Rectum

Prof. AMSM SharfuzzamanProfessor of Surgery

Sir Salimullah Medical College

Tuesday, April 11, 2023 1DR. RUBEL, SSMC

ANATOMYAnatomic divisions of the large intestine:

1. Colon2. Rectum3. Anal canal

Layers of the colon and rectum:1. Mucosa2. Submucosa3. Inner circular muscle – Coalesces distally

to create the internal anal sphincter.4. Outer longitudinal muscle – Separated

into three teniae coli in the colon; teniae converge proximally at the appendix and distally at the rectum.

5. Serosa – Covers the intraperitoneal colon and one third of the rectum.




Colorectal and Anorectal Vascular Supply

The arterial supply to the colon is highly variable. In general, the arterial supply to the colon is as follows:1. Superior mesenteric artery branches

a. Ileocolic artery (absent in up to 20 percent of people) supplies blood flow to the terminal ileum and proximal ascending colon.

b. Right colic artery supplies the ascending colon.c. Middle colic artery supplies the transverse colon.

2. Inferior mesenteric artery branchesa. Left colic artery supplies the descending colon.b. Sigmoidal branches supply the sigmoid colon.c. Superior rectal artery supplies the proximal rectum.

The terminal branches of each artery form anastomoses with the terminal branches of the adjacent artery and communicate via the marginal artery of Drummond (complete in only 15–20 percent of people).Tuesday, April 11, 2023 5DR. RUBEL, SSMC

Colorectal and Anorectal Vascular Supply-contd.

3. Internal iliac artery branchesa. Middle rectal artery (variable presence and

size).b. Internal pudendal artery branch.

i. Inferior rectal artery supplies the lower rectum and anal canal.A rich network of collaterals connects the terminal arterioles of each of these arteries, thus making the rectum relatively resistant to ischemia.




Venous drainageExcept for the inferior mesenteric vein, the veins of the colon, rectum, and anus parallel their corresponding arteries and bear the same terminology.

The inferior mesenteric vein ascends in the retroperitoneal plane over the psoas muscle and continues posterior to the pancreas to join the splenic vein. The venous drainage of the rectum parallels the arterial supply.

The superior rectal vein drains into the portal system via the inferior mesenteric vein.

The middle rectal vein drains into the internal iliac vein.

The inferior rectal vein drains into the internal pudendal vein, and subsequently into the internal iliac vein.

A submucosal plexus deep to the columns of Morgagni forms the hemorrhoidal plexus and drains into all three veins.



Colorectal and Anorectal Lymphatic DrainageThe lymphatic drainage of the colon originates in a network of lymphatics in the muscularis mucosa.Lymphatic vessels and lymph nodes followthe regional arteries.

Lymphatic channels in the upper and middle rectum drain superiorly into the inferior mesenteric lymph nodes.

Lymphatic channels in the lower rectum drain both

superiorly into the inferior mesenteric lymph nodes and laterally into the internal iliac lymph nodes.

The anal canal has a more complex pattern of lymphatic drainage. Proximal to the dentate line, lymph drains into both the inferior mesenteric lymph nodes and the internal iliac lymph nodes.

Distal to the dentate line, lymph primarily drains into the inguinal lymph nodes, but also can drain into the inferior mesenteric lymph nodes and internal iliac lymph nodesTuesday, April 11, 2023 11DR. RUBEL, SSMC



Colorectal and Anorectal Nerve SupplyThe nerves to the colon and rectum parallel the course of the arteries.

1. Sympathetic (inhibitory) arise from T6-T12 and L1-L3.

2. Parasympathetic (stimulatory) innervation to the right and transverse colon is from the vagus nerve; parasympathetic nerves to the left colon arise from sacral nerves S2–S4 to form the nervi erigentes.

The external anal sphincter and puborectalis muscles are innervated by the inferior rectal branch of the internal pudendal nerve. The levator ani receives innervation from both the internal pudendal nerve and direct branches of S3–S5.

