3Large Bowel Obstruction Introduction Background:An emergent conditionRequires early identification and prompt surgical interventionColonic obstruction may result fromInfectious/inflammatoryNeoplasticMechanical pathologyVolvulusIncarcerated herniaStrictureObstipationEtiologyAge dependentSerosa can expand to only a variable but limited diameterRupture and fecal soilage of the peritoneal cavity can occur
4Large Bowel Obstruction Introduction Pathophysiology:Caused by anatomic abnormalityLeads toColonic distentionAbdominal painAnorexiaLate in the courseFeculent vomitingPersistent vomitingMay result inDehydration and electrolyte disturbances.
5Large Bowel Obstruction Introduction Pathophysiology:Rotating or twisting of the cecum or sigmoidCauses abrupt onset of symptomsSigmoid volvulusUsually occurs in older individualsHistory of straining at stoolCecal volvulusFeatures a congenital defect in the peritoneumInadequate fixation of the cecumIt generally occurs in much younger individualsVenous drainage and arterial inflow are compromised by a closed loop obstructionAs the colon twists on its mesentery
6Large Bowel Obstruction Age Most common in elderly individualsIncidence of neoplasms and other causative diseases is higher in this population.In neonatesColonic obstruction may be caused byAn imperforate anusor other anatomic abnormalitiesMay be secondary to meconium ileusIn pediatricsHirschsprung disease resembles colonic obstruction
7Large Bowel Obstruction Clinical Manifestations HistoryInitially focus onFailure to pass stools or gasDistinguish complete bowel obstruction from partial obstruction and from ileusAssociated with passage of some gas or stoolsFurther historical questioningMay be directed at the patient's current and past historyAttempt to determine the most likely cause.Obtain history of bowel movements, flatus, obstipation and symptomsMajor complaintsAbdominal distentionNauseaVomitingCrampy abdominal pain.
8Large Bowel Obstruction Clinical Manifestations Complete obstructionCharacterized byFailure to pass either stools or flatusPresence of an empty rectal vault upon rectal examinationPartial obstructionPatient appears obstipated but continues to pass some gas or stoolsLess urgent condition.IleusDistinguishing colonic ileus from organic obstruction is importantIleus may be suggested byAbdominal pain as a dominant feature of the clinical presentationPeritoneal signsFever and leukocytosis.Constipation also may be accompanied by some degree of fever or leukocytosis
9Large Bowel Obstruction Clinical Manifestations Obtaining a thorough history of previous bowel function, abdominal pain, and general systemic issues is important.Neoplastic obstructionHistory ofChronic weight lossPassage of melanotic bloody stoolsDiverticulitis, diverticular strictureRecurrent left lower quadrant abdominal pain over several yearsA history of aortic surgery suggests the possibility of an ischemic stricture.
10Large Bowel Obstruction Clinical Manifestations Development historyRight-sidedCan grow quite large before obstructionLarge capacity of the right colonSoft stool consistency.Sigmoid colon and rectal tumorsCause colonic obstruction more rapidlyColon is narrower and the stool is harder in that area.Large-bowel obstruction prior to perforationObstruction that dilates the colonVisceral abdominal crampsVaguePain receptors senseDistention or vigorous contraction.Peritonitis may ensue.ObstipationPatients may state that pants or belts are not fitting properly.Intervention is necessary to prevent perforation
11Large Bowel Obstruction Clinical Manifestations Obstruction secondary to intussusceptionCrampy abdominal painColickyRelieved by assuming fetal position.Weight loss and fatigue are common.FistulizationSigmoid colon to the bladderPneumaturiaMucinuriaFecaluria
12Large Bowel Obstruction Clinical Manifestations: Physical Complete physical examination is necessaryKey elements should focus onAbdomenGroinRectumAbdominal examinationStandardInspectionAuscultationPercussionPalpationBowel soundsDiminished orAbsent bowel sounds.Late stagesQuality of abdomenDistendedMay be tender.Involuntary guarding or peritoneal signsMust think about intraabdominal process such as an abcess
13Large Bowel Obstruction Clinical Manifestations: Physical Examination of inguinal and femoral regionsShould be an integral part of the examination.Incarcerated herniasFrequently missed cause of bowel obstruction.Left-sided inguinal herniaColonic obstruction often is caused bySigmoid colon incarcerated in the hernia.
