(Preterm) Premature Rupture of Membranes

last authored: July 2010, David LaPierre
last reviewed:

 

 

 

Introduction

Premature rupture of membranes (PROM) occurs when the fetus is over 37 weeks gestation; if under 37 weeks, it is termed preterm premature rupture of membranes (PPROM). Both PROM and PPROM result in increased risk to mother and baby.

 

Almost 90% of women who are at term will go into labour after 24 hours of PROM. Of women with PPROM, approximately half go into labour within 24 hours, and 70-80% begin labour within one week.

 

PROM occurs in 8% of term pregnancies and 2-3.5% of preterm pregnancies. It is responsible for almost 1/3 of preterm births.

 

 

 

The Case of Mrs Halston

Mrs. Halston presents to Labour and Delivery at 33 weeks gestation, concerned that 'her waters might have broken".

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Causes and Risk Factors

Causes for PROM and PPROM include:

Risk factors include:

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Signs and Symptoms

  • history
  • physical exam

History

A careful history is important in determining likelihood of PROM or PPROM.

Take note of:

  • amount
  • timing
  • odour
  • persistence
  • colour

Physical Exam

Vitals of mother and baby

  • fever
  • baby NST

Digital exam should be avoided due to risk of ascending infection.

Sterile speculum exam is helpful for a number of reasons:

  • assess pooling in the posterior fornix
  • flow of fluid from the cervix, especially when coughing
  • ferning (see under 'labs' below)
  • Nitrazine paper test (see under 'labs' below)

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Investigations

  • lab investigations
  • diagnostic imaging

Lab Investigations

Assess for GBS status.

 

Rupture of membranes may be assessed in a number of ways via sterile speculum exam:

 

Visual inspection includes looking for pooling in the posterior fornix. Asking the woman to cough (Valsalva maneuver) may allow visualization of amniotic fluid leaking from the cervical os.

 

Ferning

Sample fluid from posterior fornix and place on slide; let air dry for 10 minutes and examine, unstained, under a microscope.

 

Nitrazine swabs

Sample fluid from posterior fornix. Normal vaginal pH is 4.5- 6.0. Amniotic fluid pH is 7.1 - 7.3. False positive tests can occur with blood, vaginal infections, alkaline urine, and semen. High negative predictive value

 

Fetal fibronectin

helpful between 24-34 weeks.

Place in the posterior fornix for 10 seconds. Wait 30-120 minutes for result.

Predictor of preterm deliver in 7-14 days.

  • high NPV
  • low PPV

Contraindications:

  • anything in the vagina within 24 hours (including digital exam)
  • GA above 34 weeks
  • bleeding
  • cervix dilated greater than 3 cm

Diagnostic Imaging

Transvaginal US: measures effacement

<2.5 cm under 28 weeks suggests increased risk of PTB

advantages

  • quite noninvasive
  • quick and easy
  • good inter-rater reliability

disadvantages

  • not available everywhere
  • need training to do

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Differential Diagnosis

The differential for rupture of membranes includes:

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Treatments

If a woman who is at high risk for cord prolapse (ie known absence of head engagement) ruptures her membranes; there is a high risk of cord prolapse. This woman should call emergency services get on her hands and knees, and be evaluated for prolapse.

 

Management of PROM and PPROM includes:

Induction vs Expectant Management

PROM: Induction of labour is recommended for term pregnancies, using oxytocin or prostaglandin.

PPROM 34-37 weeks: induction is recommended

PPROM < 34 weeks: expectant management is usually preferred, with efforts to prolong pregnancy. Important considerations include:

Provide GBS prophylaxis if status is unknown.

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Consequences and Course

Complications from PROM include:

Complications of PPROM include:

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Resources and References

 

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Topic Development

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