Sensory innervation to the anal canal is provided by the inferior rectal branch of the pudendal nerve. Whereas the rectum is relatively insensate, the anal canal below the dentate line is sensate.Tuesday, April 11, 2023 14DR. RUBEL, SSMC

CLINICAL EVALUATIONEndoscopy1. Anoscopy – The anoscope is useful for examination of the anal canal andcan generally allow examination of the distal 6–8 cm of the anus. Anoscopycan be diagnostic or therapeutic (e.g., sclerotherapy or rubber band ligationof hemorrhoids).

2. Proctoscopy – The rigid proctoscope is useful for examination of the rectumand distal sigmoid colon and is occasionally used therapeutically(e.g., polypectomy, electrocoagulation, or detorsion of a sigmoid volvulus).

3. Flexible Sigmoidoscopy and Colonoscopy – Flexible sigmoidoscopy and colonoscopy provide excellent visualization of the colon and rectum. Sigmoidoscopes measure 60 cm in length and may allow visualization as high as the splenic flexure. Partial preparation with enemas is usually adequate for sigmoidoscopy and most patients can tolerate this procedure without sedation.Colonoscopes measure 100–160 cm in length and are capable of examiningthe entire colon and terminal ileum. A complete oral bowel preparation usually is necessary for colonoscopy and the duration and discomfort of the procedure usually require conscious sedation. Both sigmoidoscopy and colonoscopy can be used diagnostically and therapeutically


Imaging1. Plain radiograph of the abdomen (supine, upright, and diaphragmatic views) are useful for detecting free intraabdominal air, bowel gas patterns suggestive of small or large bowel obstruction, and volvulus.2. Contrast studies are useful for evaluating obstructive symptoms, delineating fistulous tracts, and diagnosing small perforations or anastomotic leaks. Gastrografin is recommended if perforation or leak is suspected. Doublecontrast barium enema is more sensitive for the detection of mass lesions greater than 1 cm in diameter.3. Computed Tomography – Computed tomography (CT) is commonly employed in the evaluation of patients with abdominal complaints. Its utility is primarily in the detection of extraluminal disease, such as intraabdominalabscesses and pericolic inflammation, and in staging colorectal carcinoma.

Extravasation of oral or rectal contrast also may confirm the diagnosis of perforation or anastomotic leak. Nonspecific findings such as bowel wall thickening or mesenteric stranding may suggest inflammatory bowel disease,enteritis/colitis, or ischemia.

A standard CT scan is relatively insensitive for the detection of intraluminal lesions.


Imaging-contd.5. Magnetic Resonance Imaging (MRI) – The main use of MRI in colorectal disorders is in evaluation of pelvic lesions. MRI is more sensitive than CT for detecting bony involvement or pelvic sidewall extension of rectal tumors. MRI with an endorectal coil can be helpful in the detection and delineation of complex fistulas in ano.

6. Positron Emission Tomography (PET) – Positron emission tomography is used for imaging tissues with high levels of anaerobic glycolysis, such as malignant tumors. PET has been used as an adjunct to CT in the staging of colorectal cancer and may prove useful in discriminating recurrent cancer from fibrosis.

7. Angiography – Angiography is occasionally used for the detection of brisk bleeding (approximately 0.5–1.0 mL per minute) within the colon or small bowel. If extravasation of contrast is identified, infusion of vasopressin or angiographic embolization can be therapeutic.


Imaging-contd.8. Endorectal and Endoanal Ultrasound – Endorectal ultrasound is primarily used to evaluate the depth of invasion of neoplastic lesions in the rectum. Ultrasound can reliably differentiate most benign polyps from invasive tumors and can differentiate superficial (T1–T2) from deeper (T3–T4) tumors.

This modality also can detect enlarged perirectal lymph nodes.

Ultrasound may also prove useful for early detection of local recurrence after surgery.

Endoanal ultrasound is used to evaluate the layers of the anal canal. Internal anal sphincter, external anal sphincter, and puborectalis muscle can be differentiated.

Endoanal ultrasound is particularly useful for detecting sphincter defects and for outlining complex anal fistulas.


