Achtari Meyer , F. Salchli , H. Bettaieb , P. Hohlfeld ,C. S. de l’accouchement continu de la pression intrarectale pendant la phaseexpulsive second phase of labor Continuous recording intrarectal pressures duringthe

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ORIGINAL ARTICLE

Continuous recording intrarectal pressures during the second phase of labor ^夽

L’enregistrement continu de la pression intrarectale pendant la phase expulsive de l’accouchement

S. Meyer

^a^,∗

, F. Salchli

^b

, H. Bettaieb

^b

, P. Hohlfeld

^c

, C. Achtari

^a

aUrogynecologyUnit,DepartmentofGynecologyandObstetrics,CHUV,46,rueduBugnon, 1011Lausanne,Switzerland

bMicro-NanotechnologyDepartment,InstituteofAppliedSciences,Yverdon-les-Bains, Switzerland

cDepartmentofGynecology-Obstetrics,CHUV,Lausanne,Switzerland

Received27February2012;accepted28March2012

KEYWORDS Delivery;

Intrapelvicpressures;

Pelvicﬂoorproblems;

Pelvi-perineology

Summary Parametersofintrarectalpressure(surface areaunderpressurecurveandpeak pressure)recorded withamicrosystem deviceduring thesecond phaseoflabor showedno signiﬁcantcorrelationswithbaby’sweightormodeofdelivery.

Aimofthestudy.—Wastoassessthebiomechanicalpressuresdelivered againstpelvicﬂoor structuresduringthesecondphaseoflaborinnulliparaewomen,andtocorrelatethemwith obstetricsparameters,i.e.baby’sweightandmodeofdelivery.

Material.—Usingamicrosystemdeviceplacedintotherectumatthebeginningofthesecond phaseoflabor,twoparameterswereassessedduringthebearingeffortsin59nulliparaewomen:

thesurfaceareaunderthepressurecurveandthepeakpressure.

Results.—During11.5±9bearingeffortsof99.1±16sduration,themeanvalue ofsurface areaunderthepressurecurvewas32677±26058cm/sandthemeanvalueofthepeakpressure was60.7±24cmH2O,exceeding100cmH2Oin10%ofwomen.Thesetwoparameterswerenot correlatedwithbaby’sweight(R:0.19,P:0.15andR:0.05,P:0.71).Inthesameway,thesetwo parameterswerenotcorrelatedwiththemodeofdelivery(spontaneousorforceps/vacuum- assisted).Furthermore,theindividualvaluesofthesetwoparametersshowedgreatvariation fromonewomantoanother.

Conclusion.—This study hasshowed that parameters ofbiomechanical pressures recorded into the rectum during second phase of labor had no signiﬁcant correlations with

夽 Levelofevidence:NA.

∗Correspondingauthor.

E-mailaddress:[email protected](S.Meyer).

http://dx.doi.org/10.1016/j.purol.2012.03.011

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obstetricals parameters,explaining whythese latterhave poorpredicitive value offurther pelvicﬂoorproblems.

MOTSCLÉS Accouchement; Pressions intrapelviennes; Troublesfonctionnels duplancherpelvien; Pelvi-périnéologie

Résumé Lesparamètresdepressionintrarectale(surfacesouslacourbedepressionetpics depression)enregistrésgrâceàunmicrosystempendantlaphaseexpulsiven’ontpasmontré decorrélationssigniﬁcativesaveclepoidsdubébéoulemoded’accouchement.

Butdel’étude.—À étédemesurer lescontraintes bioméchaniquesdélivréesauxstructures neuromusculairesduplancherpelvienpendantlaphaseexpulsivedel’accouchementdansun collectifdenullipares,etdecorrélercesmesuresauxparamètresobstétricauxreprésentéspar lepoidsdubébéetlemoded’accouchement.

