hydropneumoperitoneum hy·dro·pneu·mo·per·i·to·ne·um (hī'drō-n&oomacr;'mō-pěr'ĭ-tn-ē'əm, -ny&oomacr;'-) n. The accumulation of serous fluid and gas in the peritoneal cavity. Also called pneumohydroperitoneum.
