Prenatal diagnostics

A couple faces a difficult decision when a nuchal translucency test returns a high result for chromosomal abnormality

Jane, a 35-year-old primigravida, presented at 7 weeks, 5 days' gestation.

She had no significant medical/surgical past history and a regular, 28-day menstrual cycle.

She was not on any medications, and had no known allergies. Routine antenatal investigations were unremarkable.

A transvaginal ultrasound demonstrated the fetus to have a crown-rump length 7.7mm, equivalent to 6 weeks, 6 days.

Fetal heart rate was normal.

Investigations and results
Prenatal diagnostic tests were discussed, and Jane elected to have a nuchal translucency test (see box: NT-Plus below).

Serology demonstrated the pregnancy-associated plasma protein (PAPP-A) to be 0.04 MoM (very low).