Resolution of Complete Placenta Previa

Abstract

Does Prior Cesarean Delivery Matter?lacenta previa complicates approximately 0.4% of all thirdtrimester pregnancies. Risk factors for placenta previa include prior cesarean delivery, history of placenta previa with a prior pregnancy, increasing parity, advanced maternal age, prior uterine surgery, tobacco use, and multiple gestations. Prior cesarean delivery is one of the most important risk factors for development of placenta previa, and the risk of placenta previa increases as a woman has more cesarean deliveries. After 1 cesarean delivery, the risk of previa is reported to be approximately 1.9%; the risk increases to 5.5% after 2 cesarean deliveries and reaches 14.3% after 3 cesarean deliveries. 1 Associated conditions with placenta previa include placenta accreta, malpresentation, preterm premature rupture of membranes, intrauterine growth restriction, and vasa previa. ORIGINAL RESEARCHObjectives-The purpose of this study was to prospectively assess the rate of resolution of complete placenta previa diagnosed at second-trimester sonography in patients with and without previous cesarean delivery.Methods-This prospective study evaluated patients at 3 institutions with complete placenta previa diagnosed at second-trimester screening sonography. All patients were followed with sonography every 4 to 6 weeks until either resolution of the previa or delivery occurred. Patients with persistent/nonresolving complete placenta previa underwent cesarean delivery.Results-A total of 67 patients were enrolled in the study; 18 patients had a prior cesarean delivery. Resolution of placenta previa occurred in 11 of 18 patients (61%) with a prior cesarean delivery, whereas 44 of 49 patients (90%) without a prior cesarean delivery had resolution of placenta previa (P = .012, Fisher exact test). Placental location per se (anterior or posterior) was not associated with resolution of placenta previa (P = .22). Complete placenta previa persisted to delivery in 5 of 9 patients (56%) with a prior cesarean delivery and an anterior placental location.Conclusions-This prospective study indicates that patients with a prior cesarean delivery and complete placenta previa diagnosed at second-trimester sonography are less likely to have subsequent resolution of the previa when compared to those without a history of cesarean delivery.

Complete placenta previa in the second trimester: clinical and sonographic factors associated with its resolution

“…In studies by Lal et al [11] and Eichelberger et al [19], migration rates in anteriorly situated placentae showed no difference from that of posteriorly situated ones. However, Magann et al [16] showed a higher possibility of resolution in posteriorly located previa, and attributed the phenomenon to the disproportion in the growth of uterine smooth muscles between anterior placentas and posterior ones.…”

“…However, Magann et al [16] showed a higher possibility of resolution in posteriorly located previa, and attributed the phenomenon to the disproportion in the growth of uterine smooth muscles between anterior placentas and posterior ones. Conversely, other studies believed that placenta previa with an anteriorly located placenta was more likely to migrate, and the migration was secondary to a thinner lower uterine segment on the anterior portion of the uterus, leading to a more pronounced upward migration [11,25]. While Lal et al [11] demonstrated that placental location did not influence the resolution of placenta previa.…”

“…Conversely, other studies believed that placenta previa with an anteriorly located placenta was more likely to migrate, and the migration was secondary to a thinner lower uterine segment on the anterior portion of the uterus, leading to a more pronounced upward migration [11,25]. While Lal et al [11] demonstrated that placental location did not influence the resolution of placenta previa. we found that resolution was more frequent in women with posteriorly located CPP.…”

“…The scarred lower uterine segment caused by prior surgery was believed to impede placental migration, resulting in less frequent resolution [11]. Furthermore, caesarean section served as the primary contributor to placenta accreta or increta [24], which may impede placental migration.…”

“…Furthermore, studies have reported widely different results regarding the resolution of placenta previa [11][12][13]. Multiple investigators have studied the impact of placenta location and prior caesarean section on the resolution of placenta previa but have reached notably different conclusions [5,11,[14][15][16]. It is not known whether these factors exert any effect on the resolution of CPP.…”