Anatomy of the Anal Canal

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Questions and Answers

What is the recommended treatment for absence of the rectum in a child?

No treatment necessary

Immediate colostomy

Enema administration

Surgical repair when discovered (correct)

How might a rectal injury occur during childbirth?

High-speed trauma

Perforation by the anal sphincters (correct)

Objects introduced accidentally

During enema administration

What clinical features may indicate a lower abdominal perforation?

Tenderness, guarding, and rigidity (correct)

Chest pain and shortness of breath

Flank pain and urinary symptoms

Headache and dizziness

How can an intraperitoneal perforation be identified?

Leakage of air and feces into the peritoneal cavity Signup and view all the answers

What is a possible consequence of barium peritonitis?

Rapidly becoming shocked and ill Signup and view all the answers

How should a lower rectal injury be managed?

Examination under anaesthetic, debridement, and sphincter testing Signup and view all the answers

What is the recommended initial step before treating anal conditions?

Thorough examination including sigmoidoscopy and proctoscopy Signup and view all the answers

What is typically observed upon examination of the anus in cases of fistula?

Granulating hole in the skin adjacent to the anus Signup and view all the answers

What should be located before laying open an anorectal fistula?

The Goodsall's rule Signup and view all the answers

How is an anorectal fistula described in terms of its communication path?

Communicates between the rectum and the skin through the levator ani Signup and view all the answers

What may have caused a rare anal fistula according to the text?

Iatrogenic by incautious probing of a pelvirectal abscess Signup and view all the answers

Why is an anaesthetic preserving anal muscle tone preferred during treatment?

To maintain anal muscle integrity Signup and view all the answers

What type of muscle is the internal sphincter composed of?

Circular smooth muscle Signup and view all the answers

Where does the external sphincter lie in relation to the longitudinal muscle?

Outside Signup and view all the answers

What kind of epithelium lines the upper half of the anal canal?

Columnar epithelium Signup and view all the answers

Where are the anal glands located?

At the pectinate line Signup and view all the answers

Which artery supplies blood to the rectum?

Superior rectal artery Signup and view all the answers

Where do the veins draining from the lower rectum and upper anal canal drain into?

Portal circulation via inferior mesenteric vein Signup and view all the answers

What is the main outcome when an abscess points to the perianal skin?

Development of a superficial abscess Signup and view all the answers

Which condition can lead to a pelvirectal abscess not originating from the anal area?

Appendicitis Signup and view all the answers

What could be a sign of deeper abscesses like ischiorectal or pelvirectal?

High fever Signup and view all the answers

Which organization is commonly found as the infecting organism in anal abscesses?

Escherichia coli Signup and view all the answers

When should Crohn's disease be suspected in cases of anal sepsis?

In cases of recurrent or complicated abscess distributions Signup and view all the answers

How do superficial perianal abscesses typically manifest?

With severe pain on defecation Signup and view all the answers

What is the treatment approach for fistula-in-ano?

Excising the fistula track from below Signup and view all the answers

What might result in incontinence if cut during treatment of fistula?

Anorectal ring Signup and view all the answers

What may be required for histological examination in recurrent or problematical fistulae?

Any tissue removed Signup and view all the answers

When is a tuberculous fistula-in-ano usually found?

In patients with pulmonary TB Signup and view all the answers

What is a common clinical feature associated with rectal prolapse?

Reducible prolapse Signup and view all the answers

How is minor mucosal prolapse usually treated?

Injection of haemorrhoids Signup and view all the answers

Study Notes

Anal Abscesses and Fistulae

An anal abscess is a collection of pus in the tissues surrounding the anus, which can point into the anal canal, perianal skin, or ischiorectal space.
Perianal sweat and sebaceous glands or an infected perianal haematoma can initiate a superficial perianal abscess.
Pelvirectal abscess is not of anal origin but is due to an intra-abdominal pelvic abscess collection, e.g. due to appendicitis, diverticulitis, or gynaecological sepsis.
A small proportion of anal sepsis cases are associated with Crohn's disease.

Clinical Features of Anal Abscesses

Pain in the anus begins slowly and builds up over 24 to 48 hours, becoming severe, especially on defecation.
Constitutional upset is not great in the case of superficial abscesses, but a mild fever may develop.
With deeper abscesses, such as ischiorectal or pelvirectal, a high fever, malaise, tachycardia, and leucocytosis may be present.

Treatment of Anal Abscesses

Simple abscesses require division of the membrane at the base of the anal pit.
More complicated abnormalities with fistula formation require repair at a later stage.
Absence of the rectum should be treated by defunctioning colostomy when this is discovered, and a definitive repair made when the child is older.

Injuries to the Rectum

The rectum may be injured by objects introduced by accident or deliberately, during an enema or sigmoidoscopy, or by perineal tear during childbirth.
High-speed trauma, as in road accidents, with multiple fractures of the pelvis may injure the rectum as well as the bladder and urethra.

Clinical Features of Rectal Injuries

An intraperitoneal perforation will cause leakage of air and faeces into the peritoneal cavity, leading to lower abdominal pain and peritonitis.
A lower perforation or laceration should be examined under anaesthetic, debrided, and the sphincter tested.
The history of discharge followed by healing and then further discharge is typical and may have occurred for many months or years prior to presentation.

Treatment of Rectal Injuries

A thorough examination including sigmoidoscopy and proctoscopy should be performed under anaesthetic prior to any treatment.
An anaesthetic which preserves the tone of the anal muscles is preferred.
The anal canal should be palpated and then inspected to find an internal opening, bearing in mind Goodsall's rule.

Anorectal Fistulae

An anorectal fistula is a rare condition that communicates between the rectum and the skin through the levator ani and above the anorectal ring.
Treatment of anorectal fistula is to core out the fistula track from below through the levator ani.
The anorectal ring cannot be cut without incontinence resulting.
Sometimes a colostomy is required while the healing takes place.

Other Conditions

Prolapse of the rectum may be mucosal only or full-thickness rectal prolapse.
Clinical features include bleeding, mucous discharge, a prolapsing swelling, and incontinence of faeces.
Treatment of minor degrees of mucosal prolapse may involve injections of haemorrhoids or excision of the mucosa.

Anatomy of the Rectum and Anus

The internal sphincter is a thickening of the circular smooth muscle of the bowel alongside the anal canal.
The external sphincter lies outside the longitudinal muscle and is composed of striated muscle.
The anal canal is lined in its upper half by columnar epithelium, and then by intermediate cuboidal epithelium and squamous epithelium with sebaceous and sweat glands.
Anal glands are present at the pectinate line.
The blood supply to the rectum is via the superior rectal artery, middle rectal arteries, and inferior rectal arteries.
The mucosa of the lower rectum and upper anal canal contains a rich plexus of veins.

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Description

Test your knowledge on the anatomy of the anal canal including the internal and external sphincters, epithelial lining, and anal glands.