Predicting Pregnancy Loss Due to Subchorionic Hematoma

BACKGROUND AND PURPOSE:

  • There have been different reporting/grading systems for the severity of subchorionic hematoma (SCH)
    • Subjective grading as small, moderate, or large
    • Volume measurement
    • Estimation of hematoma size as a fraction of gestational sac
    • Estimated fraction of the gestational sac surrounded by hematoma
  • No previous studies have assessed grading systems and risk for pregnancy loss
  • Heller et al. (Journal of Ultrasound in Medicine, 2018) determined which SCH grading system in first trimester correlates best with miscarriage

METHODS:

  • Retrospective data review
    • First trimester live singleton pregnancies with SCH
    • Between 6-11 weeks gestational age
  • First-trimester outcome was categorized as
    • Live: Ultrasound > 14 weeks with an FH or live birth documented in the medical record
    • Demise: Ultrasound showing pregnancy loss <14 weeks or miscarriage documented in the medical record
  • SCH were categorized as
    • Subjective: SCH is graded as small, moderate or large
    • Subjective: SCH size based on fraction of gestational sac size
      • ≤10% | 11-25% | 26-50%, >50%
    • Subjective: SCH sized based on fraction of the gestational sac surrounded by hematoma using the same four percentage categories above
    • Volume: Measurement of 3 orthogonal dimensions of the SCH
  • Primary outcome
    • Determine superior SCH size estimate approach for predicting pregnancy outcome
  • Secondary outcome
    • Assess whether gestational age at the time of SCH diagnosis affects pregnancy outcome

RESULTS:

  • Total 434 sonograms met study inclusion criteria
  • Overall rate of first-trimester pregnancy failure with SCH was 12.0%
  • Rate of demise was higher when gestational age at the time of SCH diagnosis was lower (P < .001)
    • ≤7 weeks: Rate of demise was 19.6%
    • >7 to 8 weeks: Rate of demise was 14.6%
    • >8 weeks: Rate of demise was 3.6%
  • Vaginal bleeding and use of ART did not impact the rate of miscarriage
  • The size of the hematoma estimated as a fraction of gestational sac size significantly correlated with first trimester pregnancy loss (P <0.001)
    • 6-11 weeks (all GAs): AUC 0.660
    • ≤8 weeks: AUC 0.613
  • Risk of fetal demise based on hematoma size as fraction of gestational sac size (diagnosed 6-11 wks)
    • SCH <10% of GS size: 5.8%
    • SCH 10-25% of GS size: 8.9%
    • SCH 26-50% of GS size: 10.8%
    • SCH >50% of GS size: 23.3%
  • There was no statistical significance between first trimester outcome and the other 2 subjective grading methods
  • The least reliable results were obtained when volume (3 measurements) was used due to irregular shape of most SCHs

CONCLUSION:

  • The use of SCH vs gestational sac size as a ratio measurement correlated with pregnancy failure in the first trimester
  • Volume-based measurements were not accurate
  • The earlier in pregnancy an SCH is detected, the higher the rate of subsequent pregnancy loss

Learn More – Primary Sources:

Subchorionic Hematoma: Correlation of Grading Techniques With First‐Trimester Pregnancy Outcome