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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5775_Библиотеки_им_академика_М_И_Перельмана
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8. AnswerC. The rhombencephalonis visible on all exams at 8 to 10 weeksas ananechoic round
structurewithinthehead,representingthedevelopinghindbrain(medulla,pons,andcerebellum).
Anencephaly is the most common anomaly affecting the central nervous system and results from
failureofclosureoftherostralportion oftheneural tube.Theimportantultrasoundfeatureis anabsent
cranium,whichallowsdiagnosisfrom11weeksonward.
Mildventriculomegalyisdefinedasbeingpresentwhenthewidthofthelateralventricle,measuredat
theatrium,is≥10mm.
References: Cardoza JD, Goldstein RB,Filly RA. Exclusion of fetal ventriculomegaly with a single measurement: the width ofthe lateral
ventricularatrium.Radiology1988;169(3):711–714.
CyrDR,MackLA,NybergDA,etal.Fetalrhombencephalon:normalUSfindings.Radiology1988;166(3):691–692.
JohnsonSP,SebireNJ,SnijdersRJM,etal.Ultrasoundscreeningforanencephalyat10–14weeksofgestation.UltrasoundObstetGynecol
1997;9(1):14–16.
RodgersSK,ChangC,DeBardelebenJT,etal.Normalandabnormal USfindingsinearlyfirst-trimesterpregnancy: reviewofthesociety of
radiologistsinultrasound2012consensuspanelrecommendations.RadioGraphics2015;35(7):2135–2148.
9. Answer B. The ultrasound image shows a crescentic hypoechoic fluid collection adjacent to the
gestationalsacintheendometrialcavityconsistentwithsubchorionichemorrhage.
The incidenceof subchorionic hemorrhage in first trimester pregnancies with vaginal bleeding has
been reported to be 18% to 22%. Large hematomas encircling more than two-thirds of the chorionic
circumferenceareassociatedwithdoublingoftheriskofpregnancyloss.
References: Bennett GL, Bromley B, Lieberman E, et al. Subchorionic hemorrhage in first-trimester pregnancies: predictionof pregnancy
outcomewithsonography.Radiology1996;200(3):803–806.
LeiteJ,RossP,RossiAC,etal.Prognosisofverylargefirst-trimesterhematomas.JUltrasoundMed2006;25(11):1441–1445.
RodgersSK,ChangC,DeBardelebenJT,etal.Normalandabnormal USfindingsinearlyfirst-trimesterpregnancy: reviewofthesociety of
radiologistsinultrasound2012consensuspanelrecommendations.RadioGraphics2015;35(7):2135–2148.
10. AnswerC. The most accurate assessment ofgestational age during the first trimester up to and
including136/7weeksisbasedonmeasurementofthecrown-rumplength(CRL),withanaccuracyof±5
to7days.Accuracyimprovestheearlierinthefirsttrimesterthatmeasurementsaretaken.Ifpossible,the
mean of three discrete CRL measurements should be used for dating. The embryo or fetus should be
imagedinatruemidsagittalplane,withthegenitaltubercleandfetalspineinview.TheCRLismeasured
from the cranium to the caudal rump as a straight line. Mean sac diameter measurements are not
recommendedforestimatingtheduedate.
CRL measurements >84 mm (from ~14 0/7 weeks of gestation) are associated with decreasing
accuracy forgestationalagedetermination. Therefore,second-trimester biometricparameters should be
usedfordatingthesepregnancies.
Thedateoflastmenstrualperiod(LMP)istypicallyusedtoprovideaninitialcalculationoftheEDD.
TheEDDisLMP+280days.Thisestimatewillbecomeinaccurateinwomenwhodonothavearegular
28daymenstrualcycleorinthosewhoseovulationdoesnotoccuronday14.Additionally,itisestimated
thatonlyone halfofwomen accurately recall their LMP. Whenfirsttrimestergestationalageestimates
fromultrasounddifferbymorethan 7 days from LMP dating, the estimatedduedate (EDD)should be
changedtoreflecttheultrasounddating.
Reference: American College of Obstetricians and Gynecologists Committee Opinion No. 611: method for estimating due date. Obstet
Gynecol2014;124:863–866.
11.AnswerB.Thenumberofyolksacspresentinagestationalsaccanhelpdeterminetheamnionicity
ofthepregnancy.Thenumberofyolksacsandthenumberofamnioticsacsmatchiftheembryosarealive.
Foramonochorionicmonoamnioticpregnancy,therewillbe2embryos,1chorionicsac,1amnioticsac,
and1yolksac.
Reference:TanS,PektasMK,ArslanH.Sonographicevaluationoftheyolksac.JUltrasoundMed2012;31(1):87–95.
12. AnswerB. The mostsensitive predictor of preterm birth is ultrasound measurement ofcervical
length. The risk of preterm labor increases with the degree of shortening and is also higher when
discoveredearlier.Between14and30weeksofgestation,thecervixshouldmeasuremorethan30mm.