Matériel.—Enutilisantunmicrosystèmecrééàceteffet etplacédanslerectumaudébut delaphaseexpulsive,deuxparamètresontétécalculéspendantleseffortsdepousséechez 59nullipares:lasurfacesouslacourbedepressionetlespicsdepressiondéveloppéspendant lespoussées.

Résultats.—Pendantles11,5±9pousséesde99,1±16sdedurée,lavaleurmoyennedelasur- facecalculéesouslacourbedepressionaétéde32677±26058cm/setlavaleurmoyennedes picsdepressionsde60,7±24cmH2O,dépassant100cmH2Ochez10%despatientes.Cesdeux paramètresn’ontpasmontrédecorrélationssigniﬁcativesaveclepoidsdesbébésaccouchés, étantrespectivementdeR:0,19,p:0,15etdeR:0,05,p:0,71.Delamêmefac¸on,cesdeux paramètresn’ontpasmontrédecorrélationaveclemoded’accouchement(spontanéouassisté parforceps/vacuum).Deplus,lesvaleursindividuellesdecesdeuxparamètresontmontréde grandesvariationsd’uneaccouchéeàl’autre.

Conclusion.—cette étudeadémontré queles valeursdepressionsintrarectalesappréciant lescontraintes biomécaniquesexercées sur leplancherpelvien pendantla phase expulsive del’accouchementn’ont pasmontrédecorrélationssigniﬁcativesavec lepoidsdu bébéet lemode d’accouchement,expliquantpourquoicesparamètresobstétricauxnereprésentent qu’unefaiblevaleurprédictivedansl’apparitionultérieuredetroublesfonctionnelsduplancher pelvien.

Aim of the study

Theobjectiveof thisstudy wastoassess thebiomechani- calpressuresdeliveredagainstpelvicﬂoorstructuresduring thesecondphaseoflaborinnulliparaewomen,andtocor- relatethem withobstetricsparameters,i.e. baby’sweight andmodeofdelivery.

Considering that pregnancy and vaginal delivery are responsible for the onsetof genuine stress urinary incontinence, and pelvic ﬂoor damage, a striking dearth of prospectivestudiesexistsregardingtherelationshipofpreg- nancyanddeliverytotheseproblems.Thevastmajorityof publisheddataisbasedonanalysisretrievedfromquestion- naires.

Using amicrosystem device, the aim ofthis study was toassessthe importanceandtheeffects of thepressures deliveredagainstthepelvicﬂoorstructuresduringthesec- ondphaseoflaborin nulliparaewomen,correlatingthem withthedifferentobstetricsparameters.

Material

This study is the result of the scientiﬁc collaboration between urogynecology unit-obstetrics unit and a department of micro-nanotechnology (F.Salchli, Prof., Micro-Nanotechnology Department Institute of Applied

Sciences,Yverdon-les-Bains,Switzerland),sponsoredbypri- vatefundsforscientificresearchandtheofficialCTIofthe Swiss Confederation (CTI, i.e. Commission for Technology Innovation:ProjectscofinancedbytheSwissConfederation’s innovationpromotionagency).

The aim of this research wastocreate a microsystem device able to measure continuously the biomechanical pressuresonthepelvicﬂoor,torecordthesedatasinamem- ory,andtoreadthemafterwithdrawingthedeviceatthe endofthedelivery.

Themicrosystemconsistsinatitaniumcapsuleof6mm diameterand11mmlength(Fig.1)containing:

Figure 1. Microsystem inserted in the titanium capsule of 6×11mm,withthewireforelectricconductionconnectedtoan externalbattery.

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• a wheatstone bridge pressure sensor at the tip of the capsule;

• anintegratedcircuitincludinganelectronicabletointer- face the pressuresensor and a microcontrollerwithan embeddedsoftwarespeciﬁctotheapplication;

• anElectricallyErasableProgrammableReadOnlyMemory (EEPROM)storingthepressuredatameasurements.

Aﬁve-wireconnection(about1m)isusedforbirectionnal transmissionpurposeandtoconnectanexternalbatteryto themicrosystem.

