CHAPTER21
Operativebirths
RichardHayman
CHAPTERCONTENTS
Assistingavaginalbirth456
Indicationsfor ventouseorforceps456
Fetal456
Maternal456
Contraindicationstoaninstrumentalvaginalbirth457
Absolute457
Relativecontraindications(forforcepsorventouse)457
Prerequisitesforanyoperativevaginalbirth457
Birthbyventouse457
Types ofventouse457
Theuseoftheventouse458
Procedure458
Precautionsinuse459
Themidwifeventousepractitioner460
Birthbyforceps460
Characteristicsoftheobstetricforceps460Classificationof obstetricforceps460Typesofobstetricforceps460
Procedure460
Complicationsofinstrumental vaginalbirth462
Caesareansection463
Clarifyingtheindicationsforcaesareansection463
Theoperativeprocedure464
Women'srequestforcaesareansection465Psychologicalsupportandtherole ofthe midwife465Vaginalbirthaftercaesareansection(VBAC)466Postoperativecare466
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Analgesia/anaesthesia468
Researchandtheincidenceofcaesareansection:tacklinghighandrisingcaesareansectionrates471
References472
Furtherreading473
Usefulwebsites473
Thischapterdescribesthemethods ofoperativebirththatmaybeused whenthe motherisunabletogivebirthwithoutmedicalorsurgicalassistance.Therole ofthemidwifeinthese procedures willbeexplored,as willtheprinciplesof‘keepingthenormal,normal’.
Thechapteraimsto:
•identifytheareasofmidwifery carethatrelatetothepreparationforanassistedvaginalbirth(ventouse/forceps) or birthbycaesareansection(CS)
•describe theroleofthemidwifeinrelationtotheissuesofinformedconsentandthemanagementofcomplicationsfollowingassistedbirth
•considerthevarioustechniquesusedforassistedvaginalbirth(ventouse/forceps)andbirthbyCS,plustheskillsrequiredbythemidwifetoimprovetheexperienceforboththemotherandherpartner
•discussthechanging roleofthemidwifeinrelationtomedical intervention.
Assistingavaginalbirth
Assistedvaginalbirthisafrequentlyandwidelypractisedinterventionintheprovisionofcaretowomenduringchildbirth.InEnglandduring2011–12,ofthe668936births recorded,85009(13%)wereassistedwithforcepsorventouse(HealthandSocialCareInformationCentre,HospitalEpisodesStatistics2012).However,theincidenceofinstrumentalinterventionvarieswidelybothbetweenandwithincountries,andmaybeperformedasinfrequentlyas1.5%orasohenas26%.Suchdifferencesmaybelinkedtothealternativemanagementstrategiesemployedduringlabourindifferentunits(Braggetal2010).Varioustechniqueshavebeenchampionedtohelplowertheratesofoperativebirths.ThesearesummarizedinBox21.1.
Box21.1
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Usefultechniquestohelplowertheoperativebirthrate
•One-to-onecareinlabour(Hodnettetal2011)
•ActivemanagementofthesecondstagewithSyntocinon(O'Driscolletal1993;Brownetal2008)
•Uprightbirthposture/mobilization(NICE2007;Guptaetal2012)
•Delayingtheonset oftheactivesecondstageby1–2hoursinwomenwithregionalanalgesia/anaesthesia(NICE2007)
•Fetalbloodsamplingratherthanexpeditingbirthwhenfetalheartrateabnormalitiesoccur(NICE2007)
Itshouldbenoted,however,thatotherinterventions,suchasepiduralanalgesia,havebeenobservedtobeassociatedwithanincreasedriskofinstrumentalvaginalbirthandhavebeensuggestedtobelinkedtoanincreasedriskofbirthbycaesareansection(CS)(Anim-Somuahetal2011).However,such‘disadvantages’mustbebalancedagainstthehigherratesofmaternalsatisfactionthatthisformofanalgesiaprovides.Itisuptothewomantomakeaninformedchoiceastowhichofthebenefitsandrisksaremostimportant,notup totheafendingmedicalstafftomakedidactic decisionsonherbehalf.Indeed,whilstithasbeencommented(JohansonandMenon1999)that,ingeneral,maternaloutcomeswouldbeimprovedbyloweringinstrumentalbirthrates,noevidencetosupportsuchastatementhaseverbeenforthcoming,asitisnoteasytoseewhatthealternativesareforawomanwho,despiteherownbestefforts,hasnotbeenabletosecurea‘normalbirth’.
Indicationsforventouseorforceps
Theindicationsforassistedvaginalbirth maybesimplycategorizedintofetal andmaternal.However,thereasonscitedforinterventionarefrequentlyimpreciseasmultiplefactorsofteninteract.
Fetal
•Malpositionofthefetalhead(occipitolateralandoccipitoposterior).Suchpositionsoccurmorefrequentlyinthepresenceofregionalanaesthesia,asalterationsinthetoneofthepelvicfloormayimpedethespontaneousrotationtotheoptimaloccipitoanteriorpositionduringthedecentofthepresentingpart(vertexofthefetalhead).
•Fetal‘distress’isacommonlycitedindicationforinstrumentalintervention;however,‘presumedfetalcompromise’isamorecomprehensiveterm(unlessafetalbloodsamplehasbeenobtainedshowinghypoxiaandacidosis,inwhichcase‘fetalhypoxia’shouldbeused)(NICE[NationalInstituteforHealthandClinicalExcellence]2007).
•Electiveinstrumentalinterventionforinfantsofreducedweight.Ininfantsweighing
1.5kg,deliverywithforcepsdoesnotconferanadvantage overspontaneousbirthand
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mayincreasetheincidenceofintracranialhaemorrhage.Ventousecarriesthesamerisks,butinadditionshouldbeavoidedininfantsof<34+6weeks ofgestation.
•Assistedvaginalbreechbirth.Forcepscanbeappliedtotheafter-comingheadtocontrolthebirthofthevertex,asituationwheretheventouseiscontraindicated.
Maternal
•Thecommonestmaternalindicationsarethoseofmaternaldistress,exhaustion,orprolongationofthesecondstageoflabour.Thishasbeensuggestedasgreaterthan2hours in aprimigravida(3hours if anepiduralis insitu),ormorethan 1hourinamultipara(2hoursifanepiduralisinsitu)(NICE2007).
•Medicallysignificantconditionssuchas:aorticvalvediseasewithsignificantoutflowobstruction;myastheniagravis;significantantepartumhaemorrhageduetoplacentalabruptionorvasapraevia;severehypertensivedisease;andpreviousCS(tominimizetheriskofscarrupture).
Contraindicationstoaninstrumentalvaginalbirth
Absolute
•Thevertexis≥1/5thpalpableabdominally.
•Thepositionasdeterminedbyavaginalexamination(occipitoanterior/posteriororlateral)ofthefetalheadis unknown.
•Beforefulldilatationofthe cervix(althoughapossibleexceptionoccurswiththeventousebirthofasecondtwin).
•Whentheoperatorisinexperiencedininstrumentalvaginalbirth.
Inadditiontheventouseshouldnotbeused:
•Ingestationsof<34+6weeksbecauseoftheincreasedriskofintracranialhaemorrhageinthefetus.
•Withthefetuspresentingbytheface.
•Ifthereisasignificantdegreeofcaputthatmayeitherprecludecorrectplacementofthecupor,moresinisterly,indicateasubstantialdegreeofcephalopelvicdisproportionCPD).
Relativecontraindications(forforcepsorventouse)
•Fetalbleedingdisorders(e.g.alloimmunethrombocytopenia)orapredispositiontofractures(e.g.osteogenesisimperfecta)arerelativecontraindicationsspecificallytoanoperativebirthwiththeventouse. However, the comparative risksofabirthbyadifficultsecondstagecaesareansectionmustalsobeconsideredandadiscussionundertakenantenatallyaboutthemostappropriateplanforbirth(itmaybewisertorecommendthatsuchwomenhaveanelective CS).
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•Thereisminimalriskoffetalhaemorrhageifthevacuumextractorisemployedfollowingfetalbloodsamplingorapplicationofascalpelectrode.
Prerequisitesforanyoperativevaginalbirth
•Ruptureofthemembranesmustbeconfirmed.
•Thecervixmustbefullydilated.
•Cephalicpresentationwithidentificationoftheposition(occipitoanterior/posteriororlateral).
