w w w . j c o l . o r g . b r
Journal of
Coloproctology
Original Article
Establishing the normal ranges of female and male anal canal and rectal wall vascularity with color Doppler anorectal ultrasonography
Sthela M. Murad-Regadas
a,b,c,∗, Francisco Sergio Pinheiro Regadas
a, Iris Daiana Dealcanfreitas
a, Francisco Sergio Pinheiro Regadas Filho
a,c, Graziela Olivia da S. Fernandes
a, Matheus Couto Furtado Albuquerque
a, Carolina Murad Regadas
c, Marina Murad Regadas
caUniversidadeFederaldoCeará(UFC),FaculdadedeMedicina,DepartamentodeCirurgia,Fortaleza,CE,Brazil
bUniversidadeFederaldoCeará(UFC),HospitaldasClínicas,UnidadedeFisiologiaAnorretaleAssoalhoPélvico,Fortaleza,CE,Brazil
cHospitalSãoCarlos,DepartamentodeCirurgiaColorretal,UnidadedeFisiologiaAnorretaleAssoalhoPélvico,Fortaleza,CE,Brazil
a r t i c l e i n f o
Articlehistory:
Received1March2018 Accepted26March2018 Availableonline30April2018
Keywords:
Analcanalvascularization Rectumvascularization Color-doppler
Endoanalultrasound Endorectalultrasound
a bs t r a c t
Studyobjectives:Toevaluatebloodsupplyintheanalcanal,rectalwallandmesorectalfat ofmenandwomen,usingcolorDopplerendorectalsonographytoestablishnormalranges forvascularparameters.
Methods:Aprospectivecross-sectionalstudyconductedatatertiary-carehospitalrecruited asymptomaticvolunteers(≤50years).Vascularitypercentageandindexwerecalculatedfor definedregions.
Results:Vascularitypercentageandindexweresignificantlyhigherinthepuborectalis,mid- level externalandupperinternalanalsphincter comparedtothelowanalcanal;these parameterswerehigherinmenthaninwomenatupperandmiddlelevelsoftheinner analcanalstructures.Atmid-level,vascularitywasgreaterintheexternalcomparedto theinternalanalsphincterinbothsexes;however,attheupperlevelitwasgreaterinthe puborectaliscomparedtotheinternalanalsphincterinwomen.Vascularitywasgreater intherectalwallcomparedtothemesorectalfat,withnodifferencebetweenmiddleand lowerlevels.
∗ Correspondingauthor.
E-mail:smregadas@hospitalsaocarlos.com.br(S.M.Murad-Regadas).
https://doi.org/10.1016/j.jcol.2018.03.005
2237-9363/©2018SociedadeBrasileiradeColoproctologia.PublishedbyElsevierEditoraLtda.ThisisanopenaccessarticleundertheCC BY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Conclusions: Bloodsupplyishighestatupperlevelsoftheanalcanal;however,innerstruc- tures arebetterirrigatedin men.Moreover,the rectalwallis betterirrigatedthanthe mesorectalfat.Establishingnormalrangesmaypermitfuturecomparisonsofthestudied structuresindiseasestatesaswellasthehormonalandagerelatedchanges.
©2018SociedadeBrasileiradeColoproctologia.PublishedbyElsevierEditoraLtda.Thisis anopenaccessarticleundertheCCBY-NC-NDlicense(http://creativecommons.org/
licenses/by-nc-nd/4.0/).
Estabelecendopadrõesnormaisdavascularizac¸ãodocanalanaleda parederetalemindivíduosdosexomasculinoefemininocomultrassom anorretalcomDopplercolorido
Palavras-chave:
Vascularizac¸ãodocanalanal Vascularizac¸ãodoreto Dopplercolorido Ultrassomendoanal Ultrassomendorretal
r e s u m o
Objetivo:Avaliarvascularizac¸ãodocanalanal,parederetalegorduramesorretalemhomens e mulheres, usando ultrassonografiaendorretal comDoppler coloridoparaestabelecer parâmetrosvascularesdenormalidade.
Métodos: Estudoprospectivotransversalincluindovoluntáriosassintomáticoscomaté50 anos.Medidososvaloresdaporcentagemedoíndicedevascularizac¸ãoforamcalculados pararegiõesescolhidas.
