The clinical significance of large placental lakes

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.

Presence and Size of Placental Lakes on 20-Week Fetal Anatomy Ultrasound and Obstetrical Outcomes

Our objective was to determine if placental lake presence or size is associated with adverse pregnancy outcomes. This was a retrospective cohort of patients who had fetal anatomy ultrasounds at 18-22 weeks and delivered between 2018 and 2022. Placental lakes were classified as small (>2.0 to 3.9 cm) or large (≥4 cm). Multiple gestations, placenta previas, and placenta accretas were excluded. Outcomes included low birthweight, cesarean delivery, primary cesarean for non-reassuring fetal heart tracing, fetal growth restriction, preterm birth, and severe preeclampsia. A total of 1052 patients were included; 294 had placental lakes (204 small, 90 large). No differences in pregnancy outcomes were observed.

Doppler evaluation of normal and abnormal placenta

Doppler techniques are needed for the evaluation of the intraplacental circulation and can be of great value in the diagnosis of placental anomalies. Highly sensitive Doppler techniques can differentiate between the maternal (spiral arteries) and fetal (intraplacental branches of the umbilical artery) components of the placental circulation and assist in the evaluation of the placental functional units. A reduced number of placental functional units can be associated with obstetric complications, such as fetal growth restriction. Doppler techniques can also provide information on decidual vessels and blood movement. Abnormal decidual circulation increases the risk of placenta accreta. Doppler evaluation of the placenta greatly contributes to the diagnosis and clinical management of placenta accreta, vasa previa, placental infarcts, placental infarction hematoma, maternal floor infarction, massive perivillous fibrin deposition and placental tumors. However, it has a limited role in the diagnosis and clinical management of placental abruption, placental hematomas, placental mesenchymal dysplasia and mapping of placental anastomoses in monochorionic twin pregnancies. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Sonographic Evaluation of a Large Placental Chorangioma

Placental chorangioma is a rare, benign tumor of the placenta. Chorangiomas are typically small, are asymptomatic, and pose no threat to pregnancy. However, in extreme cases, large placental chorangiomas can cause maternal and fetal complications associated with poor outcomes and fetal demise. Prenatal sonography is an accurate method for diagnosing these benign tumors based on grayscale imaging and color Doppler assessment of intratumoral vascularity. Early diagnosis is critical in predicting the potential for subsequent maternal and fetal complications, planning sonographic surveillance, treating maternal symptoms, and delivery planning. This case study discusses the diagnosis and management of a large placental chorangioma in an otherwise uncomplicated pregnancy.

Oxidative stress and the evolutionary origins of preeclampsia

In this speculative paper, I consider the relationship between oxidative stress and the evolution of placentation in eutherian mammals. I argue that epitheliochorial placentation, in which fetal tissues remain separated from maternal blood throughout gestation, has evolved as a protective mechanism against oxidative stress arising from pregnancy, particularly in species with unusually long gestation periods and unusually large placentas. Human beings comprise an unusual species that has the life history characteristics of an epitheliochorial species, but exhibits hemochorial placentation, in which fetal tissues come into direct contact with maternal blood. I argue that the risk of preeclampsia has arisen as a consequence of the failure of human beings to evolve epitheliochorial placentation.

Morphological changes of placental syncytium and their implications for the pathogenesis of preeclampsia

Preeclampsia is a hypertensive disease that complicates many pregnancies, typically presenting with new-onset or worsening hypertension and proteinuria. It is well recognized that the placental syncytium plays a key role in the pathogenesis of preeclampsia. This review summarizes the findings pertaining to the structural alterations in the syncytium of preeclamptic placentas and analyzes their pathological implications for the development of preeclampsia. Changes in the trophoblastic lineage, including those in the proliferation of cytotrophoblasts, the formation of syncytiotrophoblast through cell fusion, cell apoptosis and syncytial deportation, are discussed in the context of preeclampsia. Extensive correlations are made between functional deficiencies and the alterations on the levels of gross anatomy, tissue histology, cellular events, ultrastructure, molecular pathways, and gene expression. Attention is given to the significance of dynamic changes in the syncytial turnover in preeclamptic placentas. Specifically, experimental evidences for the complex and obligatory role of syncytin-1 in cell fusion, cell-cycle regulation at the G1/S transition, and apoptosis through AIF-mediated pathway, are discussed in detail in the context of syncytium homeostasis. Finally, the recent observations on the aberrant fibrin deposition in the trophoblastic layer and the trophoblast immature phenotype in preeclamptic placentas and their potential pathogenic impact are also reviewed.

Three-dimensional high-definition flow in the diagnosis of placental lakes

Placental lakes are sonolucent areas often found in the normal placenta. Most of them are asymptomatic. They are sometimes related to placenta accreta or intrauterine fetal growth restriction, among other conditions. Although Doppler sonography is useful for evaluating noxious placental lakes, it is not easy to adapt Doppler studies to conventional two-dimensional color Doppler sonography because of the low-velocity blood flow and high vascularity in the placenta. Here, we demonstrate how three-dimensional high-definition imaging of flow provides a novel visual depiction of placental lakes, which helps substantially with the differential diagnosis. As far as we know, there have been no previous reports of observation of placental lakes using three-dimensional high-definition imaging of flow.

A pictorial guide for the second trimester ultrasound

Introduction: The second trimester ultrasound remains an important screening tool for detecting fetal abnormalities. This pictorial guide for the second trimester ultrasound is designed to assist practitioners to produce a high quality diagnostic survey of the fetus by demonstrating and describing recommended images. Methods: Each image is discussed in detail and has an associated drawn line diagram to aid in the identification of the important features of that image. There is a description of the salient landmarks and relevant measurements. Result: The authors hope this article may act as a useful guide to all practitioners performing second trimester ultrasounds.