•Adequatepelvisasascertainedbyclinicalpelvimetry.
•Thefetalheadmustbe <1/5thpalpableperabdomen,withthepresentingpart at orbelowtheischialspines.
•Adequateanalgesia/anaesthesia.
•Emptybladder/noobstructionbelowthefetalhead(contractedpelvis/ovariancyst).
•Aknowledgeableandexperiencedoperatorwithadequatepreparationtoproceedwithanalternativeapproachifnecessary.
•Anadequatelyinformedwoman(withsignedconsentformdetailingappropriaterisks/benefits/complicationsasthesituationdemands).
Birthbyventouse
Theventouseisessentiallyasuctioncup(madefromplasticormetal)thatisconnected(viatubing)toavacuumsource.Followingtheplacementofthecupontothefetalhead,tractioncanbeappliedtoassistthebirth.
Thereisnodefinitiveguideas towhichinstrument touseonwhichoccasion. Howevertheventousecupmaynotbesuccessfulatsecuringbirthand thereforeobstetricforcepsshouldbechosenifthereis:
•suspectedfetalmacrosomia
•excessivecaputormoulding
•poormaternaleffortduetoexhaustion(whichmaybecompoundedbyepiduralanalgesiaandpoorsensation)
•gestation<34completedweeks.
Typesofventouse
Untilrecently,themostcommonlyusedventouseinuseintheUnitedKingdom(UK)wasthatofthe‘soh’orsiliconecupdesign(Fig.21.1A).Whilstthesecupshavetheundoubtedadvantagesofbeingextremelymalleable(reducingmaternaltraumabybeingmoreeasytocorrectlyplacewithinthevagina)andhavingareducedincidenceoffetalscalptraumawhencomparedtoothercupdesigns,sohcupshaveapoorersuccessratethanmetalcupsinachievingavaginalbirth(RCOG[RoyalCollegeofObstetriciansand
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Gynaecologists]2011).
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FIG. 21.1(A)Thesoftcupventouse.(B)TheKiwiOmniCupTM.(C)Birthbyventouse.
MetalcupventousedesignsareoftheBirdorMalstromtypes,whichhaveacentrallyplacedtractionchainwithalaterallylocatedvacuumconduit.Theycomeindiametersof4,5and6cm.
Boththestandardsohandmetalcupdesignsrequirethegenerationofanoperatingvacuumfromanexternalsource–andassuchthesepiecesofequipmentrequiretwooperatorsfortheirsuccessfuluse(onetocontroltheplacementoftheventouseandassistthebirth,theother(mostcommonlytheafendingmidwife)tocontrolthedegreeofvacuumthatisgenerated.
Morerecentadvancesindesignhaveremovedtheneedfortheexternalsuctiongeneratorsbyincorporatingthevacuummechanisminto‘hand-held’pumps(e.g.KiwiOmniCupTM)asillustratedin Fig.21.1(B).Suchdevicesaresafeandmaybeusefulforrotationalbirthsbecausetheyare lowprofile andareeasilymanoeuveredintothecorrectposition.However,theyhaveasignificantlyhigherfailureratethantheconventionalmetalcupventouse,withcupdetachmentsoccurringmorefrequently.
Theuse oftheventouse
Theventouseismorefrequentlyemployedbyobstetriciansthantheobstetricforcepsduetoitsapparenteaseofuseandcomparativesafety.However,repeatedmeta-analyseshavedemonstratedthattheventouseislesslikelytoachieveasuccessfulvaginalbirththanforceps,althoughbothtypesofinstrumentsareassociatedwithaloweringoftheoverallCSrate(Johansonand Menon1999).Althoughtheventouseisassociatedwithan
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increasedriskofneonatalcomplicationssuchascephalohaematoma(Chapter31),otherfacial(nervepalsies)andsignificantcranialinjuries(fractures)aremorecommonwithforceps.
Procedure
•Therationaleforthebirthis discussedwiththewomanandherpartner.Theprocedureisexplainedandconsentobtained(writtenconsentshouldbeobtainediftimeallows).
•Thewoman'slegsshouldbeplacedintothelithotomyposition.
•Whilstinhalationalanalgesiamaybesufficient(entonox–N2O),morecommonlyapudendalnerveblockwithperinealinfiltrationmaybeadministered,oranepidural,ifalreadyinsitu,maybetoppedup.
•Onceadequateanalgesiaisassured,thematernalbladderisemptied.
•Thefetalheartrate (FHR)mustbecontinuouslymonitored(withacardiotocograph–CTG).
•Forthesuccessfuluseoftheventouse,itisessentialtodeterminethe flexionpoint,whichislocated,inanaverageterminfant,alongthesagittalsuture3cmanteriortotheposteriorfontanelle(andthus6cmposteriortotheanteriorfontanelle).Thecentreofthecupshouldbeplaceddirectlyoverthis,as failuretoadequatelypositionthecupcanleadtoaprogressivedeflexionofthefetalheadduringtraction.
Theoperating vacuumpressurefornearlyallventouseisbetween0.6and 0.8kg/cm2(60–
80kPa/500–800cmH2O).Noevidenceexiststhatastepwisereductioninpressureimprovestherateofsuccessfulbirthwhencomparedwithalinearreduction.Usingthelafertechniquewithasilasticcup,acaputsuccedaneum(Chapter31)isformedinstantly,andwiththemetalcuporOmniCupTM,anadequatechignonisproducedin<2minutes.Itisimportanttonotethatacupof5cmdiameterissuitablefornearlyallbirths,evenwithlargerbabies.
Whenthevacuumisachieved,tractionmustbeappliedtocoincidewithacontraction
andthusmaternalexpulsiveefforts.Withoutbothofthesecontributingfactors,birthwithaventousewillfail.Tractionisprovidedalong atrack definedbythecurveofCarus(Chapter3):initiallyinadownwardsandbackwardsdirection,theninaforwardandupwardmanner.Oncethefetalheadhascrowned,thevacuumisreleased,thecupremovedandwithfurthermaternaleffortsthebabywillbeborn.Inadditiontotherelativeeaseofuseandlowriskofcomplications,itisundoubtedlythissenseofcontributiontothebirththatmakes the ventouseamore satisfactorybirthingexperienceforthemotherandherpartnerthananoperativebirthwithobstetricforceps.
Precautionsinuse
Withtheventouse,theoperatorshouldallow≤2episodesofbreakingthesuctioninanyvacuumassistedbirth,andthemaximumtimefromapplicationtobirthshouldideallybe≤15minutes.Ifthereisnoevidenceofdescentwiththefirstpull,thewomanshould
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bereassessedtoascertainthereasonforfailuretoprogress.Inaddition,careshouldbetakentoensurethatnovaginalskinistrappedintheedgesofthecupasthiscanresultincomplexdegreesofperinealtraumathatcanbeextremelydifficulttorepairinasatisfactoryfashion.
Themidwifeventousepractitioner
Somemidwivesfeelthatwomenwillbebefer servedbyamidwifeventousepractitionerratherthananobstetricianand embracesuchinnovations(Tinsley2010).However,others seeitasexceedingthe limitsof normalmidwiferypractice(Charles 1999).Thefactisthatmidwifery careischanginganddeveloping,specificallywiththeadvancementofcarewithinstand-alonemidwife-ledunits.
Whilsttheideaofreducingthepsychologicaltraumatoawomanduringabirthbylimitingthenumberofcarersinafendanceatthiscrucialandcriticaltimeistobecommended,itwouldbefoolhardytoassumethatthemidwifeventousepractitionerwouldbetheprimarycarerforeverypregnantwomenoneveryoccasionthatrequiredanassistedvaginalbirth.Assuchitislikelythatamidwifepreviouslyunknowntothelabouringwomanwouldbeaskedtoassistatthemomentwhenhelpisrequired,aneventthatwouldthereforebenoless‘traumatic’forawomanorherpartnerthanaskinganobstetrician toafend.Allaccoucheurs,includingmidwife ventousepractitioners,mustbewelleducatedandtrainedbeforecarryingoutaventousebirth–althoughitishighlyunlikelythatthemorecomplexsurgicalskillsrequired ofa birthbyforcepsorCSwouldbemasteredinaddition.Itshouldberememberedthatasaventousewillfailinupto20%ofcases,eveninthemostskilledhands,havingnoabilitytochangeinstrumentsorresorttobirthbyCSwillplacethosemidwiveswhoworkasventousepractitionersinisolationinamostunenviableposition.
