Intestinal Obstruction 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 intestine necrosis

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

Bezoar

What is cause?

Intramural Tumors Crohn’s Disease (inflammatory strictures) Intussusceptions

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 -Prerenal azotemia(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

Small intestinal obstruction: supine

Small intestinal obstruction: upright

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

SB loops filled with fluid & decompressed colon

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 Pneumatosis intestinalis (air in the bowel wall) Portal venous gas Mesenteric haziness Poor uptake of IV contrast into 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

SBO secondary to an abscesses

Small bowel series (small bowel follow through) Enteroclysis - Contrast Solution via a long nasoenteric catheter - Double contrast technique (mucusal surface & small lesions) - Rarely performed in the acute setting C.T enteroclysis

Jejunojejenal intussusceptions

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 ?

Management NGT (Decreased Nausea, Distention, Risk of vomiting and Aspiration) Urinary Catheter(urine output:0.5-1ml/kg/h) + Broad – Spectrum antibiotics

Surgical Therapy Complete small bowel obstruction Colon Obstruction -R/O: Pseudo obstruction

Conservative Therapy Partial small bowel obstruction (48 h) Early postoperative (3-5 days after abdominal surgery) obstruction (2-3 weeks) + TPN Crohn’s disease obstruction Carcinomatosis

Ileus Temporary impaired intestinal motility Absence of a lesion-causing mechanical obstruction Reversed with time as the inciting factor is corrected

Causes of ileus Post laparotomy Metabolic&electrolyte derangements Hospitalized patients Uremia,Diabetic coma Drugs:opiates,psychotropic agents,anticholinergic agents Retroperitoneal hemorrhage or inflammation Intraabdominal sepsis,systemic sepsis Intestinal ischemia

Post op Ileus Surgical-induced sympathetic reflexes Inflammatory response mediator release Anesthetic/Analgesic effect

Return of normal motility Small bowel motility 24h Gastric motility 48 h Colonic motility 3-5 days Listening of bowel sounds is not a reliable indicator that ileus has fully resolved Passing flatus or bowel movement is more useful

Clinical Presentation Nausea, Vomiting Lack of faltus or bowel movements Abdominal distention Diminished or absent bowel sounds

Diagnosis Ileus occurs in the absence of abdominal surgery Ileus persist beyond 3-5 days postoperatively

Imaging Abdominal radiographs: distinction between ileus & mechanical obstruction is difficult Small bowel loops distention + air in the colon & rectum :possibility of adynamic ileus

CT: test of choice - Exclude complete mechanical obstruction - presence of intra-abdominal abscess or peritoneal sepsis

Management Fluid resuscitation NGT Drugs/Opiates Hypokalemia/Hypocalcemia Hypomagnesemia/Hypermagnesemia