How is fundal (uterine) height measured?

From the Guidelines

Fundal height is measured by using a tape measure to determine the distance from the pubic symphysis to the top of the uterus (fundus), with the most recent and highest quality study 1 supporting this method as an essential element in assessing fetal growth. To perform this measurement, the healthcare provider asks the patient to lie flat on her back with her knees slightly bent.

• The provider locates the top of the pubic bone and the top of the uterine fundus by palpation.
• Using a flexible tape measure, they measure the distance in centimeters along the midline of the abdomen from the pubic symphysis to the top of the fundus. This measurement is typically performed at prenatal visits starting around 20 weeks of pregnancy.
• The fundal height in centimeters roughly corresponds to the gestational age in weeks between 20-36 weeks of pregnancy (for example, at 24 weeks gestation, the fundal height should be approximately 24 centimeters). This measurement helps assess fetal growth and can identify potential issues such as intrauterine growth restriction, macrosomia, multiple gestation, or abnormal amniotic fluid volume.
• Consistent technique is important for accuracy, and measurements should be taken by the same provider when possible to reduce variation, as supported by 1 and 1. It's also important to note that fundal height measurement may be skewed by other factors such as abdominal distention, as mentioned in 1 and 1. However, the most recent study 1 emphasizes the importance of fundal height measurement in assessing fetal growth, and recommends serial fundal height on customized chart from 24 weeks, with ultrasound if less than 10th centile, slow or static growth.

From the Research

Measuring Fundal Height

To measure fundal height, the following steps and considerations should be taken into account:

• The distance between the pubic symphysis and the top of the fundus should be measured in centimeters, which is expected to equal the gestational age in weeks, with the best correlation between weeks 18 and 32 2.
• The measurement can be taken manually or using ultrasound, with both methods being equivalent in terms of predictive power for determining fetal age 2.
• However, ultrasound is necessary when there is a discrepancy between the size of the fetus and the gestational age, and it is also useful for teaching the measurement of fundal height 2.
• The position of the mother during measurement can affect the results, with measurements obtained in the supine position being the largest and those in the trunk elevation with knee flexion position being the smallest 3.
• Different techniques for measuring fundal height exist, including the use of a tape measure or caliper, and the choice of landmark on the symphysis pubis and the uterine fundus, but the superiority of one technique over another has not been demonstrated 4.

Techniques and Considerations

Some key points to consider when measuring fundal height include:

• The importance of consistency in measurement technique to ensure reliable results 4.
• The need to use a rational and accurate method of measurement, rather than comparing the uterus to anatomic landmarks on the maternal abdomen 5.
• The potential for variability in measurements due to factors such as maternal position and the technique used 3, 4.
• The use of ultrasound as a more accurate method of measurement, particularly in cases where there is a size-vs-date discrepancy 2, 6.