Birthbyforceps
Characteristics oftheobstetricforceps
Allobstetricforcepsarecomposedoftwoseparateblades(determinedasrightandlehbyreferencetotheirinsertionaroundthefetalheadwithinthematernalvagina),twoshanks(shahs)ofvaryinglengthandtwohandles.Forcepsareohendescribedasnon-rotationalorrotational.Non-rotationalforcepsare‘held’togetherbyeitheranEnglish(non-sliding)lockontheshankor,inthecaseofrotationalforceps,byaslidinglockontheshank.Thebladeshaveacephaliccurveto accommodatetheformofthebaby'sheadandarefenestrated(andnotsolid)tominimizethetraumatothebaby'sheadduringbothplacementandbirth.Theyalsohaveapelviccurvetoreducetherisksoftraumatothematernaltissuesduringthebirthprocess.
Whenthebladesarecorrectlypositionedaroundthefetalskull,thehandleswillbeneatlyalignedinthehandsofthedoctorwhoappliesthemandwillbenotedto‘lockwithease’.Forcepsthat donotlockaremostcommonlyincorrectlyplaced.
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Classificationofobstetricforceps
Forcepsoperationsfallintotwocategories:mid-andlow-cavity.Mid-cavityforcepsareusedwhentheleadingpartofthefetalheadhasreachedbelowtheleveloftheischialspines;low-cavityforcepsare usedwhentheheadhasdescendedtothe levelofthe pelvicfloor.High-cavityforceps(withtheleadingpartofthefetalheadabovetheleveloftheischialspines)arenowconsideredunsafeandaCSwillbethepreferredmethodofbirthinnearlyallcases.
Typesofobstetricforceps
Wrigley'sforceps
Theseare designedforuse in outletlih-outwhenthe headisontheperineum ortoassistthebirthofthefetalheadatcaesareansection.Theyhaveashortshank,fenestratedbladeswithbothpelvicandcephaliccurves,andanEnglishlock(Fig.21.2).
FIG. 21.2Typesofforceps.Fromabove:Kielland's,Neville–BarnesandSimpson's.Notethedifferenceincephaliccurve.Therotationalforceps(Kielland's)havealongshaftandlittlepelviccurve.Wrigley'sforcepshaveashortershank.
Neville–BarnesorSimpson'sforceps
Thesearegenerallyused foralow-ormid-cavityforcepsbirthwhenthesagifalsutureisintheanteroposteriordiameterofthecavityofthepelvis.Whilsttheyhavecephalicandpelviccurvestothefenestratedblades,thehandles arelongerandheavier(Fig.21.2)thanthoseoftheWrigley's.Anderson'sandHaig–Ferguson'sforcepsarealsosimilar inshapeandsize.
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Kielland'sforceps
Thesewereoriginallydesignedtodeliverthefetalheadatastationat,orabove,thepelvicbrim.Theyarenowmorecommonlyusedfor therotationandextractionofababywhose headisin the deeptransverseoroccipitoposteriormalpositions.Bycomparison tothenon-rotationalforceps,theKielland'sforcepsbladeshavefenestratedbladeswithamuch-reducedpelviccurve(inordertoallowforthesaferotationofthefetus),longershanks(toenablerotationwithinthemid-cavityofthepelvis)and asliding lock toallowforcorrectionofanydegreeofasynclitismofthefetalhead.Theseforceps(Fig.21.2)shouldbeusedonlybyanobstetricianskilledin theirapplicationanduse,andindeedinmanyunitstheirusehasbeenabandoned.
Procedure
Inadditiontothekeypointsoutlinedforventouseonpage458,i.e.rationale,consent,urinarybladdercatheterization,FHRmonitoringandpositionofthewoman'slegs,specificissuestoconsiderare:
•Considerationshouldbegivenastothelocation ofthebirth–inthebirthingroom(lift-out orlow-cavity–nonrotationaldeliveries)orinthe obstetrictheatre (allotherforcepsbirths).
•Unliketheventouse,inhalationalanalgesiaorapudendalnerveblockwithperinealinfiltrationisunlikelytobesufficientforaforcepsbirth.Inthemajorityofinstances anepidural,ifalreadyinsitu,maybetoppedup,oraspinalanaestheticshouldbeadministered.ThesearemandatorybeforeconsiderationisgiventousingKielland'sforceps.
•Theforcepsshouldbehelddiscretelyinfront ofthewoman(tovisualize howtheywillbeinsertedpervaginum)andplacedaroundthefetalhead.Theleftbladeisinsertedbeforetherightblade,withtheaccoucheur'shandprotectingthe vaginalwallfromdirecttrauma.
•The forcepsblades cometolieparalleltotheaxisofthefetalhead,andbetweenthefetalheadandthepelvicwall.Theoperatorthenarticulatesandlockstheblades,checkingtheirapplicationbeforeapplyingtraction.Thebladesmustberepositionedortheprocedureabandonediftheapplicationisincorrect.
•Tractionshouldbeappliedinconcertwithuterinecontractionsandmaternalexpulsiveefforts.
•Aswiththeventouse,theaxis oftractionchanges duringthebirthandis guidedalong thecurve ofCarus,thebladesbeingdirectedtothe verticalastheheadcrowns(seeFigs21.3–21.6).
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FIG. 21.3Leftbladebeinginserted.Thefingersoftherighthandguardthevaginaltissue.
FIG. 21.4Rightbladebeinginserted.
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FIG. 21.5Tractionoftheheadisdownwardsuntilthispoint;whentheheadislow,thedirectionofpullisoutward,towardstheoperator.
FIG. 21.6Astheheadcrownsitisliftedupwards.
Complicationsofinstrumentalvaginalbirth
Althoughforcepsarelesslikelythantheventousetofailtoachieveavaginalbirth,theyaresignificantlymorelikely tobeassociatedwiththird-orfourth-degreetears(withorwithouttheconcurrentuse of anepisiotomy),vaginal trauma,use of generalanaesthesia,flatal,faecalandurinarycontinence(Chapter15).
Maternalcomplications
Complicationsmayinclude:
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•Traumaorsofttissue damage–occurringtothecervix,vaginaorperineum.
•Dysuriaorurinaryretention,whichmayresultfrombruisingoroedematothetissuesaroundtheurethra.
•Perinealdiscomfort.
•Haemorrhage(bothfromtissuetraumaandalsouterineatony–theriskofwhichisalwaysincreasedfollowinganassistedvaginalbirth).
Neonatalcomplications
Complicationsmayinclude:
•Marksonthebaby'sfaceandbruising(commonlycausedbythepressurefromtheforcepsbladesandaroundthecaputsuccedaneum/chignonfromtheventouse–nearlyallofwhichresolvewithin48–72hours afterbirth;seeChapter31).
•Facialpalsy,whichmayresultfrompressurefromabladecompressingafacialnerve (atransientprobleminmostinstances).
▪Prolongedtractionduringabirthwithaventousewillincreasethelikelihoodofscalpabrasions,cephalohaematomaorsub-aponeuroticbleeding(Chapter31).
Someauthorssuggestthatfailureratesof<1%shouldbeachievedusingthecorrecttechniqueandwithwell-maintainedequipment.Manyauthorsfeelthatthisisanunrealistictarget.Failureoftheventouserealisticallyarisesinupto20%ofcasesandindeedJohansonandMenon(1999)achievedvaginalbirthwiththefirstinstrumentinonly86%ofassistedbirths.
Thefollowingas factorswilloftenbefoundtohavecontributedtofailure:
Withtheventouse
•Failuretoselectthecorrectcuptype–inappropriateuseofthesilasticcup–especiallyinthepresenceofdeflexionofthefetalhead,excess caput,‘dense’epiduralblockorfetalmacrosomia(trueCPD).
•Failureoftheequipmenttoprovideadequatetractionasaconsequenceofaleakageofthevacuum.
•Incorrectcupplacement–tooanteriororlateral,withorwithoutinclusionofmaternalsofttissueswithinthecup.
Withanyinstrument
•Inadequateinitialcaseassessment–highhead,misdiagnosisofthepositionandattitudeofthehead.
•Tractionalongthewrongplane(oftentooanteriorlyandnotalongthecurveofCarus).
•Poormaternaleffortwithinadequateuseofsyntocinontomaximizethecontributionfromcoordinateduterineactivity.
