Abnormal Beta HCG

Abnormal Beta HCG
Anne Kennedy, MD
DIFFERENTIAL DIAGNOSIS
Common
  • Imprecise Menstrual Dates
  • Multiple Gestations
  • Ectopic Pregnancy
  • Retained Products of Conception (RPOC)
Less Common
  • Complete Hydatidiform Mole
  • Trisomy 21
  • Trisomy 18
Rare but Important
  • Invasive Mole
  • Choriocarcinoma
  • Embryonic/Fetal Demise
ESSENTIAL INFORMATION
Helpful Clues for Common Diagnoses
  • Imprecise Menstrual Dates
    • Maternal serum screening provides numerical risk for certain conditions based on expected levels of certain hormones
      • Levels reported as multiples of the median (MOM) for gestational age
      • Incorrect menstrual data → incorrect gestational age assessment at time of blood draw → spurious ↑ or ↓ of levels
    • All patients with abnormal serum screen should have ultrasound as next step
      • Verify gestational age
      • Look for sonographic signs of aneuploidy
    • If dates are incorrect, risk often recalculated or test redrawn
  • Multiple Gestations
    • Maternal serum hormone levels are higher in multiple than singletons
      • Greater amount of fetal tissue per gestational age week
  • Ectopic Pregnancy
    • Ectopic pregnancies are not normal pregnancies
      • Beta hCG often lower than for corresponding gestational age (GA) in a normal early pregnancy
      • Normal “doubling” of beta hCG every 48 hours in early pregnancy may not occur
    • Tubal ectopic is commonest type
      • No intrauterine pregnancy + tubal mass + echogenic cul-de-sac fluid
      • Echogenic fluid in a pregnant patient has a 90% positive predictive value for ectopic pregnancy
    • Look for ring-like mass separate from ovary
      • May have yolk sac or embryonic pole with or without cardiac activity
    • “Ring of fire”: Increased flow seen in trophoblastic tissue around ectopic
      • Do not confuse with increased flow around corpus luteum
    • Amorphous adnexal mass may be due to hematosalpinx or clot adherent to ruptured tube
    • Pseudogestational sac sign
      • Decidual cast surrounds fluid collection central in endometrial cavity
      • Lacks double decidual sac sign of normal intrauterine pregnancy
  • Retained Products of Conception (RPOC)
    • Residual trophoblastic tissue continues to produce beta hCG
      • Levels do not fall to 0 as expected
      • If levels remain elevated > 4 months post delivery, consider persistent gestational trophoblastic neoplasia
    • Solid, heterogeneous, echogenic mass in endometrial cavity
    • Persistent, thickened endometrium
    • Irregular interface between endometrium and myometrium
    • May see high velocity, low resistance flow
Helpful Clues for Less Common Diagnoses
  • Complete Hydatidiform Mole
    • No embryo or fetus
    • Beta HCG markedly elevated
    • Enlarged uterus with “swiss cheese” endometrium
      • Heterogeneous, echogenic intrauterine mass
      • Completely fills uterine cavity
      • Individual cysts that vary in size can be seen
      • Mass is vascular with high velocity, low impedance flow (mean resistive index of 0.55)
    • Bilateral, complex theca lutein ovarian cysts in 25-50%
  • Trisomy 21
    • High beta hCG associated with low unconjugated estriol, alpha fetoprotein
    • First trimester ultrasound findings
      • Increased nuchal translucency, absent nasal bone, abnormal ductus venosus flow
    • Second trimester ultrasound findings
      • Increased nuchal fold, short femur/humerus, duodenal atresia, atrioventricular septal defect
      • More minor finding include echogenic bowel, mild pyelectasis, mild ventriculomegaly, echogenic intracardiac focus
  • Trisomy 18
    • Low beta hCG associated with low unconjugated estriol, alpha fetoprotein
    • Multiple anomalies, intrauterine growth restriction
Helpful Clues for Rare Diagnoses
Aug 10, 2016 | Posted by in OBSTETRICS | Comments Off on Abnormal Beta HCG

Full access? Get Clinical Tree

Get Clinical Tree app for offline access