KEY FACTS
Terminology
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Perigestational hemorrhage (PGH): Hematoma in subchorionic space adjacent to gestational sac (GS)
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Subchorionic hematoma is synonymous with PGH
Imaging
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Hematoma appearance depends on age of blood
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Acute hematoma is echogenic
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Subacute hematoma is complex, more hypoechoic
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Old hematoma approaches sonolucent
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PGH has no blood flow on color Doppler
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Estimate PGH size compared with GS size (subjectively)
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≤ 10% vs. 11-25% vs. 26-50% vs. > 50%
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Other measurement criteria shown to be less accurate (including amount of detachment of early placenta)
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Top Differential Diagnoses
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Early twin gestation (PGH mimics 2nd sac)
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Chorioamniotic separation in late 1st trimester
Clinical Issues
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Large PGH associated with ↑ risk for pregnancy loss
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PGH > 50% of GS (with living embryo) = 23% loss rate
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PGH ≤ 10% of GS (with living embryo) = 6% loss rate
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Loss rates higher if no living embryo at time of diagnosis
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Early PGH associated with ↑ risk of pregnancy loss
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20% loss rate if ≤ 7 weeks vs. 4% if > 8 weeks
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PGH is common (symptomatic or asymptomatic)
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2% of all 1st-trimester patients have PGH
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20% of patients with vaginal bleeding have PGH
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Guarded prognosis if embryonic bradycardia
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Guarded prognosis if cervix distended with blood
Scanning Tips
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Take large field of view or cine sweeps to show PGH size compared to GS size
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Zoom into GS to look for yolk sac, embryo (transvaginal scan often necessary)
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Document embryo heart rate with M-mode in every case
next to an early gestational sac (GS) 
is shown. The internal echogenicity in the subchorionic hematoma can mimic a yolk sac 
from a dichorionic twin. Sometimes follow-up is necessary to differentiate between the 2 diagnoses.
