Abdominal Pain OSCE - Bowel Obstruction

Case Overview

• Age/Sex: 72-year-old male
• Occupation: Retired postal worker
• Setting: Presents to emergency department
• Chief complaint: "My tummy is hurting a lot and I can't keep anything down"

Patient Script

Who I Am

I'm 72, retired, I live alone in a ground-floor flat and I usually look after myself.

What Brings Me In

My stomach's been painful and swollen and I've been vomiting so I couldn't keep any food or water down.

My Story

It started about 3 days ago with a crampy pain around my belly that came and went. Over the last 48 hours the pain got worse and more constant, and in the last 24 hours my tummy has swollen up a lot and I began vomiting repeatedly (mostly yellow/green fluid). I haven't opened my bowels or passed wind for about 2 days. I feel weak and hadn't eaten for a day before I came in. I did have a mild cough and a bit of a sore throat that started 5 days ago and I took some leftover antibiotics from a friend for a couple of days (they helped the cough a bit). I tried a couple of doses of senna for constipation last week which usually helps, but it hasn't this time.

My Medical Background

• Past medical history: benign prostatic hyperplasia (BPH), osteoarthritis of knees
• Past surgical history: open appendicectomy in his 30s
• Medications: tamsulosin nightly, paracetamol PRN, over-the-counter senna occasionally
• Allergies: none known
• Social: lives alone, drinks 1–2 units alcohol/day, ex-smoker (20 pack-years, quit 20 years ago)
• Family: no known bowel cancer in first-degree relatives

What I Think & Worry About

• "I think something serious is wrong with my gut — I'm worried I might need an operation."
• "I'm scared I will be stuck in hospital for a long time because I live alone."

If You Ask Me About Other Symptoms...

• Pain: "It's worse across the middle and all over now, sharp and I can't get comfortable."
• Vomiting: "I've vomited several times today — mostly yellow, once it had a bit of green."
• Bowel motions: "I haven't opened my bowels or passed wind for about 2 days."
• Fever/chills: "I felt a bit hot on and off but I haven't checked a temperature."
• Urine: "I've been going to the loo more at night lately but I think that's just my prostrate — no burning."
• Chest: "Just that mild cough that started a few days ago, no chest pain."
• Mobility: "I've been feeling weak and sat down more; I fell getting out of the shower a week ago but was fine."

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Clinical Summary

Examination

• General: alert but uncomfortable, lying still on trolley
• Vitals: T 37.9°C, HR 110 bpm, BP 100/64 mmHg, RR 22/min, SpO2 96% on room air
• Hydration: dry mucous membranes
• Abdomen: moderate-to-marked distension; generalized tenderness worse centrally; localized guarding in the right lower quadrant; tympanic on percussion; bowel sounds high-pitched and frequent
• Hernia exam: no obvious abdominal wall or groin hernia on inspection
• Rectal exam: empty vault, no fresh blood

Investigations

• CBC: WCC 15.2 x10^9/L (mild leukocytosis) (suggests inflammatory response)
• Hb: 13.0 g/dL (within age-appropriate range)
• Electrolytes: Na 132 mmol/L, K 3.1 mmol/L (hypokalaemia), creatinine 150 µmol/L (baseline unknown; likely pre-renal)
• CRP: 120 mg/L (elevated)
• Venous lactate: 3.4 mmol/L (elevated — concern for hypoperfusion/ischemia)
• ABG (if done): metabolic alkalosis pattern (consistent with vomiting)
• Urinalysis: mild concentration, no significant leukocytes or nitrites
• Upright abdominal X-ray: multiple air-fluid levels in small bowel, dilated small bowel loops up to 4–5 cm, paucity of gas in colon (consistent with small bowel obstruction)
• CT abdomen pelvis with IV contrast: dilated proximal small bowel with transition point in mid-ileum, collapsed distal bowel, surrounding mesenteric stranding and mild free fluid (suspicious for partial strangulation)

Diagnosis

• Primary: Small bowel obstruction (SBO) with features concerning for early strangulation/ischemia

  • Evidence: history of progressive colicky pain, vomiting, obstipation, abdominal distension; plain film and CT demonstrating dilated proximal small bowel with transition point and mesenteric stranding; elevated lactate and WCC suggest possible ischemia.

• Differential diagnoses:

  • Large bowel obstruction (e.g., sigmoid volvulus) — less likely due to radiographic pattern showing small bowel dilatation and paucity of colonic distension.
  • Adynamic ileus — less likely as bowel sounds are high-pitched and imaging shows discrete transition point.
  • Mesenteric ischemia primarily from thrombotic occlusion — possible but CT shows mechanical transition point consistent with obstruction causing secondary ischemia.
  • Severe gastroenteritis — less likely given obstipation, radiographic findings, and progressive distension.

Management

• Immediate resuscitation: IV crystalloid bolus and correction of intravascular volume
• Nil by mouth (NPO) and place nasogastric tube for decompression
• IV antiemetic and cautious analgesia (avoid masking abdominal signs)
• Correct electrolyte abnormalities (replace potassium) and monitor renal function
• Urgent surgical review and escalation: likely need for operative management given CT findings and elevated lactate
• If concern for strangulation/ischemia: broad-spectrum IV antibiotics (e.g., cover gut flora) and prompt transfer to theatre as indicated
• Foley catheter for accurate fluid balance monitoring
• If CT not yet performed and patient stable: urgent contrast-enhanced CT to define cause and operative planning

Key Learning Points

• Classic SBO presentation: colicky abdominal pain, vomiting, abdominal distension and obstipation — look for the tetrad.
• Red flags for strangulation/ischemia include constant severe pain, systemic signs (tachycardia, fever), elevated WBC and lactate, localized peritonism, and CT features such as mesenteric stranding or free fluid.
• Initial management focuses on resuscitation, decompression (NG tube), electrolyte correction, and urgent surgical assessment; imaging (CT) guides operative planning.