Sonographic diagnosis of IUGR-macrosomia

Many sonographic methods have been suggested for identification of the fetus with a growth abnormality. Clearly, optimal management depends on early diagnosis. In recent years, advances in sonography have improved the ability to identify abnormal growth patterns and evaluate fetal well-being. When abnormal fetal growth is suspected, a thorough sonographic evaluation should be performed. This evaluation includes measurements of the abdominal circumference, femur length,) BPD, HC, AC, FL, and amniotic fluid volume. If these measurements confirm the suspicion of abnormal fetal growth, careful search for anomalies is mandatory. If there is no evidence of fetal compromise that would warrant delivery, measurements should be repeated in 2-3 weeks to evaluate interval growth. The following conclusions could be drawn from this literature review: 1. Intrauterine growth retardation and macrosomia are multifactorial diseases with varying degrees of severity. It is unlikely that a single sonographic parameter will allow an accurate diagnosis of all cases. 2. The type and degree of growth retardation and macrosomia depend on the intensity and duration of the underlying disease. Thus, an ultrasound assessment performed long before delivery may be of limited value. 3. Most of the sonographic parameters reviewed in this chapter are gestational age dependent. Unfortunately, gestational age is often unknown. Gestational age independent indices such as the amniotic fluid volume, FL/AC ratio, and the rate of fetal growth should be helpful in this situation. 4. The constitutionally small infant whose only problem is low birth weight should not be expected to present with any abnormal indices other than a low EFW. On the other hand, newborns who appear to be malnourished but whose birth weight is at or slightly above the tenth percentile for gestational age, may present with abnormal indirect indices indicating growth retardation (ie, HC/AC, FL/AC, Doppler velocimetry or oligohydramnios) despite a normal estimate of fetal weight. In addition, if the diagnosis of IUGR is made only with the use of birthweight for gestational age criteria, these infants are likely to be misclassified and labelled AGA. However, an abnormal ponderal index would indicate that these neonates are growth retarded. It can be concluded from this review that the use of sonographic measurements for diagnosing IUGR or macrosomia is associated with a high specificity and a somewhat lower sensitivity. Therefore, it would seem that the current ultrasound methods are more useful for excluding the possibility of abnormal fetal growth rather than for confirming it.