Pneumoperitoneum: A condition with trapped gas or air in the PERITONEAL CAVITY, usually secondary to perforation of the internal organs such as the LUNG and the GASTROINTESTINAL TRACT, or to recent surgery. Pneumoperitoneum may be purposely introduced to aid radiological examination.Pneumoperitoneum, Artificial: Deliberate introduction of air into the peritoneal cavity.Insufflation: The act of blowing a powder, vapor, or gas into any body cavity for experimental, diagnostic, or therapeutic purposes.Retropneumoperitoneum: Pathological or accidental introduction of air into the retroperitoneal space.Laparoscopy: A procedure in which a laparoscope (LAPAROSCOPES) is inserted through a small incision near the navel to examine the abdominal and pelvic organs in the PERITONEAL CAVITY. If appropriate, biopsy or surgery can be performed during laparoscopy.Pneumatosis Cystoides Intestinalis: A condition characterized by the presence of multiple gas-filled cysts in the intestinal wall, the submucosa and/or subserosa of the INTESTINE. The majority of the cysts are found in the JEJUNUM and the ILEUM.Carbon Dioxide: A colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals.Intestinal Perforation: Opening or penetration through the wall of the INTESTINES.Cholecystectomy, Laparoscopic: Excision of the gallbladder through an abdominal incision using a laparoscope.Stomach Rupture: Bursting of the STOMACH.Pressure: A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Needles: Sharp instruments used for puncturing or suturing.Diaphragmatic Eventration: A congenital abnormality characterized by the elevation of the DIAPHRAGM dome. It is the result of a thinned diaphragmatic muscle and injured PHRENIC NERVE, allowing the intra-abdominal viscera to push the diaphragm upward against the LUNG.Radiography, Abdominal: Radiographic visualization of the body between the thorax and the pelvis, i.e., within the peritoneal cavity.Tissue Adhesions: Pathological processes consisting of the union of the opposing surfaces of a wound.Helium: Helium. A noble gas with the atomic symbol He, atomic number 2, and atomic weight 4.003. It is a colorless, odorless, tasteless gas that is not combustible and does not support combustion. It was first detected in the sun and is now obtained from natural gas. Medically it is used as a diluent for other gases, being especially useful with oxygen in the treatment of certain cases of respiratory obstruction, and as a vehicle for general anesthetics. (Dorland, 27th ed)Abdominal Cavity: The region in the abdomen extending from the thoracic DIAPHRAGM to the plane of the superior pelvic aperture (pelvic inlet). The abdominal cavity contains the PERITONEUM and abdominal VISCERA, as well as the extraperitoneal space which includes the RETROPERITONEAL SPACE.Mediastinal Emphysema: Presence of air in the mediastinal tissues due to leakage of air from the tracheobronchial tree, usually as a result of trauma.Intraoperative Period: The period during a surgical operation.Video-Assisted Surgery: Endoscopic surgical procedures performed with visualization via video transmission. When real-time video is combined interactively with prior CT scans or MRI images, this is called image-guided surgery (see SURGERY, COMPUTER-ASSISTED).Laparotomy: Incision into the side of the abdomen between the ribs and pelvis.Pyometra: An accumulation of PUS in the uterine cavity (UTERUS). Pyometra generally indicates the presence of infections.Abdomen: That portion of the body that lies between the THORAX and the PELVIS.Lung Compliance: The capability of the LUNGS to distend under pressure as measured by pulmonary volume change per unit pressure change. While not a complete description of the pressure-volume properties of the lung, it is nevertheless useful in practice as a measure of the comparative stiffness of the lung. (From Best & Taylor's Physiological Basis of Medical Practice, 12th ed, p562)Abdomen, Acute: A clinical syndrome with acute abdominal pain that is severe, localized, and rapid in onset. Acute abdomen may be caused by a variety of disorders, injuries, or diseases.