14Large Bowel Obstruction Clinical Manifestations: Physical Digital rectal examinationVerify the patency of the anus in a neonate.Focus on identifyingRectal pathologyMay be causing the obstructionDetermining the contents of the rectal vault.Hard stoolsSuggests impaction.Soft stoolsSuggest obstipation.Empty vaultSuggests obstructionProximal to the level that the examining finger can reachFecal occult blood testingPositive result may suggest the possibility of a more proximal neoplasm
15Large Bowel Obstruction Clinical Manifestations: Causes Obstructions caused by:TumorsGradual onsetNormally result from tumor ingrowth into the colonic lumenDiverticulitisMuscular hypertrophy of the colonic wallRepetitive episodes of inflammationLumen becomes narrow as the colonic wall becomes fibrotic and thickenedIntussusceptionCommonly involves a tumorVolvulusIncarcerated herniaOgilvie syndromeSymptoms and definitionMay occur in elderly individuals who abuse cathartics or have diabetesLoss of peristalsis.No obstruction is evidentColon becomes significantly and dangerously dilated.Once a contrast evaluation demonstrates nonobstructive colonic dilationManagement should be pharmacologicStimulation of colonic contractionsIntravenous neostigmine has been therapeutic in these situations
17Large Bowel Obstruction Workup Lab Studies:Obtain blood for aCBCElectrolyte levelsPTType and crossmatch.Imaging Studies:Upright chest radiographWill demonstrate free air of perforatedFlat and upright abdominal radiographsMay be diagnostic of sigmoid or cecal volvulusKidney bean appearance on the radiographCTGastrografinAn enema with water-soluble contrastCT with intravenous and rectal contrast.Procedures:Nasogastric tubeIf the patient has been vomitingIntravenous fluid resuscitation (intravascular depletion)Isotonic saline or Ringer lactate solution
18Large Bowel Obstruction Workup Lab Studies:ChemistryEvaluating the dehydrationElectrolyte imbalanceMay occur as a consequence of large bowel obstructionRuling out ileus as a diagnosis.Abnormail anion gapShould prompt an arterial blood gas and/or a serum lactate levelRoutine urine specific gravity should be evaluated.A decreased hematocritWith evidence of chronic iron-deficiency anemiaSuggests chronic lower gastrointestinal bleedingColon cancer?Stool guaiac testColon cancerLeukocytosisMild leukocytosis may be seen with obstruction or constipationSevere leukocytosis should prompt reconsideration of the diagnosisIleus, secondary to an intra-abdominal or extra-abdominal infection or another process, is a possibility.
19Large Bowel Obstruction Workup Imaging Studies:Upright chest radiographWill demonstrate free air of perforatedFlat and upright abdominal radiographsMay be diagnostic of sigmoid or cecal volvulusKidney bean appearance on the radiographDemonstrates dilation of the small and/or large bowel and air fluid levelsSigmoid volvulus
20Large Bowel Obstruction Workup X-ray findingsTracing colonic air around the colon, into the left gutter, and down into the rectum or demonstrating an abrupt cut-off in colonic air suggests the anatomic location of the obstructionA dilated colon without air in the rectum is more consistent with obstructionAir in the rectum is consistent withObstipationIileusPartial obstruction.Rectal examinations may cause misleading resultsThe characteristic bird's beak of volvulus may be seen.Radiopaque contrastImaging of the colon may be performed under the following circumstances.Perform it if the diagnosis of large bowel obstruction is suspected but not proven.If differentiation between obstipation and obstruction is required, imaging with contrast is indicated.If localization is required for surgical intervention, imaging with contrast is indicated.Gastrografin (water soluble)Advantages over barium (first line)It usually does not cause chemical peritonitis if the patient has colonic perforation.It has an osmotic laxative effect that may actually wash out an obstipated colon.Barium enemaIf large bowel perforation is ruled out using a Gastrografin study andMore detailed anatomic definition is required (particularly of the right colon)CT scanningGenerally is not used initially in patients with large bowel obstruction unless a diagnosis has been madeCT scan, particularly with rectal contrast, may demonstrate a mass or evidence of metastatic disease.Generally, the findings do not alter management because these patients will be explored and operatively decompressed, regardless of the CT scan findings.
