Outcome of low-Lying placenta at 18-22 Weeks-A Prospective Observational Study

BACKGROUND Haemorrhage contributes to 25% of maternal deaths worldwide. Placenta previa i.e. Placenta attached to lower uterine segment, is an important cause of antepartum and postpartum haemorrhage and is associated with some foetal and neonatal complications as well. Most of the low-lying placentas found at early weeks of pregnancy migrate to upper uterine segment before term or before delivery. METHODS This prospective observational study was conducted on the outcome of low-lying placenta at 18-24 weeks, in the Department of Gynaecology and Obstetrics, NRS Medical College, Kolkata from May 2013 to April 2014. 75 asymptomatic women with low lying placenta (distance less than or equal to 2 cms from the internal cervical os), discovered by trans-abdominal USG and/or transvaginal sonography at 18 to 22 weeks of gestation. They were observed up to 6 weeks post-partum for maternal and foetal complications. RESULTS Placenta was found to migrate to upper uterine segment in 77.3 % cases. Rate of migration decreased in placenta closer to os and overlapping the os. Migration was more in posterior placenta than anterior placenta which was statistically significant. Persistence of low-lying placenta at term was associated with higher age and increasing parity of the mother; in both these situations the association was statistically significant. H/o previous Caesarean section was associated with persistence of low-lying placenta about 1.9 times more commonly than in cases with no such history. Prior termination of pregnancy ( MTP ) was associated with higher chance of persistence of low lying placenta at term or delivery ( 27.7%) with odds ratio of 1.44; whereas multiple pregnancy (odd's ratio= 1.1) and prior placenta previa (odd ratio 1.1) are minor risk factors for persistence of low lying placenta at term or delivery. Low lying placenta if associated with bleeding in early months showed less chance of migration at term or delivery. Higher incidence of ma-presentation, atonic PPH, preterm birth and iatrogenic CS was found in persistent placenta previa group. Unlike other complications, there is slightly increased preterm delivery rate in migrated group also. Among foetal complications, IUGR and congenital anomalies, birth asphyxia, neonatal death were more common in persistent placenta previa group compared to migrated group, which was statistically significant. CONCLUSIONS So, cases found with low lying placenta in early months, should be assessed carefully regarding presence of risk factors of persistence in lower segment. Mother should be counselled regarding this possibility of migration and also maternal and foetal risks in case placenta persists in low position.