When occurring between two parts of the intestine, it is known as an enteroenteral fistula, between the small intestine and the skin as an enterocutaneous fistula, and between the small intestine and the colon as a colocutaneous fistula.The following list is sorted by the International Statistical Classification of Diseases and Related Health Problems. H: Diseases of the eye, adnexa, ear, and mastoid process
(H04.6) Lacrimal fistula
(H05.81) Carotid cavernous fistula
(H70.1) Mastoid fistula
Craniosinus fistula: between the intracranial space and a paranasal sinus
(H83.1) Labyrinthine fistula
Perilymph fistula: tear between the membranes between the middle and inner ears
Preauricular fistula
Preauricular fistula: usually on the top of the cristae helicis of the ears

I: Diseases of the circulatory system
(I25.4) Coronary arteriovenous fistula, acquired
(I28.0) Arteriovenous fistula of pulmonary vessels
Pulmonary arteriovenous fistula: between an artery and vein of the lungs, resulting in shunting of blood. This results in improperly oxygenated blood. (I67.1) Cerebral arteriovenous fistula, acquired
(I77.0) Arteriovenous fistula, acquired
(I77.2) Fistula of artery

J: Diseases of the respiratory system
(J86.0) Pyothorax with fistula
(J95.0) Tracheoesophageal fistula, between the trachea and the esophagus. This may be congenital or acquired, for example as a complication of a tracheostomy. K: Diseases of the digestive system
(K11.4) Salivary gland fistula
(K31.6) Fistula of stomach and duodenum
(K31.6) Gastrocolic fistula
(K31.6) Gastrojejunocolic fistula – after a Billroth II a fistula forms between the transverse colon and the upper jejunum (which, post Billroth II, is attached to the remainder of the stomach). Fecal matter passes improperly from the colon to the stomach and causes halitosis.
Also known as an ear pit or preauricular sinus. (Q26.6) Portal vein-hepatic artery fistula
(Q38.0) Congenital fistula of lip
(Q38.4) Congenital fistula of salivary gland
(Q42.0) Congenital absence, atresia and stenosis of rectum with fistula
(Q42.2) Congenital absence, atresia and stenosis of anus with fistula
(Q43.6) Congenital fistula of rectum and anus
(Q51.7) Congenital fistulae between uterus and digestive and urinary tracts
(Q52.2) Congenital rectovaginal fistula

T: External causes
(T14.5) Traumatic arteriovenous fistula
(T81.8) Persistent postoperative fistula

Causes
Disease: Infections including an anorectal abscess and inflammatory diseases including Crohns disease and ulcerative colitis can result in fistulas. Fistulas to the anus may occur in hidradenitis suppurativa. In women, fistulas can also occur following pelvic infection and inflammation. Surgical and medical treatment: Complications from gallbladder surgery can lead to biliary fistulas. As well as being congenital or resulting from trauma, arteriovenous fistulas are created purposefully for hemodialysis. Radiation therapy to the pelvis can lead to vesicovaginal fistulas. Persistent gastrocutenaous fistulas can develop after gastrostomy. Trauma: Prolonged childbirth can lead to fistulas in women, in whom abnormal connections may occur between the bladder and vagina, or the rectum and vagina. An obstetric fistula develops when blood supply to the tissues of the vagina and the bladder (and/or rectum) is cut off during prolonged obstructed labor. The tissues die and a hole forms through which urine and/or feces pass uncontrollably. Vesicovaginal and rectovaginal fistulas may also be caused by rape, in particular gang rape, and rape with foreign objects, as evidenced by the abnormally high number of women in conflict areas who have developed fistulae.