what is bowel obstruction?
mechanical blockage of the bowel
what is functional bowel obstruction? what else is it known as?
bowel is not mechanically blocked but does not work properly, for example due to inflammation, electrolyte derangement or recent surgery.
a.k.a paralytic ileus
what are the most common causes of small bowel obstruction?
adhesions
herniae
what are the most common causes of large bowel obstruction?
malignancy - this until proven otherwise
diverticular disease
volvulus
describe the pathophysiology of third spacing in bowel obstruction
• Bowel segment becomes occluded
‣ Causes gross dilatation of the proximal limb of bowel
‣ Causes increased peristalsis of the bowel
‣ Leads to secretion of large volumes of electrolyte-rich fluid into the lumen
what is needed in the management of bowel obstruction due to third spacing?
urgent fluid resuscitation and close attention to fluid balance
what is a ‘closed-loop’ obstruction?
if there are two bowel obstructions, one distal to the other, e.g. due to a twist in the bowel or in the large bowel if the ileocaecal valve is competent
what is the complication of a closed-loop obstruction?
the bowel will continue to distend, stretching it until it becomes ischaemic and perforates
** surgical emergency
what are the possible features of bowel obstruction in a patient’s history?
- abdominal pain (colicky or cramping) due to bowel peristalsis
- vomiting -> gastric, then bilious, then faeculent
- abdominal distension
- absolute constipation (wind and faeces)
what is a red flag sign with the pain that is experienced in bowel obstruction?
any pain that is originally colicky in nature that is now constant or worse on movement is a sign that ischaemia is developing
what are the clinical signs of intestinal obstruction?
- abdominal distension
- possible underlying cause, such as surgical scars, cachexia from malignancy or hernia
- focal and rebound tenderness -> indicates ischaemia
- on percussion, tympanic sounds
- on auscultation, tinkling bowel sounds
what are the differential diagnoses for intestinal obstruction?
paralytic ileus
toxic megacolon
constipation
what investigations are done when suspecting bowel obstruction?
- laboratory tests (FBC, U&Es, CRP, lactate and group and save)
- CT imaging
- abdominal Xray (CT used more now)
why is CT imaging a good modality for bowel obstruction?
- more sensitive
- can differentiate between mechanical obstruction and pseudo-obstruction
- can demonstrate the site and cause of obstruction
- may show metastases
what can be seen on an abdominal XRay in small bowel obstruction?
- dilated bowel (>3cm)
- central abdominal location
- valvulae conniventes visible (lines completely crossing the bowel)
what can be seen on an abdominal X-ray in large bowel obstruction?
- dilated bowel (>6 cm)
- peripheral location
- haustral lines visible (indents go halfway there)
what are the signs of bowel ischaemia?
- pain worsened by movement
- focal tenderness (rebound and guarding)
- pyrexia
briefly describe the management of bowel obstruction
- urgent fluid resuscitation and careful attention to fluid balance
- if no signs of ischaemia or strangulation, initial management is conservative
- patient with closed loop bowel obstruction or evidence of ischaemia require urgent surgery
what is the conservative management of bowel obstruction?
- Nil-by-mouth
- nasogastric tube to decompress the bowel
- start IV fluids and correct electrolyte imbalances
- urinary catheter and fluid balance
- analgesia and anti-emetics
how is adhesional small bowel obstruction treated usually?
conservatively - usually resolves this way
what is the surgical management of bowel obstruction?
nature if the management depends on the underlying cause but usually involves laparotomy
if resection is necessary, the bowel ends can be re-joined or a stoma may be necessary
when is surgical management needed for bowel obstruction?
- suspicion of intestinal ischaemia
- closed loop bowel obstruction
- small bowel obstruction in a virgin abdomen (no surgery)
- cause that requires surgical correction (e.g. strangulated hernia or obstructing tumour)
- patient fails to improve on conservative methods (after >48 hours)
what are the complications of bowle obstruction?
- bowel ischaemia
- bowel perforation-> faecal peritonitis
- dehydration and renal impairment due to 3rd spacing
what is volvulus?
torsion of the bowel
- twisting of a loop of intestine around its mesenteric attachment, resulting in a closed loop bowel obstruction
