation sequence   
  • Low-set ears | recessed chin | prominent bilateral epicanthal folds  
  • Limb contractures 
  • Skeletal malformations   

Management 

• Counsel regarding risks and benefits of expectant management vs immediate delivery  
  • Immediate delivery should be offered as an option  
• If patient chooses expectant management and no infection  
  • Outpatient surveillance is an option  
    • Give information to return to hospital immediately if signs or symptoms of bleeding, labor or infection (self-monitor temperature) 
    • Advise return to hospital at time of viability  
• Corticosteroids and latency antibiotics: Data currently limited at <24 weeks  
  • Offering antibiotics as early as 20w0d is an option 
  • Consider offering a single course of corticosteroids as early as 23w0d of gestation due to risk of delivery within 7 days   
• Antenatal corticosteroids and latency antibiotics (see below for Preterm PROM) are recommended upon reaching viability 

Preterm PROM at 24w0d-33w6d

• Expectant management in a hospital setting is recommended  
  • If there are maternal and/or fetal contraindications to expectant management, delivery is recommended 
  • Proceed to delivery at 34w0d  
• If a patient opts for expectant management beyond 34w0d, discuss risks benefits  
  • Expectant management should not extend beyond 37w0d  
• Antenatal (single course) corticosteroids are recommended 
• Latency antibiotics are recommended  
  • Eunice Kennedy Shriver NICHD MFMU Network trial regimen  
    • IV ampicillin [2 g every 6 hours] and erythromycin [250 mg every 6 hours] for 48 hours followed by oral amoxicillin [250 mg every 8 hours] and erythromycin base [333 mg every 8 hours] for an additional 5 days (7 days total) 
  • Amoxicillin–clavulanic acid  
    • Not recommended due to increased risk for necrotizing enterocolitis 
  • Allergy to β-lactam antibiotics 
    • Not well studied but erythromycin alone may be an alternative 
  • Unclear as to whether cerclage should be removed or retained but if retained, antibiotic therapy should not be extended beyond 7 days    
• Patients with PROM before 32w0d and imminent delivery are candidates for fetal neuroprotective treatment with magnesium sulfate (MgS04) 
• HSV infection and Preterm PROM
  • Risk of vertical transmission is 30-50% with primary HSV and 3% with recurrent HSV   
  • Recurrent active HSV  
    • Expectant management is recommended 
    • Initiate HSV therapy 
    • Cesarean section is indicated if active disease or prodromal symptoms are present at time of delivery   
  • Primary HSV
    • Management less clear due to high risk of vertical transmission  
    • HSV therapy is recommended  
    • Cesarean delivery recommended if active lesions are present  
• HIV infection and Preterm PROM 
  • Optimal management is uncertain due to concern of vertical transmission with PROM 
  • Management should include a physician with expertise in the management of HIV in pregnancy and standard HIV guidelines should be followed   
  • Most recent data suggest that vertical transmission risk my not be increased if the patient is on highly active antiretroviral therapy with a low viral load and has received antepartum and intrapartum zidovudine 
  • Management should be individualized 
    • If gestational age is early, but patient is on appropriate therapy with a low viral load expectant management may be appropriate  

Late Preterm, Early Term and Term PROM (≥ 34w0d)

• Delivery is recommended  
  • If no spontaneous labor, induce labor with oxytocin 
    • Allow adequate time (12-18 hours) for latent phase to progress before performing a cesarean section for failed induction of labor  
  • Induction with prostaglandins equally as effective as oxytocin but may have higher rates of chorioamnionitis  
  • Insufficient data to recommend for or against cervical ripening with mechanical methods such as a Foley balloon 
  • Insufficient evidence to recommend antibiotic prophylaxis beyond GBS indications  
• If a patient declines delivery and requests expectant management, counsel regarding risks and benefits 
  • If fetal and maternal status are reassuring, expectant management ‘may be acceptable’   
• Late preterm (34w0d-36w6d)  
  • Management is similar to early term and term, except that if no previous steroids were administered, a single course of betamethasone may be considered between 34w0d-36w6d  

Key Points:

PROM-Related Risks 

• Preterm birth 
  • 50% of patients will deliver within 1 week 
  • Risks associate with prematurity include RDS, sepsis, IVH and NEC  
• Infection
  • Preterm PROM and intrauterine inflammation are associated with increased risk of neurologic injury   
  • Intraamniotic infection (15-25%) 
  • Postpartum infection (15-20%) 
• Abruption (2-5%) 
• Infection and umbilical cord accidents are associated with a 1 to 2% chance for fetal demise  

Additional Clinical Considerations

• Membranes may reseal spontaneously leading to good outcomes   
• Hospital admission is recommended if the fetus is viable to monitor for signs of infection, abruption and fetal compromise   
  • Acceptable strategy includes periodic ultrasound for fetal growth and FH monitoring (precise timing not established) 
  • No clinical utility evidence for the use of serial WBC counts or other infectious markers  
• Use of tocolysis  
  • Therapeutic tocolysis is not recommended  
• GBS as per standard protocol 
  • GBS prophylaxis should be given based on prior culture results or intrapartum risk factors if cultures not performed or unavailable 

PROM Following Amniocentesis 

• Risk of PROM following amniocentesis is 1%   
• Outpatient, expectant management  
• Monitor regularly with ultrasound and counsel patients to watch for signs of infection, bleeding and/or miscarriage  
• Contrary to spontaneous PROM, good outcomes have been reported   
  • AF fluid reaccumulated within 1 month in 72% of patients 
  • Perinatal survival rate was 91%  

Preterm PROM and Future Pregnancies  

• Increased risk of recurrent PROM and preterm birth  
• Offer progesterone supplementation starting at 16-24 weeks 
• Consider cervical length screening  

• Consider cerclage for women with the following:  
  • Current singleton pregnancy 
  • Prior spontaneous preterm birth < 34 weeks  
  • Cervical length < 25 mm prior to 24 weeks  

Learn More – Primary Sources:  

ACOG Practice Bulletin 188: Prelabor Rupture of Membranes

FDA: Risks Associated with Use of Rupture of Membranes Tests – Letter to Health Care Providers

FDA News Release: FDA alerts healthcare providers, women about risks associated with improper use of rupture of membranes tests

Potter’s Sequence

Related ObG Topics:

Antenatal Corticosteroids – When to Administer?

Updated Guidance on GBS Screening and Prophylaxis

SMFM Statement: Choice of Progestogen for Preterm Birth Prevention

PROM 37 Weeks and Beyond: Induction or Watchful Waiting?

Foley Bulb Catheter for Induction Following PROM in Nulliparas

What are the reVITALize Obstetric and Gynecology Data Definitions?

Alternatives to Indigo Carmine When Diagnosis of PROM is Equivocal