Human Chorionic Gonadotropin (hCG) and Pregnancy Detection

Human Chorionic Gonadotropin (hCG)

Human chorionic gonadotropin (hCG) is a hormone produced by the trophoblast cells that surround a developing embryo during pregnancy. Its primary function is to maintain the corpus luteum, which in turn produces progesterone essential for sustaining the pregnancy. Detection of hCG in maternal blood or urine forms the basis of most pregnancy tests.

hCG Production and Levels

hCG levels begin to rise rapidly after implantation, typically around 6 to 12 days post-conception. Levels continue to increase throughout the first trimester, peaking around 8 to 10 weeks of gestation, before gradually declining. Variations in hCG levels can occur due to individual differences and multiple gestation pregnancies.

Blood Tests for hCG Detection

Quantitative blood tests, also known as serum hCG tests, measure the precise amount of hCG in a blood sample. These tests offer higher sensitivity and accuracy compared to urine-based tests, enabling earlier detection and monitoring of pregnancy. They are often used to:

• Confirm pregnancy at earlier stages.
• Monitor ectopic pregnancies.
• Assess the viability of a pregnancy.
• Detect molar pregnancies.

Qualitative vs. Quantitative hCG Tests

Qualitative blood tests simply determine the presence or absence of hCG, providing a positive or negative result. Quantitative blood tests, on the other hand, provide a numerical value representing the hCG concentration in mIU/mL (milli-international units per milliliter). This numerical value provides additional information to healthcare providers for managing pregnancies.

Limitations and Considerations

While blood tests are highly accurate, false-positive results can occur due to certain medications or conditions. False-negative results can arise from testing too early in pregnancy or due to laboratory error. Interpretation of results should always be done in consultation with a healthcare professional.