Intestinal Obstruction

Question 1

Define intestinal obstruction?

Answer 1

obstuction of the normal movement of bowel contents- mechanical blockage of bowel due to structural blockage

Question 2

what are the classification of intestinal obstruction?

Answer 2

small or large bowel

partial or complete obstruction

simple or strangulated

Question 3

what is the typical presentation for intestinal obstruction?

Answer 3

diffuse pain, constipation, and v abdo distension, tinkling BS

if abdo tenderness-> suspect strangulation

Question 4

what are the different causes of bowel obstruction- classfying to extramural, intramural, intraluminal?

Answer 4

Extramural (beyond walls/ boundaries)

• Hernia
• Adhesions - small bowel
• Bands
• Volvulus(twisting)

Intramural (within boundaries/wall)

• Tumours
• Single site
• Multifocal – usually peritoneal met (nodules pressing from the outside)
• Inflammatory strictures(e.g. Crohn’s strictures, diverticulitis)
• Gallstone ileusoccurs 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

Intraluminal (inside lumen)

• Pedunculated tumours
• Foreign body (e.g. bezoars, gallstones)
• Faecal impaction

Question 5

outline the epidemiology of intestinal obstruction?

Answer 5

common

more common in elderly-> increasing incidence of adhesions, hernias and malignancy

Question 6

what are the presenting symptoms of intestinal obstruction?

Answer 6

• Severe gripping colicky pain with periods of ease
• Abdominal distension– more marked as obstruction progresses
• Frequent vomiting(it may be bile-stained or faeculent)
• Absolute constipation
• Anorexia

In small bowel obstruction, the pain tends to be colicky (cramping and intermittent) in nature, with spasms lasting a few minutes. The pain tends to be central and mid-abdominal. Vomiting may occur before constipation in small bowel ob. In large bowel obstruction, the pain is felt lower in the abdomen and the spasms last longer.

Question 7

what is the difference between the pain and contraction in a small and large bowel obstruction?

Answer 7

small bowel obstruction

• pain is colicy ( crampy and intermittent)
• spasms last few mins
• pain is centrsal and mid- abdominal
• vomiting before constipation

Large Bowel obstruction

• pain felt over lower abdomen
• spasms last longer

Question 8

what are the signs of intestinal obstruction on physical examination?

Answer 8

Abdominal distension with generalised tenderness

May see visible peristalsis

Tinkling bowel sounds

Peritonitis - absent bowel sounds, guarding and rebound tenderness

Inspect for hernias

palpable rectal mass

Look for abdominal scars- previous abdominal surgery increases the risk of adhesions

Inspect for abdominal mass(e.g. intussusception, carcinoma)

Question 9

what are the appropriate investigations for intestinal obstruction and what are the results?

Answer 9

AXR (also do a erect CXR and a PR exam)

FBC – increased WBC (rarely decreased RBC)

U&Es - Hyponatraemia, hypokalaemia, met alkalosis

CT scan – more sensitive

Question 10

compare the abdominal x ray in large and small bowel obstruction?

Answer 10

Small bowel obstruction:

• dilated bowel >3cm
• central gas shadows with valvulae conniventes that completely cross the lumen and no gas in large bowel

Large bowel obstruction

• dilated bowel >6cm or >9cm if at caecum,
• peripheral gas shadows proximal to the blockage with haustra which do not cross whole lumen width

Question 11

outline the general management of intestinal obstruction?

Answer 11

drip and suck management

NBM, insert NG tube

Gastric aspiration via NG tube if the patient is vomiting

IV fluids to rehydrate

Electrolyte replacement

Analgesia

Urinary catheter and fluid balance

Monitor vital signs, fluid balance and urine output

Question 12

what are the indications for the surgical management of intestinal obstruction?

Answer 12

considered in patients who have not improved with conservative management after 48 hours, have signs of peritonism, a palpable mass or a virgin abdomen (no previous surgery)

Strangulation and large bowel obstruction require surgery. Ileus and incomplete small bowel obstruction can be managed conservatively, at least initially.

Emergency laparotomy in acute obstruction

Question 13

what are the possible complications of intestinal obstruction?

Answer 13

Dehydration

Bowel perforation

Peritonitis

Toxaemia (blood poisoning by toxins from a local bacterial infection)

Gangrene of ischaemic bowel wall

Question 14

summarise the prognosis of intestinal obstruction?

Answer 14

Variable

Dependent on the general state of the patient and the prevalence of complications