Bowel Obstruction Flashcards
What happens as a consequence of bowel obstruction?
Gross dilatation of proximal limb of bowel
Increased peristalsis
Electrolyte-rich fluid is secreted into the bowel often called “third spacing”
Urgent fluid resus and careful fluid balance is required.
What is closed loop obstruction?
Second obstruction proximally as well so there is obstruction in two ways.
This can be seen in volvulus or in large bowel obstruction with a competent ileocaecal valve.
This is a surgical emergency as the bowel will continue to distend, become ischaemic and perforate.
Most common causes of small bowel obs.
Adhesions and herniae
Most common causes of large bowel obs
Malignancy
Diverticular disease
Volvulus
How can causes of bowel obs be divided?
Into intraluminal, mural, extramural causes.
Give examples of intraluminal causes
Gallstone ileus
Ingested foreign body
Faecal impaction
Give examples of mural causes
Cancer
Inflammatory strictures
Intussusception
Diverticular strictures
Meckel’s diverticulum
Lymphoma
Give examples of extramural causes
Hernias
Adhesions
Peritoneal metastasis
Volvulus
Clinical features
Abdo pain that is colicky or cramping in nature
Vomiting (gastric -> bilious -> faeculent)
Abdo distension
Absolute constipation
Examination findings
Might show surgical scars, cachexia or obvious hernia
Abdo distension
Focal tenderness like guarding or rebound tenderness might occur (but should not be present unless there is ischaemia)
Tympanic sound and tinkling bowel sound might be heard which is a sign of bowel obstruction.
Dx
Pseudo-obstruction
Paralytic ileus
Toxic megacolon
Constipation
Laboratory tests
Urgent bloods on admission
FBC, CRP, U&Es, LFT and G&S.
VBG to evaluate signs of ischaemia (like high lactate) or for the immediate assessment of any metabolic derangement
What is the imaging of choice?
CT abdo-pelvis with IV contrast
Why are CTs superior to AXR?
More sensitive for bowel obstruction
Can differentiate between mechanical obstruction and pseudo-obstruction
Demonstrate the site and cause of obstruction for pre-op planning.
May demonstrate the presence of metastases if caused by malignancy.
AXR findings in small bowel obs.
Dilated bowel >3 cm
Central abdominal location
Valvulae conniventes are visible
AXR findings in large bowel obs.
Dilated bowel >6cm or >9cm if at caecum
Peripheral locaiton
Haustral lines visible
Why might an erect CXR be done?
To see if there is any free air under diaphragm suggesting perforation
What might an incompetent ileocaecal valve in large bowel obs.
Concurrent large and small bowel obs.
What is water soluble contrast study (fluoroscopy with gastrograffin) used for?
In small bowel obs caused by adhesions from previous surgery.
It can predict whether or not the obstruction will settle.
General management
Urgent fluid resus
Most will require a urinary catheter
Conservative management
In absence of ischaemia or strangulatino initial management is usually conservative and called drip and suck
NBM + NG tube insertion (suck)
IV fluids (drip)
Urinary cath and fluid balance
Analgesia +/- antiemetics
Management of adhesional small bowel obs.
Results from previous surgery
Treated conservatively first with a success rate of around 80%
When should a water soluble contrast study be done?
If nothing has resolved within 24h on conservative management.
If contrast does not reach the colon by 6h then it is very unlikely to resolve on its own.
Indications of surgical management
Intestinal ischaemia or closed loop bowel obstruction
Strangulation or obstructing tumour
Patients fail to improve with conservative measures typically after 48h.
What is generally done as surgical management.
Depends on the underlying cause but usually a laparotomy.
Complications
Bowel ischaemia
Bowel perforation
Dehydration and renal impairment