Resultados: Valoresdaporcentagemedoíndiceforamsignificativamentemaioresnopub- orretal,esfíncter externo(canal analmédio)e oesfíncterinterno (canalanal superior) comparadoaocanalanalinferior;essesparâmetrosforammaioresemhomensqueem mulheresnocanalanalmédioealto.Nomédio,avascularizac¸ãofoimaiornoesfíncter externocomparadoaointernoemambosossexos;contudo,nocanalanalsuperior,foi maiornopuborretalcomparadoaoesfíncteranalinternoemmulheres.Avascularizac¸ão foimaiornaparederetalcomparadaàgorduramesorretal,semdiferenc¸asentreosníveis.
Conclusões: Osuprimentosanguíneoémaiornosníveisaltosdocanalanal.Asestruturas internassãomaisirrigadas noshomens.Aparederetalé maisirrigadaqueagordura mesorretal.Os parâmetrosvascularesestabelecidospermitiráfuturascomparac¸ões das estruturasestudadasnoscasosdedoenc¸as,assimcomo,alterac¸õesqueocorremcoma idadeemudanc¸ashormonais.
©2018SociedadeBrasileiradeColoproctologia.PublicadoporElsevierEditoraLtda.Este
´eumartigoOpenAccesssobumalicenc¸aCCBY-NC-ND(http://creativecommons.org/
licenses/by-nc-nd/4.0/).
Introduction
Ultrasonographyenablesvisualizationoftheanatomicaland functional aspects of the anal canal and rectum and is a well-establishedtoolforevaluating benign, malignant,and functionaldisorders.Numerousstudieshaveshowngoodcor- relationbetweenultrasoundimagingandsurgicalfindings.1–8 Ultrasoundcanalsobeusedtoassessvascularity,andseveral studieshaveevaluatedtheefficacyofintrarectalultrasound withcolorDopplerandDopplerflowanalysisindetectingpos- sibledifferencesinbloodflowpatternsbetweenmalignant9–11 andbenign12–14analcanalandrectaldiseases.Althoughcolor Dopplerultrasoundhasbeenusedtoevaluatetissuechanges, toourknowledge nodata are availableconcerningnormal vascularizationintheanalcanalandrectalwall.
Itisknownthattheanalcanalandrectalwalldifferfrom eachotherinanatomicstructuresandinbloodvesselsupply anddistribution.Thepurposeofthisstudywastouse360◦ colorDopplerendorectalultrasonographytodeterminenor- malrangesforvascularparametersatdifferentlevelsofthe femaleandmaleanalcanal,rectalwall,andmesorectalfat
inordertoprovidereferencevaluesthatcanfacilitatefuture comparisonsofanalcanalstructuresindiseasestates.
Subjects and methods
SubjectsConsecutiveasymptomaticvolunteers(aged≤50years)were recruitedamongemployeesattwoacademichospitalsinFor- taleza(ClinicalHospitaloftheFederalUniversityofCearáand SãoCarlosHospital).Theclinicalprotocolwasapprovedbythe ResearchEthicsCommitteeoftheWalterCantídioUniversity Hospital,andallsubjectsgavewritteninformedconsent.
Prospectivesubjectswereevaluatedclinicallyandunder- went aphysicalexaminationwhichincludeddigitalexami- nation and assessmentforpelvic organprolapse according to thePelvic OrganProlapse Quantificationsystem (POP-Q) inwomen.11 Menandnulliparous womenwereincluded if theyhadnoanalcanal,rectal,orurinarydisorders.Women were included if their POP-Q status was stage 0. Subjects with fecal incontinence, constipation, urinary symptoms,
inflammatoryboweldisease,HumanImmunodeficiencyVirus (HIV),analsphincterinjury,ahistoryofcolorectalorprocto- logicalsurgery,orvaginaldeliverywereexcluded.
Endorectalultrasonography
Allsubjectsunderwent360◦ colorDopplerendorectal ultra- sonography(5–7MHz).ADoppler360◦radial-arrayendorectal ultrasoundtransducer(Hitachi-AlokaEUP-R54AW-33,Hitachi MedicalSystems, Tokyo, Japan)was used witha Hi Vision AviusUltrasoundSystem(Hitachi).
Subjectswere examinedintheleft lateral positionafter administrationofarectalenema(completed2hbeforescan- ning). After digital rectal examination, the endoprobewas introducedintotheanalcanalandtherectum.Thevascular patternsoftheanalcanalandrectumwereacquiredincolor Dopplermode.
