THE ACUTE ABDOMEN.docx

THE ACUTE ABDOMEN.docx

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THEACUTEABDOMEN

MODULE2-DiseasesandMalfunctions

简易课程

MINICOURSE4-THEACUTEABDOMEN

INTRODUCTION

Therearefewsituationsinclinicalmedicinewhichdemandpromptanddecisiveactionasfrequentlyasdoesacuteabdominalpain.Acuteconditionsoftheabdomenareproducedbyinflammatory,obstructive,orvascular

mechanismsandaremanifestedbysuddenonsetofabdominalpain,gastrointestinalsymptomsandvaryingdegreesoflocalandsystemicreaction.Theyrequireurgenttreatment,oftenincludingemergencyoperation.Theirurgencyusuallyprecludesprolongedinvestigationandtherearefewspecifictestsorexaminationswhichmaybereliedupontogiveclear-cutanswersastotheexactcauseoftheacutecondition.

Ifsurgerycarriednoriskanddidnotadverselyaffectthecourseofsomediseases,itwouldbesafetosay"ifindoubt,operate."Unfortunately,laparotomyitselfcarriesrisksandthecourseofsomedisorderssuchasacutepancreatitisandparalyticileusisadverselyinfluencedbyanesthesiaandsurgery.

Thediagnosisofacuteconditions,therefore,frequentlyresolvesitselfintoarrivingatafairlyimmediatejudgementderivedfromanaccurateanddetailedhistory,acarefulphysicalexaminationandafewselectedlabtestsandx-raystudies.Whilegatheringtheevidence,changesshouldbeevaluatedintermsofpathophysiologicalterationsratherthanspecificdiagnoses,andattentionmustbegiventotheneedforsupportivemeasureswhileinvestigationisunderway.

AnApproachtotheAcuteAbdomen

Oncompletionofthisminicourseyouwillbeableto:

1.Definetheacuteabdomen.

2.Describethecauseandpathophysiologyofthefollowingacuteabdominaldiseases:

oa.acuteappendicitis-inflammatory

ob.acutesmallbowelobstruction-mechanical

oc.mesentericvascularocclusionvascular

od.perforatedduodenalulcerperforatedviscus

oe.peritonitis

3.Identifyanddescribethesymptoms,signs,clinicalcourseandlaboratoryandx-rayfindingsfortheacuteabdominaldiseaseslistedunderObjective2.

4.Identifytheclinicalfeaturesthathelptodistinguishthesurgicalfromthenon-surgicalacuteabdomen.

5.Constructanapproachtoevaluationandmanagementoftheacuteabdomen.

MINICOURSE2.4SECTION1

OBJ.1.Definetheacuteabdomen.

DefinitionoftheAcuteAbdomen

Theacuteabdomenmaybedefinedgenerallyasanintraabdominalprocesscausingseverepainandoftenrequiringsurgicalintervention.Itisaconditionthatrequiresafairlyimmediatejudgementordecisionastomanagement.Generalcausesoftheacuteabdomenmaybedividedintosixlargecategories:

∙a.inflammatory

∙b.mechanical

∙c.neoplastic新生物

∙d.vascular

∙e.congenitaldefects先天缺陷

∙f.traumatic

Eachofthesecategorieshasmanytypicalexamples,ofwhichonlyafewofthemorecommonconditionswillbediscussedinthisminicourse.

Theinflammatorycategoryofcausesmaybedividedintotwosubgroups:

1）bacterial,and2）chemical.Somecommonexamplesofthebacterialcauseswouldincludeacuteappendicitis,diverticulitis,andsomecasesofpelvicinflammatorydisease.Anexampleofachemicalcausewouldbeaperforationofapepticulcer,wherespillageofacidgastriccontentscausesanintenseperitonealreaction.

Mechanicalcausesofanacuteabdomenincludesuchobstructiveconditionsasincarceratedhernia,post-operativeadhesions,intussusception,malrotationofthegutwithvolvulus,congenitalatresiaorstenosisofthegut.Themostcommoncauseoflargebowelmechanicalobstructioniscarcinomaofthecolon.

Vascularentitiesproducinganacuteabdomenincludemesentericarterialthrombosisorembolism.Whenthebloodsupplyiscutoff,necrosisoftissueresults,withgangreneofthebowel.

Congenitaldefectscanproduceanacuteabdominalsurgicalemergencyanytimefromtheminuteofbirth（withconditionssuchasduodenalatresia,omphaloceleordiaphragmatichernia）toyearsafterwardinconditionssuchaschronicmalrotationoftheintestine.

Traumaticcausesofanacuteabdomenrangefromstabandgunshotwoundstobluntabdominalinjuriesproducingsuchconditionsassplenicrupture.Historyorevidenceoftraumashouldmakethisdiagnosisfairlyobvious.

EXERCISE1OBJECTIVE1-Questions

1.Whatismeantbytheterm"acuteabdomen?

"

2.Giveanexampleofanacuteabdomenduetoeachofthefollowingmechanisms:

∙a.Inflammation

∙b.Mechanicalobstruction

∙c.Vascularentities

EXERCISE1DISCUSSION

OBJECTIVE1Answers

1.Thetermreferstoacuteconditionsarisingwithintheabdomenassociatedwithsevereabdominalpain,requiringfairlyimmediatemanagementandoftenrequiringsurgery.

