Subchorionic hematoma

Background

Placental anatomy.

• Bleeding underneath the chorion membranes enclosing the fetus in the uterus
• Most common cause of vaginal bleeding in patients who are 10-20 weeks by gestational age, make up ~11% of cases

Clinical Features

• Vaginal bleeding
• Increased risk of pregnancy loss, particularly when amounting to 25% or more of the gestational sac

Differential Diagnosis

Vaginal Bleeding in Pregnancy (<20wks)

• Ectopic pregnancy
• Subchorionic hematoma
• First Trimester Abortion
  • Complete Abortion
  • Incomplete Abortion
  • Inevitable Abortion
  • Missed Abortion
  • Septic abortion
  • Threatened Abortion
• Gestational trophoblastic disease
  • Consider when pregnancy-induced hypertension is seen before 24 wks of gestation
• Heterotopic pregnancy
• Implantation bleeding
• Molar pregnancy
• Non-pregnancy related bleeding
  • Cervicitis
  • Fibroids
  • Implantation bleeding

Vaginal Bleeding in Pregnancy (>20wks)

• Emergent delivery
• Placental abruption
• Placenta previa
• Vasa previa
• Uterine rupture
• Preterm labor
• Vaginal trauma
• Placenta accreta
• Intrauterine fetal demise

Evaluation

An 8-week fetus associated with a small (less than one-third of the chorionic sac circumference) subchorionic hematoma (arrows).

An 8-week fetus associated with a large (at least two-thirds of the chorionic sac circumference) subchorionic hematoma (arrows).

Workup

• Pregnancy test
• CBC
• Type & screen

Diagnosis

• Typically diagnosed on pelvic ultrasound