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SU28.13-17 | Intestinal, Appendicular and Anorectal Surgery — PBL Case
CLINICAL SETTING
The surgical take is busy and the consultant uses the morning to teach the firm how anatomy decides management from the foot of the bed to the operating theatre. Three patients across the gastrointestinal tract are presented in turn. For each trigger, work out the diagnosis, the investigations that would confirm it, and the principles of management — and, at every step, state the anatomical or pathological reason behind your decision.
Trigger 1: The distended abdomen on the night take
A 72-year-old woman presents with several days of abdominal distension, absolute constipation, colicky then increasingly constant lower abdominal pain, and vomiting that came on late. She has had no previous surgery. A plain abdominal film shows grossly distended peripheral loops whose haustra do not cross the full width of the lumen. The intern wonders aloud whether this could just be constipation that will settle.
DISCUSSION POINTS
- From the film alone, is this small-bowel or large-bowel obstruction, and what features tell you so?
- In an adult, how should a large-bowel obstruction be regarded until proven otherwise, and what are the two leading causes?
- What is the significance of the pain changing from colicky to constant, and how would this change your urgency and plan?
Click to reveal Trigger 2: The student with the migrating pain (discuss previous trigger first!)
Trigger 2: The student with the migrating pain
A 19-year-old man describes pain that began around the umbilicus and over a day shifted to the right iliac fossa, accompanied by loss of appetite and nausea. He lies still on the trolley. There is tenderness with rebound at the junction of the lateral one-third and medial two-thirds of a line from the umbilicus to the anterior superior iliac spine, and a low-grade fever.
DISCUSSION POINTS
- Trace the pathophysiology that explains why the pain starts centrally and then localises to the right iliac fossa.
- Name the point of maximal tenderness and describe how a clinical score such as Alvarado supports your decision-making.
- What is the definitive treatment, and how would your plan differ if, instead, he presented five days in with a tender right iliac fossa mass?
Click to reveal Trigger 3: The two patients in the proctology clinic (discuss previous trigger first!)
Trigger 3: The two patients in the proctology clinic
Two patients are seen together. The first, aged 55, reports painless bright-red bleeding that drips into the pan after defecation; proctoscopy shows enlarged cushions above the dentate line. The second, aged 32, has severe pain on defecation with a small streak of blood and a tear in the posterior midline of the anal canal with a sentinel skin tag.
DISCUSSION POINTS
- Using the dentate line, explain why the first patient's bleeding is painless and the second patient's defecation is agonising.
- What is the diagnosis and the graded/structured management for each (haemorrhoid grades I-IV; fissure ladder), and why does the posterior midline matter for the fissure?
- Before reassuring the 55-year-old that this is 'just piles', what must you do and why?
Group Task Assignments
- Build a comparison table of small-bowel versus large-bowel obstruction covering plain-film features, timing of vomiting, commonest causes, and initial management.
- Produce a one-page summary of the dentate line as the organising principle of anorectal disease, mapping innervation, drainage and the painful/painless conditions on each side.
- Draft a safe management algorithm for rectal bleeding that guarantees colorectal cancer is excluded before any anorectal complaint is labelled benign.
Learning Issues
Research these questions and bring your findings to the discussion.
- [SU28.13] What is the applied anatomy of the small and large intestine (embryological seam, SMA/IMA supply, watershed zones, radiological features) and why does it decide the operation and the X-ray?
- [SU28.14] What are the clinical features, investigations and principles of management of disorders of the small and large intestine, including obstruction, intussusception, inflammatory bowel disease and colorectal cancer?
- [SU28.15] What are the clinical features, scoring, investigations and management of appendicitis and its complications, including the appendix mass and abscess?
- [SU28.16] What is the applied anatomy of the rectum and anal canal, and why is the dentate line clinically decisive?
- [SU28.17] What are the clinical features, investigations and principles of management of common anorectal diseases (haemorrhoids, fissure, fistula, abscess)?