Whatevertheoutcome,themidwifeinafendanceisvitaltothesuccessofanymanoeuvresundertaken,encouragingthe mothertobeanactiveparticipantin herbirth,
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supportingthemotherandherpartnerthroughwhatmaybeperceivedtobea‘deviationfromnormal’andimportantly,tosupporttheclinicianundertakingtheassistedbirth.
Caesareansection
Caesareansectionisanoperativeprocedure,whichiscarriedoutunderanaesthesia(regionalorgeneral),wherebythefetus,placentaandmembranesaredeliveredthroughanincisionmadeintheabdominalwallanduterus.
TheRCOG(2001)NationalSentinelCaesareanSectionAuditreportedthattheoverallCSratewas21.5%(EnglandandWales),accountingforapproximately120000birthsperyear.WhilsttheCSratesformaternityunitsrangedfrom 10% to65%,10%ofwomenhadCSbeforelabour(rangebetweenmaternityunits4%to59%),and12%ofwomenwhowentintolabourhadaCS(rangebetweenmaternityunits 2%to22%).
ItisbelievedthatsomeofthedifferencesinCSratesobservedmaybeexplainedbydifferencesinthedemographicandclinicalcharacteristicsofthepopulation,suchasmaternalage,ethnicity,previousCS,breechpresentation,prematurity andinductionoflabour.However the exactreasonsforthesedifferencesremainsunclear.
AlthoughtherehasbeenanincreaseinCSratesoverthepast20years,thefourmajorclinicaldeterminantsoftheCSratehavenotchanged.CommonprimaryindicationsreportedforwomenhavingaprimaryCSwere:failuretoprogressinlabour(25%),presumedfetalcompromise(28%)andbreechpresentation(14%).ThemostcommonindicationsforwomenhavingarepeatCSwere:previousCS(44%),maternalrequestasreportedbyclinicians(12%),failuretoprogress(10%),presumedfetalcompromise(9%)andbreechpresentation(3%).
CurrentlyintheUK,slightlymorethanoneinsevenwomenexperiencecomplicationsduringlabourthatprovideanindicationforCS.Theseproblemscanbelife-threateningforthemotherand/orbaby(e.g.eclampsia,abruptioplacenta)and,inapproximately40%ofsuchcases,aCSprovidesthesafestrouteforbirth.Inallcasesthe principalaims mustbetoensurethatthosewomenandbabieswhoneedbirthbyCSaresodelivered,andthatthosewhodonotaresavedfromanunnecessaryintervention.
In1985,concern regardingtheincreasingfrequencyof caesarean section ledtheWorldHealthOrganization(WHO)toholdaConsensusConference(Stephenson1992).Thisconferenceconcluded thattherewerenohealthbenefitsaboveaCSrateof10–15%.TheScandinaviancountriesmanagedtoholdCSratesatthislevelduringthe1990s,withoutcomescomparabletoorbefer thanthoseofcountrieswithhigherCSrates. However,thisisnolongerthecaseandCSratesinthesecountrieshavenowincreasedtowardsthoseintheotherdevelopednations.
AlthoughmanyfactorshavebeenassociatedwithanincreaseintheCSrate,notallhavebeentothedetrimentofthemotherorbaby.Interestingly,whilsttheCSratehasrisenoverthetwoprecedingdecades,theinstrumentalvaginalbirthratehasremainedrelativelyconstant.
Clarifyingtheindicationsforcaesareansection
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NICE(2011)recommendsthattheurgencyofCSshouldbedocumentedusingthefollowingstandardizedschemeinordertoaidclearcommunicationbetweenhealthcareprofessionalsabouttheurgencyofaCS:
1.Immediatethreat tothe lifeofthewomanorfetus.
2.Maternalorfetalcompromisewhichisnotimmediatelylife-threatening.
3.Nomaternalorfetalcompromisebutneedsearlydelivery.
4.Deliverytimedtosuitwomanorstaff.
Theneedforbirthbyacategory1(‘crash’)CSisfortunatelyarareeventasitcanbeapsychologicallytraumaticeventforthewomanandherpartner.Itisalsoextremelystressfulfortheclinicalstaffinafendance.Resourcesmayhavetobeobtainedfromotherareasofclinicalcaretofacilitatesuchabirthand carestandardsriskbeingcompromisedintherushtosecurea‘safe’ outcome.Careshouldthereforebeexercisedbeforemakingthisdecision,andinuterofetalresuscitation(fluids,tocolyticsandoxygen)maygiveenoughtimeforamoreconsideredandcarefulapproach.
Indicationsforwhichelectivecaesareansectionwouldbethestronglyrecommendedmodeofbirth:
•Pastobstetrichistory
▪previousclassicalcaesareansection
▪intervalpelvicfloororanalsphincterrepair
▪previoussevereshoulderdystociawithsignificantneonatalinjury.
•Currentpregnancyevents
▪significantfetaldiseaselikelytoleadtopoortoleranceoflabour
▪monoamniotictwinsorhigher-ordermultiplepregnancy
▪placentapraevia
▪obstructingpelvicmass
▪activeprimaryherpesatonsetoflabour.
•Intrapartumevents
▪presumedfetalcompromiseinthefirststage
▪maternaldiseaseforwhichdelayindeliverymaycompromisethesafetyofthemother
▪absolutecephalopelvicdisproportion(browpresentationsetc).
Theselistsarenotcomprehensive andfactorsorotherindicatorsmayco-existtoinfluencethedecision-makingprocess.
Theoperativeprocedure
•Therationalefortheinterventionisdiscussedwiththewomanandherpartner.Theprocedureisexplainedandconsentobtained(writtenconsentmustbeobtainedinallcasesotherthanacategory1or‘crashsection’).Forelectiveproceduresconsentmaybetakeninadedicatedpreoperativeassessment(thedecisionhavingbeenpreviouslydiscussedandagreedintheantenatalclinicbyaseniorclinicianinconsultationwith
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thewomanandherpartner).
•Apreoperativeassessmentincludes:weightandobservationsofbloodpressure,pulseandtemperature.Thewomanis gowned,make-up,the presenceofanynailvarnishandjewelleryremoved(rings/ear-ringstaped).
•Thewomanisvisitedbytheanaesthetistandtheoperatingdepartmentpractitionerpreoperatively,andassessed.Ananaestheticchartwillbecommenced.
•Resultsofanybloodteststhathavebeenrequestedareobtained(fullbloodcount,groupandsaveandcrossmatch,ifrequired).
•Thewomanwillhavefastedandhavetakentheprescribedantacidtherapy.
•Manywomenprefertohaveurinarycatheterizationinthetheatreoncetheregionalorgeneralanaesthetichasbeenadministered.Howeversomewomenwillprefertohavethisprocedureundertakeninthe privacyoftheirroombeforeenteringtheoperatingtheatre.
•Asthewoman willneedtolie flat,itisessentialthatawedgeorcushionisused,orthetableis tilted,todirect thegraviduterusawayfromtheinferiorvenacava.The risks ofsupinehypotensionsyndromewillthusbereduced.
•Theregionalorgeneralanaestheticswillbeadministered.
•Asurgical‘timeout’shouldbecarriedoutoneverywomanenteringtheoperatingtheatrepriortothepreparationoftheskin.Incompetenthandsthistakes amatterofsecondsdramaticallyimprovingsafetywhilstnotdelayingthebirthtoanyperceptibledegree.
•Theskinispreparedinaccordancewithlocalandnationalguidelines.Currently,itremainsunclearwhatkindofskinpreparationmightbethemostefficaciousinthepreventionofpostCSsurgicalwoundinfection(Hadiatietal2012).
•Intravenousantibioticsshouldbeadministeredassurgicalprophylaxisbeforetheskinisincised.Thisreducestheriskofmaternalinfectionmorethanprophylacticantibioticsgiven afterskinincision,andnoeffectonthebabyhasbeendemonstrated.
Theanatomicallayersthatneedtobebreachedinordertoreachthefetusare:skin,subcutaneousfat,rectussheath, muscle(rectusabdominis),abdominalperitoneum,pelvicperitoneumanduterinemuscle.
