Friday Board Review

Board Review by Alex Hilbmann

Vital signs:

T: 37⁰C HR: 71 bpm O2 Sat: 100% BP: 112/92

A 29 year old female reports to the emergency department for abnormal scant vaginal bleeding. Initially, she believed that the bleeding was an early menstrual period but it has now persisted longer than her usual menses with less volume. She denies any other complaints, including pelvic pain, fevers, or vaginal discharge. Patient has attended OB/GYN appointments yearly and denies any previous history of sexually transmitted infections or abnormal pap smears. Pelvic exam reveals scant bleeding from the cervical os with no adnexal or cervical tenderness. No masses are appreciated upon palpation of bilateral adnexa. Transvaginal ultrasound reveals no intrauterine pregnancy or adnexal abnormalities. Point of care urine pregnancy test is positive. Quantitative beta-hcg results at 542 miU/mL. Vital Signs listed above. What is the next best step in management of this patient?

  1. Consultation to OB/GYN for concern of ectopic pregnancy
  2. Official transvaginal ultrasound read by Radiology
  3. Administration of methotrexate and discharge home
  4. Discharge home with 2 day OB/GYN follow up

Answer: D.

Our patient is currently experiencing scant vaginal bleeding with no findings on transvaginal ultrasound, a positive pregnancy test, and a beta hcg below 1500 miU/mL.  1500 miU/mL is what is known as the “discriminatory zone” for transvaginal ultrasound (6,000 miU/mL for transabdominal). This discriminatory zone is a level of beta-hcg which an intrauterine pregnancy (IUP) would be expected to be seen on ultrasound. When beta-hcg is above the discriminatory zone, and therefore an IUP should be visible on ultrasound, the absence of an IUP on ultrasound suggests ectopic pregnancy until proven otherwise. With this patient however, we are below the discriminatory zone and therefore the absence of IUP (with no other findings suggesting ectopic pregnancy) does not make ectopic pregnancy a more likely diagnosis than pregnancy with implantation bleeding at this time. The beta hcg of an IUP should double by two days, whereas an ectopic pregnancy would decrease less than twofold. This can be assessed by the patient’s OB/GYN at her follow up, and given the patient’s stable condition she can be discharged home.

Tintinalli, J., Ma, O., Yealy, D., Meckler, G., Cline, D., Thomas, S. and Stapczynski, J., 2020. Tintinalli’s emergency medicine. 9th ed. [New York]: McGraw-Hill Education, pp.615-620.


Fadial, T., 2018. Differential Diagnosis of Ultrasound in Ectopic Pregnancy. [online] Differential Diagnosis of. Available at: <> [Accessed 2 October 2022].

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