Fetal Anemia



Fetal Anemia


Karen Y. Oh, MD



DIFFERENTIAL DIAGNOSIS


Common



  • Alloimmunization



    • Rh Incompatibility


    • Other Antibodies


  • Infection



    • Parvovirus B19


Rare but Important



  • Hemangioendothelioma


  • Leukemia


  • Fanconi Anemia


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Clinical history is often key to diagnosis



    • Watch for fetal anemia with maternal history of isoimmunization



      • Usually with Rh negative maternal blood types


      • Can have other minor antibody sensitizations


    • Obtain history of potential viral exposures


  • Look for associated fetal abnormalities which can cause fetal anemia



    • Tumors


    • Vascular malformations


  • Always consider anemia when a fetus presents with hydrops


  • Middle cerebral artery (MCA) Doppler peak systolic velocity (PSV) measurements elevated in anemia



    • Very accurate noninvasive method to screen for fetal anemia


Helpful Clues for Common Diagnoses



  • Rh Incompatibility



    • Occurs in women who are Rh (-)



      • Indicates absence of D antigen in erythrocyte membrane


    • Results from maternal immune response against RhD antigen on fetal red blood cells



      • Maternal anti-D antibodies cross placenta


      • Leads to lysis of fetal erythrocytes


    • Prophylaxis should be given routinely if woman is Rh (-) and when fetal and maternal blood could be in contact



      • Ectopic pregnancy


      • Post chorionic villus sampling or amniocentesis


      • Following spontaneous or elective abortion


      • Maternal trauma


      • At time of delivery of an Rh + infant


      • Prophylactic dose given at approximately 28 weeks gestation


    • If no prior history of antibody sensitization → correlate with antibody titers to assess for risk of fetal anemia


    • If history of prior sensitization → plan for increased surveillance and monthly antibody titer until critical titer reached (generally 1:8-1:16)



      • Once critical titer reached, then follow serial MCA-PSV


    • Fetal hemolytic disease similar to or more severe in subsequent pregnancies


    • Serial ultrasound evaluation



      • Monitor for hydrops


      • Check PSV in MCA


      • Increased PSV indicates worsening fetal anemia


      • Follow-up interval and intervention based on PSV measurements compared to normative scale (Mari zones A-D)


    • Cordocentesis and transfusion if anemia severe


  • Other Antibodies



    • Most sensitizations caused by incompatible blood transfusions



      • Includes Kell, Duffy, Kidd, E, C, c and multiple other antigens


    • Similar management of pregnancy as with Rh alloimmunization


  • Parvovirus B19



    • 20-30% of women who become infected during pregnancy transmit to fetus



      • 4% risk of fetal hydrops


      • Highest risk of fetal death if infected < 20 wks gestation


    • Fetal anemia causes sonographic findings



      • Parvovirus attacks red blood cell precursors


      • Involvement of cardiac myocytes may contribute to hydrops


    • Ascites most common presenting finding



      • Progression to hydrops in severe cases


    • Maternal infection should be managed by high risk specialist



    • Weekly ultrasound for 10-12 weeks after seroconversion



      • Check for developing hydrops


      • Monitor MCA Doppler PSV to assess for fetal anemia


      • Intrauterine transfusion warranted for fetal anemia


Helpful Clues for Rare Diagnoses

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

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