The pressurecurves wereanalysed withnewly created software. The raw pressure measurementswere ﬁrst de- noisedandcalibrated,andtheneachbearingwasidentiﬁed usingtime-domainanalysis.Thesoftwareprovidedasout- put:• the intensity of the highest pressures,i.e. ‘‘peakpres-

sure’’,recordedduringeachbearingeffort(cmH2O);

• the‘‘amount’’ofpressuredeliveredbythe‘‘descending’’

headofthebabyduringeachcontractioncalculatedfrom the sum of the surface areas under the pressurecurve recordedduringallbearingefforts(cmH2O/s),usingthe formula

Total amount of pressure=^Nmax

N=1

(

tend

tstart

fN (t)^•dt)

Nmax=contractionnumber.

tstart=contractionstart.

tend=contractionend.

Fifty-nine nulliparae women of 29±4 years old were enrolledinthisstudy;theygaveinformedconsentandethics approval was obtained (Ethic’s comitee approval number 197/06).Theinformedconsentwasgiventothepatientby themedicalteam(MDandmidwives),orduringpregnancy controls, or beforethe beginning of the labor, in case of electiveinduction,oratthebeginningofthelaborincase ofspontaneouslabor.

Exclusion criteriaincluded: pretermlabour, non-vertex presentation, multifetal pregnancy, multiparity (two or moreprevious pregnancies),placental abnormalities, pre- eclampticdeliveries,uterinestructuralanomaliesorscars, andfetalheartrateabnormalities.

Labormanagementof phaseIwascarriedonobserving the classical obstetricals rules. At thebeginning of phase II of labor, before any bearing efforts, the midwive con- nected themicrosystem(Fig.1)tothebatteryand,then, introduced it into the rectum at about 10cmof the anal margin.ThenphaseIIofthelaborwascarriedonaccording theusual obstetricalrules. Allwomenbegan pushingonly after thefetal head haddescended toat least+1station.

Afterdeliveryofthebaby,themicrosystemwaswithdrawn fromthe rectum, deconnected fromthe battery,cleaned withsalinewater,andsendedtotheingeniorteamforthe measurementsofthepressurecurverecorded.

The demographicandobstrical datasofthispopulation aregiveninTable1.

Statistic analysis: when data distributions were ascer- tainedtobenormal,accordingtotheKolmogorov-Smirnov test,statisticalcomparisonswereperformedusingthet-test forindependentgroups. Insomecases,thecorrespondent

non-parametric procedure, the Mann-Whitney test, was used,becauseofthenon-normalityofthedistributions.Cor- relationswereassessedusingtheparametricprocedure.All signiﬁcancelevelsweresetto␣=0.05two-ways.

Results

Parametersofthesecondphaseoflaborarementionnedin Table2:thesevaluesaredescribedforthewholepopulation ofnulliparaewomen.Theyarealsodescribedandcompared considering their mode of delivery, i.e. forceps/vacuum- assistedor spontaneous.The durationof phaseII oflabor wassigniﬁcantly longer in forceps/vacuum-assisted deliveries compared to spontaneous deliveries (49.9±21.9 vs 34.3±23.8min,P:0.006).

The frequency of bearing efforts and the interval betweenthemshowedimportantvariationswhencompared fromone nulliparaetoanother. Onthe sameway,women forceps/vacuum-assistedhadasigniﬁcanthighernumberof bearing efforts when compared to women spontaneously delivered(13.7±8.8vs9.6±8.1,P:0.04).

The parametersrecorded by themicrosystem, i.e. the meanvalue of the surface areaunder thepressure curve recorded during all bearing efforts and the mean value of the peak pressures recorded at the tip of the bearing effortsin each women are alsodescribed in Table 2:

they showed no signiﬁcant differences between sponta- neousand assisted deliveries, even if the mean value of the surface area under the pressure curve were higher inforceps/vacuum-assisteddeliveredwomencomparedto spontaneouslydeliveredwomenandapproachessigniﬁcance (36702.9±23977.4vs29452±28049.0cmH2O/s,P:0.07).

