Gastro 52 Anus

Hemorrhoids are normal, vascular tissue within the submucosa located in the anal canal. They are thought to aid in anal continence by providing bulk to the anal canal.

• External hemorrhoids are located distal to the dentate line
• Internal hemorrhoids are located proximal to the dentate line
• Mixed hemorrhoids are located both proximal and distal to the dentate line

• Hemorrhoidal bleeding is almost always painless and is usually associated with a bowel movement, although can be spontaneous.
• The blood is typically bright red (arterial blood) and coats the stool at the end of defecation or may drip into the toilet.

• Grade I - protrude into the anal canal but do not prolapse
• Grade II - prolapse with straining or defecation but reduce spontaneously
• Grade III - prolapse and usually require manual reduction
• Grade IV - prolapsed and cannot be reduced and are thus at risk of strangulation and thrombosis

• The CCI Score takes into account the frequency of incontinence and the extent to which it alters a person's life.
• Format: 5 questions assessing type of incontinence (solid, liquid, gas, wears pad, lifestyle alteration).

• Dietary modifications
• Rubber band ligation - for 1st-3rd degree hemorrhoids.
• Sclerotherapy
• Infrared and laser coagulation

Indications of surgery - Grade III and Grade IV hemorrhoids.

Thrombosed hemorrhoids - excised within 72 hours, Should be excised, and not incised, as this may increase the risk of rethrombosis.

• Traditional Haemorrhoidectomy
• - Closed (Ferguson) hemorrhoidectomy
• - Open (Milligan-Morgan) hemorrhoidectomy

Stapled hemorrhoidopexy - excision of a circumferential portion of the lower rectal and upper anal canal mucosa and submucosa with a circular stapling device

• Anterior or posterior midline
• Lateral fissures should raise the possibility Crohn’s disease, tuberculosis, syphilis, HIV/AIDS, or carcinoma

• Medical management
• - effective for acute anal fissures
• - Topical nitrates (0.2% to 0.4% nitroglycerin) or calcium channel blockers (0.2% nifedipine or 2% diltiazem)
• - Temporary chemodenervation of the internal anal sphincter by injection of botulinum toxin (Botox) - promote increased blood flow to the affected anoderm, allowing the fissure to heal.

• Surgical management
• - Lateral internal sphincterotomy remains the operation of choice. Extent of sphincterotomy may be up to the level of the dentate line or to the fissure apex.
• - In patients with chronic or recurrent fissure with hypotensive anal sphincter - fissurectomy with endoanal advancement flap-

• An anal abscess usually originates from an infected anal crypt gland.
• There are typically 8 to 10 anal crypt glands, arranged circumferentially within the anal canal at the level of the dentate line.
• The glands penetrate the internal sphincter and end in the intersphincteric plane.
• An anal abscess develops when an anal crypt gland becomes obstructed with inspissated debris, which permits bacterial growth and abscess formation.
• The suppuration follows the path of least resistance and the infected fluid collects in the space where the gland terminates.

• A. Simple - Perianal abscess
• B. Complex
• 1. Ischiorectal -  penetrate through the external anal sphincter into the ischiorectal space and present as a diffuse, tender, indurated, fluctuant area within the buttocks. 

2. Intersphincteric - They are located in the intersphincteric groove between the internal and external sphincters. As a result, they often do not cause perianal skin changes, but can be palpated as a fluctuant mass protruding into the lumen during digital rectal examination. 

3. Supralevator -  Supralevator abscesses can originate from two different sources: the typical cryptoglandular infection that travels superiorly within the intersphincteric plane to the supralevator space and an inflammatory pelvic process such as perforated diverticular disease or Crohn's disease, or a perforated neoplastic process. As a result, it is important to obtain a history of potential sources of pelvic infection.

4. Horseshoe abscess - Horseshoe abscesses form in the potential space posterior to the anal canal that is bounded by the pelvic floor superiorly, the anococcygeal ligament inferiorly, and the coccyx and anal canal. Because of these relatively rigid boundaries, abscesses in this space are forced into the ischiorectal space, where they can be unilateral or bilateral.

Anal abscesses should be drained in a timely manner. Lack of fluctuance should not be a reason to delay treatment. Simple and superficial abscess are drained under local anesthesia. Complicated large abscess or in presence of immunosuppression (AIDS, diabetes mellitus, chemotherapy), systemic symptoms (fever) need drainage under anesthesia.  

Perianal abscess - simple skin incision is adequate, De-roofing should be done. The incision should be kept as close as possible to the anal verge, without injury to the underlying sphincter muscle, to minimize the length of any potential fistula that may form.

Intersphincteric abscesses - drained into the anal canal by dividing the internal anal sphincter at the level of the abscess

• Supralevator abscess - cause of abscess must be determined before drainage
• - extension of an ischiorectal abscess should be drained via the skin overlying the buttock.
• - originating from a pelvic process should be drained into the rectum to avoid creating an extrasphincteric fistula.

