Diagnosing Ectopic (Tubal) Pregnancy With hCG Levels

Pregnant Woman In Consultation with Doctor, Abdominal Exam
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An ectopic pregnancy occurs when a fertilized egg implants somewhere outside the uterus (the womb). The term tubal pregnancy is also sometimes used, as ectopic pregnancies implant in one of the fallopian tubes about 95% of the time.

While it is also referred to as a tubal pregnancy, an ectopic pregnancy can implant on the cervix, ovary, or elsewhere in the abdomen. 

An ectopic pregnancy cannot survive (is nonviable). If it's not treated, a fallopian tube could rupture and cause severe, potentially life-threatening blood loss. Due to these risks, ectopic pregnancies must be terminated. 

Low or Slow-Rising hCG Levels

When you're pregnant, your body releases a hormone called human chorionic gonadotropin (hCG). A low or slow-rising hCG level can be a sign of an ectopic pregnancy, but looking at hCG levels alone is not usually enough for a doctor to make the diagnosis.

While a slow-rising or low hCG level can indicate an ectopic pregnancy, it does not mean that you are definitely experiencing one. There are other reasons for slow-rising hCG levels.

  • You're not very far along in your pregnancy. If you have only had one low hCG level, you might just be very early in your pregnancy. Predicting whether a pregnancy is ectopic is easier when doctors can compare at least two hCG measurements taken over two or three days. This allows them to see if the hCG level is rising and if so, how quickly.
  • You're further along in your pregnancy. hCG levels tend to rise more slowly toward the middle and end of the first trimester. If you've had at least two hCG levels done and the hormone is not doubling every two to three days, these levels still might be considered normal if it is because you are further along in your pregnancy.
  • You're miscarrying. Your hCG level will stop rising and start dropping if you are having a miscarriage. If you experience vaginal bleeding or abdominal cramping, or if you notice the loss of pregnancy symptoms (such as breast tenderness, fatigue, and morning sickness), it's possible that you are having a miscarriage rather than an ectopic pregnancy.

Diagnosing Ectopic Pregnancies

If your doctor thinks you are having an ectopic pregnancy, they will usually perform an ultrasound (sonogram). The imaging test uses high-frequency sound waves to see inside your uterus. If no gestational sac appears inside the uterus by around week five of gestation, it's a red flag that could signal an ectopic pregnancy. 

Your doctor might also need to do a pelvic exam to feel for a mass in the fallopian tube and to see if you have any pain or tenderness in your pelvic organs.

If you are diagnosed with an ectopic pregnancy, your doctor can use an injectable drug or minimally invasive surgery to terminate the pregnancy. If you are concerned about your future fertility, know that it is possible to have ​viable pregnancies after an ectopic pregnancy.

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  1. Parker VL, Srinivas M. Non-tubal ectopic pregnancy. Arch Gynecol Obstet. 2016;294(1):19-27. doi:10.1007/s00404-016-4069-y.

  2. Panelli DM, Phillips CH, Brady PC. Incidence, diagnosis and management of tubal and nontubal ectopic pregnancies: a review. Fertil Res Pract. 2015;1:15. doi:10.1186/s40738-015-0008-z.

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