Appendicitis: Acute inflammation of the APPENDIX. Acute appendicitis is classified as simple, gangrenous, or perforated.Appendectomy: Surgical removal of the vermiform appendix. (Dorland, 28th ed)Appendix: A worm-like blind tube extension from the CECUM.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.Intestinal Perforation: Opening or penetration through the wall of the INTESTINES.Abdominal Abscess: An abscess located in the abdominal cavity, i.e., the cavity between the diaphragm above and the pelvis below. (From Dorland, 27th ed)Fecal Impaction: Formation of a firm impassable mass of stool in the RECTUM or distal COLON.Acute Disease: Disease having a short and relatively severe course.Cecal Diseases: Pathological developments in the CECUM.Rupture, Spontaneous: Tear or break of an organ, vessel or other soft part of the body, occurring in the absence of external force.Gangrene: Death and putrefaction of tissue usually due to a loss of blood supply.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.Appendiceal Neoplasms: Tumors or cancer of the APPENDIX.Diagnostic Errors: Incorrect diagnoses after clinical examination or technical diagnostic procedures.Mesenteric Lymphadenitis: INFLAMMATION of LYMPH NODES in the MESENTERY.Diverticulitis: Inflammation of a DIVERTICULUM or diverticula.Hernia, Femoral: A groin hernia occurring inferior to the inguinal ligament and medial to the FEMORAL VEIN and FEMORAL ARTERY. The femoral hernia sac has a small neck but may enlarge considerably when it enters the subcutaneous tissue of the thigh. It is caused by defects in the ABDOMINAL WALL.Radiography, Abdominal: Radiographic visualization of the body between the thorax and the pelvis, i.e., within the peritoneal cavity.Retrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.Torsion Abnormality: An abnormal twisting or rotation of a bodily part or member on its axis.Tomography, X-Ray Computed: Tomography using x-ray transmission and a computer algorithm to reconstruct the image.Cecal Neoplasms: Tumors or cancer of the CECUM.Abscess: Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection.Laparotomy: Incision into the side of the abdomen between the ribs and pelvis.Lithiasis: A condition characterized by the formation of CALCULI and concretions in the hollow organs or ducts of the body. They occur most often in the gallbladder, kidney, and lower urinary tract.