A Quad Screen is a maternal blood screening test that is similar to the Triple Screen Test (also know as AFP Plus, the Kettering test, the Bart’s test, and Multiple Marker Screening). However, the Quad Screen looks for not only the three specific substances evaluated in those tests (AFP, hCG, and Estriol) but also a fourth substance known as Inhibin-A. It is done mainly to determine the risk of the pregnant mother carrying a child with Down syndrome. Many patients who have had a tubal ligation reversal are older and will opt for this screening test. This blood analysis is usually performed between the 16th and 18th week of pregnancy. This is used to categorize a patient as either high-risk or low-risk. A high-risk mother is then advised to have further testing which will analyze cells from the fetus for the presence of structural chromosomal problems.
What is meant by a positive Quad Screen?
A positive test means having a high risk of chromosomal abnormalities or neural tube defects. The Quad Screen can be implicated as an early precursor with an extensive deal of ensuing scientific improvements to deal the underlying problems. Patients with a positive screening are then further recommenced for more insightful and specific procedures. Most tubal reversal patients will elect to undergo invasive procedures such as an amniocentesis.
Sensitivity adjustments of the Quad Screen:
Although 78% sensitivity and 5% false-positive rate of the test makes it widely available in most countries as a common option to classify risk, the estimated sensitivity of the risk is calculated and attuned on certain factors including:
o the expectant mother’s age
o diabetic condition of the mother
o twins or other multiple gestation
o the gestational age
o weight of the mother
o ethnicity may also be adjusted in markers
These factors influence the markers, and thus interpretation is indicated for the increased risk.
This involves combined first-trimester nuchal translucency and PAPP –A, plus second-trimester Quad Screening, and improves sensitivity to 90%. As most tubal reversal pregnancies occur in older patients, many will opt for the Integrated Screen.
Limitations of the Quad Screen:
1. The test is not for a definite diagnosis
2. The test is only a precursor for more predictive amniocentesis.
3. The age of the mother is indicative for amniocentesis.