Large bowel obstruction Flashcards
Pathophysiology of bowel obstruction
-Bowel completely obstructed –> distends due to bacterial overgrowth with gas forming organisms and air that is swallowed and constant stream of enteric fluids –> increased luminal pressure–> oedema and fluid sequestration from increased pressure in the capillary bed –> ischaemia –> infarction –> necrosis and eventually perforation
If colon obstructed distally, what tends to perforate
-If the ileocaecal valve is competent, the caecum tends to perforate
Aetiology of large bowel obstruction
- Colorectal cancer
- Sigmoid volvulus
- Diverticular stricture
- Others: fecal impaction, foreign body, hernia, adhesions, radiation strictures, carcinomatosis
Differential diagnosis of large bowel obstruction
- Small bowel obstruction
- Ileus
- Hirschprung’s disease
- colonic pseudo obstruction
- Congenital leiomyopathy
- toxic megacolon
Symptoms of large bowel obstruction
- Early onset obstipation and abdominal distension
- Abdominal pain is usually mild and vomiting occurs late
A patient who can pin point the exact time at which the obstruction occurred is likely suffering from ?
Volvulus
examination findings in large bowel obstruction
- Degree of abdominal distension
- Abdomen can be completely non tender and soft or if perforation is imminent, tender
- Bowel sounds can be increased or absent
- PR examination to look for rectal tumour
signs of Small bowel obstruction on abdominal xray?
Distended loops of bowel in a central distribution and the presence of linea coniventes (lines that run across the entire width of the bowel)
signs of large bowel obstruction on xray
- Large bowel obstruction has a more peripheral distibution and haustra (indentations along the border of the bowel)
- However: sigmoid and transverse colon can lie in the centre of the abdomen and can have lines that transverse the entire width of the bowel as a result of over distension and kinking
What investigations are used to detect the site of bowel obstruction
- Water soluble contrast enema
- CT scan with rectal contrast
- Barium should be avoided
Basic management of large bowel obstruction
- Large bore IV access and patient resuscitated as clinically indicated
- Urinary catheter to monitor output and organ perfusion
- If patient vomiting - nasogastric tube
- Assess renal function and electrolytes
Management of obstruction proximal to the splenic flexure
Midline laparotomy and a right hemicolectomy or extended right colectomy.
A primary anastomosis can be performed unless patient is haemodynamically unstable or presence of overt peritoneal sepsis
What is the three stage procedure for left sided obstruction (usually done for rectal cancer)
- stage one: proximal stoma created to decompress the colon
- Stage two: Obstructing lesion (usually cancer) is removed
- Stage three: the stoma is closed
What is the two stage procedure for a left sided obstruction (commonly done for sigmoid ca)
- Stage 1: resection of obstructing lesion and creation of colostomy (hartmanns procedure)
- Stage 2: Closure of colostomy
What are the two options for a one stage procedure for a left-sided obstruction
- Subtotal colectomy and Ileorectal anastomosis
- Segmental colectomy, on table washout and primary repair
