The most recommended diagnostic test in the 16th week of pregnancy is amniocentesis. This is an invasive prenatal technique that is performed by puncturing the mother's abdominal wall to extract amniotic fluid. This fluid is analyzed in the laboratory to obtain the baby's karyotype.
The purpose of this technique is to detect chromosomal abnormalities in the baby. However, less amniocentesis is being performed nowadays due to the emergence of other less dangerous prenatal tests.