Rectal Fistula: An abnormal anatomical passage connecting the RECTUM to the outside, with an orifice at the site of drainage.Fistula: Abnormal communication most commonly seen between two internal organs, or between an internal organ and the surface of the body.Arteriovenous Fistula: An abnormal direct communication between an artery and a vein without passing through the CAPILLARIES. An A-V fistula usually leads to the formation of a dilated sac-like connection, arteriovenous aneurysm. The locations and size of the shunts determine the degree of effects on the cardiovascular functions such as BLOOD PRESSURE and HEART RATE.Intestinal Fistula: An abnormal anatomical passage between the INTESTINE, and another segment of the intestine or other organs. External intestinal fistula is connected to the SKIN (enterocutaneous fistula). Internal intestinal fistula can be connected to a number of organs, such as STOMACH (gastrocolic fistula), the BILIARY TRACT (cholecystoduodenal fistula), or the URINARY BLADDER of the URINARY TRACT (colovesical fistula). Risk factors include inflammatory processes, cancer, radiation treatment, and surgical misadventures (MEDICAL ERRORS).Cutaneous Fistula: An abnormal passage or communication leading from an internal organ to the surface of the body.Bronchial Fistula: An abnormal passage or communication between a bronchus and another part of the body.Vascular Fistula: An abnormal passage between two or more BLOOD VESSELS, between ARTERIES; VEINS; or between an artery and a vein.Gastric Fistula: Abnormal passage communicating with the STOMACH.Urinary Fistula: An abnormal passage in any part of the URINARY TRACT between itself or with other organs.Esophageal Fistula: Abnormal passage communicating with the ESOPHAGUS. The most common type is TRACHEOESOPHAGEAL FISTULA between the esophagus and the TRACHEA.Biliary Fistula: Abnormal passage in any organ of the biliary tract or between biliary organs and other organs.Pancreatic Fistula: Abnormal passage communicating with the PANCREAS.Rectovaginal Fistula: An abnormal anatomical passage between the RECTUM and the VAGINA.Vesicovaginal Fistula: An abnormal anatomical passage between the URINARY BLADDER and the VAGINA.Respiratory Tract Fistula: An abnormal passage communicating between any component of the respiratory tract or between any part of the respiratory system and surrounding organs.Vaginal Fistula: An abnormal anatomical passage that connects the VAGINA to other organs, such as the bladder (VESICOVAGINAL FISTULA) or the rectum (RECTOVAGINAL FISTULA).Tracheoesophageal Fistula: Abnormal passage between the ESOPHAGUS and the TRACHEA, acquired or congenital, often associated with ESOPHAGEAL ATRESIA.Urinary Bladder Fistula: An abnormal passage in the URINARY BLADDER or between the bladder and any surrounding organ.Arterio-Arterial Fistula: Abnormal communication between two ARTERIES that may result from injury or occur as a congenital abnormality.Arteriovenous Shunt, Surgical: Surgical shunt allowing direct passage of blood from an artery to a vein. (From Dorland, 28th ed)Carotid-Cavernous Sinus Fistula: An acquired or spontaneous abnormality in which there is communication between CAVERNOUS SINUS, a venous structure, and the CAROTID ARTERIES. It is often associated with HEAD TRAUMA, specifically basilar skull fractures (SKULL FRACTURE, BASILAR). Clinical signs often include VISION DISORDERS and INTRACRANIAL HYPERTENSION.Digestive System Fistula: An abnormal passage communicating between any components of the digestive system, or between any part of the digestive system and surrounding organ(s).Central Nervous System Vascular Malformations: Congenital, inherited, or acquired abnormalities involving ARTERIES; VEINS; or venous sinuses in the BRAIN; SPINAL CORD; and MENINGES.Pleural DiseasesOral Fistula: An abnormal passage within the mouth communicating between two or more anatomical structures.Cavernous Sinus: An irregularly shaped venous space in the dura mater at either side of the sphenoid bone.Embolization, Therapeutic: A method of hemostasis utilizing various agents such as Gelfoam, silastic, metal, glass, or plastic pellets, autologous clot, fat, and muscle as emboli. It has been used in the treatment of spinal cord and INTRACRANIAL ARTERIOVENOUS MALFORMATIONS, renal arteriovenous fistulas, gastrointestinal bleeding, epistaxis, hypersplenism, certain highly vascular tumors, traumatic rupture of blood vessels, and control of operative hemorrhage.Duodenal Diseases: Pathological conditions in the DUODENUM region of the small intestine (INTESTINE, SMALL).Urethral Diseases: Pathological processes involving the URETHRA.Esophageal Atresia: Congenital abnormality characterized by the lack of full development of the ESOPHAGUS that commonly occurs with TRACHEOESOPHAGEAL FISTULA. Symptoms include excessive SALIVATION; GAGGING; CYANOSIS; and DYSPNEA.Brachiocephalic Veins: Large veins on either side of the root of the neck formed by the junction of the internal jugular and subclavian veins. They drain blood from the head, neck, and upper extremities, and unite to form the superior vena cava.Oroantral Fistula: A fistula between the maxillary sinus and the oral cavity.Renal Dialysis: Therapy for the insufficient cleansing of the BLOOD by the kidneys based on dialysis and including hemodialysis, PERITONEAL DIALYSIS, and HEMODIAFILTRATION.Dura Mater: The outermost of the three MENINGES, a fibrous membrane of connective tissue that covers the brain and the spinal cord.Aortic Diseases: Pathological processes involving any part of the AORTA.