Whenconsideredseparatelyforeachwomen,thesetwo parametersshowedagreatrangeofdistribution(Fig.2).

In10%of them,themeanvaluesofthepeakpressures exceeded100cmH2Oandin12%,theywerefoundbetween 80cmH2Oand100cmH2O.

Onthesamehand,theimportanceofthestandarddevi- ationofthepeakpressurevaluesobservedineachwomen couldbeimportant, beingfound higherthan 80cmH2O in twowomen,andmorethan40cmH2Oinfourwomen.

Calculated for each woman, the correlation between meanvaluesof thesurfaceareaunderthepressurecurve andthebaby’sweightwasweakandnotsigniﬁcant(R:0.19, P:0.15)aswellasthecorrelationbetweenmeanvalueof thepeakpressuresandthebaby’sweight(R:0.05,P:0.7) (Fig.3).

Discussion

Identiﬁcation of a population of women at high risk for delivery-relatedpelvicﬂoortraumaistheaimofthisclin- ical research. Using the collaboration with a micro-nano technologydepartment,amicrosystemdevicewascreated forassessingcontinuouslyintrarectalpressuresduringsec- ondphaseoflabor.Thismicrosystemwascreatedincluding thefollowingcriterions:beinglessinvasiveaspossible,i.e.

smallestaspossible,beingeasytointroduceintothevagina ortherectum(wechoosetherectumforavoidingeventual skintraumatothebaby’shead),beingeasytomanipulate

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Table1 Obstetricsdataforthe59nulliparaewomenstudied.

Population Electiveinduction Modeofdelivery Perineum Analgesia 59primiparae

women

20%(n:12) Spontaneous:59%(n:35) Withoutepisiotomy:

53%(n:31)

Without:18%(n:11) Prematureruptureof

membranes:10%(n:

6)

Forceps:23%(n:14) Withepisiotomy:47%

(n:28)

Epidural:78%(n:46)

Post-term:7%(n:4) Vacuum:18%(n:10) Pudendalblock:4%(n:2) Others:3%(n:2)

bythemidwives(anon/offbutton),andbeingwithoutany dangersforthemotherandbaby.

Our result showed that the two pressure parameters recorded, i.e. the mean value of the surface area under thepressurecurverecordedduringallbearingeffortsand themeanvalue ofthe peakpressuresrecorded atthe tip ofthebearing efforts,were notcorrelatedwiththebirth

weightofthebabyorwiththemodeofdelivery,spontaneous or forceps/vacuum-assisted.Furthermore,thesetwopres- sureparametersshowedgreatvariationfromonewomanto another,evenwhentheygavebirthtobabiesofthesame highweight(Fig.3).

Each year, pelvic ﬂoor dysfunction affects between 300,000and400,000Americanwomensoseverelythatthey

70007200 74007600 78008000 82008400 86008800 90009200 94009600 100009800 10200 10400 10600 10800 11000

0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 3400

7000 7500 8000 8500 9000 9500 10000 10500 11000

0 200 400 600 800 1000 1200

Figure2. ‘‘Roughmeasures’’issuedfromtheEEPROMofthemicrosystemshowingcontinuousintrarectalpressuresrecordingsduring secondphaseoflaborintwowomenwithdeliveryofsameweightbabies(xaxis:durationofsecondphaseinseconds,yaxis:intrarectal pressureincmH2O).Top:OIGA3840g,surfaceareaunderthepressurecurve:130,030±2386cmH2O/s,mean valueofpeakpressure:

104±34cmH2O, durationofsecondphase3500s.Bottom: OIGA3870g,surfaceareaunderthepressurecurve:22954±1860cmH2O/s, meanvalueofpeakpressures:67±20cmH2O,durationofsecondphase1200s.

