Placental Sonolucencies
Roya Sohaey, MD
DIFFERENTIAL DIAGNOSIS
Common
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Placental Lake (PL)
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Placental Abruption (PA)
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Marginal Sinus Vessels
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Tornado-Shaped Vessels of Accreta
Less Common
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Placental Cord Insertion Cysts
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Complete Hydatidiform Mole
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Triploidy
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
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Obtain standard placenta views
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Sagittal long views
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Midsagittal to include lower uterine segment
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Parasagittal
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Axial views
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Upper, mid, lower uterus
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Use color Doppler in evaluating placental lesions
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Marginal sinus vessels have flow but abruption does not
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Both can present with retroplacental hypoechoic region
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Placental lakes often have no discernible flow
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Use real time grayscale findings to see swirling flow
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Obtain cine clip if documentation of flow is important
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Correlate placental findings with fetal findings
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Fetal anomalies suggest triploidy
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Intrauterine growth restriction suggests triploidy or placental insufficiency
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Helpful Clues for Common Diagnoses
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Placental Lake (PL)
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Enlarged intervillous vascular spaces
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Contain maternal blood
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May have fluid/fluid level
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Variable size
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Transient nature
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Change size and shape with time
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Can completely resolve
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Location
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Within placenta without appreciable border
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Subchorionic towards fetal surface
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Occasional PL are normal
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Late second trimester
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Third trimester
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Numerous PL or early PL associated with placental insufficiency
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Intrauterine growth restriction (IUGR)
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Oligohydramnios
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High resistive umbilical artery flow
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Power Doppler shows no flow in most PL
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Swirling flow seen with real time scanning
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Can thrombose and fibrose
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Increased echogenicity
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Discernible wall
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No swirling flow seen
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Placental Abruption (PA)
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Marginal PA is most common
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Hematoma has no blood flow
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Placenta margin is lifted off uterus
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Estimate how much placenta is detached
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Retroplacental PA
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May look like thick placenta when acute
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Often presents with preterm labor not bleeding
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Preplacental PA is rare
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Blood in subchorionic/subamniotic space
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May cause cord compromise if near cord insertion site
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Marginal Sinus Vessels
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Retroplacental sonolucency
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Normal maternal venous vessels
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Mostly myometrial veins
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Doppler will often show flow
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Tornado-Shaped Vessels of Accreta
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Enlarged intraplacental lacunae
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Triangle-shaped bizarre lucencies
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Slow flow like with PL
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Look for signs of accreta
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Loss of myometrium
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Invasion beyond uterine confines: Scan with full bladder to look for invasion
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Use color Doppler to evaluate for vascular flow
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MR may help with diagnosis
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Helpful Clues for Less Common Diagnoses
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Placental Cord Insertion Cysts
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Complete Hydatidiform Mole
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Gestational trophoblastic neoplasia
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100% paternal genetic makeup
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46 XX is most common karyotype
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First trimester or early second trimester diagnosis
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Ultrasound findings
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Cystic placenta
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Vascular mass
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No fetus
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Periplacental hemorrhage common
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Clinical presentation
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Bleeding
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Hyperemesis
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Elevated maternal serum hCG levels
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Triploidy
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Karyotype reveals 69 chromosomes
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Diandry if extra haploid is paternal (also called partial mole)
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Digyny if extra haploid is maternal
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Variable placenta appearance depending on source of extra chromosomes
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Large and cystic placenta if diandry
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