Interpretation
The levels may indicate increased risk for certain conditions:
| AFP | UE3 | hCG | Associated conditions |
| low | low | high | Down Syndrome |
| low | low | low | trisomy 18 (Edward's syndrome) |
| high | n/a | n/a | neural tube defects like spina bifida associated with increase levels of acetylcholinesterase in aminonic fluid, or omphalocele, or gastroschisis, or multiple gestation like twins or triplets |
An estimated risk is calculated and adjusted for the expectant mother's age; if she's diabetic; if she's having twins or other multiples, and the gestational age of the fetus. Weight and ethnicity may also be used in adjustments. Many of these factors affect the levels of the substances being measured and the interpretation of the results.
The test is for screening, not for diagnosis, and does not have nearly the same predictive power of amniocentesis or chorionic villus sampling. The screening test carries a much lower risk to the fetus, however, and in conjunction with the age-related risk of the patient it is useful to help determine the need for more invasive tests.
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