First trimester abortion

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


  • Estimates are up to 15% of pregnancies end in a 1st trimester abortion, usually due to fetal chromosomal abnormalities

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
  • 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



  • RhoGam if Rh Negative
  • 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 [1]
    • 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


  • Discharge with close OB follow-up for repeat ultrasound
  • Urgent OBGYN consult if active hemorrhage and need for Dilation and Curretage

See Also