ANORECTAL DISEASESHemorrhoidsHemorrhoids have plagued humankind since time immemorial, yet many misunderstandings regarding hemorrhoidal complaints and disease still exist. Many laypersons and physicians do not understand the anorectal area and the common diseases associated with it.

Hemorrhoids are cushions of submucosal tissue containing venules, arterioles, and smooth-muscle fibers that are located in the anal canal. Three hemorrhoidal cushions are found in the left lateral, right anterior, and right posterior positions and are thought to function as part of the continence mechanism. Because hemorrhoids are a normal part of anorectal anatomy, treatment is only indicated if they become symptomatic.



Classification1. External hemorrhoids are located distal to the dentate line and are covered with anoderm. Thrombosis of an external hemorrhoid may cause significant pain. Treatment of external hemorrhoids and skin tags are only indicated for symptomatic relief.2. Internal hemorrhoids are located proximal to the dentate line and covered by insensate anorectal mucosa. Internal hemorrhoids may prolapse or bleed, but rarely become painful unless they develop thrombosis and necrosis. Internal hemorrhoids are graded according to the extent of prolapse:

First-degree hemorrhoids—bulge into the anal canal

Second-degree hemorrhoids—prolapse through the anus but reduce spontaneously

Third-degree hemorrhoids—prolapse through the anal canal and require manual reduction

Fourth-degree hemorrhoids—prolapse but cannot be reduced and are at risk for strangulationTuesday, April 11, 2023 21DR. RUBEL, SSMC

Tuesday, April 11, 2023 DR. RUBEL, SSMC 22

StagingInternal hemorrhoids are grouped into 4 stages, as follows: Stage I - Internal hemorrhoids that bleed.

Stage II – Internal hemorrhoids that cause bleeding and prolapse with straining but return to their resting

point by themselves.

Stage III - Internal hemorrhoids that bleed and prolapse with straining and require manual effort for

replacement into the anal canal.

Stage IV - Internal hemorrhoids that do not return into the anal canal and, thus, are constantly outside.


Classification –contd.3. Combined internal and external hemorrhoids straddle the dentate line and have characteristics of both internal and external hemorrhoids.

4. Postpartum hemorrhoids result from straining during labor, which results in edema, thrombosis, and/or strangulation.

5. Rectal varices may result from portal hypertension. Despite the anastomoses between the portal venous system (middle and upper hemorrhoidal plexuses) and the systemic venous system (inferior rectal plexuses), hemorrhoidal disease is no more common in patients with portal hypertension than in the normal population. Rectal varices, however, may cause significant hemorrhage.

In general, rectal varices are best treated by lowering portal venous pressure. Surgical hemorrhoidectomy should be avoided in these patients because of the risk of massive, difficult-to-control variceal bleeding.Tuesday, April 11, 2023 24DR. RUBEL, SSMC



TreatmentMedical Therapy (dietary fiber, stool softeners, increased fluid intake, and avoidance of straining) – appropriate for bleeding first- and second-degree hemorrhoids.

Rubber Band Ligation, Sclerotherapy, Infrared photocoagulation, Laser ablation, Carbon dioxide freezing, Lord dilatation appropriate for bleeding first-, second-, and selected third-degree hemorrhoids. Excision of Thrombosed External Hemorrhoids. Acutely thrombosed external hemorrhoids generally cause intense pain and a palpable perianal mass during the first 24–72 h after thrombosis. The thrombosis can be effectively treated with an elliptical excision performed in the office under local anesthesia. Because the clot is usually loculated, simple incision and drainage israrely effective. After 72 h, the clot begins to resorb, and the pain resolves spontaneously. Sitz baths and analgesics often are helpful.Tuesday, April 11, 2023 27DR. RUBEL, SSMC

Rubber Band Ligation


Treatment-contd.Sclerotherapy can provide adequate treatment of early internal hemorrhoids. Cryotherapy and sclerotherapy are infrequently used today. Most experienced surgeons use 1 or 2 techniques exclusively.

