Premature rupture of membranes

• Prelabour rupture of membranes (PROM)

  • Rupture of foetal membranes at least 1 hour prior to the onset of labour
  • At least 37 weeks gestation
  • Minimal risk to the mother and foetus
• Pre-term prelabour rupture of membranes (P-PROM)

  • Rupture of foetal membranes occurring before 37 weeks
  • Higher rates of maternal and foetal complications
  • Associated with 40% of preterm delivery
• Foetal membranes:

  • Consist of the amnion (inner later) and chorion (outer)
  • Under normal circumstances, become weaker at term in preparation for labour
  • Weakening due to apoptosis and collagen breakdown by enzymes
• Pathophysiology of P-PROM:

  • Early activation of normal physiological processes
  • Infection - will have positive amniotic fluid cultures
  • Genetic predisposition
• PROM risk factors:

  • Smoking (especially <28 weeks)
  • Previous PROM/pre-term delivery
  • Vaginal bleeding during pregnancy
  • Lower genital tract infection
• P-PROM risk factors:

  • Invasive procedures e.g. amniocentesis
  • Polyhydramnios
  • Multiple pregnancy
  • Cervical insufficiency
• Clinical features:

  • Typical history is women experiencing a painless popping sensation, followed by a gush of watery fluid
  • Can be non-specific such as gradual leakage of watery fluid, or a change in the colour or consistency of vaginal discharge
  • Speculum exam - fluid draining for the cervix and pooling in the posterior vaginal fornix
  • Avoid digital vaginal exam until in active labour - as it can prolong the time between rupture of membranes and onset of labour
• Investigations:

  • Usually made by history and positive exam findings
  • Actim-PROM: swab test looking for insulin-like growth factor binding protein-1 (IGFBP-1) - much higher concentration in amniotic fluid
  • Amnisure - looks for placental alpha microglobulin-1 (PAMG-1)
  • High vaginal swab - may grow group B streptococcus - antibiotics needed
  • Ultrasound is not used routinely - reduced levels of amniotic fluid
• Rupture of the fetal membranes releases amniotic fluid – which acts to stimulate the uterus. Therefore, the vast majority of women with rupture of membranes will fall in to labour within 24-48 hours. There is very little that can be done to halt this.
• Management >36 weeks:

  • Monitor for signs of chorioamnionitis (infection)
  • Antibiotics if swab positive for GBS
  • Watch and wait for 24 hours, or consider induction of labour
  • Induction and delivery recommended if greater than 24 hours
• Management 34-36 weeks:

  • Monitor for signs of chorioamnionitis - advise to avoid sexual intercourse (increased risk of infection)
  • Prophylactic erythromycin
  • Further antibiotics if GBS positive
  • Corticosteroids - development of foetal lungs
  • Induction and delivery recommended
• Management 24-33 weeks:

  • Monitor for chorioamnionitis and advise to avoid sexual intercourse
  • Prophylactic erythromycin
  • Corticosteroids
  • Aim expectant management until 34 weeks
• Complications:

  • Outcomes generally correlates with the gestational age of the foetus
  • Majority of women at term will enter spontaneous labour within 24 hours
  • Chorioamnionitis - inflammation of foetal membranes due to infection
  • Oligohydramnios - increases risk of lung hypoplasia
  • Neonatal death
  • Placental abruption
  • Umbilical cord prolapse