Small Bowel Obstruction

Question 1

Common causes of SBO in adults

Answer 1

Previous surgery causing adhesions
Incarcerated hernia (inguinal, ventral, incisional, umbilical, parastomal)
Crohn's
Malignancy
Appendicitis

Question 2

Common causes of SBO in children

Answer 2

Appendicitis
Intussusception
Intestinal atresia
Volvulus

Question 3

Pathogenesis of SBO

Answer 3

Obstruction causes proximal dilation and obstipation (may take 12-24 hrs; although acutely may have hyperperistalsis distally leading to diarrhoea)
Proximal dilation causes abdominal pain and cramping
If prolonged and severe, may obstruct venous outflow and lead to bowel ischaemia, necrosis, perforation, etc

Question 4

Pathogenesis of electrolyte disturbances in SBO

Answer 4

Bowel wall oedema and disruption of normal bowel functions results in increased luminal fluid
Increased luminal fluid causes transudative fluid loss into peritoneal space
Results in electrolyte disturbance

Question 5

Clinical presentation of SBO

Answer 5

N+V
Abdo pain and distension
Constipation
Normal or increased bowel sounds (absent if secondary ileus - more severe?)

Question 6

AXR findings for SBO

Answer 6

Air-fluid levels on erect AXR
Ladder pattern due to plicae circularis
Proximal distension (>3cm) + no colonic gas