Assessments
Todefinevascularparametersandassesspotentialdifferences amongvariouslevelsandstructures,theanalcanalandrec- tumweredividedintodifferentmanuallydelineatedregions ofinterest.Theanal canalregionwasdivided into3levels (upper,middle, andlow anal canal)at2depths (outerand innerstructures).Theouterstructuresincludedthepuborec- talispluslongitudinalmuscleattheupperlevel,theExternal Anal Sphincter (EAS) plus longitudinalmuscle atthe mid- dlelevel,andtheEASatthelowerlevel.Theinner(deeper) structures included the Internal Anal Sphincter (IAS) plus thesubepithelialtissuesatboththeupperandmiddlelevels (Figs.1–3).
Theregionsofinterestfortherectumincludedtherectal wallandmesorectalfatat2positions:5–6cm(low)and8–9cm (middle)fromtheanalverge(Fig.4).
Thesystemautomaticallycalculatedthevascularityper- centageandvascularityindexwithineachregionofinterest.
Vascularitypercentagewasdefinedasthepercentageofpix- elswithintheregionofinterestthatshowedacolorDoppler signalofanyintensity(indicatingthepresenceofbloodflow).
Vascularityindexwasdefinedasthemeanpowerofeachpixel withintheregionofinterest.
Thesystem also automaticallycalibrated distancesand colorhuesasflowvelocitiesandcalculatedthecolorpixelarea andflowvelocity–encodedbyeachpixel–insideeachregion ofinterest.ThesamesetupofcolorDopplermodewasused for all participants (Pulse Repetition Frequency [PRF=0.5];
gain=50%;velocity=3.3cm/s).
Thestructures were traced manually at each level and thedeviceautomaticallymeasuredthevascularparameters twice,calculatedthemean,andmadecomparisonsbylevel, structure,andsex.
Statisticalanalysis
Theanatomic structureswerecomparedaccordingtolevel, depth,andsexandwithregardtovascularitypercentageand index.Differencesbetweengroupswereassessedbymeansof theStudentttestforcontinuousdata.Thelevelofstatistical significancewassetatp<0.05.
DatawereanalyzedusingSPSSsoftware(version14.0for Windows;IBM-SPSS,Chicago,IL).
Results
Subjectcharacteristics
BetweenAugust2012andFebruary2013,atotalof31volunteer subjectsconsentedtoparticipateinthis study.Ofthese,31 subjectsmetinclusioncriteriaandwereenrolledinthestudy.
Thestudypopulationincluded15women,withameanageof 31(SD=6.4;range23–47years),and16men,withameanage of38(SD=7.4;range27–48years).
Analcanal
Table1presentsthe vascularparametersfortheouter and innerstructuresoftheanalcanalat3levels(upper,middle, andlow)inwomenandmen.
Women
Evaluationoftheouterstructuresoftheanalcanalinwomen showed significantly highermean vascular percentage and vascularindexvaluesinthepuborectalis(upperlevel)andin themid-levelEASthanintheEASatthelowerlevel,butthere wasnodifferencebetweenthepuborectalisandtheEASatthe middlelevel.Evaluationoftheinnerstructuresattheupper andmiddlelevelsshowedthatthevascularpercentageand indexfortheIASweresignificantlyhigherattheupperlevel thanatthemiddlelevel.Comparisonoftheouterandinner structuresshowedthatbothvascularpercentageandindex weresignificantlyhigherinthepuborectalisthanintheupper IASandalsosignificantlyhigherinthemid-levelEASthanin themid-levelIAS.
Men
Asinwomen,assessmentoftheouterstructuresoftheanal canalinmenshowedthatthevascularpercentageandindex werebothsignificantlyhigherinthepuborectalisandinthe mid-level EAS than in the low EAS, but no difference was observedbetweenthepuborectalisandthemid-levelEAS.Of theinnerstructuresinmen,theIAShadsignificantlyhigher meanvascularity percentageandindexvaluesattheupper level than atthe middle level. Incontrast to women,men showednodifferenceinvascularitypercentagebetweenthe puborectalisandtheupperIAS.However,asinwomen,the vascularityindexinmenwassignificantlyhigherinthepub- orectalisthanintheupperIAS.Bothvascularitypercentage andindexweresignificantlyhigherinthemid-levelEASthan inthemid-levelIAS.
Comparisonsbetweenmenandwomen
No significant differences were found between men and women regardingeithervascularity percentageor indexin any of the outer anal canal structures. However,men had higher values for both vascularity percentage and index at the upper and middle levels of the inner anal canal structures.
