Bowel Obstruction Flashcards
Give the key clinical features of obstruction.
Think CAVA! Colicky abdo pain Abdo distension Vomiting (the more proximal the obstruction, the earlier it occurs) Absolute constipation (no faeces or flatus)
Other features can include:
Tinkling bowel sounds.
Sloshing sound can be heard due to fluid accumulation.
Dehydration and strangulated hernias.
What investigations would you perform on a patient with suspected strangulation?
Bloods:
FBC
U&E’s to identify electrolyte imbalance.
Plain abdo radiograph:
Key investigation!
Gentle contrast studies:
Use water soluable contrast medium eg gastrograffin.
—not as dangerous as barium if leakage occurs.
—without preparation to minimise perforation risk.
A CT confirms the nature and site of the obstruction (esp. To stage tumours) and identifies other details.
How would you manage a patient with bowel obstruction?
Conservative: Think drip and suck for 48-72 hours. •Nil by mouth •Nasogastric tube to decompress stomach —Aspiration of contents removes swallowed air, decreases nausea and vomiting and prevents aspiration •Fluid resuscitation.
Improvement indicated by decreasing NG aspirated, decreased pain and passage of flatus.
Surgery is indicated if no improvement and in specific situations:
often only involves division of adhesions/ hernia repair.
If evidence of peritonitis and bowel is involved (and not prepared) a two stage Hartmann’s procedure may be used to respect affected bowel.
Surgery is indicated if:
•Failure of conservative therapy
•Strangulation- urgent! For tender, irreducible hernial mass- avoid infarction.
•Tumour
•Most right sided tumours- resection and primary anastamosis
•Some, usually L sided require Hartmann’s
•Large bowel obstruction more likely to need surgical intervention than small bowel.
List causes of functional bowel obstruction.
After surgery - paralytic ileus
Metabolic disorders - pseudo-obstruction.
What can cause paralytic ileus?
Peritonitis Blood in abdo Opiates Handling of bowel in surgery Electrolyte imbalance —Especially hypokalaemia
How is paralytic ileus resolved?
By treating the primary cause.
What can cause pseudo-obstruction?
anti-cholinergic and anti-Parkinsonism drugs Renal failure Trauma (spinal/hip/pelvic fracture) Orthopaedic procedures Variety of metabolic disorders.
How can functional obstruction present?
Usually mimics mechanical obstruction:
•Bowel sounds are diagnostically absent
•No peristalsis
How would you teat a patient with functional bowel obstruction?
Treatment is conservative.
Correct fluid and electrolyte balance.
NG tube passed
Decompressing sigmoidoscopy can be indicated in pseudo-obstruction.
Laparotomy AVOIDED unless there is sepsis.
Describe the radiological features of intestinal obstruction, small bowel vs large bowel. •Diameter •Bowel markings •Dilated loops •Gas •Fluid levels
Diameter:
Small intestine - >3
Large intestine - >8
Bowel markings:
Small intestine - Valvulae conniventes AKA plicae circulares (crossing all the way across bowel wall).
Large intestine - Haustra (tenae coli, pass a third of the way around the wall.
Dilated loops:
Small intestine - Central
Large intestine -Peripheral
Gas:
Small intestine - none in large bowel
Large intestine - none in small bowel unless Ileocaecal valve is incompetent.
Fluid levels:
Small intestine - Short and many
Large intestine - Long and Few
List potential causes of a mechanical bowel obstruction.
Sigmoid volvulus
Closed loop obstruction
Hernial strangulation
Colorectal cancer - most common cause.