Intestinal Obstruction

Intestinal ObstructionDefinitionInability of the intestinal contents to pass distally in the lumen of intestine either from a mechanical barrier or absence of peristalsis without any mechanical barrier is known as Intestinal obstruction.Mortality and Morbidity depend upon the early recognition and correct diagnoses of obstruction.If untreated death occur in 100% of patients with strangulated obstruction.ClassificationIntestinal obstruction can be classified in many ways.Depending upon the nature of obstruction Dynamic obstruction Adynamic obstruction.Dependind upon the Cause of obstruction Intraluminal causes Gall stones ileus Food bolus obstruction Roundworm mass Foreign body In the wall of the Gut Strictures Crohns disease Carcinomas Adhesions Outside the wall of the Gut Volvulus Intussusception Obstructed Hernia Congenital Bands ClassificationDepending upon Severity Acute Obstruction Chronic Obstruction Acute on Chronic ObstructionDepending upon Blood Supply Simple Obstruction Strangulated ObstructionDepending upon the site Small bowel obstruction Large bowel obstructionPathophysiologyIrrespective of the etiology and acuteness of onset, in Dynamic obstruction the proximal Bowel dilates and develops an Altered motility.Dilation Obstruction leads to proximal dilation due to accumulation of intestinal secretions and swallowed air. this bowel dilation stimulates cell secretory activity resulting in more fluid accumulation and progressive dilatation.Altered motility accumulation of secretion in the intestine lumen stimulates increased peristalsis both above and below the obstruction . below the obstruction increased peristalsis leads to frequent loose stools and flatus early in the course of disease.Above the obstruction increased peristalsis try to overcome the obstruction,if the obstruction is not relieved the bowel begins to dilate causing a reduction in the peristaltic strength ultimately resulting in flaccidity and paralysis.PathophysiologyThe distention Proximal to obstruction is caused by two factors Gas : obstruction leads to significant proliferation of both aerobic and anaerobic organisms resulting in considerable gas production , Nitrogen being the predominant(90%) Gas along with Hydrogen Sulfide. Fluid : Fluid is made up of various digestive juices e.g 1500ml of saliva\d, 2L of gastric juice\d,3L of intestinal secretion\d,1L of pancreatic juice and bile\d. Following obstruction fluids accumulates in the bowel wall and any excess fluid is secreted in the lumen. Because absorption is retarded ,dehydration and electrolytes disturbance is inevitable. Causes include Reduced oral intake defective intestinal absorption result of vomiting sequestration in bowel lumenPathophysiologyInterference with blood supply : as the tension within the bowel loops become more and more , venous congestion takes place resulting in edema of bowel wall. If the obstruction is not relieved capillary rupture and hemorrhage takes place. In case of volvulus and intussusception arterial compromise takes place fast which causes gangrene of bowel wall very early. Transmigration of Organisms : both aerobic and anaerobic organisms transmigrate through the gangrenous bowel and results in peritonitis. The organism release powerful endotoxins which are absorbed from peritonial surface and cause gram negative shock or septic shock which caries high mortality.Clinical FeaturesThere are Four Cardinal features of Dynamic Obstruction.Colicky painDistentionVomitingAbsolute constipationThe clinical features are also influenced by the site of obstruction whether small bowel large bowel and on the onset of obstruction whether Acute or Chronic or Acute on Chronic

Clinical FeaturesIn High Small Bowel Obstruction Vomiting occurs early and is profuse with rapid dehydration. Distention is minimal with little evidence of fluid levels on abdominal radiograph.In Low Small Bowel Obstruction Pain is predominant with central Distention . Vomiting is delayed. Multiple central fluid levels are seen in abdominal radiograph.In Large Bowel Obstruction Distention is early and pronounced. Pain is mild and Vomiting and Dehydration is late. The proximal colon and caecum are distended on abdominal radiograph.Other FeaturesDehydration : Most common in small bowel obstruction because of repeated vomiting and fluid sequestration. Signs of dehydration appears early ( ? )Hypokalemia : not a common feature in simple mechanical obstruction. An increase in serum potassium, amylase and LDH may be associated with presence of Strangulation along with leucocytosis or leucopenia.Pyrexia : In the presence of obstruction indicates Onset of IschemiaIntestinal perforationInflammation associated with obstructing disease.Hypothermia : Indicates Septic shock.Abdominal tenderness : localized tenderness indicates pending and established ischemia.Signs of peritonism : indicates overt infarction or perforation.Feature of StrangulationIt is important to distinguish strangulating from non-strangulating obstruction because the Former is a surgical emergency. The diagnoses is entirely clinical. Features includeConstant PainTenderness with RigidityGuarding and absent bowel soundFeatures of Septic ShockIn case of External hernia the lump is tense, tender, irreducible with no expansile cough impulsePain is never completely absent in strangulation.Symptoms Usually commence suddenly and recur regularly.Any tenderness present is of great significance and need frequent reassessment.InvestigationsComplete Blood Picture : Low Hb% indicates underlying malignancy. Increased total WBC count indicates infection or sepsis.Electrolytes : most of the electrolytes are low in cases of intestinal obstruction.Plain X-ray Abdomen : in erect position is an important investigation in cases of intestinal obstruction.Multiple gas fluid levels are pathognomic of IO. Gas level appears earlier than fluid levels.Plain X-ray may demonstrate Gall stone ileus or foreign body.Sigmoid volvulus appear as a large dilated loop.Jejunum is characterized by Regularly placed mucosal folds called volvulae conniventes placed opposite to each other. They are produced by valves of kirkring.Large bowel is characterized by Haustrations : Incomplete mucosal folds, not placed opposite to each other. They are large. Caecum has no haustrations. However it appears as a round gas shadow in RIF.Multiple air-fluid levels

Air-fluid levels

Haustrations

Small bowel obstruction

Treatment of Acute IOThere are Three main measures used to treat acute IO. Gastro-intestinal drainageFluid and electrolyte replacementRelief of ObstructionSurgical treatment is necessary for most cases of IO but should be delayed until resuscitation is complete, provided there is no signs of Strangulation or evidence of closed-loop obstruction. Indications of early surgical interventionObstructed or strangulated external herniaInternal intestinal strangulationAcute obstruction