Typically the pump function of the heart during systole is normal, but an echocardiogram will show flow reversal during diastole. This disease is classified using regurgitant fraction (RF), or the amount of volume that flows back through the valve divided by the total forward flow through the valve during systole. Severe disease has an RF of >50%, while progressive aortic regurgitation has an RF of 30–49%. Mitral stenosis
Chest x-ray in mitral stenosis will typically show an enlarged left atrium, and may show dilation of the pulmonary veins. ECG can show left atrial enlargement, due to increased pressures in the left atrium. Echocardiography is helpful in determining the severity of the disease by estimating the pulmonary artery systolic pressure. This test can also show leaflet calcification and the pressure gradient over the mitral valve. Severe mitral stenosis is defined as a mitral valve area <1.5 cm2. Progressive mitral stenosis has a normal valve area but will have increased flow velocity across the mitral valve. Mitral regurgitation
Chest x-ray in mitral regurgitation can show an enlarged left atrium, as well as pulmonary venous congestion. It may also show valvular calcifications specifically in combined mitral regurgitation and stenosis due to rheumatic heart disease. ECG typically shows left atrial enlargement, but can also show right atrial enlargement if the disease is severe enough to cause pulmonary hypertension. Echocardiography is useful in visualizing the regurgitant flow and calculating the RF. It can also be used to determine the degree of calcification, and the function and closure of the valve leaflets.
Enterocutaneous fistula: between the intestine and the skin surface, namely from the duodenum or the jejunum or the ileum. This definition excludes the fistulas arising from the colon or the appendix. Gastric fistula: from the stomach to the skin surface
(K38.3) Fistula of appendix
(K60) Anal and rectal fissures and fistulas
(K60.3) Anal fistula
(K60.5) Anorectal fistula (fecal fistula, fistula-in-ano): connecting the rectum or other anorectal area to the skin surface. This results in abnormal discharge of feces through an opening other than the anus. (K63.2) Fistula of intestine
Enteroenteral fistula: between two parts of the intestine
(K82.3) Fistula of gallbladder
(K83.3) Fistula of bile duct
Biliary fistula: connecting the bile ducts to the skin surface, often caused by gallbladder surgery
Pancreatic fistula: between the pancreas and the exterior via the abdominal wall

M: Diseases of the musculoskeletal system and connective tissue
(M25.1) Fistula of joint

N: Diseases of the urogenital system
(N32.1) Vesicointestinal fistula
(N36.0) Urethral fistula
Innora:between the prostatic utricle and the outside of the body
(N64.0) Fistula of nipple
(N82) Fistulae involving female genital tract / Obstetric fistula
(N82.0) Vesicovaginal fistula: between the bladder and the vagina
(N82.1) Other female urinary-genital tract fistulae
Cervical fistula: abnormal opening in the cervix
(N82.2) Fistula of vagina to small intestine
Enterovaginal fistula: between the intestine and the vagina
(N82.3) Fistula of vagina to large intestine
Rectovaginal: between the rectum and the vagina
(N82.4) Other female intestinal-genital tract fistulae
(N82.5) Female genital tract-skin fistulae
(N82.8) Other female genital tract fistulae
(N82.9) Female genital tract fistula, unspecified

Q: Congenital malformations, deformations and chromosomal abnormalities
(Q18.0) Sinus, fistula and cyst of branchial cleft
Congenital preauricular fistula: A small pit in front of the ear.