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Table2 Parametersof the second phaseof labor of the59 nulliparaewomen studied, includingparametersof the wholepopulationandthosespontaneouslydeliveredorforceps/vacuum-assisteddelivered,with,inthelasttworows, theparametersrecordedbythemicrosystem,i.e.themeanvaluesofthepeakpressuresandthemeanvaluesofthe surfaceareaunderthepressurecurve.

Mean Median SD n Pvalue

DurationofphaseIoflabor(min) Modeofdelivery

Forceps/Vacuum 287.5 285.0 124.0 28 0.262NS

Spontaneous 254.1 250.0 102.6 31

Allpatients 268.9 257.5 112.8 59

DurationofphaseIIoflabor(min) Modeofdelivery

Forceps/Vacuum 49.9 51.5 21.9 28 0.006**

Spontaneous 34.3 28.0 23.8 31

Allpatients 42.2 35.5 24.1 59

Baby’sweight(g) Modeofdelivery

Spontaneous 3218.6 3180.0 418.1 31

Allpatients 3266.8 3240.0 412.3 59

Numberofbearingdownefforts Modeofdelivery

Forceps/Vacuum 13.7 11.5 8.8 28 0.041**

Spontaneous 9.6 6.0 8.1 31

Allpatients 11.5 8.5 8.6 59

Numberofbearingdownefforts/10min Modeofdelivery

Spontaneous 2.8 3.2 1.3 31

Allpatients 2.8 3.0 1.2 59

Durationofbearingdownefforts(sec) Modeofdelivery

Spontaneous 99.8 98.8 16.7 31

Allpatients 99.1 97.0 15.6 59

Durationbetweenbearingdownefforts(sec) Modeofdelivery

Spontaneous 70.3 66.6 23.7 31

Allpatients 71.9 70.4 20.3 59

Meanvalueofthepeakpressure(cmH2O) Modeofdelivery

Spontaneous 61.3 53.2 24.2 31

Allpatients 60.7 53.3 23.6 59

Meanvalueofthesurfaceareaunderthepressurecurve(cmH2O/s) Modeofdelivery

Spontaneous 29452.9 20431.8 28049.0 31

Allpatients 32677.9 22224.3 26058.3 59

NS:non-signiﬁcantdifference;**highlysigniﬁcant.

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0 20000 40000 60000 80000 100000 120000 140000

2000 2500 3000 3500 4000 4500

Baby's weight (gr) Area of bearing efforts (cmH2O*sec)

0 20 40 60 80 100 120 140 160

2000 3000 4000 5000

Baby's weight (gr) mean values of the maximum peak pressures (cmH2O)

Figure3. Top:scatterplotshowingthecorrelationbetweensur- faceareaunderthepressurecurverecordedduringbearingdown efforts(meanvalues)andthebaby’sweightineachofthe59nulli- paraewomen.Bottom:scatterplotshowingthecorrelationbetween peakpressuresrecordedduringbearingdownefforts(meanvalues) andbaby’sweightineachofthe59nulliparaewomen.

requiresurgery.Approximately 30% oftheoperationsper- formed are re-operations [1].Urinary incontinence is the mostprevalentpelvicﬂoordysfunctionlinkedtobirthand isresponsiblefor16billiondollarsannualexpense[2—4].

Among established risk factors for developping urinary/fecalincontinence, pregnancy,parityandobstetrical factorsareconsideredasimportantetiologicalfactors.Most damageofthepelvicfloorobviouslyoccursduringfirstdeliv- ery. Objective findings have demonstrated that pudendal nerve‘‘stretch’’damages,direct‘‘crushing’’ofneuromus- cular junctions, tears of anchoring tissues of pelvic floor structurescanbefoundaftervaginaldeliveriesconsidered as‘‘normal’’deliveries[5].

