Placentomegaly



Placentomegaly


Roya Sohaey, MD



DIFFERENTIAL DIAGNOSIS


Common



  • Hydrops


  • Acute Placental Abruption


  • Macrosomia


  • Twins


Less Common



  • Battledore Placenta


  • Intrauterine Growth Restriction (IUGR)


Rare but Important



  • Triploidy


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Normal placenta is < 40 mm thick


  • Placenta grows approximately 1 mm/wk



    • 10 wk placenta = 10 mm


    • 20 wk placenta = 20 mm


    • 30 wk placenta = 30 mm


  • Evaluate placental attachment



    • Normal attachment



      • Hydrops


      • Macrosomia


      • Diabetes


      • IUGR


    • Small attachment



      • Battledore placenta


    • Heterogeneous attachment



      • Abruption


  • Evaluate placental morphology



    • Increased sonolucencies



      • Triploidy


      • IUGR


    • Focal thickening



      • Dichorionic twins


      • Focal abruption


    • Large thin placenta



      • Monochorionic twins


    • Heterogeneous thick placenta



      • Abruption


      • IUGR


  • Use Doppler to assess placental function



    • Uterine artery Doppler



      • Low resistive flow in second trimester


      • Post systolic notch abnormal > 18 wks


    • Umbilical artery (UA) Doppler



      • Low resistive flow after 2nd trimester


      • Absent diastolic flow abnormal > 16 wks


      • Systolic/diastolic ratio < 3.0 if > 30 wks


      • Reversed diastolic flow always abnormal


    • Fetal middle cerebral artery (MCA) Doppler



      • Higher resistive flow than UA


      • Severe IUGR leads to ↓ resistance


  • Use MCA peak systolic velocity to assess for fetal anemia



    • Insonation angle is important



      • 0° angle on MCA


    • Use normogram to compare with gestational age



      • ↑ Velocity suggests anemia


Helpful Clues for Common Diagnoses



  • Hydrops



    • Excessive fetal body fluid



      • Skin edema


      • Pleural effusion


      • Ascites


      • Pericardial effusion


    • Hydrops if ↑ fluid in 2 areas


    • Amniotic fluid findings variable



      • Polyhydramnios


      • Oligohydramnios


    • Placenta edema



      • More likely if immune hydrops


    • Common causes of nonimmune hydrops



      • Infection


      • Aneuploidy (Turner most common)


      • Heart failure


      • Fetal anemia of any etiology


  • Acute Placental Abruption



    • Acute blood has same echogenicity as placenta



      • Mimics thick placenta


      • Becomes hypoechoic with time


    • Direct hemorrhage into placenta can occur



      • Most common with retroplacental abruption


      • Arterial hemorrhage


    • Use power Doppler



      • No flow in hematoma


    • > 50% detachment associated with > 50% fetal death


  • Macrosomia



    • Definition



      • Estimated fetal weight > 90th percentile


      • Birthweight > 4500 g


    • Causes



      • Hereditary


      • Diabetes


      • Beckwith-Wiedemann (BW)


    • Polyhydramnios




      • Both hereditary causes and diabetes associated with ↑ fluid


      • Impaired swallowing if macroglossia and BW


  • Twins



    • Dichorionic twins may have appearance of single large placental mass



      • “Twin peak” or “delta” signs are focal point where 2 placentas meet


      • Thick membrane (4 layers) extends from “peak” or “delta”


    • Large thin placenta of monochorionic twinning



      • No triangular peak


      • Thin membrane (two layers)


Helpful Clues for Less Common Diagnoses

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Aug 10, 2016 | Posted by in OBSTETRICS | Comments Off on Placentomegaly

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