From the Guidelines
Venous lakes on prenatal ultrasound are typically normal findings that represent dilated veins in the fetal brain, most commonly seen in the choroid plexus, and are generally considered benign variants. These small, fluid-filled spaces are most frequently observed during the second trimester and often resolve spontaneously before birth. No specific treatment or intervention is required for isolated venous lakes, and they do not typically warrant additional follow-up unless they are unusually large or associated with other abnormal findings, such as growth restrictions or chromosomal disorders, as noted in studies on fetal growth restriction and Doppler assessment 1. The significance lies in distinguishing these normal variants from true intracranial cysts or other structural abnormalities that might require further evaluation, as emphasized in guidelines for assessing fetal well-being 1. If venous lakes are found alongside other brain abnormalities, then additional testing, such as fetal echocardiography or Doppler velocimetry, might be recommended to assess fetal cardiac function and well-being 1. The underlying mechanism involves normal variations in the development of the cerebral venous system during fetal growth, where some veins may temporarily dilate before achieving their final configuration. Parents can be reassured that these are common developmental variants, but it's crucial to monitor fetal development closely, especially in high-risk pregnancies, to ensure the best possible outcomes for the fetus, as highlighted in the most recent guidelines on fetal growth restriction management 1. Key points to consider include:
- Venous lakes are common and usually benign
- They are most frequently seen in the second trimester
- Isolated venous lakes do not require additional follow-up unless associated with other abnormalities
- Distinguishing venous lakes from other structural abnormalities is crucial
- Additional testing may be necessary if other abnormalities are present
- Close monitoring of fetal development is essential, especially in high-risk pregnancies, as supported by recent studies and guidelines 1.
From the Research
Significance of Venous Lakes on Prenatal Ultrasound
The presence of venous lakes on prenatal ultrasound can be an indicator of potential placental pathologies, which may affect patient management and pregnancy outcomes.
- Venous lakes, also known as placental lakes or lacunae, are anechoic zones in the placenta that can be detected through ultrasonography 2.
- These zones can be associated with various pathologies, including oncological, fetal, and maternal complications, and may require multidisciplinary surgery and close collaboration between sonographers, obstetricians, geneticists, and pathologists 2.
- The diagnosis and treatment of placental lakes require a thorough understanding of their etiologies and diagnostic measures, and a diagnostic flowchart can aid clinicians in this dense differential diagnosis 2.
Clinical Significance and Management
The clinical significance of venous lakes is not yet fully established, and their diagnosis and management can be challenging due to the wide variety of ultrasound findings, especially on color Doppler examination 3.
- Placental lakes are usually considered a physiological dilation of intervillous space with a relatively good obstetrical outcome, but they can be associated with perinatal complications and may influence pregnancy management 3, 4.
- The ultrasonographic assessment of placental abnormalities, including venous lakes, can help identify potential complications and inform pregnancy management, and repeated ultrasonographic examination, together with biologic investigations, is important for prenatal differential diagnosis 4.
Association with Pregnancy Outcomes
The presence of venous lakes has been associated with an increased risk of poor pregnancy outcomes, including hypertensive disease in pregnancy, fetal growth restriction, and low umbilical cord pH 5.
- However, the significance of abnormal placental lakes and thickness at different gestations with maternal and fetal outcomes is not statistically significant, and further research is needed to fully understand the relationship between venous lakes and pregnancy outcomes 5.
- In some cases, venous lakes have been associated with fetal growth restriction and reversed middle cerebral artery end-diastolic flow, which can be indicators of poor fetal outcome due to placental insufficiency 6.