The Beta-HCG and Ectopic Pregnancy. Myth-Busting.
Question: Can we use the serum HCG to rule out ectopic pregnancy?
The below is from an AJEM November 2024 Review Article on ectopic pregnancies
Traditional teaching is that unless the β-hCG level is beyond the discriminatory zone (1,500-4,000 mIU/mL depending on the institution), you may not be able to see evidence of an intrauterine pregnancy. The pitfall here is that this discriminatory zone is actually ONLY applicable for a developing, healthy IUP and cannot be applied to ectopic pregnancies.
The discriminatory zone cannot be used as a threshold value for ultrasound ordering in patients who need an ectopic rule-out.
The decision to ultrasound a pregnant patient with abdominal pain and/or vaginal bleeding should NOT be based on the β-hCG level. However, it can be useful to help interpret ultrasound findings and make disposition decisions based on this level.
In a recently published retrospective study, more than half of patients with proven ectopic presented with β-hCG levels less than 1,500 mIU/mL, and almost half of the ruptures also had β-hCG levels below this level.
Listen to an EMA Review of this study
There have been cases of ectopic pregnancies (even ruptured ones) in patients with β-hCG < 100 mIU/mL.!!!
**Pregnant + No definitive IUP documented in their history who presents with abdominal pain or vaginal bleeding gets an ultrasound. Remember...we as ED providers can do this scan at bedside in 1 min and show there is an IUP. If it's indeterminant or no IUP, then send to radiology.**
All patients with a positive pregnancy test and symptoms such as vaginal bleeding, cramping, abdominal or pelvic pain, or concerns of ectopic pregnancy need to undergo an ultrasound to verify pregnancy location and assess for viability, no matter the hCG level. This is in accordance with recommendations from the American College of Obstetrics and Gynecology (ACOG)
Remember 1.5%-2% of pregnancies in the US will be ectopic pregnancies. However, 15-20% of patients who present to the ED with vaginal bleeding and abdominal pain with a positive pregnancy test will ultimately be diagnosed with an ectopic pregnancy. Remember, the impact of ectopic pregnancy on people of color is disproportionate!
No pattern of signs of symptoms on presentation can definitively exclude ectopic pregnancy or rupture. Get the US.
Resources Cited
Eisaman DM, Brown NE, Geyer S. Relationship of Beta-Human Chorionic Gonadotropin to Ectopic Pregnancy Detection and Size. West J Emerg Med. 2024;25(3):431-435. [pubmed]
Jeffers, K., Koyfman, A., & Long, B. (2024). Updates in emergency medicine: Ectopic pregnancy. The American journal of emergency medicine, 85, 90–97. [pubmed]
American College of Obstetricians and Gynecologists' Committee on Practice Bulletins—Gynecology (2018). ACOG Practice Bulletin No. 193: Tubal Ectopic Pregnancy. Obstetrics and gynecology, 131(3), e91–e103.[pubmed]
Cheers,
Dillon
