SU28.13-17 | Intestinal, Appendicular and Anorectal Surgery — Assignment

CLINICAL SCENARIO

A 68-year-old man is referred to the surgical clinic with a six-week history of altered bowel habit (looser, more frequent stools), intermittent dark-red rectal bleeding mixed with the stool, and unintentional weight loss. He is pale. Over the same week, the on-call team also reviews a 20-year-old student admitted overnight with central abdominal pain that has migrated to the right iliac fossa, with anorexia and nausea, and tenderness with rebound at McBurney's point. You are the intern asked to prepare a structured account that uses intestinal and anorectal anatomy to reason through both presentations for the firm's teaching meeting.

1. Applied anatomy underpinning the cases

Summarise the surgically relevant anatomy of the small and large intestine (embryological seam, SMA/IMA supply, watershed zones, valvulae conniventes vs haustra) and of the anorectum (the dentate line and its consequences).

Guidance: Emphasise features that change the operation or the X-ray: SMA/IMA seam and the splenic-flexure watershed; central full-width valvulae conniventes vs peripheral partial haustra; the dentate line dividing painless visceral from painful somatic disease.

2. The older man: differential and the colorectal-cancer reasoning

Construct a differential for altered bowel habit with rectal bleeding and anaemia in a 68-year-old, and justify why colorectal cancer must lead. Contrast right-sided and left-sided presentations.

Guidance: Tie anaemia to a right-sided lesion and obstruction/altered habit/PR bleeding to a left-sided lesion. Invoke the adenoma-carcinoma sequence and the rule 'never call rectal bleeding just piles'. Mention exclusion of haemorrhoids only after excluding cancer.

3. Investigation and staging of the colorectal case

Outline the investigations you would arrange and how the tumour would be staged.

Guidance: Colonoscopy with biopsy, CT for staging; name Dukes and TNM staging and what they add. Note bloods (FBC for anaemia, CEA as a baseline tumour marker).

4. The young patient: appendicitis reasoning and management

Explain the pathophysiology of acute appendicitis as a clinical diagnosis, the role of scoring (Alvarado), and the definitive management, including how you would manage an appendix mass versus an abscess.

Guidance: Trace luminal obstruction → distension → ischaemia → perforation; explain migratory pain, anorexia, McBurney's tenderness; appendicectomy is definitive; contrast conservative management of an uncomplicated appendix mass with drainage of an abscess.

5. Integrating anatomy with safe management

Draw the threads together: how does anatomy keep the patient safe in each case? Address the danger sign in obstruction and the safety reflex in anorectal bleeding.

Guidance: Explain the shift from colicky to constant pain as the marker of strangulation; the watershed zone's relevance to anastomosis; and why every anorectal bleed needs a per-rectal examination and, where red flags exist, a colonoscopy.