Fig.1–Femaleanalcanal–upperanalcanal–regionsofinterest.PR,puborectal;LM,longitudinalmuscle;IAS,internalanal sphincter;ST,subepithelialtissues.(A)Outerstructures;(B)Innerstructures.
Fig.2–Femaleanalcanal–middleanalcanal–regionsofinterest.EAS,externalanalsphincter;LM,longitudinalmuscle;
IAS,internalanalsphincter;ST,subepithelialtissues.(A)Outerstructures;(B)Innerstructures.
Fig.3–Femaleanalcanal–lowanalcanal–regionof interest–outerstructures.
Rectumandmesorectalfat
Table2presentsthevascularparametersfortherectumand themesorectumatthemiddleandlowlevels.
Women
Themeanvascularitypercentageandindexweresignificantly higherintherectalwallthaninthemesorectalfatatboththe middleandlowlevels.However,nodifferencesinvascularity percentageorindexwereobservedbetweenmiddleandlow levelsofeithertherectalwallorthemesorectalfat.
Men
Asinwomen,themeanvascularitypercentageandindexin menwerebothsignificantlyhigherintherectalwallthanin themesorectalfatatlowandmiddlepositions,andnosignif- icantdifferenceswereseeninvascularitypercentageorindex incomparisonsofmiddlevslowlevelsoftherectalwallorof mesorectalfat.
Comparisonsbetweenmenandwomen
No significant differences were found between men and womenregardingvascularityoftherectalwallormesorectal fatateithermiddleorlowlevels.
Discussion
Treatment ofanorectaldisorders requiresextensiveknowl- edge of anatomy. Detailed evaluation of vascularity may be important for understanding the physiopathology of
Fig.4–Maleanalcanal–middleposition–regionsofinterest.(A)Rectalwall;(B)Mesorectalfat.
Table1–Vascularitypercentageandvascularityindexfortheouterandinnerstructuresoftheanalcanalat3levels (upper,middle,andlow)inwomenandmen.
Vascularity% Vascularityindex
Women(n=14) Men(n=16) Women(n=14) Men(n=16) Outerstructures,mean±SD(range)
Upper-levelPR+LM 6.0±2.2a(3.1–10.7) 6.4±2.6a(2.6–10.3) 0.29±0.19(0.12–0.71)a 0.25±0.17(0.05–0.61)a Mid-levelEAS+LM 5.0±2.4a(1.8–8.9) 6.0±1.6a(3.3–7.7) 0.27±0.18(0.12–0.71)a 0.28±0.14(0.07–0.53)a Lower-levelEAS 2.4±1.2a(0.7–4.7) 3.2±1.9a(0.6–6.1) 0.06±0.03(0.01–0.13)a 0.09±0.07(0.01–0.26)a Comparisonbylevel(p)
Upper-levelPRvs.mid-levelEAS 0.29 0.66 0.10 0.72
Upper-levelPRvs.lower-levelEAS 0.0001 0.007 0.0009 0.01
Mid-levelEASvs.lower-levelEAS 0.005 0.002 0.0009 0.002
Innerstructures,mean±SD(range)
Upper-levelIAS+SE 3.7±2.7b(0.8–8.1) 6.6±2.9b(1.5–10.9) 0.30±0.30(0.02–0.79)b 0.76±0.52(0.09–1.80)b Mid-levelIAS+SE 0.6±0.4c(0.1–1.1) 2.0±1.7c(0.2–4.8) 0.03±0.04(0.0–0.11)d 0.14±0.17(0.0–0.49)d Comparisonbylevel(p)
UpperIASvs.midIAS 0.001 0.001 0.01 0.01
Outervs.innerstructures(p)
Upper-levelPRvs.upper-levelIAS 0.04 0.84 0.01 0.01
Mid-levelEASvs.mid-levelIAS 0.0001 0.0001 0.0003 0.03
PR,Puborectalis;LM,LongitudinalMuscle;EAS,ExternalAnalSphincter;IAS,InternalAnalSphincter;SE,SubepithelialTissues.
a Nosignificantdifferencebetweenmenandwomen:p>0.05.
Significantlyhigherinmenthaninwomen:
b p=0.02.
c p=0.01.
d p=0.048.
such disorders in order to choose the best methods of treatment. Various Doppler techniques have been used to understanddistributionofvascularityinbenignand malig- nant disorders.9–15 Thisis the first report using 360◦ color Doppleranorectalultrasonographytoassessthevascularity ofstructures at different levels of the anal canal, rectum, andmesorectalfat.Theadvantageofthistechniqueisthat itmakesitpossibletomeasurevascularitycircumferentially instead of by quadrant. The 360◦ endoluminal approach clearly identified and enabled quantitative assessment of vascularparametersforinnerandouteranatomicstructures atupper,mid,andlowlevelsoftheanalcanal,andatmiddle andlowlevelsoftherectalwallandmesorectalfat.
