hCG Test

The human chorionic gonadotropin (hCG) hormone is produced by the cells that eventually give rise to the placenta after implantation of the fertilised egg inside the uterus. Small traces of hCG start appearing in the blood around 6 to 10 days after conception and in urine a few days later.

The hCG hormone assists the corpus luteum, enabling it to synthesise progesterone, which is necessary for the maintenance of the uterine lining in the initial stages of pregnancy before the placenta starts producing hormones.

Levels of this hormone remain low in cases other than pregnancy. It may be elevated in some medical conditions or after fertility treatments that use hCG injections.

How Are hCG Levels Measured?

Blood hCG Test

A blood test determines the accurate level of hCG in the bloodstream. This type of test is highly sensitive when compared to a home pregnancy test and is more precise and faster.

Doctors can order one of two types of blood hCG tests:

• Qualitative hCG Test: Determines presence of hCG.
• Beta-hCG Test: Tests the precise concentration of hCG.

Urine hCG Pregnancy Test

The home pregnancy tests determine the level of hCG in the urine. Although simple and convenient, they are less sensitive than blood tests and may fail to determine very early pregnancies.

Serial hCG Testing

Instead of depending on only one result, serial testing is carried out to assess if the hCG levels increase or decrease appropriately.

What Do High hCG Levels Mean?

Higher-than-expected hCG levels may occur for several reasons.

Multiple Pregnancy

Twin or higher-order pregnancies often produce more hCG than singleton pregnancies, although hCG alone cannot confirm twins.

Incorrect Pregnancy Dating

If conception occurred earlier than estimated, hCG levels may appear higher because the pregnancy is further along than expected.

Molar Pregnancy

A molar pregnancy is a rare condition in which abnormal tissue grows inside the uterus instead of a healthy pregnancy. It is often associated with unusually high hCG levels and requires prompt medical treatment.

Other Medical Conditions

Rare tumours, certain cancers, or hormonal conditions may also increase hCG levels. Additional testing is necessary to determine the cause.

What Do Low hCG Levels Mean?

Lower-than-expected hCG levels do not always indicate a problem. They may simply reflect earlier-than-estimated pregnancy.

Early Pregnancy

Testing too soon after implantation may produce lower hCG values that rise normally over the following days.

Ectopic Pregnancy

In an ectopic pregnancy, the fertilised egg implants outside the uterus. hCG levels often rise more slowly than expected. This is a medical emergency requiring immediate evaluation.

Miscarriage

Falling or plateauing hCG levels may suggest pregnancy loss, although ultrasound is needed to confirm the diagnosis.

Incorrect Pregnancy Dating

Late ovulation or delayed implantation can make the pregnancy appear younger than expected, resulting in lower hCG levels.

Symptoms Associated with Abnormal hCG Levels

Abnormal hCG levels alone rarely produce any symptoms; rather, it is the underlying cause that causes visible symptoms.

Vaginal Bleeding

Spotting is common in the early stages of pregnancy, while persistent or heavy bleeding needs medical attention.

Pelvic Pain

Pelvic pain, especially severe and unilateral, may indicate ectopic pregnancy or some other critical problem.

Nausea and Vomiting

High hCG levels may be one of the factors causing severe nausea and vomiting, resulting in hyperemesis gravidarum.

Pregnancy Complications

Abnormal hCG patterns may occasionally be associated with pregnancies that need closer monitoring to check fetal growth and development.