Idiopathic pneumoperitoneum without gastrointestinal perforation in a low-birth weight infant: A rare type of air leak syndrome oleh Hideaki Nakajima, MD, Masaya Yamoto, MD, Koji Fukumoto, MD, Akinori Sekioka, MD, Akiyoshi Nomura, MD, Kei Ohyama, MD, Yutaka Yamada, MD, Naoto Urushihara, MD