You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Which of the following is useful in first trimester screening for Down's syndrome? and explain in detail?
Down&;s syndromeScreeningUSG markersMaternal age - Age >35, the screening test is offered.Biochemical testsUltrasonographyFirst-trimester screening for Down&;s syndromePAPP-A. hCG (biochemical tests)NT (nuchal translucency) (USG)PAPP-A pregnancy-associated plasma protein-decreases in Down&;s syndromeSerum beta hCG - elevated in Down&;s syndromeNuchal translucency increases in aneuploid fetus in first-trimester: 3.5 mm is significant done at 11-14 weeksSensitivity of combined NT thickness and 1st trimesterbiochemical tests are 90%.Second-trimester screening for Down&;s syndromeTriple test and quadruple tests are done in second trimesterat 15-20 weeksTriple test: hCG, AFP, unconjugated estriolQuadruple test: Triple test + inhibinNuchal fold thickeningMild renal pelvis dilatationEchogenic intracardiac focusEchogenic bowelSho femurSho humerus(Refer: Mudaliar and Menon&;s Clinical Obstetrics, 11th edition, pg no: 466)