Pulmonary sequestrations detected by antenatal ultrasound

We present three cases of abdominal and abdomino-thoracic extra-lobar pulmonary sequestrations detected by antenatal ultrasound (US) over a 12-month period. In addition, we briefly refer to a case previously described. A cystic mass was demonstrated in the left upper abdomen of the fetus in all four cases, with two extending into the thorax. The diagnosis was confirmed postnatally by fine-needle biopsy and later excision of the mass. In all four cases the lesion did not interfere with the pregnancy, and only one child demonstrated transient effects of mild pulmonary hypoplasia. Review of the antenatal scans showed that in each case the sequestration did not appear to grow during the pregnancy, with a relative decrease in size. Extra-lobar sequestration should always be considered in the differential diagnosis of an abdominal mass diagnosed on antenatal US, especially if cystic and extending from the abdomen through the diaphragm into the mediastinum. Although abdominal sequestrations are rare in comparison to thoracic lesions at postnatal diagnosis, they represent 21 of the 40 published series of pulmonary sequestrations diagnosed on antenatal US.