Operative hemorrhoidectomy. A number of surgical procedures have been described for elective resection of symptomatic hemorrhoids. All are based on decreasing blood flow to the hemorrhoidal plexuses and excising redundant anoderm and mucosa:

1. Closed Submucosal Hemorrhoidectomy

2. Open Hemorrhoidectomy

3. Stapled HemorrhoidectomyTuesday, April 11, 2023 29DR. RUBEL, SSMC



Stapled Hemorrhoidectomy Stapled hemorrhoid surgery, or procedure for prolapsing hemorrhoids (PPH), has recently become prominent. It was first described in 1997-1998. During PPH, a specially designed circular stapler with smaller staples is used. The technique involves placing a suture in the mucosa and submucosal layers circumferentially approximately 3-4 cm above the dentate line. The stapler is placed and slowly closed around the purse string. Care is taken to draw excess internal hemorrhoidal tissue into the stapler. The stapler is fired, resecting the excess tissue and placing a circular staple line above the dentate line. This results in resection of excessive internal hemorrhoidal tissue, pexy of the internal hemorrhoidal tissue left behind and interruption of the blood supply from above. It can be done as an outpatient, using local anesthesia with intravenous (IV) sedation. PPH is mainly used to treat internal hemorrhoids not amenable to conservative and nonoperative therapies. PPH does not directly affect the external tissue. Reports have described shrinking of external hemorrhoidal tissue after PPH, probably from decreased blood flow. PPH combined with judicial excision of occasional skin tags is also reported, with good results

Stapled Hemorrhoidectomy



Preoperative detailsHemorrhoid surgery can usually be performed using local anesthesia with IV sedation. Regional or general anesthetic techniques are also used. Routine preoperative workup for these techniques is required. Simple distal rectal evacuation is required for a clean operative field. Distal rectal evacuation is best achieved by small-volume saline enemas

Postoperative detailsAttention to regular and soft bowel movements is important. Bulk agents (eg, psyllium seed) and oral fluids are important. Bathing in tubs for comfort and hygiene is part of the routine. Judicious narcotic administration relieves pain.

Complications of hemorrhoidectomy1. Postoperative pain – Pain can be significant following excisional hemorrhoidectomy, and requires analgesia with oral narcotics, nonsteroidal antiinflammatory drugs, muscle relaxants, topical analgesics, and sitz baths.

2. Urinary retention – Urinary retention occurs in 10–50 percent of patients after hemorrhoidectomy. The risk of urinary retention can be minimized by limiting intraoperative and perioperative intravenous fluids, and by providing adequate analgesia.

3. Fecal impaction – Risk of impaction may be decreased bypreoperativeenemas or a limited mechanical bowel preparation, liberal use of laxativespostoperatively, and adequate pain control.


4. Bleeding – Massive hemorrhage can occur after hemorrhoidectomy. Bleeding may occur in the immediate postoperative period (often in the recovery room) as a result of inadequate ligation of the vascular pedicle, and mandates an urgent return to the operating room. Bleeding may also occur 7–10 days after hemorrhoidectomy when the necrotic mucosa overlying the vascular pedicle sloughs. Although some of these patients may be safely observed, others will require an exam under anesthesia to ligate the bleeding vessel or to oversew the wounds if no specific site of bleeding is identified.

5. Infection – Infection is uncommon after hemorrhoidectomy; however,necrotizing soft-tissue infection can occur with devastating consequences.Severe pain, fever, and urinary retention may be early signs of serious infection. If this is suspected, an emergent examination under anesthesia,drainage of abscess, and/or debridement of all necrotic tissue are required.

6. Long-term sequelaeA. incontinence (usually transient)B. anal stenosisC. ectropion (Whitehead deformity)


Complications of hemorrhoidectomy-contd.

