General: Bowel Obstruction

Question 1

Outline the pathophysiology of a bowel obstruction

Answer 1

Mechanical blockage = structural pathology physically blocks the normal passage of intestinal contents

Occlusion = proximal dilation = increased peristalsis = secretion of large volumes of electrolyte rich fluid into the bowel = urgent fluid resuscitation is vital

2nd bowel obstruction proximally (twist) = closed-loop obstruction = surgical emergency due to ischaemia and ultimately perforation

Question 2

What is the aetiology of a bowel obstruction?

Answer 2

Small bowel = adhesions, herniae

Large bowel = malignancy, diverticular disease, and volvulus

Question 3

How does bowel obstruction present?

Answer 3

Abdo pain = colicky or cramping, secondary to the bowel peristalsis (any pain that is colicky that is now constant = red sign for ischaemia)

Vomiting = initially of gastric contents, before becoming bilious and then eventually faeculent

Abdominal distension

Absolute constipation = failure to pass flatus and faeces

Evidence of underlying cause = surgical scars, cachexia from malignancy, or obvious hernia) and abdominal distension

Ischaemia = focal tenderness, guarding and rebound tenderness

Question 4

How should a bowel obstruction be investigated?

Answer 4

Abdo exam, PR

Bloods = FBC, CRP, U+Es, G+S

VBG = high lactate in ischaemia, assess metabolic derangement secondary to dehydration/excessive vomiting

Assess for dehydration and sepsis

CT - location of obstruction, cause, perforation, necrosis, inflam

AXR (SI = >3cm, central, valvulae conniventes visible) (LI = >6cm, peripheral, haustral lines visible)

eCXR = air under diaphragm suggest bowel obstruction rupture

Question 5

Outline how a bowel obstruction should be managed

Answer 5

Urgent fluid resuscitation is vital = IV fluids (drip)

Urinary catheter = fluid balance

Closed loop or ischemic bowel = urgent surgery = laparotomy, resection, stoma

NBM – NG tube to decompress the bowel (suck)

Analgesia as required with suitable anti-emetics

Definitive management is dependent on aetiology

Question 6

What are the possible complications from a bowel obstruction?

Answer 6

Bowel ischaemia

Bowel perforation = faecal peritonitis (high mortality)

Dehydration and renal impairment