Fetal Mediastinal Shift
· Diaphragmatic hernia-May contain abdominal viscera, e.g. bowel peristalsis.
· Cystic adenomatoid malformation-
· Diaphragmatic eventration- Abdominal viscera may be seen in the thorax by US. Diagnosis requires visualization of the diaphragm. The abdominal circumference usually remains normal.
· Unilateral pleural effusion-US shows anechoic fluid surrounding a lung and displacing the mediastinum. The heart may appear smaller than normal. Large effusions may evert the diaphragm.
· Unilateral lung hypoplasia-Search should be made for associated anomalies causing external pressure on the developing lung.
· Bronchogenic cyst- These may be intrapulmonary or mediastinal in location and often closely related to the trachea or mainstem bronchi. US appearances may be those of a unilocular or multilocular cyst. There is an association with hemivertebrae.
· Neuroenteric cyst-Associated with vertebral abnormalities. Sonography typically shows a unilocular, thin walled cyst, although muftilocular cysts have been described. The diagnosis is suggested by the position of the cyst adjacent to the bowel and spine.
· Bronchial atresia-The affected lung may appear normal at midpregnancy; later examinations may show an abnormally echogenic lung with anechoic, dilated, mucus-filled bronchi. Mucus retention and lobar or pulmonary enlargement may cause mediastinal shift.
· Esophageal duplication cyst-Seen as focal fluid collections adjacent to the esophagus. Communication with the esophageal lumen is uncommon and allows the cyst to collapse. Associated anomalies are also uncommon.
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