Inhibin A in Dehradun

What is a Inhibin A?

Inhibin A is produced by the placenta, and its level in the second trimester forms one of the four markers of the quadruple test, alongside AFP, hCG and unconjugated estriol. Those four are combined with maternal age, weight and accurate gestational age to generate a numerical risk estimate for Down syndrome, Edwards syndrome and neural tube defects. Inhibin A was added to the older triple test specifically because it improved detection, and in pregnancies affected by Down syndrome it tends to run higher than expected. The quadruple test exists mainly for women who present too late for first-trimester combined screening, which requires the nuchal translucency scan between 11 and 13 weeks, and it is performed between about 15 and 20 weeks. Two points are essential and apply to every marker in the panel. This is screening, producing a probability rather than an answer, and a high-risk result is not a diagnosis: most women who screen high-risk have entirely healthy babies. And accurate dating by ultrasound is required, because marker levels change week by week and wrong dates make the risk figure invalid.

Why take this test?

Inhibin A is measured as part of the quadruple test in the second trimester, typically between 15 and 20 weeks, and it is never ordered alone. It is offered principally to women who missed the window for first-trimester combined screening, and sometimes alongside it in sequential screening protocols. Its purpose is to identify pregnancies where the estimated risk is high enough to warrant offering a diagnostic test, either the non-invasive prenatal test which analyses fetal DNA in the mother's blood, or amniocentesis which gives a definitive answer but carries a small procedure risk. Screening is a choice, and it is worth discussing with your obstetrician beforehand what you would want to do with a high-risk result, since that conversation is far more useful before testing than after. Take any result back to your obstetrician rather than interpreting the individual marker values, which mean little outside the calculation.

• Part of the quadruple test between 15 and 20 weeks of pregnancy
• For women who missed first-trimester combined screening
• Interpreted with AFP, hCG, estriol, maternal age and accurate dating
• Identifying pregnancies to offer diagnostic testing
• As part of sequential screening protocols
• Not meaningful as a standalone marker

FAQs: Inhibin A in Dehradun