Considering these facts, we have to appreciate pelvic ﬂoortraumaasareality,notasamyth.Stressurinaryincon- tinence is observed in 20 to34% of women after vaginal delivery[6,7],persistsinpostpartumperiodin29%ofwomen inwhomitappearedduringpregnancyandpresentsdenovo in16%ofpregnancy-continentwomen[8].

Fecal incontinence is seen in 4 to 7% of primiparous women,andtransanalultrasonographydemonstratesoccult analsphincterlesionsin35%ofprimiparas[9].

Trauma to pelvic ﬂoor musculature, with avulsion of thepubovisceralmusclefromthepelvicsidewall,seemsto occurin15to30%ofvaginallyparouswomenandisassoci- atedwithpelvicorganprolapse[10,11].

Effective prevention of pelvic ﬂoor trauma is to-day impossible, even if we know that vaginal delivery is associated with an increased frequency of stress urinary incontinenceandfecalurgency/gasincontinencewhencom- paredwithcesareansection10yearsafterdelivery[12]..

Ontheother hand,itis well-knownthatdoingsystem- atically to each pregnant woman an elective caesarean sectionfor avoidingpelvicﬂoorproblems wouldrepresent an unnecessary overtreatment in about 89% of the cases, epidemiologicstudy,carriedonthelifetimerisk ofunder- goingasingleoperationforPOPandUI,havingestimatedit tobeonly11.1%[13].

Until now, only studies using intrauterine pressures recordinghavebeencarriedonduringdelivery.

Schatz, in the 1880s, wasthe ﬁrst person to describe direct intrauterine pressure measurements during labour.

Sincethisperiod,fewstudieshavebeenpublished.Allmann etal.,in1996,describedthetemporalrelationshipbetween intrauterine pressure and head-to-cervix forces in labour usinganintrauterinepressurecatheter[14,15].

Morerecently,Bumischietal.,measuringalsointrauter- ine pressureusing a sensor-tipcatheter inserted into the uterine cavity, found increasing pressures amplitudes of 65mmHginwomenbearingwithspontaneousorenhanced contractionsandof99mmHginwomenbearingdownwith Valsalva efforts, the basic intrauterine pressure being of 25mmHg.Theyconcludethatwomeninlaborincreasetheir intrauterinebasalpressure62%by activelypushingwitha contraction,butalsothatthisincreaseshowgreatvariation whencomparedfromonewomentoanother,witharange varyingfrom0to192%[16].Thesameteamalsofoundtran- sient increasesof their expulsive forces(always reﬂected byintrauterinepressure)by86%oftheirbaselinecontrac- tionwhenusingvalsalvaandfundalpressuresimultaneously [17], andstill greaterwhen a McRobertsmanoeuver(legs hyperﬂexedby135^◦)wasused(ValsalvainMcRoberts’posi- tionincreasedthetheamplitudefrom103(88—118)mmHg to129(114—144)mmHg)[18].

Amarenco et al. did a similar work in 13 nulliparae women:measuringintravesicalandintrauterinepressures, they found similar increases of intrauterine pressures of 50±20mmHg with increases of intravesical pressures reaching31±6mmHg,correlatingwithsimilarincrease of electricactivityofintercostalmuscle[19].

Intrauterinepressures recordingsmaynotberepresen- tative of intrapelvicpressures, areinvasive and fromthis fact cannotbeapplicable forroutineassessment in deliv- eryroom.Itwasthereasonwechooseintrarectalpressure recordings.Furthermore,uptonow,wewereunabletoﬁnd similarresearch involving intra-vaginal or intrarectal con- tinuouspressurerecordingsduringstageIand/orstageIIof vaginaldelivery.

Ourintrarectalpressuresmeasurementsrecordedduring phaseIIoflaborshowedsimilarvaluesasintrauterinepres- sureincreasesmeasurementsbyBumischietal.:themean values of the highests ‘‘bearing peak’’pressure recorded intherectumareabout60cm±24cmH2Obutwithahigh range of variations when compared from one woman to another,goinguptovaluesashighas140cmH2O.