Anal FissureA fissure in ano is a tear in the anoderm distal to the dentate line. Most analfissures occur in the posterior midline. Ten to 15 percent occur in the anteriormidline. Less than 1 percent of fissures occur off midline.Symptoms and Findings: Characteristic symptoms include tearing pain with defecation and hematochezia. On physical examination, the fissure can often be seen in the anoderm by gently separating the buttocks. Patients are often too tender to tolerate digital rectal examination, anoscopy, or proctoscopy. •An acute fissure is a superficial tear of the distal anoderm and almost always heals with medical management. •Chronic fissures develop ulceration and heaped-up edges with the white fibers of the internal anal sphincter visible at the base of the ulcer. There is often an associated external skin tag and/or a hypertrophied anal papilla internally. These fissures are more challenging to treat and may require surgery.

A lateral location of a chronic anal fissure may be evidence of an underlying disease such as Crohn disease, human immunodeficiency virus, syphilis, tuberculosis, or leukemia.



Anal Fissure


Anal Fissure


Anal Fissure

TreatmentTherapy focuses on breaking the cycle of pain, spasm, and ischemia:1. Dietary changes – bulk agents, stool softeners, and warm sitz baths.

2. Topical agents – Lidocaine jelly or other analgesic creams, nitroglycerinointment, oral and topical diltiazem, and topical nifedipine (effective inmost acute fissures, but will heal only approximately 50–60 percent ofchronic fissures).

3. Botulinum toxin – Botulinum toxin causes temporary muscle paralysis and has been proposed as an alternative to surgical sphincterotomy for chronic fissure.

Although there is limited experience with this approach, results appear to be superior to other medical therapy, and complications such as incontinence are rare.Tuesday, April 11, 2023 40DR. RUBEL, SSMC

Treatment-contd.4. Surgical sphincterotomy – Surgical therapy has been recommended for chronic fissures that have failed medical therapy, and lateral internal sphincterotomy is the procedure of choice for most surgeons. Approximately 30 percent of the internal sphincter fibers are divided. Healing is achieved in more than 95 percent of patients by using this technique and most patients experience immediate pain relief.

Recurrence is rare (less than 10 percent), but the risk of minor incontinence ranges from 5–15 percent.


Anorectal Sepsis and Cryptoglandular AbscessRelevant AnatomyInfection of an anal gland in the intersphincteric space results in the formationof an abscess that enlarges and spreads along one of several planes in theperianal and perirectal spaces. The anatomy of these spaces influences thelocation and spread of infection.1. Perianal space – surrounds the anus and laterally becomes continuous withthe fat of the buttocks2. Intersphincteric space – separates the internal and external anal sphincters.3. Ischiorectal space (ischiorectal fossa) – located lateral and posterior to the anus and bounded medially by the external sphincter, laterally by the ischium, superiorly by the levator ani, and inferiorly by the transverse septum.The two ischiorectal spaces connect posteriorly above the anococcygeal ligament but below the levator ani muscle, forming the deep postanal space.4. Supralevator spaces – above the levator ani on either side of the rectum(communicate posteriorly).


Anorectal Sepsis and Cryptoglandular AbscessRelevant Anatomy


Anorectal Sepsis and Cryptoglandular AbscessRelevant Anatomy


DiagnosisPain is the most common presenting complaint. A palpable mass often is detected by inspection of the perianal area or by digital rectal examination. Occasionally, patients will present with fever, urinary retention, or life-threatening sepsis. The diagnosis of a perianal or ischiorectal abscess can usually be made with physical exam alone.

However, complex or atypical presentations may require imaging studies (CT or MRI) to fully delineate the anatomy of the abscess.


TreatmentAnorectal abscesses should be treated by drainage as soon as the diagnosis isestablished. If the diagnosis is in question, an examination under anesthesia is often the most expeditious way both to confirm the diagnosis and to treat the problem. Antibiotics are only indicated if there is extensive cellulitis or if the patient is immunocompromised, has diabetes mellitus, or has valvular heart disease.

Surgical treatment is based in part on the location of the abscess:Perianal Abscess – painful swelling at the anal verge. Most can be drainedunder local anesthesia. Larger, more complicated abscesses may requiredrainage in the operating room.

