Intestinal obstruction

Question 1

What is intestinal obstruction?

Answer 1

Intestinal obstruction = blockage to free passage of contents of the gut

Can be small or large bowel

Types:
Ileus = reduced bowel motility causing functional obstruction

Simple = one obstructing point, no vascular compromise

Closed loop (volvulus) = two obstructing points, forming a loop of grossly distended bowel at risk of perforation
E.g. sigmoid volvulus
Tenderness and perforation occur most commonly at the caecum where the bowel is the thinnest and widest

Strangulated = vascular compromise

Question 2

What is the aetiology of intestinal obstruction?

Answer 2

Small bowel
Adults
Most common: hernias and adhesions (75%)
Other: Malignancy, Crohn’s

Children
Appendicitis
Intussusception
Intestinal atresia
Volvulus

Large bowel
Most common: colon cancer (90%)
Other: constipation, diverticular stricture, volvulus, hernias
Sigmoid or caecal volvulus = most common

RFs: elderly, psychiatric illness
Very common in Africa and Asia
Coffee bean sign on AXR

Other causes
Paralytic ileus = bowel ceases to function with no peristalsis
Causes: Abdominal surgery, spinal injury, low K/Na

Pseudo-obstruction = massive colon dilation with no cause found
Related to: Pneumonia, MI, stroke, AKI

Post-op ileus
Bezoars
Body packers = packets of illicit drugs swallowed and trapped
Meckel’s diverticulum = distal ileum contains embryonic remnants of gastric and pancreatic tissue
Meconium ileus = in CF, loss of pancreatic enzymes fails to clear the sticky meconium
Distal intestinal obstruction syndrome = faecal material accumulates and adheres to lining of the intestinal wall
Complication of CF

Question 3

What are the risk factors of intestinal obstruction?

Answer 3

Old age
Female gender
Mental illness
Megacolon
Previous abdominal surgery
IBD
Malrotation
Hernia
Cancer

Question 4

What is the epidemiology of intestinal obstruction?

Answer 4

Most are small bowel obstruction
Incidence increased in Crohn’s patients (25%)
Incidence hugely increase in patients who have had previous surgery

1/3 of colorectal malignancies present with obstruction

Mainly affects adults >70 yrs old

Question 5

What are the symptoms of intestinal obstruction?

Answer 5

Cardinal features of obstruction

1. Vomiting
2. Colicky pain
3. Constipation
4. Distention

Symptoms
Vomiting and nausea - Faecal vomiting, More likely with small bowel

Abdominal pain - Colicky, Occurs early, Not always present in chronic obstruction, Constant = large bowel
Sharp and constant, with localised peritonism = strangulated

Anorexia

Constipation - Absolute = no flatus passed = distal obstruction

Large bowel
PR bleeding
Empty rectum
Palpable abdominal mass

Question 6

What are the signs of intestinal obstruction?

Answer 6

Cardinal features of obstruction

1. Colicky pain
2. Vomiting
3. Constipation
4. Distention

Signs
Distention - More in LBO

Abnormal bowel sounds -Tinkling bowel sounds, Absent = ileus

Tympanic abdomen - Due to air in stomach

Palpable abdominal/rectal mass

Abdominal tenderness - Severe suggests ischaemia or perforation

Dehydration

Visible peristalsis

Hernia

Fever

Systemic unwellness

Question 7

What are appropriate investigations for intestinal obstruction?

Answer 7

Bloods
FBC: elevated WBC, anaemia (LBO)
Elevated creatinine, amylase/lipase

Plain AXR
Normal bowel size: 3cm = small bowel, 6cm = large bowel, 9cm = caecum

SBO
Dilated intestinal loops
Valvulae conniventes completely cross lumen
Air-fluid levels (SBO)

LBO
Dilated intestinal loops
Gas shadows proximal to obstruction
Coffee-bean sign = sigmoid volvulus
Embryo sign = caecal volvulus + gas bubble

Perforation

Rigler’s sign

CXR - Assess for perforation

Other investigations
Contrast enema
CT
Laparoscopy - Appendicitis, malrotation, tumour

Question 8

What is the management of intestinal obstruction?

Answer 8

Surgical referral
NBM
Peritonitic
Laparotomy

Drip and suck
NG tube - Decompression reduces flow towards obstruction
IV fluids

Analgesia
Oxygen
Catheterise

Question 9

What are the possible complications of intestinal obstruction?

Answer 9

Necrosis - Almost inevitable with untreated complete SBO

Perforation - Most commonly in caecum – risk dramatically increases when diameter >10-12cm

Peritonitis

Sepsis

Death - Particularly in LBO

Question 10

What is the prognosis for intestinal obstruction?

Answer 10

Small bowel obstruction
If untreated, universally fatal = medical emergency
Progression to intestinal necrosis/perforation/sepsis

Large bowel obstruction
Colorectal cancer
Reduced 5-year survival

Sigmoid volvulus
Without surgical treatment, recurrence rates are 40-60%