A nurse is assessing the fundal height of a pregnant client at 28 weeks gestation during a routine prenatal visit. Which finding would be considered normal for this gestational age?
1Fundal height of 24 cm
2Fundal height of 32 cm
3Fundal height of 28 cm✓ 정답
4Fundal height of 20 cm
해설
At 28 weeks, fundal height in cm should approximate gestational age in weeks, with a normal range of ±2-3 cm. A measurement of 28 cm is expected, indicating appropriate fetal growth.
Fundal height measurement is a foundational, non-invasive screening tool used during prenatal visits to estimate fetal growth and gestational age. The measurement, taken in centimeters from the symphysis pubis to the top of the uterine fundus, should correlate closely with the week of gestation between approximately 20 and 36 weeks. This relationship, known as McDonald's rule, provides a quick clinical reference point.
Analyzing the Expected Finding at 28 Weeks
For a client at 28 weeks gestation, the expected normal fundal height is 28 cm. A discrepancy of more than 2 to 3 cm from the gestational week warrants further investigation, as it may indicate conditions such as fetal growth restriction, oligohydramnios, multiple gestation, or inaccurate dating.
Applying this principle to the options provided:
- A measurement of 24 cm or 20 cm at 28 weeks would be considered smaller than expected, potentially signaling a small-for-gestational age (SGA) fetus or fetal growth restriction (FGR). As noted in a service evaluation on antenatal detection, SGA is closely associated with FGR, and both are significant risk factors for adverse outcomes, making accurate fundal height screening a critical step in risk reduction .
- A measurement of 32 cm would be larger than expected, which could suggest a macrosomic fetus, multiple gestation, or polyhydramnios.
- A measurement of 28 cm aligns perfectly with the gestational age, representing the expected physiological progression of uterine growth .
Clinical Reasoning and Pathophysiology
The progressive increase in fundal height reflects the growth of the fetus, placenta, and amniotic fluid volume. While the provided research on oral hygiene interventions and postpartum uterine involution does not directly dictate fundal height norms, the principle of using a simple, reproducible measurement as a screening tool is a parallel concept. Just as newborn foot length is being studied as a simple anthropometric proxy to identify low birth weight and preterm infants in resource-limited settings, fundal height serves as a universally accessible screening proxy for fetal well-being in antenatal care . A measurement that matches the gestational age provides reassurance that the uterine environment is likely supporting appropriate fetal growth. A deviation from this expected value is not diagnostic on its own but serves as a critical alert for the nurse to initiate further assessment, such as a detailed ultrasound for fetal biometry .
Clinical Practice Guide: Fundal Height Assessment
Fundal height measurement is a standard, non-invasive screening tool to monitor fetal growth during prenatal visits. Following a consistent technique ensures accurate and reliable results.
Measurement Technique
Position the client supine with an empty bladder.
Locate the symphysis pubis and the uterine fundus using palpation.
Place the zero mark of a non-stretchable tape measure on the symphysis pubis, keeping the tape midline and in contact with the abdominal contour.
Extend the tape to the top of the fundus and record the measurement in centimeters.
Interpreting Results
Between 20 and 36 weeks, the fundal height in centimeters should approximate the gestational age in weeks (McDonald's rule).
A discrepancy of more than 2–3 cm from the expected value warrants further investigation with ultrasound.
A smaller-than-expected measurement may indicate fetal growth restriction, oligohydramnios, or inaccurate dating.
A larger-than-expected measurement may indicate macrosomia, multiple gestation, or polyhydramnios.
Nursing Considerations
Document the measurement and plot it on a standardized growth chart to track trends over time.
Report any significant deviation from the expected range to the healthcare provider promptly.
Educate the client that fundal height is a screening tool and that variations may simply reflect individual differences or require a follow-up ultrasound for clarification.
Fundal Height — The distance in centimeters from the symphysis pubis to the top of the uterine fundus, used to screen fetal growth.
McDonald's Rule — A clinical guideline stating that from roughly 20 to 36 weeks gestation, fundal height in centimeters equals the weeks of gestation.
Fetal Growth Restriction (FGR) — A condition where a fetus fails to achieve its genetically determined growth potential, often detected by a smaller-than-expected fundal height.