Human chorionic gonadotrophin (HCG) measurements in women with pregnancy of unknown location

Last edited 09/2023 and last reviewed 09/2023

Human chorionic gonadotrophin measurements in women with pregnancy of unknown location

• women with a pregnancy of unknown location could have an ectopic pregnancy until the location is determined
• do not use serum hCG measurements to determine the location of the pregnancy
• serum hCG measurements should only be used for assessing trophoblastic proliferation to help to determine subsequent management
• to determine subsequent management of a pregnancy of unknown location
  • take 2 serum hCG measurements as near as possible to 48 hours apart (but no earlier). Take further measurements only after review by a senior healthcare professional
    
    
    • for a woman with an increase in serum hCG concentration greater than 63% after 48 hours:
      • inform her that she is likely to have a developing intrauterine pregnancy (although the possibility of an ectopic pregnancy cannot be excluded)
      • offer her a transvaginal ultrasound scan to determine the location of the pregnancy between 7 and 14 days later. Consider an earlier scan for women with a serum hCG level greater than or equal to 1500 IU/litre
        • If a viable intrauterine pregnancy is confirmed, offer her routine antenatal care
        • If a viable intrauterine pregnancy is not confirmed, refer her for immediate clinical review by a senior gynaecologist
          
          
    • for a woman with a decrease in serum hCG concentration greater than 50% after 48 hours:
      • inform her that the pregnancy is unlikely to continue but that this is not confirmed and
      • provide her with oral and written information about where she can access support and counselling services and
      • ask her to take a urine pregnancy test 14 days after the second serum hCG test, and explain that:
        • if the test is negative, no further action is necessary
        • if the test is positive, she should return to the early pregnancy assessment service for clinical review within 24 hours
          
          
    • for a woman with a decrease in serum hCG levels less than 50%, or an increase less than 63%, refer her for clinical review in the early pregnancy assessment service within 24 hours

For women with a pregnancy of unknown location, when using serial serum hCG measurements, do not use serum progesterone measurements as an adjunct to diagnose either viable intrauterine pregnancy or ectopic pregnancy.

Reference:

• 1) NICE (September 2023).Ectopic pregnancy and miscarriage: diagnosis and initial management