A postnatal X-ray of abdomen of a neonate shows 'double bubble sign'. It is seen with:

In duodenal atresia, postnatal abdominal plain radiographs show gaseous distention of the stomach and proximal duodenum (the "double-bubble" radiologic sign). With protracted vomiting, there is less air in the stomach and less abdominal distention. Absence of distal intestinal gas suggests atresia or severe extrinsic obstruction, whereas a pattern of intestinal air scattered over the lower abdomen may indicate paial duodenal obstruction. Ref: Sundaram S.S., Hoffenberg E.J., Kramer R.E., Sondheimer J.M., Furuta G.T. (2012). Chapter 21. Gastrointestinal Tract. In W.W. Hay, Jr., M.J. Levin, R.R. Deterding, J.J. Ross, J.M. Sondheimer (Eds), CURRENT Diagnosis & Treatment: Pediatrics, 21e.