Small Bowel Obstruction
Epidemiology
Majority is caused by previous surgery (60%)
Crohn's disease is also a significant cause (25%)
Accounts for 60-75% of intestinal obstruction
Main Causes
Hernia
Malignancy
Adhesions (60%)
Crohn's disease
Usually secondary to previous abdominal surgery
Increased incidence in; pelvic, gynaecology and colorectal surgery
Abnormal protrusion of an organ or tissue out of the body cavity in which it normally lies
Particularly in the developing world
Untreated can result in strangulation
Pathophysiology
Obstruction of the bowel leads to bowel distension above the block with increased secretion of fluid into the distended bowel
Also leads to proximal dilation, above the block, resulting in:
Mechanical obstruction is most common e.g. adhesions, hernia and Crohn's
Untreated, obstruction leads to
More dilation results in decreased absorption and mucosal wall oedema
Increased pressure with the intramural vessels becoming compressed resulting in ischaemia and/or perforation
Increased secretions and swallowed air in the small bowel
Necrosis
Perforation
Ischaemia
Clinical Presentation
Nausea and anorexia
Tenderness suggests strangulation and urgent surgery is required
Less distension as compared to LBO 9since the more distal the obstruction the greater the distension
Constipation with NO passage of wind occurs LATE in SBO
Profuse vomiting that follows pain - VOMITING occurs earlier in SBO compared to LBO
Increased bowel sounds
Pain - initially colicky (starts and stops abruptly) then diffuse, pain is higher in the abdomen than in LBO
Diagnosis
FBC essential
CT
Examination of hernia orifices and rectum
Abdominal X-ray
Distended loops of bowel proximal to obstruction
Fluid levels seen
Shows central gas shadows that completely cross the lumen and no gas in the large bowel
Gold standard to localise lesion accurately
Treatment
Analgesia and antiemetic
Antibiotics
Bowel decompression
Surgery - to remove obstruction done by laparotomy (open surgery)
Aggressive fluid resuscitation