Intestinal obstruction Flashcards
What is intestinal obstruction?
Obstruction of normal movement of bowel contents: mechanical blockage
How may intestinal obstruction be classified?
Small or Large bowel
Partial or Complete obstruction
Simple or Strangulated
Extramural, intramural or intraluminal
List 4 causes of extramural intestinal obstruction
Hernia (SB)
Adhesions (SB)
Bands
Volvulus (LB)
List 4 causes of intramural intestinal obstruction
Tumours: Single or Multifocal (LB)
Inflammatory strictures (e.g. Crohn’s)
Diverticular strictures (LB)
Intussusception
List 3 causes of intraluminal intestinal obstruction
Pedunculated tumours
Foreign body (e.g. bezoars, gallstones)
Faecal impaction
Describe the epidemiology of intestinal obstruction
COMMON
More common in ELDERLY due to increased incidence of adhesions, hernias + malignancy
List 5 symptoms of intestinal obstruction
Severe gripping colicky pain with periods of ease
Abdo distension
Vomiting (may be bile-stained or faeculent)
Absolute constipation
Anorexia
Describe pain in small bowel obstruction
Colicky (cramping + intermittent), with spasms lasting a few minutes.
Pain central + mid-abdominal.
Vomiting may occur before constipation
Describe pain in large bowel obstruction
felt lower in the abdomen + spasms last longer.
List 5 signs of intestinal obstruction
Abdo distension with generalised tenderness
Visible peristalsis
Tinkling bowel sounds
Tympanic to percussion
Peritonitis: absent bowel sounds, guarding + rebound tenderness
List 4 investigations used for intestinal obstruction
Bloods
ABG/ VBG (High lactate indicates poor bowel perfusion)
AXR: Assists dx + localisation
CT: establishes cause
What may be seen on abdominal x-ray in small bowel obstruction?
dilated bowel >3cm
Central gas shadows
Valvulae conniventes (completely cross the lumen)
No gas in large bowel
What may be seen on abdominal x-ray in large bowel obstruction?
Dilated bowel >6cm or >9cm if at caecum
Peripheral gas shadows proximal to the blockage
Haustra which don’t cross whole lumen width
What may FBC show in intestinal obstruction?
Increased WBC (inflammation) Anaemia (if Ca)
Describe general management of intestinal obstruction
Drip + suck: NGT (decompress) + IV fluids to rehydrate + correct electrolyte imbalance
Analgesia
Urinary catheter + monitor fluid balance
In which cases is surgical management considered for intestinal obstruction?
Strangulation Closed loop obstruction Obstructing tumour If not improved with conservative management after 48 hrs If perforation or peritonitis suspected
List 4 complications of intestinal obstruction
Dehydration
Bowel perforation leading to Peritonitis
Toxaemia (blood poisoning)
Gangrene of ischaemic bowel wall
What is the prognosis for intestinal obstruction?
Variable
Dependent on the general state of the patient + prevalence of complications
How does Gallstone Ileus occur?
When a stone erodes through the gallbladder into the duodenum, forming a cholecysto-duodenal fistula
= mechanical obstruction caused by an impacted gallstone in the small bowel
Which obstructions can be managed conservatively (at least initially)?
Ileus
Incomplete small bowel obstruction
What surgery is required in in acute obstruction?
Emergency laparotomy
What should you look out for when suspecting intestinal obstruction?
Hernias Abdo scars: previous abdo surgery increases risk of adhesions Abdo mass (e.g. intussusception, carcinoma)
What bloods should be taken in suspected intestinal obstruction?
FBC CRP: HIGH U+E's: deranged due to vomiting Glucose (Exclude DKA) G+S
What is it important to monitor in patients with intestinal obstruction?
Electrolyte changes
3rd space losses (causes dehydration)
What may cause a metabolic alkalosis in intestinal obstruction?
Hypokalaemia due to vomiting
Sequestration of fluid in distended bowel loops (3rd spacing) causing dehydration
What may cause a metabolic acidosis in intestinal obstruction?
Anaerobic metabolism by ischaemic cells producing lactic acid
Lysis of ischaemic cells releasing intracellular K+
What is Ileus?
Slowing of GI motility + distention, with no mechanical intestinal obstruction
