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| Question | Answer |
| What are the mechanical causes of IO? | Intra luminal - stools, gallstone ileus, foreign body Intra mural - malignant strictures, inflammatory strictures e.g. TB/Crohn's/diverticulitis, colitis Extra-mural - intraperitoneal bands and adhesions, hernia, volvulus (sigmoid/cecum), intussusception, lymph node compression, SMA syndrome |
| What are the functional causes of IO? | Paralytic ileus and pseudo-obstruction |
| What does paralytic ileus lead to? | Accumulation of gas & fluid with associated distension, vomiting, absence of bowel sounds and obstipation |
| What are causes of paralytic ileus? | 1. Post-operative (most common) - physiological, self-limiting within 2-3 days 2. Infection - intra-abdo sepsis 3. Reflex ileus - retroperitoneal hematoma, intra-abdo inflammation/peritonitis, biliary/renal colic, trauma, spinal cord injury above T5 4. Ischemic bowel 5. Metabolic - uremia & hypoK most common, DKA, hypothyroidism, drugs e.g. opiate, antacids, TCA |
| What are causes of pseudo-obstruction? | 1. Idiopathic SI pseudo-obs 2. Acute colonic: toxic megacolon, ogilvie syndrome 3. Chronic colonic: Hirschsprung, paraneoplastic immune mediated (small cell lung CA), infection (Chagas' disease) |
| What bowel changes does IO lead to? | 1. Distal collapse (below level of obstruct) 2. Proximal Dilation - stool, gas, fluid accumulation 3. Strangulation: compromised venous return --> increased capillary pressure --> local mural distension due to fluid and cellular exudation --> compromised arterial supply --> ischemic bowel --> oedematous and infarcts --> gangrene and perforation --> peritonitis and septicaemia 4. Simple obstruction: 1 obstruction, no vascular compromise 5. Closed loop obstruction: obstruct at 2 points, forming grossly distended bowel --> at risk for perforation, >10cm requires urgent decompression |
| What are the 4 cardinal symptoms of IO? | |
| What other history to ask? | Symptoms of GIT bleed, infection; past surgeries; underlying GIT disorders; RF for ischemic bowel: atherosclerotic, heart disease, past strokes; suspicion of malignancies: LOW, LOA, prev cancer, family history of cancer |
| What investigations to do? | Diagnostic Invx 1. AXR - supine & erect 2. X-ray KUB 3. Barium Enema 4. Colonoscopy 5. CT colonography Assess Complications 1. FBC - any infections, anemia 2. U/E/Cr - dehydration, intraluminal 3rd space loss, vomiting 3. ABG - acidosis from bowel schema, alkalosis due to vomiting 4. Lactate - anaerobic respiration 5. Amylase - acute pancreatitis 6. Erect CXR - free air under diaphragm, aspiration pneumonia 7. AXR: Rigler's sign/double-wall sign --> pneumoperitoneum ; Thumb-print sign --> ischemic bowel Pre-Op 1. GXM 4 pints of blood 2. PT/PTT 3. ECG / Cardiac enzymes |
| What is the acute management? | Rule out surgical emergencies: ischemic bowel with necrosis, perforation/peritonitis, obstructed and strangulated abdominal hernia, volvulus, closed-loop obstruction 1. ABC 2. Keep NBM 3. NG tube suction 4. IV fluid rehydration 5. Urinary catherization 6. Correct electrolyte abnormalities 7. Prophylactic BSAbx 8. CVP monitoring 9. Surgical decompression |
| What is the definitive management? |
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