Atransverselowerabdominalincision(bikinilineincision)isusuallyperformedwiththeskinandsubcutaneoustissuesincisedusingatransversecurvilinearincisionataleveloftwofingerbreadthsabovethesymphysispubis.Thesubcutaneoustissuesaresubsequentlyseparatedbybluntdissectionandtherectussheathincisedtransverselyfor2cmeithersideofthemidline.Thisincisionisthenextendedwithscissorsorbluntdissection beforethefacialsheath isseparatedfrom theunderlyingmuscle.Therectiareseparatedfromeachother,theperitoneumincisedandtheabdominalcavityentered.
Thefoldoftheperitoneumovertheanterioraspectoftheloweruterinesegmentandabovethebladderisincisedandthebladdermobilizedandreflecteddown.Theuterusisincisedtransverselytakingcarenottocausesurgicaltraumatothefetus(asignificantriskinthepresenceoflowlevelsofamnioticfluid).Thesurgeon,withhelpfromthe
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surgicalassistant(whomustapplyfundalpressure),willthensecurethesafedeliveryofthebaby.
Themainreasonforpreferringtheloweruterinesegmenttechniqueisthereducedincidenceofdehiscenceoftheuterinescarinanysubsequentpregnancyand/orbirthwhencomparedtoaclassicalorverticalincision(whichmaybetheonlysurgicalapproachthatissuitableinsituationssuchasanteriorwallplacentapraevia,inextremeprematurity(wherenoloweruterinesegmentmaybeformed)orinthepresenceofdenseadhesionsfromprevioussurgery.
Oxytocics(abolusof5IUofSyntocinon)shouldbegivenbytheanaesthetistaherbirthofthebabyandclampingoftheumbilicalcord.Whenthebabyandplacentahavebeendelivered,theuterusisclosedintwolayersandtherectussheathandskinsutured.Mostsurgeonsuseabraidedpolyglactinsuture(Vicryl)foralllayers.Thewoundisthendressedandthevaginaswabbedtoremoveanyclots.Thisalsoallowsafinalintraoperativeassessmentofanyongoingbleedingfromwithintheuterus.
WomenhavingaCSshouldbeofferedthromboprophylaxisbecausetheyareat increasedriskofvenousthromboembolism(Lewis2007;CMACE[CentreforMaternalandChildEnquiries]2011).Thechoiceofmethodofprophylaxis(forexample,graduatedstockings,hydration,earlymobilization,lowmolecularweightheparin)should takeintoaccount riskofthromboembolicdisease,althoughinmost cases itissimplest,andsafest,toadministerlowmolecularweightheparintoallwomenuntiltheyarefullymobile.Thosewithanincreasedrisk(e.g.maternalobesityorconcurrentmaternalmorbidity)shouldhaveamoreformalassessmentofriskandanindividualizedcareplanputinplace.
Earlyskin-to-skin contactbetweenthewomanandherbabyshouldbeencouragedandfacilitatedasitimprovesmaternalperceptionsoftheinfant,motheringskills,maternalbehaviour,breastfeedingoutcomesandreducesinfantcrying(Chapter34).Inaddition,womenwhohavehadaCSshouldbeofferedadditionalsupporttohelpthemtostartbreastfeedingassoonaspossibleaherthebirthoftheirbaby.Thisisbecausewomenwhohavehadacaesareansectionarelesslikelytostartbreastfeedinginthefirstfewhoursaherthebirth,but,whenbreastfeedingisestablished,theyareaslikelytocontinueas womenwho havehadavaginalbirth.
Women'srequestforcaesareansection
Thereasonsbehindthe‘demands’forbirthbyCSarefrequentlycomplex.Despitethefocusofafentioninthemedia,evidencesuggeststhatveryfewwomenactuallyrequestCSintheabsenceofmedicalindicationsandthe‘tooposhtopushcohort’areinanextrememinority (ChafferandRoyle2000;Weaveretal2007).However,theaccountsofwomenwhohavehaddifficultexperiencesofchildbirthdescribe‘knowingsomethingwaswrongbutbelievethattheywerenotlistenedto’arealltoofamiliarlyencountered.SuchwomenfrequentlypublicizetheirproblemsviaFacebookorothersocialmedianetworks,fuellingtheideaof‘themagainstus’,andthejoysof anyfuturepregnancyriskbeingoverwhelmedbythefocusforabirthbyCSwhatevertherationalebehindtheir
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beliefs.
Psychologicalsupportandtheroleofthemidwife
Choiceisanimportantelementinunderstandingthissequence.Womenexpecttobeactivelyinvolvedintheircareandallstaffinvolvedmustensurethatrecent,validandrelevantinformationisprovidedinacomprehensiblemanner.Thiswillhelpwomentodecidewhatisbestforthem,inrelationtotheirownspecificcircumstances.Themidwife,asan informed,confidentandcompetentpractitioner,willhaveapivotal roleinthisprocessandbeabletoprovidewomenwithclearandunbiasedinformationconcerningthechoicesavailable(McAleese2000).Thiswillohenrelievethestressofthesituationandhelpwomenmakeacompetentdecision,supportingtheminthemidstofanymisgivings.
One-to-onecarefromasupportperson duringlabourcaninfluencetherateofbirthbyCSasacontinual,supportivepresenceinlabourisundoubtedlyofconsiderablebenefit,bothtothewomanandtoherfamily(WalkerandGolois2001;Hodnefetal2011).Itisimportantthatmidwivesrecognizethepositiveimpactonoutcomesoftheircontinuouspresenceduringestablishedlabour(NICE2007;Hodnettetal2011).
Psychologicalsupportmechanisms mayalsohelpthesewomentoovercometheirfearsand,assuch,itmaybeappropriatetodeveloplinkswithtrainedcounsellorstoenablewomentoexploretheiranxietiesandreachamoreinformedandrationaldecisionpriortoelectingtoundergomajorabdominal surgery.However,NICE(2011)recommendsforwomenrequestingaCSthatif,aherdiscussionandofferofsupport(includingperinatalmentalhealthsupportforwomenwithanxietyaboutchildbirth,seeChapter25),avaginalbirthisstillnotanacceptableoption,aplannedcaesareansectionshouldbeoffered.
Vaginalbirthaftercaesareansection(VBAC)
ZiadehandSunna(1995)reportedthatthewidespreadadoptionofa policywhereby80%ofwomenwithapriorCSshouldhaveaVBACwouldpotentiallyeliminateuptoone-thirdof birthsbyCS.Thisisstillthe targettowardswhich those providingcare towomeninpregnancystrive.
WhenadvisingaboutthemodeofbirthaherapreviousCSitisimportanttoconsiderthematernalpreferencesand priorities,therisksandbenefitsofrepeatCSandtherisksandbenefitsofplannedVBAC,includingtheriskofunplanned(i.e.emergency)CS.
NICE(2011)recommendsthatwomenwhohavehaduptoandincludingfourcaesarean sectionsshouldbeinformedthatthe risksoffever,bladder injuriesandsurgicalinjuriesdonotvarywiththeplannedmodeofbirthandthattheriskofuterinerupture,althoughhigherforplannedvaginalbirth,israre.Howeveritisa‘brave’clinicianwhowouldchoose torecommendvaginalbirthasasafeoptionin thosewomenwho havehadtwoprevious CS.
Itisalsoimportanttorememberthatpregnantwomenwith bothapreviousCSanda
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previousvaginalbirthshouldbeinformedthattheyhaveanincreasedlikelihoodofachievingavaginalbirththanwomenwhohavehadapreviousCSbutnopreviousvaginalbirth.
Pareetal(2006)arguedthattheconcernsaroundthesafetyofVBACignoredthepotentialdownstreamconsequencesofastrategywhereby multipleelectiverepeatcaesareansectionsareconsideredtobethesaferoption.Theseincludeanincreasedlengthofstayinhospitalandincreasedrisksofplacentapraeviaandaccretainfuturepregnancies.Theyconfirmedthatforwomenwhodesiretwoormoreadditionalchildren,therisksofmultiplecaesareansectionsoutweightherisksofaVBACattempt.
CriteriaforasuccessfulVBAC:
•AdequatesupervisionincludingcontinuouselectronicfetalmonitoringwithCTG.
•Allthefacilitiesforassistedbirtharereadilyavailable.
•Progressofthelabourissufficient,observedbothinthedescent ofthepresentingpartandbythedilatationofthecervix.
•Thewomanandherpartnerarefullyinformedabouttherisksandbenefits.
