What is the symphysis fundal height (SFH) measurement?

From the Guidelines

Symphysis fundal height (SFH) measurement is the distance from the top of the maternal pubic bone to the top of the uterine fundus, approximately corresponding to the gestational age in weeks when measured between 16 and 36 weeks of gestation. This measurement is a useful tool for estimating gestational age and fetal growth during pregnancy.

Key Points to Consider

• The SFH measurement is typically taken using a flexible measuring tape or, if not available, finger breadths can be used as a surrogate for centimeters 1.
• The measurement can be affected by various factors such as abdominal distention, fetal position, and maternal obesity, which may skew the accuracy of the gestational age estimation.
• Classically accepted rule-of-thumb landmarks can also be used to estimate gestational age, including the uterus being palpable above the pubic symphysis at 12 weeks, at the level of the umbilicus at 20 weeks, and at the level of the xiphisternum at 36 weeks 1.
• It is essential to note that the fundal height may not always be a reliable predictor of gestational age, particularly in the last month of pregnancy when the fetal head engages into the pelvis, potentially diminishing the fundal height from 36 to approximately 32 cm 1.

Clinical Application

• The SFH measurement should be taken at each prenatal visit after 16 weeks, with the patient in a supine position and an empty bladder, to ensure consistency and accuracy.
• Significant deviations from the expected measurement may indicate potential complications such as intrauterine growth restriction, macrosomia, or incorrect dating of the pregnancy, which would require further evaluation with ultrasound assessment 1.

From the Research

Definition and Purpose of Symphysis Fundal Height (SFH) Measurement

• SFH measurement is commonly practiced to detect fetal intrauterine growth restriction (IUGR) and abnormal fetal growth 2, 3.
• The measurement is used to assess fetal growth and detect potential complications, such as small-for-gestational age babies 4, 5.
• SFH measurement is a simple and non-invasive method that can be used to screen for fetal growth disturbances 6.

Methodology and Interpretation of SFH Measurement

• SFH is measured in centimeters from the symphysis pubis to the top of the uterus (fundus) 4, 6.
• The measurement is typically taken at regular intervals during pregnancy, starting from around 20 weeks of gestation 4, 6.
• The results are often plotted on a curve to track fetal growth and detect any deviations from the expected growth pattern 4, 5, 6.
• The curve can be used to identify babies that are small or large for their gestational age 5, 6.

Effectiveness and Limitations of SFH Measurement

• There is insufficient evidence to determine whether SFH measurement is effective in detecting IUGR 2, 3.
• Studies have shown that SFH measurement has a low sensitivity and specificity for detecting small-for-gestational age babies 2, 3.
• However, SFH measurement can be a useful screening tool when used in conjunction with other methods, such as ultrasound measurement of fetal parameters or clinical palpation 2, 3.
• Further research is needed to fully evaluate the effectiveness and limitations of SFH measurement in detecting abnormal fetal growth 2, 3, 6.