Uterine Fundal Height at Symphysis Pubis
The uterus is palpable at the symphysis pubis at 12 weeks gestation (Answer B).
Clinical Landmark for Gestational Age Estimation
The American Heart Association guidelines provide clear rule-of-thumb landmarks for estimating gestational age based on fundal height 1:
- 12 weeks: The uterus becomes palpable above the pubic symphysis
- 20 weeks: The uterus reaches the level of the umbilicus
- 36 weeks: The uterus reaches the level of the xiphisternum
Bimanual Examination Findings
Physical examination findings corroborate this timeline 1:
- At 10-12 weeks gestation, the uterus is approximately the size of a grapefruit and begins protruding from the pelvis
- The uterus starts becoming larger and softer between 8-10 weeks, but is not yet consistently palpable abdominally at the symphysis pubis
- Before 12 weeks, the uterus remains a pelvic organ and requires bimanual examination for assessment
Important Clinical Caveats
Several factors can affect the accuracy of fundal height assessment 1:
- Body habitus: Abdominal distention and increased body mass index significantly reduce the reliability of fundal height as a predictor of gestational age
- Multiple gestations: Fundal height measurements are less reliable
- Fetal position: The fundus can be a poor predictor when the fetus is not in a longitudinal lie
The symphysis-fundal height measurement becomes more reliable between 16-36 weeks gestation, when the height in centimeters approximately corresponds to gestational age in weeks 1.
Why Other Options Are Incorrect
- 10 weeks (Option A): Too early—the uterus is still enlarging within the pelvis and not yet consistently palpable above the symphysis pubis 1
- 16 weeks (Option C): By this time, the fundus is already well above the symphysis pubis, typically midway between the symphysis and umbilicus 1
- 20 weeks (Option D): The fundus has reached the umbilicus by this gestational age 1