Laboratory Screening and Diagnostic Testing Flashcards

When is routine Group B Streptococcus (GBS) screening recommended?

Answer: At 36 0/7-37 6/7 weeks

Per ACOG, a rectovaginal culture is done at 36 0/7-37 6/7 weeks. Positive women receive intrapartum antibiotic prophylaxis.

When is Rh immune globulin routinely given to an unsensitized Rh-negative woman?

Answer: At about 28 weeks and within 72 hours after birth of an Rh-positive baby

Standard prophylaxis is at about 28 weeks, plus within 72 hours after delivery if the newborn is Rh-positive. It is also given after bleeding events or invasive procedures.

At what gestational age is the 1-hour 50 g glucose challenge test usually done for gestational diabetes screening?

Answer: 24-28 weeks

Routine screening for gestational diabetes is done at 24-28 weeks, and earlier for women with risk factors.

Anemia in pregnancy in the first and third trimesters is defined as hemoglobin below what level?

Answer: 11 g/dL

The CDC and ACOG define anemia as hemoglobin under 11 g/dL in the first and third trimesters, and under 10.5 g/dL in the second.

An elevated maternal serum alpha-fetoprotein (MSAFP) is most associated with which condition?

Answer: Open neural tube defect

High MSAFP suggests open neural tube defects or abdominal wall defects, and may also reflect incorrect dating or multiples. Low levels are associated with Down syndrome.

Which urine finding on dipstick, combined with elevated blood pressure after 20 weeks, raises concern for preeclampsia?

Answer: Protein

New hypertension with proteinuria after 20 weeks is a hallmark of preeclampsia. Protein of 1+ or greater on a dipstick warrants a quantitative evaluation.