ACOG Practice Bulletin 226 Questions with
Complete Solutions
What percentage of pregnancies affected with Down syndrome occur in women 35 or older at
the time of delivery? Approximately 22% (21.6%)
What is nondisjunction? Nondisjunction is the failure of homologous chromosomes or
sister chromatids to separate subsequent to metaphase in meiosis or mitosis so that one
daughter cell has both and the other neither of the chromosomes.
When a positive or abnormal screening test result occurs the patient should be counseled
regarding the adjusted likelihood or probability of carrying a fetus with the aneuploidy the
pregnancy is at an increased chance for. True
When a negative screening test result is obtained (low risk), the patient should simply be told
that they are at a low chance to have a fetus affected with a chromosome abnormality.
False. It is recommended that patient's with both high and low risk results be given the
probability for aneuploidy if it can be estimated.
,Name one thing that should be discussed regarding the limitations of aneuploidy screening.
The potential for the fetus to be affected by a genetic disorder or abnormality that is not
evaluated by the screening or diagnostic tests being offered.
Name three topics you should discuss with a patient who learns that their pregnancy is affected
with a chromosome abnormality In the event that a prenatal diagnosis of fetal
aneuploidy is made, the patient must be counseled appropriately so that she can make
informed decisions regarding pregnancy management. Counseling should include:
1. Adoption
2. Pregnancy termination
3. Referral to a tertiary care center for delivery of the newborn if needed
4. Perinatal hospice care as appropriate for a child with a condition that is incompatible with life
5. Patients found to have a fetus with a chromosomal abnormality often benefit from referral to
a genetics professional for further detailed counseling.
Name three markers that are evaluated in first trimester screening for aneuploidy. This
screening typically is performed when the crown-rump length measures between 38-45 mm
and 84 mm (generally between 10 0/7 weeks and 13 6/7 weeks of gestation) First-
trimester screening includes:
, 1. Nuchal translucency measurement
2. Free β-hCG or total human chorionic gonadotropin (hCG)
3. Pregnancy-associated plasma protein A analyte levels PAPP A
What maternal factors are used in calculating the chance for a pregnancy to be affected with
aneuploidy with analyte screening. 1. Maternal age
2. Weight
3. Race
4. Number of fetuses.
There are two methods of classifying nuchal translucency as thickened, what are they? A
nuchal translucency is considered thickened
1. If it measures 3.0 mm - 3.5 mm or more (cutoff is chosen by MFM unit)
2. If it measures in the 99th percentile for the crown-rump length
Complete Solutions
What percentage of pregnancies affected with Down syndrome occur in women 35 or older at
the time of delivery? Approximately 22% (21.6%)
What is nondisjunction? Nondisjunction is the failure of homologous chromosomes or
sister chromatids to separate subsequent to metaphase in meiosis or mitosis so that one
daughter cell has both and the other neither of the chromosomes.
When a positive or abnormal screening test result occurs the patient should be counseled
regarding the adjusted likelihood or probability of carrying a fetus with the aneuploidy the
pregnancy is at an increased chance for. True
When a negative screening test result is obtained (low risk), the patient should simply be told
that they are at a low chance to have a fetus affected with a chromosome abnormality.
False. It is recommended that patient's with both high and low risk results be given the
probability for aneuploidy if it can be estimated.
,Name one thing that should be discussed regarding the limitations of aneuploidy screening.
The potential for the fetus to be affected by a genetic disorder or abnormality that is not
evaluated by the screening or diagnostic tests being offered.
Name three topics you should discuss with a patient who learns that their pregnancy is affected
with a chromosome abnormality In the event that a prenatal diagnosis of fetal
aneuploidy is made, the patient must be counseled appropriately so that she can make
informed decisions regarding pregnancy management. Counseling should include:
1. Adoption
2. Pregnancy termination
3. Referral to a tertiary care center for delivery of the newborn if needed
4. Perinatal hospice care as appropriate for a child with a condition that is incompatible with life
5. Patients found to have a fetus with a chromosomal abnormality often benefit from referral to
a genetics professional for further detailed counseling.
Name three markers that are evaluated in first trimester screening for aneuploidy. This
screening typically is performed when the crown-rump length measures between 38-45 mm
and 84 mm (generally between 10 0/7 weeks and 13 6/7 weeks of gestation) First-
trimester screening includes:
, 1. Nuchal translucency measurement
2. Free β-hCG or total human chorionic gonadotropin (hCG)
3. Pregnancy-associated plasma protein A analyte levels PAPP A
What maternal factors are used in calculating the chance for a pregnancy to be affected with
aneuploidy with analyte screening. 1. Maternal age
2. Weight
3. Race
4. Number of fetuses.
There are two methods of classifying nuchal translucency as thickened, what are they? A
nuchal translucency is considered thickened
1. If it measures 3.0 mm - 3.5 mm or more (cutoff is chosen by MFM unit)
2. If it measures in the 99th percentile for the crown-rump length
