pneumoperitoneum

[nōō′mō-pĕr′ĭ-tn-ēəm]
n.
  1. The presence of air or gas in the peritoneal cavity as a result of disease or for the treatment of certain conditions.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.