AUBF - Chapter 7.4 Flashcards
Which of the following statements about amniotic fluid bilirubin measured by scanning spectrophotometry is true?
A. 410-nm peak is caused by hemoglobin and 450-nm peak is caused by bilirubin
B. Baseline correction is not required because a diode array detector is used
C. Chloroform extraction is necessary only when meconium is present
D. In normal amniotic fluid, bilirubin increases with gestational age
A. 410-nm peak is caused by hemoglobin and 450-nm peak is caused by bilirubin
Which test best correlates with the severity of hemolytic disease of the fetus and newborn (HDFN)?
A. Rh antibody titer of the mother
B. Lecithin/sphingomyelin (L/S) ratio
C. Amniotic fluid bilirubin
D. Urinary estradiol
C. Amniotic fluid bilirubin
Which is the reference method for determining fetal lung maturity (FLM)?
A. Human placental lactogen
B. L/S ratio
C. Amniotic fluid bilirubin
D. Urinary estriol
B. L/S ratio
Which of the following statements regarding the L/S ratio is true?
A. A ratio of 2:1 or greater usually indicates adequate pulmonary surfactant to prevent RDS
B. A ratio of 1.5:1 indicates fetal lung maturity in pregnancies associated with diabetes mellitus
C. Sphingomyelin levels increase during the third trimester, causing the L/S ratio to fall slightly during the last 2 weeks of gestation
D. A phosphatidylglycerol (PG) spot indicates the presence of meconium in the amniotic fluid
A. A ratio of 2:1 or greater usually indicates adequate pulmonary surfactant to prevent RDS
Which of the following conditions is most likely to cause a falsely low L/S ratio?
A. The presence of PG in amniotic fluid
B. Freezing the specimen for one month at –20°C
C. Centrifugation at 1,000 × g for 10 minutes
D. Maternal diabetes mellitus
C. Centrifugation at 1,000 × g for 10 minutes
Which of the following statements accurately describes human chorionic gonadotropin (hCG) levels in pregnancy?
A. Levels of hCG rise throughout pregnancy
B. In ectopic pregnancy, serum hCG doubling time is below expected levels
C. Molar pregnancies are associated with lower levels than expected for the time of gestation
D. hCG returns to nonpregnant levels within 2 days following delivery, stillbirth, or abortion
B. In ectopic pregnancy, serum hCG doubling time is below expected levels
Which of the ff. statements regarding pregnancy testing is true?
A. β-Subunits of hCG, thyroid-stimulating hormone (TSH), and follicle-stimulating hormone (FSH) are identical
B. Antibodies against the β-subunit of hCG cross-react with luteinizing hormone (LH)
C. A false-positive result may occur in patients with heterophile antibodies
D. Serum should not be used for pregnancy tests because proteins interfere
C. A false-positive result may occur in patients with heterophile antibodies
SITUATION: A pregnant woman was seen by her physician, who suspected a molar pregnancy. An hCG test was ordered, and hCG levels were found to be low. The sample was diluted 10-fold and the assay was repeated. The level was found to be grossly elevated. What best explains this situation?
A. The wrong specimen was diluted
B. A pipeting error was made in the first analysis
C. Antigen excess caused a falsely low result in the undiluted sample
D. An inhibitor of the Ag–Ab reaction was present in the sample
C. Antigen excess caused a falsely low result in the undiluted sample
Which assay result is often approximately 25% below the expected level in pregnancies associated with Down syndrome?
A. Serum unconjugated estriol
B. L/S ratio
C. Amniotic fluid bilirubin
D. Urinary chorionic gonadotropin
A. Serum unconjugated estriol
Which of the following statements about alpha fetoprotein (AFP) is correct?
A. Maternal serum may be used to screen for open neural tube defects
B. Levels above 4 ng/mL are considered positive
C. Elevated levels in amniotic fluid are specific for spina bifida
D. AFP levels increase in pregnancies associated with Down syndrome
A. Maternal serum may be used to screen for open neural tube defects
First-trimester screening for Down syndrome can be performed using which markers?
A. AFP and unconjugated estriol
B. Free β hCG and pregnancy-associated plasma protein A
C. Intact hCG and dimeric inhibin A
D. Dimeric inhibin B and AFP
B. Free β hCG and pregnancy-associated plasma protein A
When performing marker screening tests for Down syndrome, why are results expressed in multiples of the median (MoM), rather than in concentration?
A. Concentration is not normally distributed
B. MoM normalizes for gestational age
C. Some tests cannot be reported in mass units
D. Mean cannot be determined accurately for these analytes
B. MoM normalizes for gestational age
Which test for 21 trisomy is not recommended for women who are carrying twins?
A. First trimester triple marker screening
B. Maternal plasma cell free fetal DNA
C. Chorionic villus sampling
D. Second trimester quad marker screening
B. Maternal plasma cell free fetal DNA
Which statement regarding the fetal fibronectin test is true?
A. A positive test is correlated with a low probability of delivery within 14 days
B. The test should not be performed before week 24 or after the end of week 34
C. The test is performed on amniotic fluid
D. The test is used to identify amniotic fluid after rupture of the fetal membranes
B. The test should not be performed before week 24 or after the end of week 34
What is the term for spermatozoa in which the anterior portion of the headpiece is smaller than normal?
A. Azoospermia
B. Microcephaly
C. Acrosomal deficiency
D. Necrozoospermia
C. Acrosomal deficiency