Postoperativecare
AherbirthbyCSwomenshouldbeobservedonaone-to-onebasisbyaproperlytrainedmemberofstaffuntiltheyhave regainedairwaycontrol,haveobservedcardiorespiratorystabilityandareabletocommunicateeffectively.Aherrecoveryfromanaesthesia,observations(respiratoryrate,heartrate,bloodpressure,painandsedation)shouldberecordedevery15minutesintheimmediaterecoveryperiod(forthefirst30minutes)andthereahereveryhalf-hourfor2hours,and hourlythereaherprovidedthattheobservationsarestableorsatisfactory.Iftheseobservationsarenotstable,morefrequentobservationsandmedicalreviewarerecommended.Inadditionthewoundandlochiamustbeinspectedevery30minutestodetectanyongoingbloodloss.Ifthemotherintendstobreastfeed,thebabyshouldbeputtothebreastassoonaspossible, a processthatcan usuallybeachievedwith minimaldisturbance totheundertakingof theseroutineobservations.
Forwomenwhohavehadintrathecalopioids,thereshouldbeaminimumhourlyobservationofrespiratoryrate,sedationandpainscoresforatleast12hoursifdiamorphinehasbeen administeredandfor24hoursinthecaseof morphine.Forwomenwhohavehadepiduralopioidsorpatient-controlledanalgesia(PCA)withopioids,thereshouldberoutinehourlymonitoringofrespiratoryrate,sedationandpainscoresthroughouttreatmentandforatleast2hoursafterdiscontinuationoftreatment.
Postoperativeanalgesia
Postoperativeanalgesiashould begivenonaregularbasisandmaybegiveninavarietyofways:
•Ongoingepiduralanaesthesia/analgesia.Womenshouldhavediamorphine(3mg)orfentanyl(100µg)administeredintotheepiduralspaceforintra-andpostoperative
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analgesiaasitreducestheneedforsupplementalanalgesiaafteracaesareansection.Intravenousorintramuscularadministrationofdiamorphine(2.5–5mg)isasuitablealternative.However,intramuscularorintravenousanalgesiashouldneverbegiveninconjunctionwithepiduralopioidsforatleastthefirst4hoursafteradministrationoftheepiduraldosebecauseofthecumulativeeffectsandrisksofrespiratorydepression.
•PCAusingopioidanalgesicsmaybeofferedaftercaesareansectionasanalternativepainreliefregimen.
•Antiemetics(e.g.cyclizine;prochlorperazine)areusuallyprescribedwhenopioidsarerequired.
•Analgesia,suchasdiclofenac(oralorrectal)orparacetamol(oral,intravenousorrectal)arethemainstaysofpostoperativeanalgesia.
•Oraldrugs(e.g.dihydrocodeine,codydramol,ibuprofenorparacetamol).
Providing therearenocontraindications(historyofkidneydisease,sensitivitytononsteroidalanti-inflammatorydrugs [NSAIDs],peptic ulcer,severe brifleasthma),NSAIDsshouldbeofferedpost-caesareansectionasanadjuncttootheranalgesics,astheyreducetheneedfortheadministrationofopioids.
Carefollowingregionalblock
Followingbirthunderepiduralorspinalanaesthesia,thewomanmaysitupassoonasshewishes,providedherbloodpressure isnotlow.Allobservationsmustberecordedasdescribedabove.
WomenwhoarerecoveringwellaherCSandwhodonothavecomplicationscaneatanddrink whentheyfeelhungryorthirsty,atwhichpointtheintravenousfluidinfusioncanbediscontinued.
Thebabyshouldremainwiththemotherunlessthereisamedicalreasonforcarebeingprovidedelsewhere(e.g.onaspecialcareorneonatalintensivecareunit)andindeed theyshould betransferredtothepostnatalward togetheronceitissafetodoso.Suchcareisundoubtedlyofbenefittoawoman'spsychologicalhealthandlong-termwellbeing.
Careinthepostnatalward
Oncecareistransferredtothepostnatalward,thebloodpressure,temperature,respirationsandpulsemustbecheckedevery4hoursandrecordedusingamodifiedobstetricearlywarningscorechart(MOEWS)(Lewis2007).Inaddition,thewoundandlochiashouldbeinspectedatthesametime.Removaloftheurinarybladdercathetershouldbecarriedoutonceawoman ismobileaheraregionalanaestheticandnotsoonerthan12hoursaherthelastepidural‘topup’dose.Healthcareprofessionalscaringforwomenwhohave hadaCSandwhohave urinarysymptomsshouldconsiderthepossiblediagnosisof:urinarytractinfection,stressincontinence(whichoccursinabout4%ofwomenaherCS)orurinarytractinjury(whichoccursinabout1per1000womenaherbirthbyCS).
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Themothershould beencouragedtomoveherlegsandtoperformlegandbreathingexercises,howeverroutinerespiratoryphysiotherapydoesnotneedtobeofferedtowomenaheracaesareansectionundergeneralorregionalanaesthesia,asitdoesnotimproverespiratoryoutcomessuchascoughing,phlegm,bodytemperature,chestpalpationandauscultatorychanges.
Thewoman should behelpedtogetoutofbedassoonaspossiblefollowingaCS,andshouldalsobeencouragedtobecomefullymobile.Prophylacticlowmolecularweightheparinandantiembolicorthromboembolicdeterrent(‘TED’)stockingsshouldbeprescribed.However,thefirstdoseoflowmolecularweightheparinshouldbedelayeduntil4hoursaftertheintrathecalinjectionorremovaloftheepiduralcatheter.
WomenwhohavehadageneralanaestheticforCSmayfeelverytiredanddrowsyforsomehours. Awomanmaycomplainofafeelingofdetachmentandunrealityandmayfeelthatshedoesnotrelatewelltothebaby.Thewomanwhoisconcernedshouldbereassuredandbe giventheopportunitytotalkfreely.
Themothermustbeencouragedtorestasmuchaspossibleandtactfuladvicemayneedtobegiventohervisitors.Ifthemotherbecomestootired,helpis neededwithcareforthebaby.Thisshould,preferably,takeplaceatthemother'sbedsideandshouldincludesupportwithbreastfeeding.Theclip-oncots,whichmaybeafachedtothemother'sbed,areinvaluableinpromotinggoodcare(Fig.21.7).
FIG. 21.7Babyinclip-oncot,adjacenttoandwithineasyreachofmotherwheninbed.
Caesareansectionwoundcareshouldinclude:removingthedressing24hoursaherthedelivery,assessingthewound forsignsofinfection(suchasincreasingpain,rednessordischarge)separationordehiscence,encouragingthewomantowear loosecomfortableclothesand cofonunderwear,gentlycleaningand dryingthewound dailyifneededandplanningtheremovalofsuturesorclipsifrequired.
SomewomenmayhavealingeringfeelingoffailureordisappointmentathavinghadanemergencyCSandmayvaluetheopportunitytotalkthisoverwiththemidwifeorothercliniciansinvolvedinhercare.IndeeditisconsideredtobegoodpracticefortheobstetricianwhoundertooktheCStoreviewthewomanpostpartum,notonlyin ordertodiscusstheproblemsthatnecessitatedthesurgicalintervention,butalsotocounselabouttheoptionsforanyfuturepregnancy.
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Healthcareprofessionalscaringforwomenwhohaveheavyand/orirregularvaginalbleeding followingCSshouldbeawarethatthisismorelikelytobeduetoendometritisthanretainedproductsofconception.Asaconsequence,shouldthiscomplicationbesuspected,firstlinetreatmentwithbroadspectrumantibioticsshouldbeimplementedratherthanreferralforultrasound assessment. However,ifthereareanyconcernsaboutthecompletenessoftheplacentaltissueormembranes,referralforseniorreview atanearlystageshouldbethepreferredcourseofaction.
Whilstthelengthofhospitalstayislikelytobelongeraheracaesareansection(anaverageof3–4days)thanaher avaginalbirth (average1–2days), womenwho arerecoveringwell,areapyrexialanddonothavecomplicationsfollowingCSshouldbeofferedearlytransferhome(aher24hours)fromhospitalandfollow-upathome,asthisisnotassociatedwithmoreinfantormaternalreadmissionscomparedwithlatertransfer.
