Intestinal Obstruction

Question 1

Aetiology and risk factors of small bowel obstruction

Answer 1

Adhesions: previous surgery
Hernia ± incarceration, ventral, incisional, umbilical, parastomal
Malignancy
Crohn’s
Appendicitis

RF: previous abdominal surgery, malrotation, crohn’s disease, hernia, appendicitis, intestinal malignancy, intussusception, volvulus, intestinal atresia, foreign-body ingestions

Question 2

Aetiology and risk factors of large bowel obstruction

Answer 2

Malignancy (90%)
Volvulus, sigmoid or caecal
Stricture e.g. diverticular, inflammatory, ischaemic,
Hernia, foreign body, benign neoplasm, pelvic abscess, endometriosis

RF: older age, female sex, mental illness, megacolon, low or high dietary fibre, previous colorectal resection, IBD, laxative abuse, diabetes

Question 3

Symptoms and signs of small bowel obstruction

Answer 3

Constipation/failure to pass flatus or stool
Abdominal pain and tenderness (cramp, severe, intermittent)
Nausea and vomiting
Abdominal distension
Fever
Groin swelling

Obs: pyrexia, tachycardia
Abdo: distension, tenderness, palpable mass, Peritonitis (rebound tenderness, guarding)

Question 4

Symptoms and signs of large bowel obstruction

Answer 4

Abdominal pain and tenderness (colicky, pain on movement/coughing/deep breaths)
Abdominal distension
Nausea and vomiting
Change in bowel habits, Hard faeces or soft stools
Recent weight loss
Rectal bleeding
Fever
Tenesmus
Groin swelling

Obs: pyrexia, tachycardia
Abdo: distension, tenderness, palpable mass, Peritonitis (rebound tenderness, guarding), tympanic abdomen on percussion, absent bowel sounds

Question 5

Investigations for intestinal obstruction

Answer 5

Urine pregnancy
Urinalysis: ?DKA, UTI
ECG: ?arrhythmia

ABG: ?lactate (tissue perfusion)
FBC: raised WC, ?anaemia
CRP: elevated
U&Es: Hyponatraemia, hypokalaemia, elevated urea and creatinine (dehydration)
Lipase/amylase: ?pancreatitis
Glucose: ?DKA
Clotting, G&S, cross match: for surgery

AXR: obstruction
CXR: ?perforation (pneumoperitoneum)
CT AP: ?tumour, hernia, volvulus, gallstone, ischaemia
Contrast/gastrograffin follow through: ?SBO
Contrast enema/endoscopy: ?LBO

Question 6

What should you look for on AXR for intestinal obstruction

Answer 6

Small bowel is obstructed if it’s diameter measure > 3 cm.
Large bowel is defined as obstructed when it is > 5cm in diameter.
Beyond these limits, the bowel is at severe risk of perforating.

Small bowel
- Gaseous distension of small bowel
- Central
- Valvulae conniventes
- Diameter >3cm

Large bowel
- Gaseous distension of large bowel or kidney bean shape in volvulus
- Peripheral
- Haustra
- Diameter >5cm

Question 7

Management for bowel obstruction

Answer 7

“Drip and suck” + conservative measures

1. Fluid resus, oxygen
2. Analgesia e.g. morphine
3. NG decompression + make NBM
4. Correct underlying cause

± surgery - adhesiolysis
± antibiotics (esp. pre-op)

Question 8

Complications of bowel obstruction

Answer 8

Intestinal necrosis
Sepsis
Multi-organ failure
Intra-abdominal abscess
Short bowel syndrome
Intestinal perforation

Question 9

Prognosis of bowel obstruction

Answer 9

SBO is a major cause of morbidity and mortality, and it can be fatal in untreated patients due to its progression to intestinal necrosis, perforation, sepsis, and multi-organ failure.
SBO is medical emergency, and those who are treated in a timely manner have a very good prognosis
Colonic volvulus has mortality rates of 9.4% and 6.6%
Colorectal malignancy has an adverse effect on long-term prognosis