Term prelabour rupture of membranes

It is 06:15 and a well 39-week primigravida walks into the birth suite with wet leggings and no contractions. Nothing about her needs an emergency. Everything about her needs a decision, and the decision has a clock attached to it: from the moment those membranes went, the risk of infection has been climbing while the chance of spontaneous labour has been ticking down.[1][4]

Overview and definition

Term prelabour rupture of membranes is spontaneous rupture of the membranes at or after 37+0 weeks, before labour begins. Two other definitions travel with it and examiners like them separated: [6][4]

• Prolonged rupture of membranes — commonly defined at 18 or 24 hours, and used as a risk factor in neonatal sepsis assessment rather than as a management trigger in its own right.[9][6]
• Suspected Triple I — the NICHD replacement for intrapartum "chorioamnionitis": a documented fever without a clear source plus at least one of fetal tachycardia over 160 bpm for 10 minutes or longer, a maternal white cell count over 15 000 per cubic millimetre in the absence of corticosteroids, or definite purulent fluid from the cervical os.[7]

The two management strategies are planned early birth (induction immediately or within about 24 hours) and expectant management (no planned intervention within 24 hours, with surveillance). Everything else in this topic is a variation on choosing between them.[2]