From the Research
A placental venous lake measuring 1.8 cm on anatomy ultrasound is generally not concerning if everything else appears normal. These venous lakes (also called placental lakes or subchorionic lakes) are common findings during pregnancy ultrasounds and represent areas of maternal blood pooling within the placenta. The size of 1.8 cm falls within what is typically considered normal, as venous lakes under 5 cm are usually not associated with adverse pregnancy outcomes, as suggested by a recent review of the literature 1. No specific treatment or additional monitoring is needed for an isolated placental venous lake of this size in an otherwise normal pregnancy.
Some studies have reported adverse outcomes associated with placental lakes, including hypertensive disorders of pregnancy, fetal growth restriction, and intrauterine fetal demise, particularly if the lakes are multiple and large and the placenta is thick 1. However, these findings are not directly applicable to a single, small placental lake like the one in question. The clinical significance of large placental lakes has been investigated, and while some studies have found correlations between large lakes and adverse outcomes, such as fetal small-for-gestational-age status 2, these findings do not necessarily apply to smaller lakes.
In the context of this case, where the placental venous lake is small (1.8 cm) and isolated, with no other abnormal findings, the risk of adverse pregnancy outcomes is likely low. The formation of these structures is a part of normal placental development, where maternal blood enters the intervillous space through spiral arteries and sometimes pools before returning through venous channels. While very large lakes or those associated with other abnormal findings might warrant closer monitoring, a 1.8 cm venous lake as an isolated finding should not cause concern and does not affect placental function or fetal development, as supported by the most recent and highest quality study available 1. Your regular prenatal care schedule can continue as planned.
Key points to consider include:
- The size of the placental lake (1.8 cm) is within the normal range.
- The lake is isolated, with no other abnormal findings.
- The patient's pregnancy has been otherwise normal.
- The risk of adverse outcomes associated with small, isolated placental lakes is low, according to the most recent literature review 1.