Recently, a diagnostic panty-linerkit—「AL-SENSE」®(Commonsense,Caesarea,Israel)wasdevelopedtode-tectamnioticfluidleak.Itsmechanismofactionisde-scribedelsewhere[1].Thepanty-linerhasseveralad-vantages.Firstly,itiswornbythewomenforsomehours,soitreflectsarelativelylengthytimeperiodandnotasinglepointintime,whichincreasesitssensitivityindetectingminoramnioticfluidleakage.Inaddition,itcontainsauniquepolymerthatiscapableofdifferenti-atingamnioticfluidfromurine.
Inpreviousthirdtrimesterclinicalstudies[1,2],theAL-SENSEpanty-linertestwasdocumentedasasensi-tivetoolfordiagnosingprematureruptureofthemem-branes(PROM)anddifferentiatingamnioticfluidleaksfromurinaryincontinence.Onestudyshowed100% test,microscopicevaluationforferning andultrasounddeterminationofintra-uterineamnioticvolume[2].Thesenegativeand87.1%positivepredictivevalues,withasensitivityof100%andspecificityof75%.Another studyshowed94.7%negativeand87%positivepredic-tivevaluewithasensitivityof96%andspecificityof84%.Thepanty-linerwascomparedtoaseriesofcon-ventionaltestssuchasspeculumexamination, nitrazineresultswereconfirmedbyanotherstudy[3]comparingthepanty-linertesttospeculumexaminationfordetec-tionofrupturedmembranes;itfound 98% sensitivityand65%specificity.
Thosestudiesenrolledwomenmostlyatthethirdtri-mester.However,sinceamnioticfluid leakage duringthesecondtrimesterhasevenmoreseriouscomplica-tionsandpooroutcomesthanduringthethirdtrimester,thepresentstudywasundertakentoestablishtheAL-SENSEreliabilityinthesecondtrimesterandtovalidatethestabilitytimeofthepositivecolorofAL-SENSEstainsevenafterexposuretoverysmallofearlysecondtrimesteramnioticfluid.Theamnioticfluidwasdrawnatgeneticamniocentesisbetween18and23weeksofgestation.
ThestudywasapprovedbythelocalInstitutionalRe-viewBoard(Helsinkicommittee)andwritteninformedconsentwasobtainedfromeachpatientpriortoenrollment.
TheAL-SENSE comprisesaregularpanty-linerand iswornasanyotherhygienicpanty-liner.Insidethepanty-linertheAL-SENSEcontainsonestripof(color)indicatorthatissensitivetopHlevels. The indicatorstripreactsimmediatelytoanycontactwithamnioticfluidorothervaginaldischargeofpH5.2orgreater.ObservingachangeinthecolorofthepHindicatorin-dicateseitheraleakofamnioticfluidoraurineleak. Theindicatorswereplacedinadryingboxandobservedtodeterminethestabilityofthestain.
Duringamniocentesisperformedformedicalreasons(primarilyageover35years),between18and23weeksofgestation,0.5mlofamnioticfluid,ofthe30mlusu-allydrawn,wereusedforthisstudy.
Twovolumesofamnioticfluid,100µland400µl,weredrippedontotwoAL-SENSEpantylinersnum-bered1and2,respectively.Afterfiveminutestheindi-catorstripwasremovedfromtheAL-SENSEandthestripswereplacedinthedryingunits.
Thecolorstatuswasrecordedfrombothpanty-linersimmediately,after5and10minutes,andthenevery10minutesforthefirst30minutesandwithin1,2,6and12hoursafterremovingtheindicatorstripandplacingitinthedryingunit.
3.StatisticalAnalysis
StatisticalanalyseswereperformedusingSAS®v9.1(SASInstitute,CaryN.C.,USA).Descriptivestatisticsarepresentedinatable.Studyresultsarepresentedascountsorpercentagestogetherwitha95%exactbino-mialconfidenceintervalwhenrelevant.
4.Results
Fifty(50)womenwereenrolledinthestudy;49(98%)completedit.Onepatientwasexcludedduetoaprotocoldeviation.
ThedistributionofgestationalageispresentedinTa-ble1;mostwomenwereintheir18th-19thweekofges-tation.