2.Oneexampleofeachis:

∙a.Acuteappendicitis

∙b.Incarceratedhernia

∙c.Mesentericarterialthrombosis.Ofcourse,therearemanyothers.

MINICOURSE2.4SECTION2

OBJ.2.Describethecauseandpathophysiologyofthefollowingacuteabdominaldiseases:

∙a.Acuteappendicitis-inflammatory

∙b.Acutesmallbowelobstructionmechanical

∙c.Mesentericvascularocclusion-vascular

∙d.Perforatedduodenalulcer-perforatedviscus

∙e.Peritonitis

CauseandPathophysiologyofAcuteAbdomen

a.AcuteAppendicitis

Inflammationintheappendixhasthesamefeaturesandfollowsthesamecourseasinflammationelsewhereinthegut.Itsimportanceisafunctionofitsfrequencyasaserioussurgicalconditionwithsignificantcomplications.

Obstructionoftheappendiceallumenbyfecalithswithinterferenceofthevascularsupplyareimportantfeaturesinitspathogenesis.Theessentialelementcausinginflammationofthewalloftheappendixisinvasionbybacteria.Theusualorganismsintheinflamedappendixarecolonbacilliandstreptococci,organismscommonlyfoundintheintestinaltract.Obstructionofthelumenandvascularocclusionprobablycontributebybreakingdowntheresistanceofthewalloftheappendixtoinvasionbypotentialpathogensinthegut.

Theearliestlesionisasuperficialulcerationofthemucosa.Spreadthenoccursfromthemucosatothemusclelayersandtheserosaandthelumenmaybecomefilledwithpus.Interferencewithcirculationleadstoareasofnecrosisandperforationoftheappendix,withspreadofinfectiontotheperitonealcavity.Iftheinfectionbecomeswalledoffaroundtheappendixalocalizedabscessmayresult.Otherwiseageneralizedperitonitisresults.

Thesamesortofinflammatoryprocessmayoccurinacutediverticulitiswhichusuallyinvolvesthedescendingandsigmoidcolon.Thisispromotedbythelodgingoffecalmaterialinadiverticulumwithspreadofinflammationtosurroundingtissue,andisaccompaniedbyleftlowerquadrantpain.

Inacutecholecystisthereisinflammationofthewallofthegallbladderduesochemicaldamagefromtheactionofconcentratedbile,promotedbyanobstructionofthecysticduct,usuallybystones.Bacterialinfectionwithstreptococciorcolonbacillimaysupervene.Inacutecholecystisthegallbladderislargeandhasathickedematouswall.Themucosashowsareasofulcerationandnecrosisandleukocytesarepresentinthewall.Pusmayfillthecavity,withanempyemaofthegallbladder.Necrosisandrupturemayoccur.

b.AcuteSmallBowelObstruction

Completeobstructiontothepassageofintestinalcontentiscausedeitherbymechanicalobstructionofthelumenorbyparalysisoftheintestinalmuscles（paralyticileus）andmaycausedeathinarelativelyshortperiodoftimeunlessrelieved.Acutemechanicalobstructionofthesmallboweliscausedmostcommonlyeitherbystrangulatedherniaorbyadhesionsandbands,usuallypost-operative,withtheperitonealcavity.

Agehasasignificantinfluenceonthecauseofsmallbowelobstruction.Innewborns,congenitalproblemssuchasatresiaofthegutareimportantcausesofobstructionandinsmallchildrenintussusceptionisencounteredwithfrequency.Theobstructionmaybeanentirelymechanicalocclusionofthelumen,whichisthecasewithanincarceratedhernia,congenitalatresiaofthelumenofthegut,andkinkingandexternalcompressionofthegutbyperitonealadhesions,usuallypost-operativeinorigin.

Theremay,however,beanassociatedinterferencewiththebloodandnervesupplyfortheintestines,inwhichcasethebowelissaidtobestrangulated.Obstructionsuchasanincarceratedhernia,ifnotpromptlyreduced,causesincreasingedemaofthegutwithimpairmentofthebloodsupply.Volvuluswithtwistingofthemesenteryandintussusception（whereonesegmentofthesmallbowelinvaginatesintoanother）alsocauseinterferencewithnerveandbloodsupply.Ischemicnecrosisorinfarctionofthebowelwalloccursunlessthebloodsupplyispromptlyrestored.Theinvolvedportionoftheintestinebecomesinturncongested,edematous,necroticandfinallygangrenous.Ingeneral,thehigherthesiteofanobstructionwithintheintestinaltract,themoreseverearetheassociatedsymptomsofexcessivevomitingwithdehydrationandchemicaldisturbancesoccurringbecauseofagreatlossofwaterandelectrolytes.

Themostcommoncauseoflowerintestinalobstructioniscarcinomaofthedistalportionofthecolon.Thedevelopmentoftheclinicalpictureisslowerthaninsmallbowelobstructionandpatientsdonotappearasillincomparablestages.Usuallytheacuteepisodeoflargebowelobstructionissuperimposedonprogressivechangeofbowelhabits,withdecreasingcaliberofthestoolsandincreasingconstipation.

Functionalintestinalobstructionduetoneurogenicfactorswhichcauseparalysisoftheintestinalmuscleandfailureofperistalsisisfairlycommon.Itistermedadynamicorparalyticileusanditoccurstosomeextentinmostpatientswhohaveundergoneabdomi