Becausethe participants were asymptomatic volunteers agedupto50years,thestudyprovidesreferencevaluesfor these areas. There was a very large variation in the nor- malrangesforallmeasurements.Inbothsexes,thegreatest degreeofvascularitywasfoundattheupperlevelsoftheanal canalandleastinthelowanalcanal.Comparedwiththeupper levels,thelowanalcanalrequiresonlyamodestbloodsupply andmanyofitsbloodvesselsaresmallindiameter.Wealso analyzedtheanalcanalaccordingtothefunctionsofthemus- clesintheouterstructures,includingthelongitudinalmuscle, puborectalis, and EAS (voluntary muscles), as well as the innerstructures,includingsubepithelialtissuesandtheIAS(a smoothmuscleinastateofcontinuousmaximalcontraction,
Table2–Vascularitypercentageandvascularityindexmeasuredintherectalwallandmesorectalfatat2levels(middle andlower)inwomenandmen.
Vascularity% Vascularityindex
Women(n=14) Men(n=16) Women(n=14) Men(n=16)
Middlelevel,mean±SD(range)
Rectalwall 10.9±8.3a(4.0–29.7) 12.2±7.0a(1.9–24.0) 1.59±1.37a(0.39–5.46) 1.74±0.98a(0.14–3.27) Mesorectalfat 4.1±3.2a(0.4–9.6) 4.6±2.6a(1.1–9.6) 0.37±0.27a(0.03–0.73) 0.59±0.34a(0.20–1.30)
Rectalwallvs.mesorectalfat 0.01 0.0008 0.006 0.0003
Lower-level,mean±SD(range)
Rectalwall 12.8±7.0a(2.2–22.3) 11.4±7.2a(1.1–23.5) 1.52±1.27a(0.28–4.21) 1.72±1.23a(0.09–3.60) Mesorectalfat 5.9±4.1a(0.5–12.6) 4.0±3.3a(0.2–10.5) 0.52±0.57a(0.04–2.11) 0.51±0.58a(0.01–2.20)
Rectalwallvs.mesorectalfat 0.01 0.002 0.02 0.003
Comparisonbylevel(p)
Midvs.lowerrectalwall 0.7 0.78 0.9 0.96
Midvs.lowermesorectalfat 0.25 0.62 0.45 0.68
a Nosignificantdifferencebetweenmenandwomen:p>0.05.
representinganaturalbarriertotheinvoluntarylossofstool andgas).Inbothsexes,greatervascularitywasfoundinthe outerstructuresoftheupperandmid-levelanalcanalthanin theinnerstructures,reflectingrequirementsforalargesupply ofbloodintheouterstructures,possiblybecausetheycontain striatedmuscles,whicharethickerthansmoothmuscles.
Previousstudieshaveshownthatanalcanalmuscles(both striated and smooth muscles) are longer in men than in women.Wefoundgreatervascularityattheupperandmid- dlelevelsoftheinneranalcanalstructuresinmencompared withwomen.Howevernodifferenceswerefoundbetweenthe sexesregardingvascularityofthemiddleorlowrectalwallor mesorectalfat.Vascularitywasgreaterintherectalwallthan inthemesorectalfatatbothlevelsandinbothsexes.Despite itsthinnerrectallayer,therectalwallrequiresalargeblood supplyandhasmanyhigh-diameterbloodvessels.
Onelimitationofthismethod isthenecessityforman- ualdelineationoftheregionofinterest.However,theimage hashighresolutionandisthereforeabletoeasilyidentifythe anatomic structuresand muscles inordertoassess vascu- larity.Futuredevelopmentofthemethodmayenable3D/4D analysisofthe vasculardistribution andquantitativevolu- metricassessmentofthevesselnetwork.Inthemeantime, becausetheDoppler360◦endorectalultrasoundisarelatively newtechnique,furtherstudies shouldcompareit withthe useofdifferentultrasoundmethods,suchastransperinealor transvaginaltechniques.