Analgesia/anaesthesia
Pudendalblock
Thisistheprocedurewherelocalanaestheticisinfiltratedintothetissuearoundthepudendalnervewithin thepelvis(Fig.21.8).ThepudendalnerveemergesfromthespineattheleveloftheS2–S4vertebraeand‘descends’intothepelviscrossingbehindtheischialspineasitdoesso.Thepudendalnervesuppliesthelevator animuscles,thedeepandsuperficialperinealmusclesandthesensorynerves(pain/stretchandtemperature)ofthelowervaginaandperineum.Apudendalneedle(aspecificallydesignedneedleincorporatingasheathguard)isemployedwithupto20mloflocalanaesthetic,usually1%lidocaine(lignocaine),beinginjectedintotheregionaroundandbelowtheischialspine.Asbothmotorand sensorynervesareaffected withthistechniqueitmaybeusedtoprovideanalgesiaforthelowervaginaandperineum,andisthereforeusedduringforcepsandventouseinstrumentalbirths.
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FIG. 21.8Locatingthepudendalnerve.
Perinealinfiltration
SeeChapter15forinfiltrationandrepairofepisiotomy,aswellasthird-andfourth-degreeperinealtrauma.
Regionalanaesthesia
Thetwomostcommonlyemployedregionalanaesthetic techniquesarethoseofepiduralandintrathecal(spinal)anaesthetic.
Theepiduralspaceisthespacelocatedwithinthebonyspinalcanaljustoutsidethedura mater. Incontactwiththeinnersurfaceofthedura isanother membranecalledthearachnoidmater.Thecerebrospinalfluid(CSF)iscontainedbetweenthearachnoidmaterandthepiamater,anothermembranethatliesdirectlyincontactwiththespinalcord.Inadults,thespinalcordterminatesatthelevelofthelowerborderoftheL2vertebrabelowwhichliesabundleofnerves knownas thecaudaequina(‘horse’stail’).
Insertionofanepiduralneedleinvolvesthreadinganeedlebetweenthespinalvertebrae,throughtheligamentsandintotheepiduralpotentialspacetakinggreatcarenottopuncturetheduramaterimmediatelybelow,whichcontainstheCSF.
Techniques
Procedures involvinginjection of anysubstance intothe epiduralspace require theoperatortobetechnicallyproficientinordertoavoidcomplications.
Thesubjectismostcommonlyplacedintheseatedorlateralpositions.Intravenousaccessismandatory.
Followingastandardaseptictechniqueprotocol,thelevelofthespineatwhichthecatheter/spinalneedleistobeplacedisidentified.
Epidural
Theiliaccrestisacommonlyusedanatomicallandmarkforlumbarepiduralinjections,asthis level roughlycorrespondswiththe fourthlumbarvertebra,which isusuallybelowthe terminationofthe spinalcord. Followingtheinfiltrationoflocalanaesthetic,aTuohyneedleisusuallyinsertedinthemidline,betweenthespinousprocesses,passingbelowthevertebrallaminauntilreachingtheligamentumflavumandtheepiduralspace.Aslightclicking sensationmaybefeltbytheoperatorasthetipoftheneedlebreachestheligamentumflavumandenterstheepiduralspace.
AsyringecontainingsalineisafachedtotheTuohyneedle–mostpractitionersusingthelossofresistancetopressuretoidentifythattheneedleiscorrectlyplaced.
Acatheteristhenthreadedthroughtheneedle(typically3–5cmintotheepiduralspace),theneedlewithdrawnandthecathetersecuredtotheskinwithadhesivetapeordressingstopreventitbecomingdislodged.
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Thecatheterisafineplastictube,throughwhichanaestheticdrugsmaybeinjectedintotheepiduralspace.Manyepiduralcathetershavethreeormoreorificesalongtheshahatthedistaltip(farend)ofthecathetertoallowrapidandevendispersaloftheinjectedagentsmorewidelyaroundthecatheterandreducetheincidenceofcatheterblockage.
Apersonreceivinganepiduralforpainreliefmayreceivelocalanaesthetic(mostcommonlylevo-bupivacaine),withorwithoutanopioid(mostcommonlyfentanyl).Theseareinjectedinrelativelysmalldoses,comparedtowhentheyareinjectedintravenouslyorintramuscularly.
Forashortprocedure, theanaesthetistmayintroduceasingledoseofmedication(the‘bolus’technique),althoughtheeffectsofthiswilleventuallywearoff.Thereaher,theanaesthetistormidwifemayrepeatthebolusprovidedthecatheterremainsundisturbed.Foraprolongedeffect,acontinuousinfusionofdrugsmaybeemployed.Howeverthereisevidencethatpatientcontrolledepiduralanalgesia(PCEA),wherebytheadministrationofthebolusesiscontrolledbythepatient(uptoapredeterminedmaximumdose)providesbeferanalgesiathanacontinuousinfusiontechnique,althoughthetotaldosesreceivedbytheindividualareoftenidentical.
Typically,theeffectsoftheepiduralblockarenotedbelowaspecificlevelonthebody
–ablockatorbelowtheT10sensorylevelisidealforwomeninlabourorduringbirth.Nonetheless,givingverylargevolumesintotheepiduralspacemayspreadtheblockhigher.
Theepiduralcatheterisusuallyremovedpriortotransfertothepostnatalward.
Spinalanaesthesia
Intrathecal(spinal)anaesthesiaisatechniquewherebyalocalanaestheticdrugisinjectedintothecerebrospinalfluidthroughafine(24–26gauge)spinalneedle.Thetechniquehassomesimilaritytoepiduralanaesthesia.However,importantdifferencesinclude:
•Intrathecalanaesthesiarequiresalowerdoseofdrugandhasafasteronsetthanepiduralanaesthesia.
•Theblockachievedwithspinalanaesthesiaistypicallydescribedasbeingmoredense.
•Aspinalanaestheticblocktypicallylastsfor2hours,howeverit cannotbetoppedup,asnocatheterisinserted.
•Intrathecalinjectionsareperformedbelowthesecondlumbarvertebralbodytoavoiddamagingthespinalcord.
Complications
AccordingtotheAssociationofAnaesthetistsofGreatBritainandIreland(AAGBI)(2002),theseinclude:
•Failuretoachieveanalgesiaoranaesthesiaoccursinabout5%ofcases,whileanother15%experienceonlypartialanalgesiaoranaesthesia.Ifanalgesiaisinadequate,anotherepiduralmaybeattempted.
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•Thefollowingfactorsareassociatedwithfailuretoachieveepiduralanalgesia/anaesthesia:obesity,historyofapreviousfailureofepiduralanaesthesia,historyofsubstanceabuse(withopiates),advancedlabour(cervicaldilatationofmorethan7cmatinsertion)andprevioushistoryofspinalsurgery.
•Accidentalduralpuncturewithheadache(common,about1in100insertions).Theepiduralspaceinthe adultlumbarspineisonly3–5mmdeep.Itisthereforecomparativelyeasytoaccidentallypuncturethedura(andarachnoid)withtheneedle,causingcerebrospinalfluid(CSF)toleakoutintotheepiduralspace.Thismay,inturn,causeapost-duralpunctureheadache(PDPH).Thiscanbesevereandlastseveraldays,andinsomerare casesweeksormonths.It iscausedbyareductioninCSFpressureandischaracterizedbyposturalexacerbationwhenthesubjectraiseshis/herheadabovethelyingposition.Ifsevereitmaybesuccessfullytreatedwithanepiduralbloodpatch,howevermostcasesresolvespontaneouslywithtime.
•Bloodytap(about1in30–50).Itiseasytoinjureanepiduralveinwith the needle.Inpeoplewho havenormalbloodclotting,itisextremelyrareforsignificantcomplicationstodevelop.However, peoplewhohaveacoagulopathymaybeatincreasedrisk.
•Cathetermisplacedintothesubarachnoidspace(rare,lessthan1in1000).Ifthecatheterisaccidentallymisplacedintothesubarachnoidspace(e.g.afteranunrecognizedaccidentalduralpuncture),normallycerebrospinalfluidcanbefreelyaspiratedfromthecatheter(whichwouldusuallyprompttheanaesthetisttowithdrawthecatheterandre-siteitelsewhere).If,however,thisisnotrecognized,largedoses ofanaestheticmaybedelivereddirectlyintothecerebrospinalfluid.Thismayresultinahighblock,or,morerarely,atotalspinal,whereanaestheticis delivereddirectlytothebrainstem,causingunconsciousnessandsometimesseizures.
•Neurologicalinjurylastinglessthan1year(rare,about1in6700).
•Death (veryrare,lessthan1in100000).
•Epiduralhaematomaformation(veryrare,about1in168000)
•Neurologicalinjurylastinglongerthan1year(extremelyrare,about1in240000).
