Extrauterine Pregnancy: Test and Diagnosis

1st order laboratory parameters – obligatory laboratory tests.

  • Human chorionic gonadotropin (ß-HCG)1,2 specific for the detection of trophoblastic tissue (cell layer that forms the outer boundary of the blastocyst (embryo in the early stages of development) of an intrauterine (“located in the uterus“) or an extrauterine (“located outside the uterus”) pregnancy (EUG); normally, a continuous increase in ß-HCG occurs during the first weeks of pregnancy (SSW). The peak value is reached in the 10th-12th SSW and remains stable until the 16th SSW. Thereafter, it slowly decreases. An important diagnostic criterion is the HCG doubling/48 h (so-called doubling time) in the first seven weeks of pregnancy. Note: The minimum increase in a vital pregnancy within this period is 35%.In extrauterine pregnancy (EUG; also in disturbed intrauterine early pregnancy), the increase is usually lower, reaches a plateau and then may even fall; ß-HCG must be routinely monitored in all therapeutic procedures of EUG until the value falls below the detection limit.If the diagnosis can not be initially confirmed, a new analysis must be performed after 2 days and then every 2 to 7 days.
  • Progesterone2 (if the progesterone level is below 20 ng/ml, this supports the suspicion of EUG or a non-intact intrauterine pregnancy/pregnancy in the uterine cavity).

1A normal increase in ß-HCG is indicative of a normal pregnancy, but does not rule out EUG! In about 20% of cases of extrauterine pregnancy, an HCG course is observed that resembles a vital intrauterine (” inside the uterine cavity”) pregnancy. In 10% of cases, the course is similar to that of an early miscarriage. 2The combination of the two parameters – together with vaginal ultrasonography – and the course of the ß-HCG level lead to confirmation of the diagnosis.

Note: A cut-off value of the HCG level, above which the typical signs of an intrauterine pregnancy (pregnancy within the uterus) must be visible sonographically, is suggested to be 3,500 mIU/ml. This high value is intended to help avoid misdiagnosis and curettage (scraping) in intrauterine pregnancy.

HCG rise for diagnosis of EUG or disturbed early pregnancy (early pregnancy).

Baseline HCG level(mIU/ml) Expected increase after 48 hours in intact intrauterine pregnancy
< 1500 > 49
1500-3000 > 40
3000 > 33

Interpretation