First trimester abortion

See Vaginal bleeding in pregnancy (less than 20wks) for diagnostic approach to early vaginal bleeding in pregnancy.

Background

• Estimates are up to 15% of pregnancies end in a 1st trimester abortion, usually due to fetal chromosomal abnormalities
• Primary risk factors include history of prior miscarriage and advanced maternal age
  • Other risk factors include heavy alcohol use, uterine structure abnormalities, and systemic maternal disease

Abortion Types

Classification	Characteristics	OS	Fetal Tissue Passage	Misc
Threatened	Abdominal pain or bleeding; < 20 weeks gestation	Closed	No	If < 11 weeks (with fetal cardiac activity) 90% progress to term. If between 11 and 20 weeks 50% progress to term
Inevitable	Abdominal pain or bleeding; < 20 weeks gestation	Open	No
Incomplete	Abdominal pain or bleeding; < 20 weeks gestation	Open	Yes, some
Complete	Abdominal pain or bleeding; < 20 weeks gestation	Closed	Yes, complete expulsion of products	Distinguish from ectopic based on decreasing hCG and/or decreased bleeding
Missed	Fetal death at <20 weeks without passage of any fetal tissue for 4 weeks after fetal death	Closed	No
Septic	Infection of the uterus during a miscarriage. Most commonly caused by retained products of conception	Open	No, or may be incomplete	Uterine tenderness and purulent discharge from the OS may be present

Clinical Features

• Visualize any clots or bleeding from external os
• Assess internal os as open or closed based on ability to pass finger through os
• Pregnancy ≤ 13 weeks

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

Evaluation

• See Vaginal Bleed Pregnant (less than 20wks)
• Type and Screen/ABO
• Hemoglobin
• Transvaginal or transabdominal ultrasoundultrasound finding:
  • +IUP = threatened abortion
    • Ectopic ruled-out unless on fertility drugs
  • Empty uterus + free fluid/adnexal mass = Ectopic
  • Empty uterus + no free fluid / no mass
    • Beta-HCG:
      • >1,500 = Presumed ectopic
      • <1,500 = Indeterminate: follow serial B-HCG levels in 48hrs (if no peritonitis)
        • Increased >66% = normal IUP
        • Increased <66% = Ectopic

Management

• RhoGam can be considered if Rh Negative
  • Recent 2024 ACOG practice guideline update recommends forgoing routine Rh testing and RhoGam for patients less than 12 weeks
• IVF and/or PRBCs if severe bleeding
• Misoprostol only for < 12 weeks gestation: give 800mcg vaginally, dose can be repeated once within 7 days if no response
  • If available, mifepristone 200mg PO should be given 24 hours prior to first dose of misoprostol (NNT = 6)
  • Supportive care with anti-emetic and NSAIDs for misoprostol side effects
• D&C and OB/gyn consult may be necessary if medical management fails or continuous products/vaginal bleeding > 7-14 days

Disposition

• Discharge Criteria
  • After brief period of observation and if hemodynamically stable
  • Discharge w/ pain medications and close OB follow-up for repeat ultrasound
  • Give strict return precautions (heavy vaginal bleeding, worsening pain, or fever)
• Admission Criteria
  • If hemodynamically unstable, septic, or suspect gestational trophoblastic disease/ectopic pregnancy
  • Urgent OBGYN consult if active hemorrhage and need for Dilation and Curettage

See Also

• Vaginal Bleeding (Main)
• Vaginal bleeding in pregnancy (less than 20wks)

External Links

• Merk Manual: Spontaneous Abortion (Miscarriage)
• emDocs: Bleeding in Early Pregnancy and Threatened Miscarriage