Dorothy Isabella Bulas MD, Presenter: Nothing to Disclose

1) Review the US and MRI appearance of congenital diaphragmatic hernia prenatally. 2) Discuss the role of fetal MRI in guiding prenatal care and predicting postnatal outcome. 3) Correlate prenatal findings with postnatal diagnosis and outcome.

CDH are the result of incomplete closure of the pleuroperitoneal canal. By US, herniated bowel loops into the hemithorax can mimic a multicystic lung mass. When left sided (88%), the stomach can herniate into the hemithorax, and nonvisualization of the stomach within the abdomen is a clue in the diagnosis. When right sided or when the stomach is infradiaphragmatic, mediastinal and cardiac deviation may be the first hint that a CDH is present by US . MRI is helpful in confirming the diagnosis, and can provide specific information on size of diaphragmatic defect, amount of liver herniation, delineating bowel in the chest and measuring lung volume. MR is particularly useful in the evaluation of right and bilateral CDH. The prognosis depends on the side of the herniation, the position of the liver, and associated abnormalities. Bilateral hernias are typically fatal. When liver is down, survival has been reported to be 90%; when liver is in the chest survival can be less than 50%. Associated abnormalities decreases survival. Currently, no single lung volume measurement has been proven to be an absolute indicator of postnatal outcome. The lung head ratio (LHR) is a measurement of the right lung; divided by the head circumference. If the LHR <1, outcome is worse with survival rate as low as 45%. Absolute total lung volumes by MR can be compared with expected lung volumes for age. A ratio between; observed and predicted lung volume can also be obtained by obtaining the total lung volume (right lung vol + left lung vol) and divided by predicted lung volume (thoracic vol - mediastinal vol x 100).The modified McGoon index has been used to predict the risk of developing severe pulmonary hypertension. The right and left pulmonary artery dm are added and divided by the aortic dm. If the result is < 0.8 the fetus is at high risk of developing pulmonary hypertension and at low risk if it is > 1.0.

Bulas, D, Fetal Imaging of Congenital Diaphragmatic Hernia.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11000204.html