Procedures for Prenatal Diagnosis By Jeffrey S Dungan, MD, Northwestern University, Feinberg School of Medicine Reviewed / Revised Oct 2022 View Patient Education Prenatal Ultrasonography Amniocentesis Chorionic Villus Sampling Percutaneous Umbilical Blood Sampling Preimplantation Genetic Testing (PGT) All procedures used to diagnose genetic disorders, except ultrasonography, are invasive and involve slight fetal risk.