Gestational Age Assessment Practice Exam
2026 Practice Questions & Study Guide |
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Question 1
A pregnant patient reports that the first day of her last normal
menstrual period was January 8, 2026. Her menstrual cycles are
regular and approximately 28 days long. Using the standard
obstetric method of calculating the estimated date of delivery,
which date is most appropriate?
A. October 1, 2026
B. October 8, 2026
C. October 15, 2026
D. November 15, 2026
Answer: C. October 15, 2026
Rationale: The estimated date of delivery is traditionally
calculated as 280 days, or 40 weeks, from the first day of the
,last menstrual period. For a January 8, 2026 LMP, adding 280
days gives October 15, 2026. This calculation assumes a regular
28-day menstrual cycle and ovulation around day 14. If cycles
are substantially longer or shorter than 28 days, the calculation
may require adjustment. The calculation is an estimate rather
than a guarantee of the actual delivery date.
Question 2
A patient is uncertain of her last menstrual period. An
ultrasound performed at 8 weeks and 4 days demonstrates a
crown-rump length consistent with 8 weeks and 5 days. Which
statement best describes the significance of this finding?
A. The pregnancy should automatically be redated because
ultrasound is always more accurate than menstrual dating.
B. The ultrasound estimate is highly useful because first-
trimester crown-rump length is among the most accurate
methods of establishing gestational age.
C. The ultrasound should be ignored because menstrual dating
is always preferred.
D. The pregnancy should be dated from the estimated time of
conception rather than gestational age.
,Answer: B. The ultrasound estimate is highly useful because
first-trimester crown-rump length is among the most accurate
methods of establishing gestational age.
Rationale: First-trimester crown-rump length is a highly
accurate biometric measurement for estimating gestational
age. Its accuracy is greatest when obtained early in pregnancy
because fetal growth differences between individual
pregnancies are relatively small at that stage. When the
menstrual history is uncertain or unreliable, a reliable first-
trimester ultrasound can provide an important basis for
establishing or confirming the estimated date of delivery.
Ultrasound does not literally measure conception; obstetric
gestational age is conventionally counted from the first day of
the last menstrual period, approximately two weeks before
conception in a typical cycle.
Question 3
A patient states that her last menstrual period began on March
3, 2026. Assuming a regular 28-day cycle, what is the
approximate gestational age on September 1, 2026?
A. 24 weeks 0 days
B. 25 weeks 0 days
, C. 26 weeks 0 days
D. 27 weeks 0 days
Answer: B. 26 weeks 0 days
Rationale: Gestational age is calculated from the first day of the
LMP rather than from the date of conception. From March 3 to
September 1, 2026, approximately 182 days have elapsed. Since
182 days equals 26 weeks, the gestational age is approximately
26 weeks 0 days. This illustrates why gestational age is
generally about two weeks greater than the actual embryonic
or fetal age when conception occurs near the expected time of
ovulation.
Question 4
Which fetal measurement is generally considered the preferred
ultrasound measurement for dating a pregnancy during the
early first trimester?
A. Abdominal circumference
B. Biparietal diameter
C. Crown-rump length
D. Femur length
Answer: C. Crown-rump length