In this section
The majority of women who undergo pre-labour rupture of their membranes (PROM) go into labour spontaneously.
In patients with preterm PROM who are managed expectantly, there is an inverse relationship between gestational age at the time of membrane rupture and delivery—in women near term, 50% labour within 5 hours of PROM and 95% give birth within 28 hours1—with mid-trimester pPROM, only 56% will deliver within 7 days and 22% remain undelivered after 4 weeks2.
In general, prior to 34 weeks, the risks of prematurity predominate – respiratory distress syndrome, chronic lung disease, intraventicular haemorrhage, retinopathy and necrotising enterocolitis. After 34 weeks the greatest risk to the foetus is infection.
PROM Pre-labour rupture of membranes
PIPER Paediatric Infant Perinatal Emergency Retrieval
Confirming the diagnosis
An accurate diagnosis of rupture of the membranes is crucial to management decision-making. Avoid digital examination (unless there is a suspicion of cord presentation/prolapse) and perform a gentle speculum examination, visualising the cervix and posterior fornix.
While lower genital tract swabs are overall a poor predictor of the development of infection in women with pPROM3, take the opportunity to perform vaginal swabs for group B streptococcus, trichomonas vaginalis and mycoplasma hominis, and consider uPCR subsequently for chlamydia, gonorrhoea and ureaplasma. Note any apparent dilatation of the cervix, obvious liquor leakage through the os and a ‘washed out’ appearance of the upper vagina. Various proprietary indicator strips are also available to assist in the diagnosis, but may have a significant false positive rate.
The presence of contractions should be noted, and a cardiotocograph trace commenced.
Signs of infection should be actively sought. Clinically this includes maternal fever, tachycardia, an offensive discharge and uterine tenderness.
An ultrasound scan is useful to assess fetal size, presentation and normality, as well as liquor volume.
Optimising the gestation at delivery
There is no evidence to support the use of prophylactic tocolytics to improve neonatal outcome prior to the onset of contractions.
If pPROM occurs before 34 weeks and labour begins, it should be inhibited to allow the use of corticosteroids, providing there is no sign of sepsis, antepartum haemorrhage or any other contraindication to steroid use. If pPROM occurs between 34-37 weeks and labour begins, there is no satisfactory evidence to guide management.
If a cervical suture is present, there is a very high risk of developing sepsis. The suture should be removed as soon as possible, though ideally after arrival at a site equipped to safely deliver, and prompt delivery should be considered whatever the gestation.
Prospective randomised controlled trials have found a significant prolongation of pregnancy and a significant reduction in the incidence of chorioamnionitis, neonatal sepsis, necrotising enterocolitis and respiratory distress syndrome where antibiotics have been used4-6. The recommendations of the ORACLE trial7 (oral erythromycin 250mg four times per day for 7 days) would be the standard treatment used, though other regimes have been proposed and are of comparable efficacy.
Women with rupture of membranes >18 hours should be given IV group B streptococcus prophylaxis when they labour. Known carriers of group B streptococcus who present with PROM should be treated with IV penicillin (alternatively use clindamycin or erythromycin in case of penicillin allergy), and in most cases labour should be augmented within 6 hours of presentation. Note that the presence of gram positive cocci on a Gram stain of a cervical swab should not lead to a presumptive diagnosis of GBS, and cultures should be awaited.
Amniocentesis has been suggested between 32-36 weeks gestation to assess fetal lung maturity and suitability for induction of labour. This approach has not been widely adopted, and should be reserved to centres with experience in invasive ultrasound-guided procedures. Where intrauterine infection is suspected, amniocentesis may be useful, seeking an amniotic fluid glucose <1mM, a positive Gram stain or a positive amniotic fluid culture8-10.
If there is clinical evidence of sepsis or pathogens are detected from the genital tract swabs, antibiotics should be prescribed and delivery expedited. Where the pathogen has not been clearly identified, IV penicillin, gentamicin and metronidazole should provide appropriate cover.
Call PIPER Perinatal on 1300 137 650
Unless already at a site with appropriate neonatal facilities to manage a potential preterm birth at the gestation presenting, in utero transfer is usually required.
A midwife escort is NOT usually required, as the skill set of the paramedics are sufficient to provide safe care in most cases, and delivery in transit is not anticipated.
In most cases, you will be asked to reassess cervical dilatation before the patient leaves by ambulance, and if there has been further cervical dilatation despite tocolysis, call back the PIPER Perinatal consultant immediately, as in utero transfer may no longer be a safe option.
While extremely preterm infants are significantly advantaged by being born in a tertiary centre after a successful in utero transfer, delivery in transit is to be avoided as it will seriously compromise the infant. The PIPER Perinatal on-call consultants are all senior clinicians, and will be assisted in determining the safety of a particular transfer by receiving timely and accurate information from referring clinicians, as well as input from the duty PIPER Neonatal consultant. If transfer is not considered feasible, PIPER Neonatal will provide neonatal support and retrieval.
Use of magnesium sulphate as prophylaxis against cerebral palsy
While there is evidence that pre-birth administration of magnesium sulphate reduces the incidence of cerebral palsy in surviving extremely premature infants, it is NOT recommended that this be administered prior to in utero transfer.
After discussion with the Directors of the three tertiary maternity services, it has been agreed that use of magnesium sulphate will be deferred until the patient has arrived at the tertiary centre and been assessed there.
The exception could be in those cases where in utero transfer has been deemed inappropriate due to labour progressing, and birth is intended to occur at the peripheral maternity unit, where it MAY be feasible to administer magnesium sulphate. But note that in most cases, nifedipine tocolysis will be continuing, in order to slow labour and increase the likelihood of the PIPER Neonatal retrieval team arriving before or very soon after birth, so magnesium sulphate will remain relatively contra-indicated. Please discuss on a case-by-case basis with the PIPER Perinatal consultant.