•Paraplegia(extremelyrare,1in250000).
Generalanaesthesia
Despitetheincreasinguseofregionalanaesthesia,generalanaesthesiaisrequiredinupto5%ofwomenrequiringanaesthesiaduringbirth.Generalanaesthesiacanusually bemorerapidlyadministeredthanaregionalblock, andisthereforeofvaluewhenspeedisimportant(suchaswhenthefetusisinseriousjeopardy).Womenarepre-oxygenated(theyaregivenoxygentobreatheforseveralminutes)priortothe‘rapidsequence’inductionofanaesthesiawiththeintravenousadministrationofanaesthetic(e.g.thiopentoneorpropofol)followedbyamusclerelaxant(e.g.suxamethonium)andcricoidpressureisapplied(essentialtoreducetherisksofaspirationofstomachcontents).Maternalunconsciousnessensueswithinsecondsandorotrachealintubationissecuredwith acuffedtube.There are minimalside-effects andrelativelylifle negative fetal
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consequenceatthetimeofbirthprovidedmeticulouspracticesareinplace.
Anaesthesiaissustainedbyinhalationalanaestheticmeans(commonlyenfluraneorsevoflurane)withanopioidadministeredintravenouslyafterclampingthecord.
Difficultorfailedintubation
Thisconditionismorelikelytooccurinpregnantwomen,particularlywiththosewhohavepregnancy-inducedhypertensionorwhoareobese.Accesstothelarynxmaybeobstructedordifficulttoviewinthesewomenandthereforeanticipationofthedisorderisthekeytoitsmanagement.Shoulddifficultiesbeanticipated,anaesthetistsshouldcarryouttheintubationusingawell-lubricatedstyletorbougietoaidtheendotrachealintubation.
Themanagementofafailedintubationisprimarilytomaintainadequateoxygenationviaassistedventilationofthe womanuntiltheeffectsofsuxamethoniumandthiopentonehavewornoffandthewomanhasregainedconsciousness.Thisisdonethroughthecontinuedapplicationofcricoidpressureandventilationviaafacemask.
Itisthereforeimperativethatsurgeryisnotcommenceduntiltheanaesthetisthassecuredtheairwayandconfirmedthatthewomanisadequatelyventilated.
Complications
Althoughsurgicalandanaesthetictechniqueshave improved,womenare stillmoreliabletosufferfromcomplicationsandtohaveincreasedmorbidityfollowingcaesareansectionundergeneralanaestheticwhencomparedtoregionalblockade.
Mendelson'ssyndrome
ThisconditionwasdescribedbyMendelsonin1946.Itisachemicalpneumonitiscausedbytherefluxofgastriccontentsintothematernallungs duringageneralanaesthetic.Theacidicgastriccontentsdamagethealveoli,impairinggaseousexchange.Itmaybecomeimpossibletooxygenatethewomananddeathmayresult.Thepredisposingfactorsare:thepressurefrom thegravid uteruswhen thewomanislyingdown,and theeffectof theprogesteronerelaxingsmoothmuscleandthecardiacsphincterofthestomach.Analgesicsadministeredduringlabour(e.g.pethidine)cancausesignificantdelayingastricemptyingandwilltherebyexacerbatetheserisks.
PreventionofMendelson'ssyndrome
Antacidtherapy.
Prophylactictreatmentshouldbeadministeredtoallwomeninwhomacaesareanisplannedoranticipated.Ausualregimenisforwomenhavinganelectiveoperationtobegiventwodosesoforalranitidine150mgapproximately8hoursapart.Ifageneralanaestheticisanticipated,30mlofsodiumcitrateshouldbeorallyadministeredimmediatelybeforeinduction.
Cricoidpressure.
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Thisisatechniquewherebypressureisexertedonthecartilaginousringbelowthelarynx,thecricoid,tooccludetheoesophagusandpreventreflux(Fig.21.9).Thisisthemostimportantmeasureinpreventingpulmonaryaspiration.Cricoidpressureisadministeredduring theinductionofa general anaesthetic (mostcommonlybyanoperatingdepartmentpractitioner)andismaintaineduntilthetrachealtubeisconfirmedasbeingcorrectlypositionedandthesealofthecuffinflated.
FIG. 21.9Cricoidpressureshowingocclusionoftheoesophagusbypressureappliedtothecricoidcartilage.
IntheUKthemostrecentreviewintoanaestheticcomplicationsduringpregnancyandchildbirth,forthe2006–2008triennium,reviewed 127casesinwhichanaestheticserviceswereinvolvedinthecareofwomenwhodiedfromeitheradirectorindirectcauseofmaternaldeath.Thiscomprised49%(127of261)ofallthematernaldeathsduringthatperiod.Fromthesedeathstheassessorsidentifiedseven(3%)womenwhodiedfromproblemsdirectlyassociatedwithanaesthesiaarateof0.31deathsper100000womenwhogavebirth.However,ina further18 deaths, anaesthetic managementcontributedtotheoutcomeortherewerelessonstobelearned.Therewerealso12womenwithseverepregnancy-inducedhypertensionorsepsisforwhomobstetriciansorgynaecologistsfailedtoconsultwithanaestheticorcritical-careservicessufficientlyearly,whichtheassessorsconsideredmayhavecontributedtothedeaths.
Itwasconcludedthat:
•Theeffectivemanagementoffailedtrachealintubationisacoreanaestheticskillthatshouldberehearsedandassessedregularly.
•Therecognitionandmanagementofsevere,acuteillnessinapregnantwomanrequiresmultidisciplinaryteamwork.Ananaesthetistand/orcritical-carespecialistshouldbeinvolvedearly.
•Obstetricandgynaecologyservices,particularlythosewithoutanon-sitecritical-careunit,musthaveadefinedlocalguidelinetoobtainrapidaccessto,andhelpfrom,critical-carespecialists(CMACE2011).
Researchandtheincidenceofcaesareansection:tackling
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highandrisingcaesareansectionrates
LowCSratesareassociatedwithlowlevelsofinterventionandhighlevelsofpsychologicalsupport.Itisdifficulttodecipherwhethercaesareansectionrateshavebeenaffected byinterventions,suchasproactivemanagementoflabour–thatis,artificialruptureofmembranesanduseofoxytocin–orwhetherotherfactorshaveinfluencedthese.
NICE(2011)guidelinesrecommendthattheclinicalinterventionsproven toreducetherates ofbirthbyCS includeallthekeypointshighlightedinBox21.2.
Box 21.2
Cinicalinterventionsproventoreducetheratesofbirthby
CS
•Externalcephalicversion(ECV)at36weeks
•Continuoussupportinlabour
•Inductionoflabourforpregnanciesbeyond41weeks
•Use ofapartogramwitha4houractionlineinlabour
•Fetalbloodsamplingbeforecaesareansectionforabnormalcardiotocographinlabour
•Supportforwomenwho choose vaginalbirthaftercaesareansection
Source:NICE2011
WhilethereisnoacceptedoptimalrateforCSintheUK,someunitsmanagetokeeptheir CSratebelow20%.Ifreductionsintheratearetobeachieved,effortsshould focusonwherethereisthemostpotentialforreduction:reducingprimary CS,particularly infirst-timemothers,andincreasingratesofVBAC.
Toprovidemoremeaningfulinformationtowomenwhentheyarechoosingtheirmodeofbirth,NICEhasrecommendedthatthereisapressingneedtodocumentthemedium-tolong-termoutcomesinwomenandtheirbabiesaheraplannedCSoraplannedvaginalbirth.Theynotethatitshouldbepossibletogatherdatausingstandardizedquestions(traditionalpaper-basedquestionnaires,face-to-faceinterviewsandInternet-basedquestionnaires)aboutmaternalsepticmorbiditiesandemotionalwellbeingupto1yearaheraplanned CSinapopulationofwomenwhohaveconsentedforfollow-up.
NICE(2011)alsocommentthatitwouldbeimportanttocollecthigh-qualitydataoninfantmorbiditiesaheraplannedCScomparedwithaplannedvaginalbirth.Along-termmorbidityevaluation (between5 and10yearsaher theCS)couldusesimilarmethodologytoassessadditionalsymptomsrelatedtourinaryandgastrointestinalfunction.
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Acknowledgement
The author would like to acknowledge the contribution ofAdela Hamilton to thischapter.
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