#Grand Rounds

Is Subchorionic Hematoma in the First Trimester Associated with Adverse Outcomes Beyond 20 Weeks?

BACKGROUND AND PURPOSE:

Naert et al. (Obstetrics & Gynecology, 2019) sought to determine whether first-trimester subchorionic hematomas are associated with adverse outcomes >20 weeks

Retrospective cohort study
Participants
- Singleton pregnancies
- First prenatal visit <14 weeks
Adverse outcomes
- Gestational age at delivery | Preterm birth
- Birth weight | Birth weight <10th percentile
- Gestational hypertension | Preeclampsia
- Abruption
- IUFD >20 weeks
- Cesarean delivery
- Blood transfusion
- Antepartum admissions
Study design
- All patients had first-trimester ultrasound
- Adverse pregnancy outcomes > 20 weeks compared between women with and without subchorionic hematomas
Statistical analysis
- Regression analysis used to adjust for confounding
- 80% power to detect a 5% absolute difference in the frequency of preterm birth (from 10% to 15%)

2,172 women included
- subchorionic hematoma: 17.9% | Mean largest diameter 2.1±1.4 cm
No differences found for the following
- Maternal age | Race | IVF | BMI | Medical comorbidities
In subchorionic hematoma cohort
- First ultrasound performed earlier in gestation
  - 8w5d vs 9w6d (P<0.001)
- Vaginal bleeding was more common
  - 31.9% vs 7.9% (P<0.001)
Univariate analysis and subsequent regression analysis did not show association between subchorionic hematoma and adverse pregnancy outcome
However, vaginal bleeding (adjusted for subchorionic hematoma and gestational age at ultrasound examination) was independently associated with
- Preterm birth (<37 weeks of gestation)
- Birth weight <10th percentile

First trimester subchorionic hematomas in singleton pregnancy is not associated with adverse pregnancy outcomes at more than 20 weeks gestation

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