INTESTINAL OBSTRUCTION
Dr. Rezvan Mirzaei
PathophysiologyGas & 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 resolvedPassing 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