Thecriticismswecouldbringtothisstudycouldbethe followings:

• weconsideredthepressureparametersmeasuredbythe microsystemasintrapelvicﬂoorpressures:aretheydif- ferentfromintrauterinepressures?Wecannotanswerto thisquestion asweavoidedasimultaneousrecordingof intrauterinepressureswithinsertionofasecondmicrosys- teminto the uterine cavity, thus for avoiding eventual

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traumatothebabyandforavoidingatoomuchimportant invasiveness forthe mother.Furthermore, thesoftware hasintegratedallpressuremeasurements,whichmeans eventshavingdifferentoriginareaddedtothosethatare duetobearingeffortsduringcontraction:thesepressures phenomenon(mostpartofthetime:oneortwocouhing episodesorsmallcryingofthebearingmotherbetween bearingeffortsor intwocases:vomitingefforts)canbe detected on the pressure curve and are rare, of weak amplitude andof shortdurationandcannot modify the pressureparametersrecorded;

• therectalpressuresaremeasuredplacingthemicrosys- tematabout9to10cmoftheanalmargin:butwiththe movementoftheheadduringbearingefforts,thesensor, locatedatthetipofthemicrosystem,ismovingintothe rectalcavity andconsequently measurethepressureat differentlevelsintotherectalcavity;butthemicrosys- temstaysalwaysintherectalcavity,i.e.intothepelvic cavity;

• rectalfullnesswasnotconsideredinourmeasurements, becausesomewomenhadenemasomeothers:noenema (mostpartofthewomenhadnoenema)...butnodelivery occurswithagreatemissionofstoolsontheperineum... as notedonthe delivery ﬁle. Furthermore,we thought thatthepressureofthebaby’sheadissoimportantthat the soft mass of the residualstools intothe rectum at this moment cannot represent a barrier strong enough for enhancing modiﬁcations of thepressure parameters recorded;

• test-retestsfiabilitymeasurementsweredoneinasmall population of women investigated for urinary incontinence: two simultaneous pressure measurements were realisedduringconventionalcystometricmeasurements, one with the microsystem another witha conventional water-filledcatheter.Bothcatheterswereofcourseintro- ducedintotherectuminwomenwithoutpre-examination preparation with an enema. The correlations between thesetwopressuresrecordingswereexcellentandlargely significant(R:0.9).

A multitude of factors and structures are involved in the second phaseof labor: the myometrium, cervix, pla- centaandthefetusmustactinconcerttoassuresuccessful delivery,butwedoknowthatachievementofa‘‘perfect’’

contractileforceisnotthesolefactor:successfuldeliveryis alsoimpactedbysubtledifferencesinpelvicshapeorsize, whoaredifferentineachwoman.

The conclusion of this study was that parameters of biomechanical pressures recorded intothe rectum during secondphaseoflaborshowedimportantvariationsfromone womentoanotherandhadnosignificantcorrelationswith obstetricals parameters,explainingwhy theselatter have poorpredicitivevalueoffurtherpelvicfloorproblems.This study could also be useful in the future for obstetricians involved in medicolegal problems with women suffering fromafter-birthpelvicfloorproblems.

Thenextstepofthisoriginalclinicalresearchwillassess the correlations between these two pressure parameters andthepelvicfloorcomplaints, assessedwithspecificICS questionnairesfulfilledoneyearaftertheirdeliveryinthis populationofwomen.

Disclosure of interest

Theauthorsdeclarethattheyhavenoconﬂictsofinterest concerningthisarticle.

Funding:CTI:TheInnovationPromotionAgency,Efﬁnger- strasse27,3003Berne,Switzerland,phonenumber:+4131 3222129.

Appendix A. Supplementary data

Supplementary data associated with this article can be found,intheonlineversion,athttp://dx.doi.org/10.1016/

j.purol.2012.03.011.

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