Myometrial Thickness as a Predictor of Latency Interval in Preterm Prelabor Rupture of Membranes: A Prospective Cohort Study

PPROM is a major obstetric complication, occurring in approximately 3% of pregnancies and accounting for 30-40% of preterm births worldwide. It is defined as rupture of the fetal membranes before the onset of labor and prior to 37 weeks of gestation, creating a clinical dilemma that balances the risks of prematurity against the dangers of prolonged membrane rupture. The condition carries significant perinatal morbidity and mortality, including respiratory distress syndrome, intraventricular hemorrhage, necrotizing enterocolitis, and neonatal sepsis, alongside maternal complications such as chorioamnionitis and postpartum hemorrhage.

The latency period, defined as the interval between membrane rupture and delivery, is a critical determinant of neonatal outcomes. A longer latency permits completion of antenatal corticosteroid therapy for fetal lung maturation and antibiotic prophylaxis, thereby improving neonatal prognosis. Conversely, prolonged latency increases the risk of ascending infection, chorioamnionitis, and placental abruption, necessitating careful and individualized management, Current evidence indicates that approximately 50% of affected women deliver within 48 hours, and 70-90% within one week of membrane rupture, although latency may occasionally extend for several weeks in cases of very early PPROM according to recommendations of the American College of Obstetricians and Gynecologists.

Standard management between 24 and 34 weeks includes hospitalization, antibiotic prophylaxis, antenatal corticosteroids, and magnesium sulfate for neuroprotection before 32 weeks, alongside close maternal-fetal surveillance. Despite these well-established interventions, accurate prediction of latency duration remains a significant clinical challenge. Traditional predictors such as gestational age at rupture, amniotic fluid volume, cervical length, fetal fibronectin, and inflammatory markers have demonstrated variable sensitivity and specificity across different populations, limiting their widespread clinical utility.

Ultrasonographic assessment has become integral to PPROM management, and recent attention has focused on myometrial thickness (MT) as a potential non-invasive predictor of labor onset and delivery timing. The myometrium undergoes dynamic structural and functional changes throughout pregnancy, with thickness variations reflecting uterine contractility patterns, inflammatory responses, and the risk of imminent delivery. Studies in women with threatened preterm labor have shown that increased MT particularly at the lower uterine segment correlates with heightened uterine activity and a shorter interval to delivery . Ultrasonography provides a non-invasive method for assessing uterine morphology and myometrial activity, with increasing interest in its potential role in predicting the onset of preterm labor.

Despite encouraging preliminary findings, evidence regarding the predictive value of MT in women with PPROM remains limited, and further prospective studies are required before its routine clinical application. Furthermore, in middle-income countries, such as Egypt, where preterm birth remains a major contributor to neonatal morbidity and mortality, the development of accessible, affordable, and non-invasive predictive tools for women with PPROM is of particular clinical importance. The wide availability of ultrasound equipment makes MT measurement a feasible and cost-effective addition to routine PPROM assessment, without requiring specialized biochemical assays or advanced technology.