Ischiorectal abscesses should be drained through an appropriate incision through the skin and subcutaneous tissue overlying the infected space.

Horseshoe abscesses -  A modified Hanley procedure that drains the deep postanal space and lateral extensions of the abscess should be performed. A posterior midline incision is made extending from the subcutaneous portion of the external sphincter over the abscess to the tip of the coccyx, separating the superficial external sphincter and unroofing the deep postanal space and its lateral extension. External sphincter and muscle attachments to coccyx are not cut. Lateral incisions can be made and setons placed to drain any anterior extensions of the abscess.

• Anorectal abscess – most common cause .
• Crohn’s Disease
• Lymphogranuloma venereum
• Radiation proctitis
• Rectal foreign bodies
• Actinomycosis

• Intersphincteric: The fistula is confined to the intersphincteric plane, most common anal fistula
• Trans-sphincteric: The fistula traverses the external sphincter, communicating with the ischiorectal fossa.
• Suprasphincteric: The fistula extends cephalad over the external sphincter and perforates the levator ani.
• Extrasphincteric: The fistula extends from the rectum to the perianal skin, external to the sphincter apparatus, often results from iatrogenic injury.

●All fistula tracks with external openings within 3 cm of the anal verge and posterior to a line drawn through the ischial spines travel in a curvilinear fashion to the posterior midline.

●All tracks with external openings anterior to this line enter the anal canal in a radial fashion.

• Simple fistula - minimal involvement of the sphincter complex
• - low trans-sphincteric fistulas
• - intersphincteric fistulas

• Complex fistula - An anal fistula is defined as complex in the following situations:
• Any fistula involving more than 30 percent of the external sphincter
• Suprasphincteric fistulas
• Extrasphincteric or high fistulas, proximal to the dentate or pectinate line
• Women with anterior fistulas
• Fistulas with multiple tracts
• Recurrent fistulas
• Fistulas related to inflammatory bowel disease
• Fistulas related to infectious diseases including tuberculosis and HIV
• Fistulas secondary to local radiation treatments
• Patients with a history of anal incontinence

Simple fistulas - laying the track open by fistulotomy.

Complex fistulas

• 1. Draining seton and cutting seton - 
• -  A cutting seton is a reactive suture or elastic that is placed through the fistula tract and tightened at regular intervals. It slowly cuts through the tract, causing scarring, thus preventing the wide disruption of the anal sphincter associated with fistulotomy.
• - A noncutting or draining seton is a seton that is placed primarily for drainage. It does not cut through the sphincter. Draining setons are used at the time of the first operation to preserve the sphincter mechanism, and help eradicate the septic focus

2. Fibrin glue or porcine-derived fistula plug  that promote healing of the track by providing an extracellular matrix that serves as a scaffolding, allowing ingrowth of host tissue for incorporation and remodeling.

3. Bioprosthetic fistula plug - inserted into the fistula and then secured at the internal opening. The external opening is widened and left open to allow drainage. Over time, tissue will grow into the plug and replace the matrix, obliterating the fistula track

4.  Sliding advancement flap made of mucosa, submucosa, and circular muscle to cover the internal opening

5. Ligation of the intersphincteric fistula (LIFT) track - dissection in the intersphincteric plane for identification of the fistula track and ligation of it to obliterate the communication with the anal canal.

• Most common site for primary gastrointestinal melanoma. 
• The third most common melanoma after the cutaneous and ocular varieties.

• Etiology - 
• - No known risk factors.
• - Risk factors for cutaneous melanoma like nevus, sunlight exposure does not predispose to anal melanoma.

• Pathology - 
• - Melanoma arises from melanocytes derived from neural crest cells.
• - Carcinogenic stimuli in anal melanoma unknown

• Symptoms - 
• - Bleeding per rectum
• - Perianal itching and irritation
• - Mass protruding through anus
• - Perianal discharge

• Spread 
• - Lymphatic Spread : Inguinal & mesorectal nodes.
• - Systemic : Lung, Liver, Brain, Bone

• Diagnosis 
• - DRE and Anoscopy - polypoidal mass
• - Colonoscopy 

• Differential diagnosis 
• - Anal carcinoma/Lymphoma 
• - Perianal hematoma 

• Investigations - 
• - Proctoscopy and Biopsy
• - USG abdomen and pelvis
• - Endoluminal USG

• Immunohistochemistry - 
• - Immunohistochemistry is gold standard for diagnosis
• - Melanoma panel of markers S-100 protein Vimentin, Melan-A, HMB-45.

• Staging 
• - Stage I is local disease.
• - Stage II is local disease with regional lymph nodes.
• - Stage III is distant metastatic disease.

• Treatment - 
• A) Stage I and II
• - Surgical excision is the treatment of choice.
• - Melanoma is highly resistant to radiotherapy/chemotherapy. 
• - Surgery includes wide local excision/APR - should acheive R0 resection. 

• B0 Stage III 
• - Systemic chemotherapy - Dacarbaine, temoolamide
• - Targeted therapy - Imatinib