From the Guidelines
Yes, there is evidence supporting the use of a discriminatory beta-human chorionic gonadotropin (bHCG) level in managing patients with pregnancy of unknown location (PUL) for safe ED discharge, with a commonly used threshold of 1,500-2,000 mIU/mL. This approach is based on the understanding that below this level, an intrauterine pregnancy may not yet be visible on transvaginal ultrasound 1. Patients with PUL who are hemodynamically stable, have no signs of ruptured ectopic pregnancy (such as severe pain or free fluid on ultrasound), and have bHCG levels below the discriminatory zone can generally be safely discharged with close follow-up in 48-72 hours.
Key Considerations for Discharge
- Hemodynamic stability
- No signs of ruptured ectopic pregnancy
- bHCG levels below the discriminatory zone
- Close follow-up in 48-72 hours
- Repeat bHCG measurement to assess for appropriate rise (normally 53-66% increase over 48 hours in viable intrauterine pregnancies)
- Repeat ultrasound as needed
- Clear return precautions including worsening pain, dizziness, vaginal bleeding, or other concerning symptoms
The discriminatory zone approach works because ectopic pregnancies typically show abnormal bHCG patterns and rarely exceed these levels without being visualized, while normal pregnancies show predictable hormone increases 1. However, clinical judgment remains essential as some ectopic pregnancies can present with normal bHCG trends, and patient symptoms should always take precedence over laboratory values alone. The study by Condous et al 1 provides evidence on the utility of different discriminatory thresholds for predicting ectopic pregnancy, highlighting the importance of considering bHCG levels in the management of PUL.
From the Research
Discriminatory bHCG Level in Pregnancy of Unknown Location
- The use of a discriminatory bHCG level in the setting of pregnancy of unknown location is a topic of discussion in several studies 2, 3, 4, 5, 6.
- A discriminatory zone is defined as the value of serum hCG above which an intrauterine gestational sac should be visible on ultrasound 3.
- Studies suggest that expectant management is a safe and effective approach for most women with pregnancy of unknown location, and serum beta human chorionic gonadotropin (β-hCG) levels can be used to determine the outcome of the pregnancy 2, 4.
- However, there is no consensus on a specific discriminatory bHCG level for determining the safety of discharge from the ED to follow up closely 5.
- A survey-based evaluation found that physicians' behaviors varied when faced with pregnancy of unknown location, with different hCG thresholds for intervention, ranging from 1000-3000 IU to above 10,000 IU 5.
- It is essential to consider other factors, such as the patient's desire to keep the pregnancy, development of new symptoms, and expected gestational age, when deciding on intervention 5.
- Caution should be used when using medical treatment for abnormal pregnancies, as overuse can lead to interruption of normal pregnancies 6.