Following a positive β-hCG test, the location of the pregnancy should be confirmed via transvaginal ultrasound (TVUS). However, TVUS may not reliably detect an intrauterine pregnancy before 5 weeks' gestation or before serum β-hCG is > 1500–2000 mIU/mL. Therefore, in patients with β-hCG < 1000 mIU/mL, as seen here, TVUS should be scheduled 2–3 days after the initial test. Repeated measurement of β-hCG is also indicated to confirm an appropriate rise in concentration (i.e., doubling of β-hCG approx. every 2.5 days within the first 4 weeks of pregnancy). A slow rise in β-hCG can indicate an ectopic pregnancy or abortion, whereas a rapid rise in the value may indicate a β-hCG-secreting tumor (e.g., hydatidiform mole, choriocarcinoma) or twin pregnancy.
A history of pelvic inflammatory disease increases the risk for extrauterine pregnancy.
Source: AMBOSS - https://next.amboss.com/us/review/hhXV0cdBGU/36