What Is the Significance of Placental Lakes in Pregnancy? A Historic Literature Review

Background/Objectives: The presence of placental lakes has been recognized on obstetric ultrasounds for many years, although their influence on pregnancy and perinatal outcomes remains uncertain. Most studies evaluating outcomes are small and many outcomes are conflicting. The question remains whether placental lakes affect pregnancy outcomes and, if so, how and under what circumstances? The purpose of this review was to determine the incidence, diagnosis, pathology, management, and pregnancy outcomes to determine the influence of an isolated lake versus the influence of a lake with the presence of other factors on pregnancy and perinatal outcomes. Methods: Electronic databases (PubMed, OVID, CINAHI, Embase, and Web of Science) were searched. The only limitation was the abstract/paper had to be in English. The search years were 1980-2023. The search terms included "placenta lake" AND "pregnancy outcomes". Results: Of 323 abstracts identified, 26 full articles were selected as the basis of this review. A number of adverse outcomes have been reported with placenta lakes, including hypertensive disorders of pregnancy, fetal growth restriction, and intrauterine fetal demise. Other studies reported no adverse outcomes. A number of factors in addition to the placental lake, such as the size of the lake, number of lakes, and presence of a thick placenta, might increase the risk of adverse outcomes. Conclusions: Unfavorable pregnancy outcomes may be related to placental lakes, particularly if the lakes are multiple and large and the placenta is thick. Additional large studies are needed to determine if antenatal surveillance is helpful.