Bowel obstruction Flashcards
What happens to bowel proximal to obstruction?
Dilation even if not eating. Can be with with gas or food or fluid (gastric secretions)
What happens to bowel distal to obstruction?
Collapse
How does an upper small bowel obstruction present?
Acute onset (hours) Large volumes of vomit. Vomiting bile if obstruction distal to ampulla of Vater
How does a distal small bowel or large bowel obstruction present?
Colicky abdominal pain due to bowel peristalsing. Smooth muscle- visceral pain.
Vomiting, possiblely faeculent.
Gradual onset
General symptoms of intestinal obstruction?
Vomiting, pain, constipation, distention.
WHat does vomit of semi-digested food eaten in the last 24-48 hours with no bile sugegst?
Gastric outlet obstruction
What does vomit which is bile stained suggest?
Proximal half of small bowel
What does vomit that is thicker, brown, foul smelling vomit suggest?
A more distal obstruction of small bowel or colon
What is absolute constipation?
Neither faeces or flatus passed rectally.
Pathognenomic of bowel obstruction
What is meant by a competent ileo-caecal valve?
Backwars flow of accumulated bowel contents is prevented.
Distention of colon but not small bowel (greater risk of perforation-caecum is thin walled)
50% of patients
What is meant by an incompetent ileo-caecal valve?
The ileo-caecal valve allows backwards movement of colic contents.
Distention of small and large bowel.
50% of patients.
Delays onset of symptoms
What are the symptoms of incompete or sub total obstruction?
Intermittent vomiting and bowel movements.
Severe pain in chronic incomplete obstruction is more common because smooth muscle proximal undergoes hypertrophy and contracts harder to force contents past obstruction.
What are the physical signs of intestinal obstruction?
Dehydration (dry mouth, loss of skin turgor and elasticity)
Abdominal distention
Visible peristalsis (thin patients and chronic incomplete obstruction)
Lack of abdominal tenderness- should not be peritonitic)
Palpable mass
Resonant percussion due to gas in bowel
Check groins for hernia
Tinkling or absent bowel sounds or echoing (lots of fluid)
What do you worry about if the patient is peritonitic?
Bowel strangulation or perforation.
What are the investigations for bowel obstruction?
Suprine AXR- proximal distention of bowel with gas. You can also see competent or incompetent ileo-caecal valve. (Erect AXR will show air fluid lines- not comon practice)
Erect CXR- free gas under the diaphragm
CT scan looking for transition point (distention proximal to obstruction and collapse distal)
How is intestinal obstruction managed?
Nil by mouth Bloods Insert canula- Give IV fluids and correct elecrolytes. NG tube to decompress stomach DRIP AND SUCK for 48-72 hours and reveiw
What are the causes of bowel obstruction?
Adhesions/bands (can be congenital but often from surgery) Incarcerated hernia Volvulus Tumour Inflammatory strictures Bolus obstruction Intussusception
What are the common hernia sites?
Epigastric Umbilical/paraumbilical Incisional Spiegel (side of rectus sheath) Inguinal Femoral
Which hernias are difficult to see?
Femoral hernias- may only be seen on CT
Most common site of volvulus?
1) Sigmoid colon
Also caecum and small bowel rarely
Which patients get volvulus’?
Older patients with long term difficulties with constipation
How is a volvus treated?
Ridgid sigmoidoscopy or flexible colonoscopy
What are the most common obstructing tumours?
Colorectal cancer
What size is the caecum when at risk of perforation?
> 10cm worrying
>16cm is very likely to perforate => peritonitis
What can cause inflammatory strictures leading to bowel obstruction?
Chron’s disease (distal ileum)
Divericular disease
Usually incomplete obstruction.
What are the bolus obstructions in the GI tract and where are they commonly found?
Food bolus- distal oesophagus (stricture form cancer or reflux oesophagitis)
Impacted faeces- older people, dehydration
gallstone ileus- ileocaecal valve. (Due to fistula between gall bladder and duodenum)
Trichobezoar hair(rare)
What is intussesception?
A segment of bowel wall becomes telescoped into the segment distal to it.
Common in children.
Due to a mass in the bowel wall: enlargement of lymphatic tissue or tumour.
What are they symptoms of bowel strangulation?
Severe ischemic pain
WHat is the pathophysiology of bowel strangulation?
A segment of bowel becomes trapped. Venous return obstructed Intravascular pressure rises and then arterial flow is compromised => ischemia, infarction and perforation. Occurs in external hernia or volvus.
What is the abdominal venous pressure?
14mmHg
What is paralytic ileus, when does it occur and how is it treated?
Occurs following surgery or inflammation with peritonitis and usually effects the small intestine.
Failure of peristalsis. Less pain and bowel sounds
Generally just wait for bowel to settle. Can try drip and suck for fluid
What is adynamic bowel obstruction?
Its not mechanical obstruction but its paralysed. Gas and fluid is not moving- no peristalsis.
What is pseudo obstruction?
Acute dialition of the colon in the absence of colonic obstruction in acutely unwell patients.
What are the risk factors for pseudo obstruction?
Elderly Hip replacement surgery CABG Spinal fracture Pneumonia
How is pseudo obstruction treated?
Most resolve spontaneously.
If symptomatic and effecting diaphragm or threatening colon- decompression with colonoscope
