Placental lakes are enlarged spaces in the placenta filled with
maternal blood. These spaces are also called intervillous spaces because they
are found between the placental villi the finger-like projections of the placenta that contain fetal blood vessels
. The placental villi float in the intervillous spaces and absorb oxygen and
nutrients from the maternal blood.
The blood-filled placental lakes appear nearly black (white arrows) on ultrasound because they do not reflect soundwaves back to the ultrasound machine. Placental lakes can be seen within the placenta or on the fetal surface of the
placenta bulging into the amniotic cavity. Slow swirling blood flow (larger
arrow) may be seen
within the spaces, and the shape of the spaces tends to change with uterine
contractions. These features may help to distinguish a placental lakes from a
Placental lakes are considered to be a normal finding in most cases. However,
multiple placental lakes seen early in pregnancy in association with decreased umbilical artery blood flow
have been associated with fetal
growth restriction. In a patient with placenta previa and previous uterine
surgery multiple placental lakes should raise suspicion for placenta accreta or percreta.
Multiple placental lakes may also mimic gestational trophoblastic disease.
Synonyms: Placental vascular lacunae, placental caverns, placental venous lakes, placental sonolucencies.
Reis NS, et al. Placental lakes on sonographic examination: correlation with
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Thompson MO,; et al. Are placental lakes of any clinical significance?Placenta. 2002;23(8-9):685-90.PMID: 12361687
Jauniaux, E. and Nicolaides, K. H. 1996. Placental lakes, absent umbilical
artery diastolic flow and poor fetal growth in early pregnancy.Ultrasound Obstet Gynecol. 1996 ;7(2):141-4.PMID: 8776240
Hudon L Diagnosis and management of placenta percreta: a review.Obstet
Gynecol Surv. 1998 ;53(8):509-17. PMID: 9702791