Onehundredpercentofsamplesinbothvolumes(95%CI:(92.75%-100%))changedcolorfromyellowtobluewithinfiveminutesandthecolorremainedstable
Table1.Distributionofgestationalagebyweeks.| GestationalWeek | N | % | | 16 | 1 | 2.0 | | 17 | 3 | 6.1 | | 18 | 16 | 32.7 | | 19 | 21 | 42.9 | | 20 | 5 | 10.2 | | 21 | 1 | 2.0 | | 22 | 1 | 2.0 | | 23 | 1 | 2.0 | | Total | 49 | 100.0 |
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throughoutthetwelvehourfollow-upperiod.Initialin-dicatorcolorchangedidnotoccurattime0forallthesamples.Inthe100μlsubgroup7ofthe49samples,or14.3%(95%CI:(5.94%-27.24%)),hadadelayed colorchangeandinthe400μlsubgroup1of49,i.e.2.04%(95%CI:(0.05%-10.85%)),showedadelayincolorchange.
5.Discussion
InthepresentstudytheAL-Sensepanty-linerwasfoundtobeverysensitiveandchangeditscolorinresponseto averysmallamountofsecondtrimesteramnioticfluidobtainedatamniocentesis.Thecolorchangewasstablefor12hours,thetimedeterminedinadvanceasthecompletionofthestudy.Sofar,thevalidityoftheAL-Sensepantylinerhasbeenproveninclinicalstudiesindiagnosingprematureruptureofmembranesin thethirdtrimester[1-3].However,theeffectivenessofthistesthadnotbeentestedinsecondtrimesterpregnancies.
Thisstudyutilizedamnioticfluidobtainedduringamniocentesis.Therefore,theeffectivenessofthistestshouldbeverifiedinaclinicalsetting,asthecolorofthepanty-linermaychangeinreactiontovaginalsecretionswheninfectionsthatcauseelevatedpHarepresent(asstatedbythemanufacturer).Nevertheless,Mulhairetal.[3]foundthatwomenwithpositivehighvaginalswabsdidnotdiffersignificantlyandninewomenwithpositivehighvaginalswabhadanegativetest(nocolorchange).
ThehighpHlevelofamnioticfluid(7.42)evenat veryearlystagesofpregnancy[4],theabilityofthepanty-linertodetectit,eveninverysmallamounts (100µl),andthelongtermstabilityofthestainmakesita veryusefultoolindiagnosingcaseswithprematureruptureofthemembranesinthesecondtrimester.Thisperiodofpregnancymaybeassociatedwithsignificantmanagementdilemmasduetothehighpercentageoffetal,neonatalandmaternalcomplicationswithPROM atthattime[5-7].Thehighsensitivityofthistestinclinicalstudies(100%)makesitveryhelpfulinreassur-ingpatientsthatmembraneshavenotruptured.
Adrawbackofthistestisitslowspecificity;hence,whenthetestispositivethediagnosisshouldbeverifiedbyothermeans.However,inthisstudy,aswedrippedamnioticfluiddirectlyonthepanty-linerandtherewasnocontactwithvaginaldischargeorotherfluide,wedidnotincludeapositive/negativecontrol.
Anotherposs
IBLeuseofthistestisinpatientsexperi-encingpost-amniocentesisfluidleakage.Sincemostofthesecasesmaybefollowedexpectantly[8,9]thetestcanbeusedtoindicatecessationofamnioticfluidleak-age(whenapositivetestbecomenegative).
Inconclusion,thepanty-lineriseffectiveinthesec-ondtrimesterofpregnancyandcanbeusedatthat timetodetectsmallamountsofamnioticfluidleakage,andtoexcludeitspresenceiftheleakageconsistsofurine.Itisverysensitiveanddetectssmallamountsof amnioticfluiddrawnduringamniocentesis.
Asthepresentstudyhasbeenconductedinvitro,theefficacyofAL-Senseshouldbefurtherverifiedinclini-calstudiesofwomenwithfluidleakageduringthesec-ondtrimester,inthesamewayasithasbeentestedinwomenduringthethirdtrimester.
6.ConflictofInterests
HadarKesari-ShohamisemployedbythemanufactureroftheAL-SENSEpanty-liner.
REFERENCES
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