A6. Premature rupture of membranes
Prelabour rupture of membrane (PROM) refers to rupture of the membranes before labour begins, but after 37 weeks of gestation. If it occurs before 37 weeks of gestation, it’s called preterm prelabour rupture of membranes (PPROM). As the membranes protect against infection, early membrane rupture predisposes to intrauterine infection.
They main issue with PROM is whether to wait for spontaneous labour to begin or to induce labour. Almost all patients with PROM will go into labour within 3 days, but the risk for maternal infection increases if we choose to wait rather than to induce. However, the prognosis is very good.
In case of PPROM, preterm birth is guaranteed. The risk for chorioamnionitis, placental abruption, C-section, and umbilical cord complications (prolapse, compression) is also increased.
They’re relatively common, occurring in approximately 10% of pregnancies.
Etiology
PROM is associated with the following risk factors:
- Ascending infection from vagina
- Previous PROM
- Previous conisation
- Smoking
Clinical features
The patient presents after having experienced leaking of amniotic fluid from the vagina.
Diagnosis and evaluation
The diagnosis is made when the patient notices leaking of fluid from the vagina. Vaginal examination with speculum will reveal pooling of amniotic fluid in the posterior fornix and may reveal fluid flowing from the cervical os. If it’s uncertain that the fluid is in fact amniotic fluid, chemical tests can be used to determine this.
Ultrasound is also used. Oligohydramnios suggests membrane rupture, while normal amniotic fluid volume suggests that it’s not.
Nonstress test (CTG) should be performed to evaluate the wellbeing of the foetus.
Treatment
In most cases of PROM (week 37 or more), labour is induced. If there are signs of infection, antibiotics should be given as well.
In case of PPROM, the aim of management is to postpone delivery for as long as possible, while monitoring for (and treating) infection and the wellbeing of the foetus. If there is sign of infection or foetal distress, labour should be induced. Antibiotics should be used in case of infection
If the mother and foetus appear stable and healthy, management depends on the gestational age. If older than 34 weeks, we may perform expectant management or labour induction. Glucocorticoids should be given > 24 hours ahead of birth. Tocolytics may be used to delay delivery for up to 48 hours while waiting for glucocorticoids to take effect.
If younger than 34 weeks, induction is not performed, only expectant management is possible. Prophylactic antibiotics are given to prevent infection and delay labour.
Amnioinfusion is a possible treatment for PPROM, and the research is encouraging, but it is not recommended according to guidelines as the only evidence for its efficacy is low/moderate quality small trials according to Cochrane, UpToDate, and Norwegian guidelines. Further research is needed before it can be recommended, but it’s apparently asked on the exam regardless..