Diagnosis and differentiation of congenital diaphragmatic hernia from other noncardiac thoracic fetal masses

This retrospective study was designed to evaluate individual sonographic parameters that might help differentiate congenital diaphragmatic hernia (CDH) from other noncardiac thoracic masses such as cystic adenomatoid malformation of the lung (CAML) and congenital lobar emphysema (CLE) prenatally. Twenty-four cases of CDH, CAML, and CLE detected during prenatal ultrasound and documented postnatally (with surgical, autopsy, or radiological proof) were identified through extensive chart and record review. The hard copy gray-scale images were retrospectively reviewed for imaging characteristics that may differentiate the three entities. Additionally, the prospective diagnosis during prenatal ultrasound was also compared with the postnatal diagnosis. The most reliable indicators in our retrospective review included confident visualization of a diaphragmatic defect (92.3/100.0 PPV/NPV, p ≤ 0.002) and/or localization of the stomach within the chest as well as the presence of severe cardiac deviation (both 92.3/62.5 PPV/NPV, p ≤ 0.01). Other sonographic indicators (including the presence of cystic areas, side and size of the lesion and the presence of polyhydramnios) offered lower levels of sensitivity and specificity. Prospective diagnosis during real-time assessment was also integral, offering > 80% sensitivity and specificity (p ≤ 0.001). Accurate prenatal diagnosis of CDH is difficult despite the relative frequency of this lesion. The classic triad of a thoracic mass accompanying a displaced heart, absence of a normally positioned fluid-filled stomach and polyhydramnios, although seen with CDH, may not adequately differentiate this entity from other noncardiac fetal thoracic masses. Real-time assessment remains integral to the appropriate diagnosis.