Prelabour rupture of membranes

PROBLEM

• Watery vaginal discharge after 22 weeks gestation.

GENERAL MANAGEMENT

• Confirm accuracy of calculated gestational age, if possible.

• Use a high-level disinfected speculum to assess vaginal discharge (amount, colour, odour) and exclude urinary incontinence. 

If the woman complains of bleeding in later pregnancy (after 22 weeks), do not do a digital vaginal examination. 

DIAGNOSIS

Table S-20 

Diagnosis of vaginal discharge

MANAGEMENT

PRELABOUR RUPTURE OF MEMBRANES

Prelabour rupture of membranes (PROM) is rupture of the membranes before labour has begun. PROM can occur either when the fetus is immature (preterm or before 37 weeks) or when it is mature (term).

CONFIRMING THE DIAGNOSIS

The typical odour of amniotic fluid confirms the diagnosis. 

If membrane rupture is not recent or when leakage is gradual, confirming the diagnosis may be difficult:

• Place a vaginal pad over the vulva and examine it an hour later visually and by odour.

• Use a high-level disinfected speculum for vaginal examination:

- Fluid may be seen coming from the cervix or forming a pool in the posterior fornix;

- Ask the woman to cough; this may cause a gush of fluid.

Do not perform a digital vaginal examination as it does not help establish the diagnosis and can introduce infection. 

• If available, do tests:

- The nitrazine test depends upon the fact that vaginal secretions and urine are acidic while amniotic fluid is alkaline. Hold a piece of nitrazine paper in a haemostat and touch it against the fluid pooled on the speculum blade. A change from yellow to blue indicates alkalinity (presence of amniotic fluid). Blood and some vaginal infections give false positive results;

- For the ferning test, spread some fluid on a slide and let it dry. Examine it with a microscope. Amniotic fluid crystallizes and may leave a fern-leaf pattern. False negatives are frequent.

MANAGEMENT

• If there is vaginal bleeding with intermittent or constant abdominal pain, suspect abruptio placentae.

• If there are signs of infection (fever, foul-smelling vaginal discharge), give antibiotics as for amnionitis.

• If there are no signs of infection and the pregnancy is less than 37 weeks (when fetal lungs are more likely to be immature):

- Give antibiotics to reduce maternal and neonatal infective morbidity and to delay delivery:

- erythromycin base 250 mg by mouth three times per day for 7 days;

- PLUS amoxicillin 500 mg by mouth three times per day for 7 days;

- Consider transfer to the most appropriate service for care of the newborn, if possible;

- Give corticosteroids to the mother to improve fetal lung maturity:

- betamethasone 12 mg IM, two doses 12 hours apart; 

- OR dexamethasone 6 mg IM, four doses 6 hours apart.

Note: Corticosteroids should not be used in the presence of frank infection. 

- Deliver at 37 weeks;

- If there are palpable contractions and blood-stained mucus discharge, suspect preterm labour

• If there are no signs of infection and the pregnancy is 37 weeks or more:

- If the membranes have been ruptured for more than 18 hours, give prophylactic antibiotics in order to help reduce Group B streptococcus infection in the neonate:

- ampicillin 2 g IV every 6 hours;

- OR penicillin G 2 million units IV every 6 hours until delivery;

- If there are no signs of infection after delivery, discontinue antibiotics.

- Assess the cervix:

- If the cervix is favourable (soft, thin, partly dilated), induce labour using oxytocin;

- If the cervix is unfavourable (firm, thick, closed), ripen the cervix using prostaglandins and infuse oxytocin or deliver by caesarean section.

 

AMNIONITIS

• Give a combination of antibiotics until delivery:

- ampicillin 2 g IV every 6 hours;

- PLUS gentamicin 5 mg/kg body weight IV every 24 hours;

- If the woman delivers vaginally, discontinue antibiotics postpartum;

- If the woman has a caesarean section, continue antibiotics and give metronidazole 500 mg IV every 8 hours until the woman is fever-free for 48 hours.

• Assess the cervix:

- If the cervix is favourable (soft, thin, partly dilated), induce labour using oxytocin.

- If the cervix is unfavourable (firm, thick, closed), ripen the cervix using prostaglandins and infuse oxytocin or deliver by caesarean section.

• If metritis is suspected (fever, foul-smelling vaginal discharge), give antibiotics.

• If newborn sepsis is suspected, arrange for a blood culture and antibiotics.

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