Funneling of the cervix refers to an open internal os with gradual narrowing of the cervical canal.
Cervicalfunnelingisalmostalwaysaccompaniedbycervicalshortening.Theriskofpretermbirthisnot
increasedifcervicalfunnelingispresentwithoutshortening.
References:IamsJD,GoldenbergRL,MeisPJ,etal.Thelengthofthecervixandtheriskofspontaneousprematuredelivery.NEnglJMed
1996;334(9):567–573.
Woodfield CA,LazarusE,ChenKC,et al.Abdominalpain in pregnancy: diagnosesandimaging uniquetopregnancy—review.AJR AmJ
Roentgenol2010;194(6Suppl):WS14–WS30.
13. AnswerA. A Tis (thermal index for softtissue) is usedfor gestations earlier than 10 weeks.A
thermalindex forbone(Tib)isusedfor gestations atorlaterthan10 weeks when boneossification is
evident.
Reference:AIUMpracticeparameterfortheperformanceofobstetricultrasoundexaminations.2013.
14.AnswerB.Theultrasoundimageshowsinsertionoftheumbilicalcordbeyondthe placentaledge
consistentwithvelamentouscordinsertion.
The typical location of the umbilical cord insertion is centrally within the placental substance.
Variationsincludeeccentricandvelamentousinsertions.Eccentricinsertionsoccurwithin1cmfromthe
placentaledge.Velamentousinsertionsoccuroutsideoftheplacentaalongthechorioamnioticmembranes.
From the site of aberrant insertion, umbilical vessels travel to the placenta between the amnion and
chorion,unprotectedbyWhartonjellyandarevulnerabletorupture.Whentheexposedvesselscrossthe
internal cervical os (vasa previa), they are particularly at risk of catastrophic hemorrhage when the
supportingmembranesruptureorduringlabor.
Reference: Elasayes KM, Trout AT, Friedkin AM, et al. Imaging of the placenta: a multimodality pictorial review. RadioGraphics
2009;29(5):1371–1391.
15. Answer B. M-mode imaging should be used instead of spectral Doppler imaging to determine
embryonic/fetal heart rate in order to provide the necessary diagnostic information with the lowest
possibleultrasonicexposureinkeepingwiththeALARAprinciple.
Reference:AIUMpracticeparameterfortheperformanceofobstetricultrasoundexaminations.2013.
16. AnswerA. The umbilicalcordisconsideredtobe normal when itcontainstwo arteriesand one
vein.Thecord isa three-vesselcordaslong as any portionofthe cord contains threevessels, evenif
other segments contain onlytwo vessels. Threevessel cords are foundin90% of singleton gestations.
Fetuseswithtwovesselscords(onearteryandonevein)areatahigherriskforstructuralabnormalities
andgrowthrestriction.
Reference:HertzbergBS,MiddletonWD.Ultrasound:therequisites,3rded.Philadelphia,PA:Elsevier,2016:484.
17.AnswerB.Normalplacentalthicknessisbetween2and4cm,measurednearthemidportionofthe
organ. Thin placentas are associated with systemic vascular and hematologic disorders leading to
microinfarcts. Thick placentas are associated with fetal hydrops, antepartum infections, maternal
diabetes, and maternal anemia. Note that the placenta may appear to be thickened as a result of
myometrialcontractionsandadjacentfibroids.
Reference: Elasayes KM, Trout AT, Friedkin AM, et al. Imaging of the placenta: a multimodality pictorial review. RadioGraphics
2009;29(5):1371–1391.
18.AnswerC.Pelvicultrasoundimagefromfirsttrimesterpregnancyshowsathin-walledcyst atthe
fetalinsertionsiteoftheumbilicalcord.
Umbilical cord cysts may represent either true cysts (3.4% of first-trimester pregnancies) or
pseudocysts.Pseudocystsaremorecommonandrepresentlocalizededema andliquefactionofWharton
jellyandhavenoepitheliallining.Bothcysttypesareusuallylocatedclosetothefetalinsertionsiteand
arenotreliablydistinguishedbyultrasound.Mostcystsfoundinthefirsttrimesterresolve,andtherefore
havenoclinicalsignificance.However,adetailedfetalanatomicsurveyisrecommendedwhenumbilical
cord cysts are detected during the second or third trimesters. A 20% increased prevalence of
chromosomalorcongenitaldefectshasbeenreportedinassociationwiththedetectionofumbilicalcysts.
Arrowpointstoumbilicalcordcystatthefetalinsertionsiteofthecord.
Reference: Moshiri M,Zaidi SF,Robinson TJ,et al. Comprehensive imagingreview of abnormalitiesoftheumbilical cord. RadioGraphics
2014;34(1):179–196.
