ChangesinDopplerUltrasound Parameters ofmiddleCerebral arteryversusSonographic Parameters forPrediction ofFetal Macrosomia AComparativeStudy

Mohamed Saber Khalil Abouzeid;

Abstract


Summary
M
acrosomicinfantsaswellastheirmothersareatincreasedriskforintrapartuminjury.Perinatalmortalityismorecommonamongthesefetuses.
Themostcommonlyaccepteddefinitionformacrosomiaisthatofbirthweightequaltoorexceeding4000g.AccordingtoACOG(2000),itisreasonabletoconsiderallnewborninfantsweighing4500gormoreasmacrosomic.Themostrecentstudiesreportedanincidenceof8.9%forfetuseswithmacrosomia(>4000g).
Enlargementofthesizeofthefetusmaybegeneralizedorconfinedtocertainparts:head,neck,thorax,abdomenorpelvis.Enlargementofthesizeofthefetusasawholemaybesymmetricalorasymmetrical.
Theetiologyoffetalmacrosomiaisbelievedtobemultifactorial.Etiologicfactorsincludegestationalage,diabetesmellitus,malesex,multiparity,maternalweightgainduringpregnancy,birthweightofapriormacrosomicinfant,ethnicityaswellasgeneticandcongenitaldisorders.
Manystudieshavelargelydefinedtheessentialroleofinsulin,insulinlikegrowthfactors(IGF-I&IGF-II),andtheirreceptorsinembryonicandfetalgrowth.Otherpotentialmechanismsoffetalsomaticovergrowthincludegeneticfactors,utero-placentalconstraints,thyroidandgrowthhormones,andleptin.
Sinceitsrecognition,macrosomiahasbeenoneofthecornerstonesofdiabeticfetopathy.Hyperglycemiaexistsinwomenwithpoorlycontrolleddiabetes,glucosecrossestheplacentabyfacilitateddiffusionandthefetusmaintainsalevelofabout70-80%ofthematernalglucoseconcentration.Thisresultsinacarbohydratesurplustothefetuswithsubsequenthyperinsulinemia.Fetalhyperinsulinemiacausesdirectgrowthstimulation,increasedcellularglucoseutilization,increaseddepositionanddecreasedmobilizationoffatandincreasedproteinproduction,thisleadstoovergrowthandthebirthofaneonatewithmacrosomia.
Fetalmacrosomiahasanimportanteffectonmaternalandfetalmorbidityandmortality.Maternalcomplicationsincludearrestdisorders,protractiondisorders,instrumentaldeliverywithmoreobstetriclacerations,postpartumhemorrhageandpuerperalinfection,cesareandeliveryandshoulderdystocia.Fetalcomplicationsincludebirthinjuries,asphyxialinjuries,neonatalhypoglycemia,andchildhoodandadolescentobesity.
Birthinjuriesincludemainlybrachialplexusinjuryandfractureclavicle.Brachialplexusinjuryresultsfromdownwardtractiononthebrachialplexusduringdeliveryoftheanteriorshoulder.Erb’spalsyfrominjurytothespinalnervesC5-6.
Accurateprenataldiagnosisofmacrosomiaisimportantforplanningandtimingofthemethodofdelivery.
Therearethreemajorstrategiesusedtopredictmacrosomiawhichareriskassessment,clinicalestimationoffetalweightandultrasonography.Thestrongestriskfactorismaternaldiabetes,whichresultsinatwo-foldincreaseintheincidenceofmacrosomia.Otherriskfactorsincludeprolongedgestation,obesityandmultiparity.However,34%ofmacrosomicinfantsareborntomotherswithnoidentifiableriskfactor.
Clinicalestimationoffetalweightincludesfundallevel,measurementofthegirthcircumferenceattheleveloftheumbilicusaswellasthemeasurementofsymphysial-fundalheight.Whenclinicalestimateswerecomparedwithsonographicestimatesoffetalweight,theresultswerecomparableandclinicalestimatesperformedfavorably.
Sonographicmethodsfordiagnosisofmacrosomiaweredevelopedinhopesofimprovingclinicalestimates.Measuredparametersinclude:headcircumference(HC),abdominalcircumference(AC),thighcircumference(ThC),femurdiaphysislength(FDL),weightestimate(WE)andbodyproportionality(HC/ACandFDL/HC).ThetruevalueofUltrasonographyinthemanagementoffetalmacrosomiamaybeitsabilitytoruleoutthediagnosis.Ultrasound-derivedfetalweightestimatesalonearenotsufficientgroundsfordecidingtherouteofdelivery.
Dopplerindicesinthemiddlecerebralarteries,thecerebroplacentalDopplerratioandumblicalarteryDopplerindicesarenotsignificantparametersindiagnosisofmacrosomia.
Preventivefactorsoffetalmacrosomiaincludereductionofpre-pregnancyweightandweightgainduringpregnancy,limitationofposttermpregnancyandcontrolofdiabetes.
Themanagementofpatientswithsuspectedfetalmacrosomiaiscontroversial.Electivecesareandeliveryandlaborinductionhavebeenproposedasinterventionstopreventmaternalandperinatalcomplications.


Other data

Title ChangesinDopplerUltrasound Parameters ofmiddleCerebral arteryversusSonographic Parameters forPrediction ofFetal Macrosomia AComparativeStudy
Other Titles قياس التغيرات فى دوبلرالشريان الدماغي الأوسط مقابل قياسات الموجات فوق الصوتية فى الكشف عن العملقة الجنينية
Authors Mohamed Saber Khalil Abouzeid
Issue Date 2015

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