Vaginal bleeding in pregnancy (less than 20wks)


  • Occurs in 20-40% of 1st trimester pregnancies
  • Once IUP is confirmed by ultrasound no utility in obtaining B-hCG
  • US
    • Do not use hCG to determine whether ultrasound should be obtained

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



  • Uterus able to palpated in abdomen ~ 12 weeks
  • Uterus able to visualzed by abdominal ultrasound ~ 10 weeks
  • Open OS decreases, but does not rule-out, ectopic
  • If find POC send to pathology to rule-out trophoblastic disease
  • Large subchorionic hemorrhage increases chances of a miscarriage

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




  • By ultrasound 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

Discrimatory Zone[1]

Values are for IUP visualization, not ectopic visualization

  • Pelvic Ultrasound: hCG >1500
  • Abd Ultrasound: hCG >3000[2]


  1. RhoGAM if Rh Negative
  2. Assess need for transfusion (severe anemia or hypotension)
  3. Treat specific process:


  • Admit for:
    • Ectopic
    • Life threatening bleeding
    • Surgical abdomen

See Also



  1. Ankum WM, Van der Veen F, Hamerlynck JV, Lammes FB. Suspected ectopic pregnancy. What to do when human chorionic gonadotropin levels are below the discriminatory zone. J Reprod Med. 1995;40:525–8
  2. Wag, R. et al. Use of a !-hCG Discriminatory Zone With Bedside Pelvic Ultrasonography. Annals of Emergency Medicine. 58(1)12-20. PDF


Ross Donaldson