650 likes | 1.07k Views
Dr. Rezvan Mirzaei. Intestinal Obstruction. Pathophysiology. Gas & Fluid Accumulation within the proximal Gas Accumulation Swallowed Air (most) Produced within the intestine Fluid Accumulation Swallowed Liquids GI secretions. Gas & Fluid Accumulation.
E N D
Dr. Rezvan Mirzaei Intestinal Obstruction
Pathophysiology Gas & Fluid Accumulation within the proximal Gas Accumulation • Swallowed Air (most) • Produced within the intestine Fluid Accumulation • Swallowed Liquids • GI secretions
Gas & Fluid Accumulation • Bowel distends => intraluminal & intramural pressure rise => microvascular perfusion impaired => intestinal ischemia => necrosis (strangulated bowel obstruction) • Luminal flora change => translocation of bacteria
Small Bowel Obstruction • Ethiologies 1- Intraluminal 2- Intramural 3- Extrinsic
Extrinsic • Adhisions • Hernias - External (inguinal, femoral) - Internal (following surgery) • Carcinomatosis
Intra-abdominal Adhisions • % 75 of the cases of small bowel obstruction
Intraluminal • Foreign Bodies • Bezoars • Gallstones • Meconium
Intramural • Tumors • Crohn’s Disease(inflammatory strictures) • Intussusceptions
Clinical Presentation • Intestinal activity increases => colicky abdominal pain & diarrhea • Nausea • Obstipation • Vomiting - More prominent with proximal obstruction - More Feculent: bacterial over growth: more established obstruction
History • Prior Abdominal Operations • Presence of Abdominal disorders(ca-IBD) • Search for hernia
Signs • Abdominal distention (more in distal obstruction) • Bowel Sounds - Hyperactive initially: peristalsis is increased - Minimal in late stage: as the bowel distends ,reflex inhibition of bowel motility results in a quiet abdomen
P/E • Dehydration • Low grade fever • Abdominal scar • Hernia • Bowel sounds • Tenderness • Digital rectal exam(Check stool for blood)
Lab test - Hemoconcentration(mildly elevated hematocrit) - Electrolyte abnormalities: Na,K,BUN,Cr,ABG - Mild leukocytosis -Prerenalazotemia(BUN/Cr ratio above 20)
Diagnosis • Mechanical/Ileus • Etiology • Partial/Complete • Simple/Strangulated • Colon/Small Bowel
Partial Small Bowel Obstruction • A portion of lumen is occluded • Allowing passage of Gas & Fluid • Development of strangulation is less likely Continued passage of flatus and/or stool beyond 6 to 12 hours after onset of symptoms
Strangulated Obstruction • Abdominal pain disproportionate to abdominal findings (suggestive of intestinal ischemia) • Tachycardia • Localized abdominal tenderness • Fever • Marked Leukocytosis • Acidosis
Radiographic Examination • Abdominal series - Supine abdomen - Upright abdomen - Upright chest • Triad for Small Bowel Obstruction - Dilated small bowel loops( > 3cm in diameter) - Air-Fluid levels (upright) - Lack of air in the colon
Sensitivity of Abdominal radiographs in small bowel obstruction %70~80 • Specificity is low - Ileus - Colonic Obstruction can mimic findings
Possibility of large bowel obstruction • Small bowel loops distention + distended cecum & colon+no rectal air or stool
False-Negative Findings on Radiography • Proximal Obstruction • Bowel lumen is filled with Fluid but no gas (Preventing Visualization of air-fluid levels or bowel distention) • Closed loop obstruction
Closed Loop Obstruction • Dangerous form • Both proximal & distal obstructed (volvulus) • Accumulated Gas & Fluid can not escape • Rapid rise in luminal pressure • Rapid progression to strangulation
Computed Tomographic (CT) Scan • %80~90 sensitivity • %70~90 specificity < %50 Sensitivity: low grade or partial small bowel obstruction
CT Scan Transition Zone • Proximal dilatation • Distal decompression • Intraluminal contrast does not pass beyond the transition zone • Colon containing little gas or fluid
CT Scan • Closed loop obstruction U-Shaped or C-Shaped dilated bowel loop associated with a radial distribution of mesenteric vessels converging toward a torsion point
CT Scan Strangulation • Thickening of the bowel wall • Pneumatosisintestinalis (air in the bowel wall) • Portal venous gas • Mesenteric haziness • Poor uptake of IV contrastinto the wall of the affected bowel
CT Scan • Global evaluation of the abdomen • May reveal etiology • Water soluble contrast - Therapeutic: Reduce the overall length of hospital stay - Prognostic: appearance of the contrast in the colon within 24 hours is predictive of none surgical resolution of bowel obstruction
Small bowel series (small bowel follow through) • Enteroclysis - Contrast Solution via a long nasoentericcatheter - Double contrast technique (mucusal surface & small lesions) - Rarely performed in the acute setting • C.T enteroclysis
Indications of contrast studies • There is not enough clinical indication for immediate operation but symptoms of obstruction continue
Management • Fluid resuscitation - Depletion of intravascular volume - Decreased oral intake - Vomiting - Sequestration of Fluid in bowel lumen & wall - Isotonic Fluid - C.V.P ?