23Large Bowel Obstruction Workup Procedures:Endoscopic reduction of volvulusIndicated for sigmoid volvulus whenPeritoneal signs are absentDead bowel or perforationEvidence of mucosal ischemia is not present upon endoscopyRigid sigmoidoscopeMay be used if a flexible instrument is not availableReduction of a volvulus does not imply cureSigmoid usually revolvulizesPatients admitted, subjected to mechanical bowel preparation, and managed surgically by sigmoid resectionBarium enema for reduction of intussusceptionChildrenOften successfulAdultsSuccess is far less likely, and patients still require surgery to deal with their pathology.Cleansing enemasUsed if obstipation is suspected rather than true large bowel obstructionAlso perform them to prepare the distal colon for endoscopic evaluation.
24Large Bowel Obstruction Treatment Emergency Department CareInitial therapyDirected at patient comfortVolume resuscitationUltimate goal to decompress the large intestine.Medical Care:ResuscitationCorrection of fluid and electrolyte imbalanceNasogastric decompressionTreat temporarilyObstruction and prevent vomiting and aspirationDirected primarily at supporting the patient and treating any comorbid illnesses
25Large Bowel Obstruction Treatment Surgical Care:Surgical care is directed at relieving the obstructionObstructed lesion is resected.(most cases)Because the colon has not been cleansed, anastomosis often is risky.After resection, most surgeons perform a proximal colostomy if the obstruction is on the left side or ileostomy if it is on the right side.Diverting proximal colostomy or ileostomySubstantial comorbidity and surgical risk or in the presence of an unresectable tumorDiverting transverse loop colostomyLeast invasive procedure for a very ill patient with a left colonic obstructionPermits relief of the obstruction and further resuscitation without compromising chances for a subsequent resectionSigmoid colostomy without resectionEmployed in patients with a rectal obstruction that cannot be managed without a combined abdominoperineal approach.Cecostomy should not be performed because the diversion is inadequate.YouthSome surgeons would consider primary anastomosis, rather than ileostomy, in the right colon, assuming no intraoperative hypotension, blood loss, or other complications are present.If nonsurgical therapy employedi.e. decompressing a volvulusDeferring surgery temporarily and supporting the patient while the large bowel is cleansed so that primary anastomosis may be performed more safely is preferable
26Large Bowel Obstruction Treatment ConsultationsObtain early consultation from a general surgeonSurgical intervention frequently is indicatedDietComplete obstruction – NPOPartial obstruction – Clear liquidsSpecific casesSigmoid volvulusFirst choice is sigmoidoscopy with volvulus reduction.Second choice is sigmoid colectomy.Cecal volvulusFirst choice is hemicolectomy.Second choice is colonoscopy.Sigmoid obstruction secondary to diverticulitis or carcinomaProcedure of choice is a sigmoid resection and Hartman procedure or a sigmoid resection.Alternative is primary anastomosis.Obstruction of splenic flexureFirst choice is extended hemicolectomy.Second choice is proximal colostomy with delayed resection.
27Large Bowel Obstruction Treatment In/Out Patient Meds: Pain medicines generally should be avoided preoperativelyIf the pain is sufficiently severe to merit use of significant analgesicsPeritonitis, rather than large bowel obstruction, should be considered as the first diagnosis.Oral laxatives are contraindicated in patients with complete large bowel obstruction.Chemotherapy?Temporary or permanent colostomy?
28Large Bowel Obstruction Follow up Complications:PerforationSepsisIntra-abdominal abscessDeathPrognosis:If treated early, outcome is generally good.If secondary to carcinomaOutcome is dependent on the carcinoma prognosis
29References www.emedicine.com Large bowel obstruction, 2004 Colonic Obstruction, 2004Baker, R., Fischer, J., LBO, Mastery of Surgery, fourth edition, ppHaubrich, W., Schaffner, F., 1995, Gastroenterology, LBO, pp 1189