Bowel Obstruction. Flashcards Preview

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Flashcards in Bowel Obstruction. Deck (43):

What happens to the bowel proximal to a bowel obstruction?

It becomes dilated with air, gas, and fluid.


What happens to peristalsis during a bowel obstruction?

It is disrupted.


What does the bowel obstruction patients presentation depend on?

Dependent on the level of obstruction.


How does an upper small bowel obstruction present?

Acute onset within the last few hours.
Vomiting large volumes of gastric, biliary, salivary and pancreatic secretions.


Where do bowel obstructions occur?

Any part of the bowel.


How does an obstruction of the distal small or large bowel present?

Colicky abdominal pain and distension.
Vomiting, possibly feculent.


What does the onset of vomiting tell us about the location of a small bowel obstruction?

The quicker is starts the more proximal the blockage is.


What are the general symptoms of bowel obstruction?

Vomiting, pain, constipation and distension.


Can vomiting be present in bowel obstruction without any food intake?

Yes can occur with biliary and gastric secretions and saliva.


What kind of vomit does a gastric outlet obstruction present with?

Semi digested, eaten a day or two prior without any bile present.


What kind of vomit do we get with a small bowel obstruction?

Copious bile stained fluid.


What kind of vomit do we get with a distal obstruction?

Thicker, brown, feculent, foul smelling vomit.


What causes the pain from a bowel obstruction?

Distension of the proximal gut by air and secretions.
Colicky pain in attempt to clear the blockage.


What is complete cessation of flatus and faeces indicative of and why?

Complete bowel obstruction.
Propulsion of contents is arrested and the gas is absorbed in the distal part of the bowel.


How quick an onset of symptoms do we get with a large bowel obstruction and why?

More gradual development due to colon and cecum absorptive capacity.


What happens to the ileocecal valve in 50% of cases and what consequences does this have?

Remains competent half the time preventing backward flow. The thin walled cecum progressively dilates with swallowed air and may rupture (closed loop obstruction).
If the valve is incompetent, the small bowel dis tends and delays the onset of symptoms.


What symptoms do we get during an incomplete obstruction?

The clinical features are less defined. The vomiting may be intermittent and the bowel habits erratic.


What happens to the bowel when there is a chronic incomplete obstruction?

Leads to gradual hypertrophy of the smooth muscle of the bowel wall proximally. Peristaltic activity in the hypertrophic muscle is responsible for bouts of colicky pain. These can be more prominent than in complete obstruction.


What are the signs of obstruction?

Dehydration, abdominal distension, visible peristalsis and a relative lack of tenderness. Possibly a palpable mass, altered percussion notes and bowel sounds.


What anatomical area must we make sure we examine when a patient has a suspected obstruction and why?

The groin for an obstructing hernia.


What are the signs of dehydration?

Dry mouth, loss of skin turgor and elasticity.


What should we think if the patient is tender and has signs of a bowel obstruction?

May indicate an obstruction due to strangulation.


What can we often hear on abdominal percussion in a bowel obstruction?

Centre of abdomen tends to be resonant due to gassy distension.


What bowel sounds do we hear with a bowel obstruction?

Traditionally a high pitched tinkling.
In reality can be absent, echoing cavernous sounds or may sound like water lapping against a boat.


What investigations do we do for a bowel obstruction?

Supine xray most useful. Erect no longer done.


What do we see on an abdominal xray in a bowel obstruction?

The bowel proximal is distended with gas.
Distended small bowel loops tend to be central and have valvulae conniventes.
Distended large bowel stays in the anatomical position and have Haustra coli.
A Cut off will be seen between the distended proximal bowel and the collapsed distal bowel.


What are valvulae conniventes?

Otherwise called the plicae conniventes. The lines of smooth muscle straight across the bowel.


What is the management of a bowel obstruction?

NG tube to decompress the stomach, nil by mouth, cannula and bloods, resus with fluid and electrolytes and a surgical consult if pain.


What are mechanical causes of a bowel obstruction?

Adhesions or bands.
Incarcerated or internal hernias.
Inflammatory strictures.
Bolus obstruction.


What can cause adhesions of bands?

Congenital or resulting from past surgery or peritonitis.


What hernias can incarcerate?

Inguinal, femoral, umbilical, paraumbilical, ventral and incisional.


What is a volvulus?

Mobile bowel of loop that rotates causing obstruction at its neck.


What tumours can cause bowel obstruction?

Gastric cancer blocking the pylorus.
Small bowel tumours which are rare and large bowel cancer.


What causes inflammatory strictures and what can this result in?

Diseases like diverticular or Crohn's.
Usually result in incomplete obstruction.


What kind of bolus can cause obstruction?

Food, faeces, impacted gallstone ileus (rare) and trichobezoar (rare).


What is a trichobezoar?

A hairball.


What is Intussusception?

Segment of bowel wall becomes telescoped into the segment distal to it.


What causes an Intussusception and what patients are the more common in?

Usually initiated by a mass in the bowel wall, enlargement of lymphatic tissue or tumour.
More common in children.


What happens in bowel strangulation?

Segment becomes trapped and if not relieved will progress to infarction and perforation. Lumen becomes obstructed (incarcerated) and then the blood supply is compromised (strangulated).


What can cause pain over a hernia and what actions should we take?

Can occur in external hernia or volvulus and this needs rapid surgical evaluation.


What are the causes of a dynamic bowel obstruction?

Paralytic ileus and pseudo obstruction.


What is a pseudo obstruction?

Inability of bowel to push food properly.


What is paralytic ileus?

Obstruction of the intestine due to paralysis of the intestinal muscles. Does not need to be complete paralysis just enough to stop the contents from passing through.
Otherwise just called ileus.