The best way of diagnosing Trisomy 21 during second trimester of pregnancy is:
The main use is in diagnosing chromosomal disorders like trisomy 21.Amniotic fluid cells are cultured and karyotyping done,which may take up to 3 weeks (refer pgno:502 sheila textbook of obstetrics 2 nd edition)
Triple marker estimation
Nuchal skin fold thickness measurement
Chorionic villus sampling
Amniocentesis
Diagnosis in obstetrics