Pathophysiology
Clinical meaning
The amniotic membranes (amnion and chorion) form a fluid-filled sac that protects the fetus throughout pregnancy. Amniotic fluid has an alkaline pH (7.0-7.5) compared to acidic vaginal secretions (3.5-4.5), which forms the basis of the nitrazine test. Rupture of membranes (ROM) can be spontaneous during labor (SROM), premature before labor at term (PROM), or preterm before 37 weeks (PPROM). PPROM is an obstetric emergency due to simultaneous risks of prematurity, infection (chorioamnionitis), and cord prolapse.