General Surgery
Intestine, Colon and Anorectal Disease
MBBS surgery notes on bowel and anorectal disease: appendicitis, obstruction, colorectal cancer and haemorrhoids, mapped to NMC codes SU28.13 to SU28.18.
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Intestine, Colon and Anorectal Disease
MBBS surgery notes on bowel and anorectal disease: appendicitis, obstruction, colorectal cancer and haemorrhoids, mapped to NMC codes SU28.13 to SU28.18.
This chapter covers surgical disease of the small and large bowel and the anorectum. It spans appendicitis, intestinal obstruction, colorectal cancer, inflammatory bowel disease and the common anal conditions.
High-yield: Intestine, Colon and Anorectal Disease
- Acute appendicitis classically starts with central abdominal pain that shifts to the right iliac fossa with anorexia, nausea and low-grade fever.
- McBurney point tenderness, Rovsing sign and rebound tenderness support the diagnosis of appendicitis.
- The four cardinal features of intestinal obstruction are colicky pain, vomiting, absolute constipation and abdominal distension.
- Small bowel obstruction causes early vomiting and central colic, while large bowel obstruction causes distension and later vomiting.
- The commonest cause of small bowel obstruction is adhesions, and of large bowel obstruction is colorectal cancer.
- A sigmoid volvulus gives a hugely distended abdomen and a coffee bean sign on the abdominal radiograph.
- Colorectal cancer on the left presents with change of bowel habit and bleeding, while right-sided cancer presents with anaemia and a mass.
- The tumour marker carcinoembryonic antigen is used to monitor colorectal cancer, not to diagnose it.
- Ulcerative colitis affects the colon continuously from the rectum, while Crohn disease is patchy and can affect any part of the gut.
- Diverticular disease can cause diverticulitis, with left iliac fossa pain and fever, and lower gastrointestinal bleeding.
- Haemorrhoids present with bright red painless rectal bleeding and are graded one to four by the degree of prolapse.
- An anal fissure causes severe pain on defaecation with a small streak of bright red blood and is usually in the posterior midline.
- A perianal abscess presents with a painful, hot, tender perianal swelling and is treated by drainage.
- A fistula in ano is a track between the anal canal and perianal skin, and the Goodsall rule predicts its course.
- Rectal cancer and any change in bowel habit or rectal bleeding warrant a per rectal examination and colonoscopy.
Intestinal obstruction essentials
- **Cardinal features:** Colicky pain, vomiting, absolute constipation and abdominal distension.
- **Small bowel:** Early vomiting, central colic; commonest cause is adhesions.
- **Large bowel:** Marked distension, later vomiting; commonest cause is colorectal cancer.
- **Sigmoid volvulus:** Massive distension with a coffee bean sign on radiograph.
NMC competencies in this chapter
- **SU28.13:** Acute appendicitis and the acute abdomen
- **SU28.14:** Intestinal obstruction
- **SU28.15:** Colorectal cancer
- **SU28.16:** Inflammatory bowel disease and diverticular disease
- **SU28.17:** Anorectal disease: haemorrhoids, fissure and fistula
- **SU28.18:** Rectal examination and endoscopy of the lower gut
Frequently Asked Questions
How does acute appendicitis typically present?
With central abdominal pain that shifts to the right iliac fossa, anorexia, nausea and a low-grade fever, with tenderness at McBurney point and rebound tenderness on examination.
What are the cardinal features of intestinal obstruction?
Colicky abdominal pain, vomiting, absolute constipation and abdominal distension. Their timing and pattern help distinguish small from large bowel obstruction.
How does colorectal cancer present by side?
Left-sided cancer causes change of bowel habit and rectal bleeding, while right-sided cancer causes iron deficiency anaemia and a palpable mass because the lumen is wider.
How do haemorrhoids and an anal fissure differ?
Haemorrhoids cause bright red painless bleeding and prolapse, whereas an anal fissure causes severe pain on defaecation with a small streak of blood, usually in the posterior midline.
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