Ischiorectal Abscesses – may become extremely large and may involve oneor both sides, forming a “horseshoe” abscess. Simple ischiorectal abscessesare drained through an incision in the overlying skin. Horseshoe abscessesrequire drainage of the deep postanal space and often require counterincisions over one or both ischiorectal spaces.


Drainage of Perianal abscess


Treatment-contd.Intersphincteric Abscess – occur in the intersphincteric space and are notoriously difficult to diagnose. The diagnosis is made based on a high index of suspicion and usually requires an examination under anesthesia. Once identified, an intersphincteric abscess can be drained through a limited, usually posterior, internal sphincterotomy.

Supralevator Abscess – is uncommon and may result from extension of anintersphincteric or ischiorectal abscess upward, or extension of an intraperitoneal abscess downward. It is essential to identify the origin of a supralevator abscess prior to treatment. If the abscess is secondary to an upward extension of an intersphincteric abscess, it should be drained through the rectum.

If a supralevator abscess arises from the upward extension of an ischiorectalabscess, it should be drained through the ischiorectal fossa. If the abscess issecondary to intraabdominal disease, the primary process requires treatmentand the abscess is drained via the most direct route.


Drainage of intersphinteric abscess


Fistula in AnoA fistula-in-ano is a hollow tract lined with granulation tissue connecting a primary opening inside the anal canal to a secondary opening in the perianal skin. Secondary tracts may be multiple and from the same primary opening.Drainage of an anorectal abscess results in cure for about 50 percent of patients. The remaining 50 percent develop a persistent fistula in ano. The fistula usually originates in the infected crypt (internal opening) and tracks to the external opening. The course of the fistula often can be predicted by the anatomy of the previous abscess.



EtiologyFistula-in-ano is nearly always caused by a previous anorectal abscess. Anal canal glands situated at the dentate line afford a path for infecting organisms to reach the intramuscular spaces.

Other fistulae develop secondary to trauma, Crohn disease, anal fissures, carcinoma, radiation therapy, actinomycoses, tuberculosis, and chlamydial infections.

PathophysiologyThe cryptoglandular hypothesis states that an infection begins in the anal gland and progresses into the muscular wall of the anal sphincters to cause an anorectal abscess. Following surgical or spontaneous drainage in the perianal skin, occasionally a granulation tissue–lined tract is left behind, causing recurrent symptoms. Multiple series have shown that the formation of a fistula tract following anorectal abscess occurs in 7-40% of cases.


ClinicalHistoryPatients often provide a reliable history of previous pain, swelling, and spontaneous or planned surgical drainage of an anorectal abscess.Signs and symptoms (in order of prevalence)

Perianal discharge Pain Swelling Bleeding Diarrhea Skin excoriation External opening

Past medical history-particularly in case of complex fistula

Inflammatory bowel disease Diverticulitis Previous radiation therapy for prostate or rectal cancer Tuberculosis Steroid therapy HIV infection

DiagnosisPatients present with persistent drainage from the internal and/or external openings. In general, fistulas with an external opening anteriorly connect to the internal opening by a short, radial tract. Fistulas with an external openingposteriorly track in a curvilinear fashion to the posterior midline (Goodsallrule). However, exceptions to this rule often occur.

Fistulas are categorized based on their relationship to the anal sphincter complex and treatment options are based on these classifications1. Intersphincteric fistula – tracks through the distal internal sphincter to an external opening near the anal verge; often treated by fistulotomy (opening the fistulous tract), curettage, and healing by secondary intention.

2. Trans-sphincteric fistula – results from an ischiorectal abscess and extends through both the internal and external sphincters. “Horseshoe” fistulas usually have an internal opening in the posterior midline and extend anteriorly and laterally to one or both ischiorectal spaces by way of the deep postanal space. Fistulas that include less than 30 percent of the sphincter muscles often can be treated by sphincterotomy. High trans-sphincteric fistulas, which encircle a greater amount of muscle, are more safely treated by initial placement of a seton.


3. Suprasphincteric fistula – originates in the intersphincteric plane and tracks up and around the entire external sphincter and is usually treated with a seton.

