GI - Intussusception

Question 1

Definition

Answer 1

Telescoping of the proximal segment of bowel into the lumen of the distal segment leading to bowel obstruction and strangulation.
This most commonly occurs in the ileocaecal region

Question 2

Epidemiology

Answer 2

Young children = 6-18 months but can occur in older children and adults
Male = 3x more likely
Associated conditions:
- Recurrent viral illness = e.g. rotavirus
- Henoch-Scholein purpura (HSP) = submucosal haematomas
- Meckels diverticulum: congenital outpouching proximal to the ileocaecal valve
- Lymphoma: lymphoid tissue hyperplasia within the bowel wall
- Cystic fibrosis
- Intestinal polyps

Question 3

Signs

Answer 3

‘Sausage-shaped’ abdominal mass in the right upper quadrant
Abdominal distention
Hypovolaemic shock: significant ischaemia

Question 4

Symptoms

Answer 4

Severe, colicky abdominal pain and drawing knees up to the chest (children often pale)
Bilious vomit
Bloodstained stool ‘redcurrant jelly’ stools, which is a late feature
Irritability

Question 5

Pathophysiology

Answer 5

The focus of traction known as the ‘lead point’ about which the bowel wall becomes trapped and dragged into the distal lumen via peristalsis
In infants the lead point is often due to hyperplasticity Peyers patches (lymphoid tissue in the bowel wall) in the ileum resulting from a preceding viral infection.

Question 6

Aetiology

Answer 6

90% of cases = unknown
Preceding viral infection

Question 7

Investigations

Answer 7

Primary investigations = Blood tests
- FBC + CRP = inflammatory markers may be raised or anaemia if rectal bleeding is present
- U + E’s = deranged renal function due to vomiting resulting in pre-renal AKI
- Capillary or venous blood gas: may reveal a raised lactate with metabolic acidosis due to bowel ischaemia
FIRST LINE = Abdo USS = ‘Target sign’ = occurs due to mass where bowel telescopes into the distal segment
GOLD STANDARD = Contrast enema: both diagnostic and therapeutic. Contrast reveals area of intussusception sometimes referred to as the ‘meniscus sign’
- Abdominal radiograph = non-specific investigation to assess for dilated bowel loops secondary to bowel obstruction.

Question 8

Treatment

Answer 8

FIRST LINE =
- Resuscitation: ABCDE management is the priority as patients can present in hypovolaemic shock
- Radiological reduction:
= Most patients are treated with reduction by RECTAL AIR INSUFFLATION (first line) under radiological guidance, although a traditional barium enema is an alternative
- Contraindications include peritonitis and perforation

IV Abx: should be given to all patients to prevent intra-abdominal sepsis

SECOND LINE =
- Surgery: if radiological reduction fails or is contraindicated then surgery may be required, which involves manually squeezing the telescoped bowel. If this fails, then surgical resection of the affected segment should be performed.

Question 9

Complications

Answer 9

• Ischeamic enterocolitis: necrosis and eventual perforation of the affected segment = potentially life threatening
• Obstruction
• Gangrenous bowel