Dr. Rezvan Mirzaei. Pathophysiology Gas & Fluid Accumulation within the proximal Gas Accumulation Swallowed Air (most) Produced within the intestine.

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