The present chapter reviews the main technical aspects, indications and results of clinical use of three-dimensional ultrasonographic lung volumes. There are two methods to measure fetal lung volumes using three-dimensional ultrasonography: the technique of parallel slices and the rotational technique. Nowadays, the rotational technique is the method of choice because of reproducibility and less time consuming. Clinical indications for assessing fetal lung volumes are congenital anomalies or situations where there is an increased risk for severe pulmonary hypoplasia. Fetal lung volume is useful tool to diagnose pulmonary hypoplasia, but more important to predict the severity of this complication. Clinical situations that may benefit from fetal lung volume assessment are: congenital diaphragmatic hernia, fetal hyperechogenic lung lesions, omphalocele, premature rupture of the membranes and prolonged oligohydramnios (fetal renal/urological problems).
Keywords: Congenital adenomatoid malformation, Congenital diaphragmatic hernia, Fetal lung volumes, Lower urinary tract obstruction, Oligohydramnios, Pulmonary hypoplasia, Pulmonary sequestration, Three-dimensional ultrasonography.