However, the maternal age, weight, ethnicity etc. Double test įree beta hCG and PAPP-A are measured. Furthermore, the triple test may be combined with an ultrasound measurement of nuchal translucency. A quad test tests an additional hormone, inhibin. If only two of the hormones above are tested for, then the test is called a double test. 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. The test is for screening, not for diagnosis, and does not have nearly the same predictive power of amniocentesis or chorionic villus sampling. Incorrect estimation of gestational age is the most common cause of abnormal MSAFP levels.Having multiple gestations, such as twins, increases MSAFP because each fetus secretes its own AFP.Women with insulin-dependent diabetes mellitus have MSAFP levels that are 20% lower than the rest of the population.African-American women have MSAFP levels that are 10-15% higher than those of Caucasian women for unknown reasons.As maternal weight increases, MSAFP level decreases.Many of these factors affect the levels of the substances being measured and the interpretation of the results: Weight and ethnicity may also be used in adjustments. Neural tube defects (like spina bifida that may have associated increased levels of acetylcholinesterase in the amnionic fluid), omphalocele, gastroschisis, multiple gestation (like twins or triplets), or an underestimation of gestational age.Īn 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. The levels may indicate increased risk for certain conditions or may be benign: The triple test measures the following three levels in the maternal serum: In addition to Down syndrome, the triple and quadruple screens assess risk for fetal trisomy 18 also known as Edward's syndrome, open neural tube defects, and may also detect an increased risk of Turner syndrome, triploidy, trisomy 16 mosaicism, fetal death, Smith–Lemli–Opitz syndrome, and steroid sulfatase deficiency. The most common abnormality the test can screen is trisomy 21 ( Down syndrome). While the triple test can be performed at any point between 15 and 21.9 weeks of gestation, the highest detection rate for open neural defects is given by a test performed between 16 and 18 weeks of gestation. In some American states, such as Missouri, Medicaid reimburses only for the Triple test and not other potentially more accurate screening tests, whereas California offers Quad tests to all pregnant women. The Triple test can be understood as an early predecessor to a long line of subsequent technological improvements. A positive screen indicates an increased risk of chromosomal abnormalities (and neural tube defects), and such patients are then referred for more sensitive and specific procedures to receive a definitive diagnosis, often prenatal diagnosis via amniocentesis, although the stronger screening option of cell-free fetal DNA screening (also popularly known as noninvasive prenatal screening) is frequently offered. It is complemented in some regions of the United States, as the Quad screen (adding inhibin A to the panel, resulting in an 81% sensitivity and 5% false-positive rate for detecting Down syndrome when taken at 15–18 weeks of gestational age) and other prenatal diagnosis techniques, although it remains widely used in Canada and other countries. The Triple screen measures serum levels of AFP, estriol, and beta-hCG, with a 70% sensitivity and 5% false-positive rate. This term can encompass the 'double test' and 'quadruple test' (described below). The term 'multiple-marker screening test' is sometimes used instead. The triple test, also called triple screen, the Kettering test or the Bart's test, is an investigation performed during pregnancy in the second trimester to classify a patient as either high-risk or low-risk for chromosomal abnormalities (and neural tube defects).

Investigation performed during pregnancy in the 2nd trimester to check chromosomal abnormalities Triple test

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