4. Extrasphincteric fistula – originates in the rectal wall and tracks around both sphincters to exit laterally, usually in the ischiorectal fossa. Treatment depends on both the anatomy of the fistula and its etiology. In general, the portion of the fistula outside the sphincter should be opened and drained. A primary tract at the level of the dentate line also may be opened if present. Complex fistulas with multiple tracts may require numerous procedures to control sepsis and facilitate healing. Liberal use of drains and setons is helpful.

5. Complex, nonhealing fistula – Complex and/or nonhealing fistulas may result from Crohn disease, malignancy, radiation proctitis, or unusual infection. Proctoscopy should be performed in all cases of complex and/ornonhealing fistulas to assess the health of the rectal mucosa. Biopsies of the fistula tract should be taken to rule out malignancy.



Parks classificationThe Parks classification system defining the 4 major types of anorectal fistulas in order of decreasing frequency is as follows:

Type-1: Intermuscular (70%),Type -2: Trans-sphincteric (23%), Type-3: Extrasphincteric (5%),

Type-4: Suprasphincteric (2%).

The intersphincteric fistula is found between internal and external sphincters. The trans-sphincteric fistula extends through the external sphincter into the ischiorectal fossa. An extrasphincteric fistula passes from rectum to skin through the levator ani. Lastly, the suprasphincteric fistula spans from the intersphincteric plane through the puborectalis muscle, exiting the skin after traversing the levator ani.


Parks classification

Goodsall rule



Imaging studiesFistulography This involves injection of contrast via the internal opening, which is followed by anteroposterior, lateral, and oblique x-ray images to outline the course of the fistula tract. The accuracy rate is 16-48%. Endoanal/endorectal ultrasound Help define muscular anatomy differentiating intersphincteric from trans-sphincteric lesions and can help to evaluate the rectal wall for any suprasphincteric extension. The addition of hydrogen peroxide via the external opening can help outline the fistula tract course. This may be useful to help delineate missed internal openings. This modality has not been used widely for routine clinical fistula evaluation.


Imaging studies-contd.MRI MRI is becoming the study of choice when evaluating complex fistulae. It has been shown to improve recurrence rates by providing information on otherwise unknown extensions.

CT scan A CT scan is more helpful in the setting of perirectal inflammatory disease than in the setting of small fistulae because it is better for delineating fluid pockets that require drainage than for small fistulae.

A barium enema/small bowel series: This is useful for patients with multiple fistulae or recurrent disease to help rule out inflammatory bowel disease.


MRI


Diagnostic procedureExamination under anesthesia

An examination of the perineum, digital rectal examination, and anoscopy are performed after the anesthesia of choice is administered. This examination is necessary before surgical intervention, Several techniques have been described to help locate the course of the fistula and, more importantly, identify the internal opening.

Inject hydrogen peroxide, milk, or dilute methylene blue into the external opening and watch for egress at the dentate line. In the authors' experience, methylene blue often obscures the field more than it helps identify the opening. Traction (pulling or pushing) on the external opening may also cause a dimpling or protrusion of the involved crypt. Insertion of a blunt-tipped crypt probe via the external opening may help outline the direction of the tract. If it approaches the dentate line within a few millimeters, a direct extension likely existed. Care should be taken to not use excessive force and create false passages.

Proctosigmoidoscopy/colonoscopy Rigid sigmoidoscopy can be performed at the initial evaluation to help rule out any associated disease process in the rectum. Further colonic evaluation is performed only as indicated.

TreatmentThe goal of treatment of fistula in ano is eradication of sepsis without sacrificing continence. Because fistulous tracks encircle variable amounts of the sphincter complex, surgical treatment is dictated by the location of the internal and external openings and the course of the fistula. Fistulotomy/fistulectomy The laying-open technique (fistulotomy) is useful for 85-95% of primary fistulae (ie, submucosal, intersphincteric, low transsphincteric). A probe is passed into the tract through the external and internal openings. The overlying skin, subcutaneous tissue, and internal sphincter muscle are divided with a knife or electrocautery, thereby opening the entire fibrous tract. Curettage is performed to remove granulation tissue in the tract base. Complete fistulectomy creates larger wounds that take longer to heal and offers no recurrence advantage over fistulotomy. Some advocate marsupialization of the edges to improve healing times. Perform a biopsy on any firm, suggestive tissue.



