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)Abscess: Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection.Abdomen: That portion of the body that lies between the THORAX and the PELVIS.Brain Abscess: A circumscribed collection of purulent exudate in the brain, due to bacterial and other infections. The majority are caused by spread of infected material from a focus of suppuration elsewhere in the body, notably the PARANASAL SINUSES, middle ear (see EAR, MIDDLE); HEART (see also ENDOCARDITIS, BACTERIAL), and LUNG. Penetrating CRANIOCEREBRAL TRAUMA and NEUROSURGICAL PROCEDURES may also be associated with this condition. Clinical manifestations include HEADACHE; SEIZURES; focal neurologic deficits; and alterations of consciousness. (Adams et al., Principles of Neurology, 6th ed, pp712-6)Liver Abscess: Solitary or multiple collections of PUS within the liver as a result of infection by bacteria, protozoa, or other agents.Lung Abscess: Solitary or multiple collections of PUS within the lung parenchyma as a result of infection by bacteria, protozoa, or other agents.Epidural Abscess: Circumscribed collections of suppurative material occurring in the spinal or intracranial EPIDURAL SPACE. The majority of epidural abscesses occur in the spinal canal and are associated with OSTEOMYELITIS of a vertebral body; ANALGESIA, EPIDURAL; and other conditions. Clinical manifestations include local and radicular pain, weakness, sensory loss, URINARY INCONTINENCE, and FECAL INCONTINENCE. Cranial epidural abscesses are usually associated with OSTEOMYELITIS of a cranial bone, SINUSITIS, or OTITIS MEDIA. (From Adams et al., Principles of Neurology, 6th ed, p710 and pp1240-1; J Neurol Neurosurg Psychiatry 1998 Aug;65(2):209-12)Psoas Abscess: Abscess of the PSOAS MUSCLES resulting usually from disease of the lumbar vertebrae, with the pus descending into the muscle sheath. The infection is most commonly tuberculous or staphylococcal.Liver Abscess, Amebic: Single or multiple areas of PUS due to infection by any ameboid protozoa (AMEBIASIS). A common form is caused by the ingestion of ENTAMOEBA HISTOLYTICA.Liver Abscess, Pyogenic: Single or multiple areas of PUS due to bacterial infection within the hepatic parenchyma. It can be caused by a variety of BACTERIA, local or disseminated from infections elsewhere such as in APPENDICITIS; CHOLECYSTITIS; PERITONITIS; and after LIVER TRANSPLANTATION.Periapical Abscess: Acute or chronic inflammation of tissues surrounding the apical portion of a tooth, associated with the collection of pus, resulting from infection following pulp infection through a carious lesion or as a result of an injury causing pulp necrosis. (Dorland, 27th ed)Retropharyngeal Abscess: An accumulation of purulent material in the space between the PHARYNX and the CERVICAL VERTEBRAE. This usually results from SUPPURATION of retropharyngeal LYMPH NODES in patients with UPPER RESPIRATORY TRACT INFECTIONS, perforation of the pharynx, or head and neck injuries.