INDEX

    1st Trimester Bleeding: Ectopic Pregnancy – Diagnosis

    Obstetrics and Gynecology

    Last Updated Oct 16, 2020
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    Context

    • 2% of all pregnancies.
    • Occurs in up to 18% of ED 1st trimester patients presenting with bleeding +/- abd pain.
    • 9% of all pregnancy-related deaths and leading cause of maternal death in the 1st  trimester.
    • Abdominal pain and/or bleeding in the 1st trimester = ectopic pregnancy (EP) until proven otherwise.
    • 30% of patients presenting with bleeding and/or pain in the 1st trimester will have a pregnancy of unknown location (PUL).
    • PUL includes:
      • EP.
      • IUP – spontaneous abortion.
      • IUP – normal developing pregnancy.
    • An approach to a “rule-out” ectopic includes:
      • Localization of pregnancy on US.
      • If PUL, risk stratification with serial β-hCG and TVUS until a diagnosis of IUP or EP.
      • Balancing the risk of ruptured ectopic and the risk of ending a viable, desired pregnancy.

    Diagnostic Process

    • Classic triad: Pain (98%), amenorrhea (74%), and vaginal bleeding (56%).
    • Ruptured ectopic:
      • Hemodynamic instability.
      • Peritoneal signs (rebound tenderness, cervical motion tenderness).
    • May have normal vital signs and minimal tenderness.
    • Localize the pregnancy with transabdominal U/S, then transvaginal U/S if necessary.
    • IUP visualization on ED POCUS effectively rules out an ectopic.
    • Heterotopic pregnancies are rare, but considered with assisted reproductive technologies, as probability is higher (around 1%).

    Barash et al. (2014), AAFP2

     

    Criteria for localization of pregnancy on US:

    • If PUL, risk stratify using β-hCG:
      • A discriminatory thresholds of β-hCG indicates when IUP usually can be seen on US but the utility of this threshold has been challenged. Most recent recommended thresholds are:
        • Transvaginal US: β-hCG > 2000 – 3000 IU/L (especially before 7 weeks GA) OR the more conservative β-hCG > 3,500 IU/L suggested by American guidelines.
        • Bedside abdominal US: β-hCG > 6,500 IU/L
      • A β-hCG above the threshold and no IUP significantly increases the risk of ectopic.
      • An EP can rupture at any β-hCG level.
      • All symptomatic pregnant women presenting in the 1st trimester should have an US, irrespective of β-hCG.
    • If PUL, arrange an OB/GYN follow up and repeat β-hCG +/- TVUS in 48 hours.
      • β-hCG should rise > 55% over 48 hours in the first 7 weeks.
      • Failure to rise (falling or plateauing β-hCG) is indicative of a failing pregnancy (IUP or ectopic).
    • Subsequent β-hCG measurements and TVUS should be obtained 2–7 days apart, depending on the pattern of change.
    • The risk of rupture if there are no US findings of EP and no symptoms of rupture during diagnostic process is very low (0.03%). Therefore, there is limited risk in taking a few extra days to make a definitive diagnosis.

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    Barash et al. (2014), AAFP

     

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    Barash et al. (2014), AAFP

    Common Pitfalls

    1. Relying on the classic triad of abdominal pain, vaginal bleeding, and missed menses to consider an ectopic.
    2. Not considering a heterotopic pregnancy in a high-risk population when there is an IUP.
    3. Not considering a ruptured ectopic pregnancy when a patient has already taken methotrexate.
    4. Assuming an ectopic is ruled out with a low β-hCG.
    5. Confusing a “double sac sign” in the uterus as an IUP, when it could be a pseudogestational sac or intrauterine cyst.
    6. Assuming no products of conception on U/S signifies a completed spontaneous abortion, rather than an ectopic.
    7. Failure to arrange adequate follow up if no IUP is seen and the U/S is indeterminate.

    Resources

    Quality Of Evidence?

    Justification

    All symptomatic pregnant women in the 1st trimester should receive a pelvic U/S, irrespective of β-hCG level.

    High

    Utility of a β-hCG discriminatory thresholds at 2000-3000 IU/L.

    Moderate

    Related Information

    Reference List

    Relevant Resources

    RELEVANT CLINICAL RESOURCES

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    RELEVANT VIDEO

    Ectopic Pregnancy Scan

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