Treatment-contd.Seton placementA seton is a drain placed through a fistula to maintain drainage and/or induce fibrosis.

Cutting setons consist of a suture or a rubber band that is placed through the fistula and intermittently tightened. Tightening the seton results in fibrosis and gradual division of the sphincter, thus eliminating the fistula while maintaining continuity of the sphincter.

A noncutting seton is a soft plastic drain (often a vessel loop) placed in the fistula to maintain drainage. The fistula tract may subsequently be laid open with less risk of incontinence because scarring prevents retraction of the sphincter. Alternatively, the seton may be left in place for chronic drainage.

Higher fistulas may be treated by an endorectal advancement flap. Fibrin glue also has been used to treat persistent fistulas with variable results




Outcome and Prognosis

Approximately two thirds of patients with rectal abscesses treated by incision and drainage or by spontaneous drainage will develop a chronic anal fistula.

The recurrence rate of anorectal fistulas after fistulotomy, fistulectomy, or use of a Seton is about 1.5%.

The overall incidence of major fecal incontinence after surgical management of complex suprasphincteric fistulas is estimated at approximately 7%.

Pilonidal DiseasePilonidal disease (cyst, infection) consists of a hair-containing sinus or abscess occurring in the intergluteal cleft. These ingrown hairs may then become infected and present acutely as an abscess in the sacrococcygeal region.

Anacute abscess should be incised and drained as soon as the diagnosis is made. Once an acute episode has resolved, recurrence is common.

Definitive surgical treatment may include:1. Unroofing the tract, curetting the base, and

marsupializing the wound2. Small lateral incision and pit excision3. Flap closure, Z-plasty, advancement flap, or

rotational flap (extensive and/or recurrent pilonidal disease)


Pilonidal sinus

Hair in pilonidal sinus


Rectal ProlapseRectal prolapse (procidentia) is a protrusion of the full thickness of the rectum through the anus. The proposed causes are colonic intussusception or a sliding hernia. Essential defects may be poor rectal support and increased intra-abdominal pressure.

The condition is seen more commonly in the elderly, particularly those from nursing homes or on psychotropic drugs.

Anatomically, patients with rectal prolapse have deep rectovesical space (Douglas pouch); lax levator muscles; a weak puborectalis, with loss of the acute angle it produces between the rectum andanus by pulling anteriorly; poor fixation of the rectum to the sacrum posteriorly; and poor support from the lateral ligaments.Tuesday, April 11, 2023 69DR. RUBEL, SSMC


Clinical PresentationThe patient complains of the prolapse, rectal bleeding, ordischarge. Prolapse occurs on straining and, early in thecourse of the disease, it reduces spontaneously.With time,the patient has to reduce it manually. As the prolapseincreases, anal sphincter incompetence and incontinencedevelop. A situation of full procidentia, where the prolapsecannot be reduced, may occur.

InvestigationIt is essential that the prolapse be demonstrated. Fullevaluation of the colon is necessary with colonoscopy andbarium enema.


TreatmentSurgical treatment combines elements of bowel resection and rectal fixation. The procedures have a success rate of approximately 85% and include:1. Anterior resection and suture fixation of the fully mobilized rectum to the sacrum is appropriate for low-risk patients who have normal anal sphincter function.

2. The Ripstein procedure, in which the rectum is fully mobilized and anchored to the presacral fascia with a Teflon or Mersilene mesh, may be useful for low-risk patients with incompetent anal sphincter.

3. The Thiersch loop, used in high-risk elderly patients, is a loop of stainless steel wire placed subcutaneously around the circumference of the anus. This procedure can provide effective palliation but may be complicated by fecal compaction, infection, or erosion of the wire into therectum.


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