Applicationof360◦colorDopplerendorectalultrasonogra- phycanbeusefulinmanydifferentsituations.Forexample, patientswithhemorrhoidsshouldbeinvestigatedwiththis method.Changesinthevascularityofinnerandouterstruc- tures may correlate with the resultsof treatment, making it possibletodemonstratethe efficacy ofdifferent surgical techniques.14,15 In another application, Drudi et al.10 com- pared the ability of gray-scale transrectal ultrasound with thatofcolorDopplerimagingtodifferentiatebetweenpost- radiationfibrosis andresidualtumororlocalrelapse.Color Dopplerincreasedthespecificityoftransrectalultrasoundin differentiatingtumorrelapsefromfibrosis,demonstratingits valueintheevaluationofcarcinomaoftheanalcanal,bothin thepre-therapeuticstageandduringfollow-up,whencolor
Doppler-guided biopsy should be preferred to ultrasound- guidedbiopsy.
New researchshould evaluatesome ofthe factors that could affect the Doppler flow spectrum in the anal canal andrectum,forexample,previousstudieshavedemonstrated the influence offactors suchassex hormones,aging, par- ity, bodymassindex,andmenopause onthevascularityof various structures.16 Oliveira etal.12 evaluated theDoppler velocimetric parameters of the levator ani muscle vessels in premenopausalwomenwithand without urinary stress incontinenceandfoundthatDopplervelocimetricdifferences inthelevatoranimusclevesselsmightbeduetohormonalsta- tus.Jármy-DiBellaetal.17usedDopplervelocimetricanalysis toinvestigatetheeffectofhormonetherapyinperiurethral vessels and demonstrated that hormonal therapy ofshort duration had a positive effect on the urethral continence mechanism,increasingthenumberofperiurethralvessels.
Afurtherstudyinpatientswithsymptomsoffecalincon- tinenceand/orobstructeddefecationsyndromewithperineal descentshouldbeconductedtoinvestigatevascularparam- eters insuchpatients and toidentifyany riskfactors that couldnegativelyaffecttreatmentoutcome.Apreviousstudy18 demonstratedthatpregnancyandlabormayleadtoperineal trauma,deteriorationofvascularsupply,andnervefunction inthepelvicfloorarea,therebyimpairingurinarycontinence, butnocorrelationwithfecalincontinencewasfound.
Itwouldalsobeinterestingtostudy agroupofpatients withinflammatorydisease,becauseapreviousinvestigation19 usingpowerDopplerabdomensonographyhasshownacor- relationbetweenbowelwallvascularityanddiseaseactivity inpatientswithconfirmedCrohn’sdisease.Theauthorssug- gestedthatpowerDopplerabdomenultrasoundmaybeable tomonitoractivitychangesofthebowelwallcausedbyphar- maceuticaltreatment.Afurtherstudyshouldbeconducted toinvestigatetherelationshipbetweenanalcanalvascularity anddiseaseactivityinpatientswithperianalCrohn’sdisease.
TheusefulnessofendorectalDopplersonographicanalysis of rectal tumor vascularization before and after preopera- tiveradiotherapy hasalso beendescribed in theliterature.
Barbaro etal.20 usedcolorDopplerultrasoundtostudy the relationship between the vasculature supplying blood flow
torectalcancerand responsetoaneoadjuvantregimenin patients with rectal cancer. Homogeneous vascularity and low pulsatility index values from arterial signals sampled from the peripheralportion ofrectalmasses were positive indicatorsoftherapyoutcome.Oguraetal.9suggestedthatthe intratumoralvascularpoint indexasassessedbytransanal color Doppler ultrasonography is better than conventional immunohistochemicalanalysisasapreoperativeindicatorof angiogenesisandmayalsobeapredictorforhematogenous metastasisinrectalcarcinoma.
Inconclusion,thedegreeofvascularityvariesamongthe differentlevelsandstructuresoftheanalcanal.Bloodsup- plyishighestatupperlevelsofouterandinnerstructuresof theanalcanalinbothmenandwomen,butinnerstructures arebettersuppliedinmenthaninwomen.Inbothsexes,the rectalwallisbettersuppliedthaninmesorectalfat.Consid- eringthesevariations,thenormalrangesdeterminedinthis study using360◦ colorDopplerultrasonography may facili- tatefuturecomparisonsofanalcanaland rectalstructures indiseasestates,aswell as,the hormonalandagerelated changes.
Compliance with ethical standards
TheInstitutionalReviewBoardoftheWalterCantídioUniver- sityHospitalapprovedthestudyprotocolandallsubjectsgave theirwritteninformedconsent.
Conflicts of interest
Theauthorsdeclarenoconflictsofinterest.
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