Bowel Obstruction Flashcards
Look at the normal anatomy of the small and large bowel
Food passes through the oesophagus > stomach > small bowel (ileum) > large bowel (colon).
Note: the small bowel is connected to the large bowel.
What are the parts of the small bowel?
3 parts:
Duodenum
Jejunum
Ileum
What are the parts of the large intestine?
Caecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum and anus.
What is the most common cause of SBO and LBO?
SBO: adhesions
LBO: malignancy
What are adhesions?
What are the main causes of adhesions?
Adhesions are pieces of scar tissue that bind the abdominal contents together. They can cause kinking or squeezing of the bowel, leading to obstruction. Adhesions typically cause obstruction in the small bowel, rather than the large bowel.
Abdominal or pelvic surgery (particularly open surgery)
Peritonitis
Abdominal or pelvic infections (e.g., pelvic inflammatory disease)
Endometriosis
Name 5 causes of bowel obstruction
Adhesions
Cancer
Intussusception - when one part of the intestine slides into another.
Hernia - when an internal part of the body pushes through a weakness in the muscle or surrounding tissue wall.
Volvulus - twisting of a section of the intestine.
What are the clinical features of bowel obstruction?
Abdominal pain - colicky or cramping in nature (secondary to bowel peristalsis).
Abdominal tenderness - patient should have tenderness but should not have features of guarding or tenderness unless ischaemia is developing.
Abdominal distension
Vomiting - occurs early in proximal obstructions and late in distal. Particularly green bilious vomiting.
Absolute constipation - cannot pass stool or gas/wind
Examining for bowel obstruction:
General inspection
Palpation
Percussion
Auscultation
On examination - may show evidence of underlying cause (e.g. surgical scars, cachexia from malignancy, or obvious hernia) or abdominal distension. Ensure to assess the patient’s fluid status, as third-spacing can occur in bowel obstruction.
Palpate - for focal tenderness (including guarding and rebound tenderness on palpation).
Percussion - may reveal a tympanic sound
Auscultation - may reveal ‘tinkling’ bowel sounds, both signs characteristic of bowel obstruction.
What are the investigations of choice? Which is diagnostic?
AXR
CT-abdominal pelvis with contrast (diagnostic)
What are the normal diameters of the bowel on an AXR?
3 cm small bowel
6 cm colon
9 cm caecum
What would you see on an AXR of SBO?
White lines that pass cross across the whole width of the bowel are called valvulae conniventes. They are only found in the small bowel.
Typical abdominal X-ray features of small bowel obstruction include dilation of the small bowel (>3cm diameter) and much more prominent valvulae conniventes creating a ‘coiled-spring appearance‘.
What would see on an AXR of LBO?
The large bowel wall features pouches or sacculations that protrude into the lumen, known as haustra. Haustra are thicker than the valvulae conniventes of the small bowel and typically do not appear to completely traverse the bowel.
You would see dilated bowel loops in obsutrction
What is the initial management?
NBM - don’t put food or fluids in if there is a blockage
IV fluids - to hydrate the patient and correct electrolyte imbalances
NG tube insertion - inserted to suction fluid from the stomach so that the bowel can rest and return to normal size.
*Conservative management may be used in the first instance in stable patients with obstruction secondary to adhesions or volvulus. Where this fails, surgery is required.
