To analyze for fetal chromosomal and biochemical abnormalities, such as Tay-Sachs disease, sickle cell disease, anemia, cystic fibrosis, and Down syndrome

Explain to the patient that samples are obtained routinely at about 10 to 12 weeks’ gestation.

Tell her that the test involves a vaginal examination and ultrasound.

Obtain informed consent.

Assist the patient into the lithotomy position.

The physician checks placement of the patient’s uterus bimanually and then inserts a Graves speculum and swabs the cervix with an antiseptic solution.

If necessary, a tenaculum is used to straighten an acutely flexed uterus, permitting cannula insertion.