Diagnosing the Extrauterine Pregnancy-What You Need to Know

CLINICAL ACTIONS:

The goal of diagnosing an ectopic pregnancy is to make the determination before rupture, allowing conservative, medical treatment

Transvaginal Ultrasound (TVU)

If TVU definitively shows ectopic pregnancy (gestational sac with yolk sac and/or embryo in adnexa), or failed intrauterine pregnancy, treat accordingly

• Mass or hypoechoic area separate from the ovary is ‘suspicious’ but not diagnostic
  • PPV is only 80% and may be confused with paratubal cyst, corpus luteum, hydrosalpinx, endometrioma or bowel
• If TVU is not diagnostic, quantitative hCG becomes helpful

Quantitative hCG (qHCG)

‘Discriminatory Level’

• Absence of gestational sac in the uterus above ‘discriminatory level’ has a PPV of 50 to 70%
  • If this concept used, set qHCG level high, e.g. 3,500 mIU/mL
  • Multiple gestation may have higher qHCG levels (>2,000 mIU/mL) before ultrasound evidence of pregnancy is visible

Trending hCG levels

• If TVU is nondiagnostic and fails to show a gestational sac with yolk sac in the uterus (normally visible between 5 and 6 weeks gestation) or the adnexa
  • Measure qHCG and then repeat in 48 hours
  • Repeat again every 2 to 7 days based on level/pattern of qHCG results
  • Higher the initial level, slower the expected rate of increase
    • <1,500 mIU/mL – 49% increase rate
    • 1,500 to 3,000 mIU/mL – 40% increase rate
    • >3,000 mIU/mL – 33% increase rate
  • An increase in qHCG of less than 50% in 48 hours in an early pregnancy is very concerning but cannot determine location, i.e., ectopic vs intrauterine
    • 1% of patients with early viable pregnancies may not meet minimal increase thresholds in 48 hours

NOTE: Obtain blood type and Rh status on all women suspected of ectopic pregnancy and all Rh-negative women with bleeding should receive Rh_O(D) immune globulin (RhoGam), regardless of the final outcome of the pregnancy

SYNOPSIS:

Over 90% of ectopic pregnancies are in the fallopian tube; the remainder can occur in the cervix, ovary, uterine cornua or abdomen. Risk factors for ectopic pregnancies include tubal surgery, PID, previous ectopic pregnancy (10% with one previous ectopic rising to 25% with ≥2), infertility, assisted reproductive technologies with multiple embryo transfer, previous pelvic/abdominal surgery, age >35 years and smoking. IUDs are associated with fewer ectopics compared to women not using contraception because IUDs are such an effective method of birth control. However, if a woman does become pregnant with an IUD, the risk of an ectopic is approximately 50%. Note that at least half of women with ectopic pregnancies have no risk factors.

KEY POINTS:

Have a high index of suspicion for ectopic pregnancy in any premenopausal woman with abnormal uterine bleeding and pain

•  Aside from history and clinical examination, qHCG and TVU are critical for appropriate diagnosis
• If the patient is pregnant, the TVU is equivocal and the patient is clinically stable, follow with serial qHCGs
  • Patient must be able and willing to return for labs and follow-up ultrasounds
• The discriminatory zone, in practice, is still dependent on multiple factors, including the quality of the ultrasound machine, the skill of the sonographer, and the presence/absence of multiple gestations

Role of Endometrial Aspiration

• If TVU or qHCG is not available, or if the clinical picture remains unclear, diagnostic endometrial aspiration to confirm chorionic villi may be necessary
• Patients should be counseled in advance that this will terminate the pregnancy if intrauterine
• Consider level has ‘plateaued’ if decrease is <10% to 15% in the first 12 to 24 hours following aspiration
• ≥50% decrease qHCG level: More likely to be failed intrauterine pregnancy
  • Continue monitoring with serial qHCG measurements
  • Treat if
    • Patient becomes symptomatic
    • qHCG levels plateau or increase
• 15% to <50% decrease in qHCG level: While failed intrauterine pregnancy is possible, risk for ectopic is ‘appreciable’
  • Individualize care
  • Close follow up recommended with serial qHCG levels
  • Consider treatment for ectopic pregnancy based on clinical factors (qHCG levels plateau or increase; patient symptomatic) or high clinical suspicion

Learn More – Primary Sources:

ACOG Practice Bulletin 193: Tubal Ectopic Pregnancy

Related ObG Topics:

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

The ABCs of PID Diagnosis – What You Need to Know

Ectopic Pregnancy: Expectant Management vs. Methotrexate?

Disparities and the Management Patterns Over Time for Ectopic Pregnancy