ANAL FISTULA : DEFINITION , CAUSES , CLINICAL FEATURES & DIAGNOSIS

DEFINITION : 

Abnormal communication between anal canal & rectum with perianal skin . Eventhough multiple openings are seen in the perianal skin , the internal opening is always single .

CAUSES :

They occur due to persistent anal gland infection , which results in anorectal abscesses which rupture inside as well as outside resulting in a fistula .Once a fistula occurs , it persists because of infection & absence of rest to the part .Patients with pulmonary tuberculosis have got 1-2% chances of developing multiple fistula in ano . Such fistula are not indurated & there is watery discharge without pus .Colloid carcinoma of rectum can present as multiple fistula in  ano .
Other causes of fistula : Fistula carcinoma , Ileitis , Schistosomiasis , tuberculosis , ulcerative colitis , Anal fissure abscess .

                                                                     

 ANAL FISTULA

CLINICAL FEATURES : 

1.Persistent seropurulent discharge , keep the part always wet .
2. Previous history of anal gland infection with recurrent abscess .
3. External opening can be single or multiple with pouting granulation tissue , may discharge blood .
4.Internal opening in carcinoma felt as a 'buttonhole 'defect inside the rectum .

 

DIAGNOSIS :

External  opening is found at the button of a depressed area or with granulation tissue or it is seen with discharge  charging pus .Internal opening may be felt on digital examination as indurated area or sometimes can be seen with proctoscopy .Endorectal ultrasonography & MRI seems to identify 9internal opening & fistula .Examination uder general or regional anaesthesia .