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 if Rh Negative
  • Based off of Level C recommendation from ACOG for threatened abortion (risk of alloimmunization is low, but consequences can be significant). Specifically state it should be considered. Best course of action is to discuss this with your hospital's OB team, most will recommend it.
• 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