SUMMARY:

Pregnancy of unknown location is defined as a pregnancy where intrauterine or ectopic location cannot be confirmed.

If the location cannot be definitively determined

• Pregnancy of unknown location requires follow up and a diagnosis
• If patient is clinically stable and pregnancy is desired
  • Repeat transvaginal ultrasound and/or serial measurement of hCG

Uterine Aspiration to Determine Pregnancy Location

Perform uterine aspiration if pregnancy is not progressing normally (see ‘Related ObG Topics’ below)

• Chorionic villi present
  • Indicates failed uterine pregnancy
  • No further follow-up needed
• Chorionic villi absent
  • Monitor hCG levels 12 to 24 hours after aspiration
  • hCG plateau (decrease <10% to 15%) indicates the following possible scenarios
    • Uterine evacuation incomplete
    • Ectopic pregnancy, but not seen on ultrasound
  • hCG decrease ≥50%
    • Monitor with serial hCG measurements
    • Treat if patient becomes symptomatic or levels plateau or increase
  • hCG decrease between 15% and 50%
    • Individualize treatment
    • Follow-up with serial hCG measurements
    • Treat if (1) patient becomes symptomatic, (2) levels plateau or increase, (3) there is clinical suspicion or (4) strong risk factors for ectopic pregnancy are present

Determination of Pregnancy Location Prior to Methotrexate (MTX) Use

• Arguments against determining location prior to MTX
  • Delay in MTX treatment may result in a potentially preventable tubal rupture
• Arguments for determining location prior to MTX
  • Limits MTX exposure to those patients who actually need it
  • Confirmation/knowledge of true location may impact management of current and future pregnancies
  • Risk of rupture appears to be low if patient is closely monitored

KEY POINTS:

• Choice of uterine aspiration should be based on shared decision making
  • Discuss risk of MTX and birth defects if location not confirmed and intrauterine pregnancy continues
• Consider MTX if following met
  • Confirmed or high clinical suspicion of ectopic pregnancy
  • Hemodynamically stable
  • Unruptured mass
  • No absolute contraindications to MTX
• Absolute MTX Contraindications include
  • Intrauterine Pregnancy | Breastfeeding | Immunodeficiency | Blood Dyscrasias | Clinically Important Hepatic Dusfunction | Active Pulmonary Disease | Active Peptic Ulcer Disease | Clinically Important Renal Dysfunction | Patient sensitive to MTX | Inability to Participate in Follow-up
• Relative MTX Contraindications
  • Gestational Sac > 4 cm (TV ultrasound) | High Quantitative HCG (qHCG) | Positive FH | Refusal to Accept Blood Transfusion

Learn More – Primary Sources:

ACOG Practice Bulletin 193: Tubal Ectopic Pregnancy

Related ObG Topics:

Diagnosing the Extrauterine Pregnancy-What You Need to Know

You’ve Diagnosed the Ectopic Pregnancy – When and How to Use the Medical Option

Ectopic Pregnancy: Expectant Management vs. Methotrexate?

Ectopic Pregnancy Methotrexate Protocol: Single-Dose or 2-Dose?