Rectum and anal canal

Anal fissure: It is a tear in the anal mucosa. Causes include passing hard stools, tuberculosis, syphilis, carcinoma, herpes, IBD and AIDS. It presents with acute, extreme rectal pain aggravated by defecation and on per-rectal exam, increased tone of anal sphincter and rectal bleeding. Chronic fissure presents with a sentinel tag, which is a protruding, perianal tag of anal mucosa. Acute fissures are treated with stool softeners, rectal suppositories or creams of steroid and local anesthetic. Nitroglycerine ointment with misoprostol and botulinum toxin can be used. Chronic fissures are treated by sphincterotomy.

Anal abscess: It is collection of pus in the anorectal area that begins as an infection of the anal glands in the crypts. They may be superficial or deep. Superficial abscesses present with pain, perianal swelling, redness, tenderness and less commonly, fever. Deeper abscess are less painful, cause fever, chills and malaise and can be palpated as a fluctuant bump on per-rectal examination. It is a mixed infection with E.coli, Proteus vulgaris, Bacteroides, Streptococci and Staphylococci. Treatment is with incision and drainage and antibiotics. Some abscesses may form fistulas on rupture.

Anatomical types of anorectal abscesses

Anal fistula: A fistula is a tract that is open at both ends. Anal fistula is caused by rupture of anal abscess, IBD, diverticulitis, Chlamaydiasis, syphilis, tuberculosis, cances, HIV etc. Infection typically begins at a clogged anal gland. Outer opening of the fistula appears as a red, inflamed area that oozes pus and blood. Internal opening can be visualized by MRI, endoscopic ultrasound or fistulography with contrast. Treatment is with fistulotomy, cutting or draining setons (non-absorbable nylon or silk suture), fibrin glue or fistulectomy.

Hemorrhoids: Hemorrhoids are dilated and tortuous veins in the anorectal mucosa and can be external or internal. External hemorrhoids begin below the dentate line while internal hemorrhoids begin above the dentate line. They present with a bulge during defecation, itching or irritation, hematochezia with small amounts of fresh blood that coats the stool or stains the toilet tissue, and pain (external hemorrhoids or thrombosed hemorrhoids). Internal hemorrhoids are painless. Pregnancy, obesity, chronic diarrhea or constipation, low-fibre diet and weight lifting are associated with increased risk of hemorrhoids. Band ligation and infrared coagulation are preferred treatments for grades I to III internal hemorrhoids. Radiofrequency treatments can be used for all grades. Supportive treatment for all hemorrhoids is with sitz baths, stool softeners, analgesics. Thrombosed hemorrhoids are acutely painful and are treated by incision and removal of thrombus or excision of clot. Sclerotherapy is not preferred nowadays. Surgical excision can be done for unresponsive cases and for complications such as strangulated, gangrenous or thrombosed hemorrhoids.

Proctitis: It is inflammation of the rectal mucosa. It results from IBD, radiation, infections with N.gonorrhoeae, Chlamydia, Campylobacter, Shigella, Salmonella, Cl.difficile, HSV and CMV and anal intercourse. It presents with tenesmus, bleeding, mucousy stools and pain. Diagnosis is by proctoscopy or sigmoidoscopy and testing for infections. Treatment depends on the cause.

Rectal prolapse: In this condition, the mucosa of the rectum and anal canal or the entire thickness of the rectal wall prolapse (procidentia) through the anal opening. They can be differentiated by the presence of a sulcus between the anus and prolapsed rectum in a full thickness prolapse which is absent in a mucosal prolapse. Causes include long-term constipation, childbirth, cystic fibrosis, COPD, whooping cough, surgery etc. Surgical resection (full-thickness prolapse) or excision (mucosal prolapse) is needed.

Anorectal cancer: It is a common cancer, majority being adenocarcinomas above the denate line while squamous cell carcinomas are commoner in anal area. Risk factors include age>50 years, obesity, smoking, polyposis syndromes, Lynch syndrome, immunosuppression, anal intercourse and HPV 16 and 18. It can present as a mass, ulcer, polyp or verrucous growth. Biopsy shows neoplastic columnar epithelium, glands (in adenocarcinoma) and mucin. Tumors are cytokeratin positive. Depth of invasion is an important prognostic factor in rectal cancer while size of lesion is important in anal cancer. Rectal cancers are treated with surgery, chemotherapy and/or radiation (for higher stages). Anal cancer is treated with combination chemotherapy with mitomycin C and fluorouracil and radiation. Resistant cases are treated with abdomino-perineal resection.