19.AnswerA.Themechanicalindex(MI)andthermalindex(TI)areattemptstoassessthemechanical
and thermal bioeffects of an ultrasound beam. The MI is a measure of the potential of inducing a
cavitation-related bioeffect with ultrasound. The mechanical index is thepeak negative (rarefactional)
pressure/SQRT(centerfrequencyofthebeam).Therefore,theMIisinverselyproportionaltothecenter
ultrasoundbeamfrequencyandwilldecreasewithincreasingfrequency.Theamplitude(andrarefactional
pressure)ofacousticenergyisgreaterneartheprobeaslessenergyislosttobeamattenuation,somoving
the focal zone closer would also increase theMI.Finally, because gaindoes not affectthe ultrasound
energy,itdoesnotaffectMI.
Reference:AIUM.Section7—discussionofthemechanicalindexandotherexposureparameters.JUltrasoundMed2000;19(2):143–168.
20.AnswerB.Thethermalindex(TI)isanestimateoftheincreaseintemperaturewithinaninsonated
tissueasaresultoftissueabsorptionofacousticenergy.TheTIistheratiooftheacousticpowertothe
estimated acoustic power required to raise the tissue temperature by 1°C. Attenuation of ultrasound
energyoccursasaresultofabsorptionandscatter.Absorptionresultsinconversionofacousticenergyto
heat.Thermal andmechanical indexvaluesare intended to providean indicatorof the relative risk of
heatingandcavitationeffectstothesonographerforguidanceinfollowingtheALARAprinciple.
Reference:AmericanInstituteofUltrasoundinMedicine.Medicalultrasoundsafety,3rded.Laurel,MD:AIUM,2014.
21.AnswerD.Transvaginalultrasoundimagefromapatientinthefirsttrimesterofpregnancyshowsa
highlyechogenicyolk sac.Theimaging appearanceisconsistentwith a calcifiedyolksac. A calcified
yolksachasnotbeenreportedtobeassociatedwithaliveembryobeforethe12thweekofgestationand
wouldbeobservedonlywithadeadembryo.Theyolksacwouldundergocalcificationwithinafewdays
afterembryonicdeathhasoccurred.ThereforechoiceD,“Counsel the patient on embryonicdemise”is
correct.
References:HarrisRD,VincentLM,AskinFB.Yolksaccalcification:asonographicfindingassociatedwithintrauterineembryonicdemisein
thefirsttrimester.Radiology1988;166:109–110.
LyonsEA,LeviCS.Thefirsttrimester.In: RumackCM,WilsonSR,CharboneauJW(eds).Diagnostic ultrasound, 3rded.StLouis,MO:
CVMosbyCo.,2005:1070–1100.
TanS,PektasMK,ArsalnH.Sonographicevaluationoftheyolksac.JUltrasoundMed2012;31(1):87–95.
22. AnswerD. TheAmericanInstituteofUltrasound in Medicine (AIUM) approvedthe statement in
2005 that there was insufficient evidence of a causal relationship between diagnostic ultrasound and
adverse effectsinhumans.Therehavenot beenanyknowninstancesofinjury arising fromexposureto
diagnosticultrasound.However,ultrasoundperformedatmuchhigherintensitiesindose-effectlaboratory
studies have demonstrated ultrasound-induced bioeffects and tissue damage. As a result of increasing
applications found fordiagnostic ultrasound andtheneed forgreater diagnostic capability, discussions
betweenthemedicalcommunity,equipmentmanufacturers,andtheFDAhaveresultedinastandardthat
allows for higher outputs. Thus, the equipment operators must be informed on the prudent use of
ultrasoundimaging.
Reference:AmericanInstituteofUltrasoundinMedicine.Medicalultrasoundsafety,3rded.Laurel,MD:AIUM,2014.
8 SecondandThirdTrimesterPregnancy
Questions
1a.A26-year-oldpregnantfemalewithgestationaldiabetespresentsforfetalultrasoundscreening.The
patientunderwentultrasoundat13weeksofgestationalagefollowedbyfetalultrasoundandfetalMRIat
22weeksofgestationalage.
FetalUS:13weeks2days.
FetalUS:22weeks6days.
FetalMR:22weeks6days.
Whichofthefollowingisthemostlikelydiagnosis?
A.Hydranencephaly
B.Severehydrocephalus
C.Alobarholoprosencephaly
D.Acrania
1b.Whatmidlinefacialabnormalityisassociatedwithalobarholoprosencephaly?
A.Hypertelorism
B.Frontalbossing
C.Metopiccraniosynostosis
D.Cleftpalateandlip
2a.Aprimigravidaisreferredat22weeksofgestationalageforfollow-upofprior abnormalprenatal
ultrasoundfindingsandelevatedmaternalalphafetoprotein(1,500ng/mL).
Whatadditionalfetalanatomicimagingshouldbeperformed?
A.Fetalheart
B.Fetalbrain
C.FetalGUtract
D.FetalGItract
2b.Additionalimagesfromanatomicimagingofthefetalbrainareprovided.
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