Factors that influence the development of avulsion of the levator ani muscle in eutocic deliveries: 3–4D transperineal ultrasound study

Factors(that(influence(the(development(of(avulsion(of(the(levator(ani( muscle(in(eutocic(deliveries.(364D(transperineal(ultrasound(study.( Autores: José Antonio García Mejido* Laura Gutiérrez Palomino* Carlota Borrero González* Pamela Valdivieso Mejías* Ana Fernández Palacín** José Antonio Sainz Bueno* * Department of Gynecology and Obstetrics Hospital Universitario de Valme (Seville) ** University of Seville. Author responsible: José Antonio García Mejido Dirección: Carretera de Cádiz S/N. Hospital Universitario Valme. Sevilla, España. Teléfono: (+34) 955018385 E-mail: [email protected]. Factors(that(influence(the(development(of(avulsion(of(the(levator(ani( muscle(in(eutocic(deliveries.(364D(transperineal(ultrasound(study.( ( Abstract( Introduction* Levator(ani(muscle((LAM)(lesions(are(the(most(frequent(injuries(of(the(pelvic(floor(during( delivery.( 10?36%( of( women( report( this( lesion( during( their( first( delivery.( Many( risk( factors(have(been(proposed(but(very(few(evaluate(the(aspects(that(can(influence(during( natural(vaginal(delivery.(( ( Method* A( prospective( observational( trial( was( conducted( involving( 74( primiparous( women( following(vaginal(delivery.(Maternal,(fetal(and(obstetric(characteristics(were(analyzed.(A( transperineal( three( or( four?dimensional( (3D?4D)( ultrasound( was( offered( six( months( after(delivery(in(order(to(evaluate(avulsions(and(anomalies(of(the(hiatus.(( ( ( Results* 74( women( were( included,( 3( of( them( did( not( show( up( for( ultrasound( evaluation.( 62( (87,3%)(demonstrated(no(avulsion(in(comparison(with(9((12,7%)(who(did.(5(of(these( lesions(were(unilateral(and(4(bilateral.(Mean(newborn(weight(was(3193gr(in(the((“no( avulsion(group”(versus(3470gr(in(the(“avulsion”(group((p=0,025).( ( Discussion* According(to(the(results,(the(most(important(riskfactor(established,(for(avulsion(during( natural( childbirth,( was( the( newborn( weight.( This( contrasts( with( many( other( authors( who(have(established(that(birth(weight(has(no(impact(on(these(lesions.(( ( Conclusions* The(most(important(factor(intervening(in(the(avulsion(of(LAM(during(natural(vaginal( delivery(is(the(newborn(weight.(Patients(with(diagnosed(avulsions(present(an(enlarged( urogenital(hiatus(during(valsalva(and(maximal(contraction.(( ( Key(words:(Eutocic(delivery,(avulsion,(childbirth,(levator(ani(muscle.(( Introduction( ( Vaginal'delivery'is'an'important'factor'related'to'lesions,'muscular'or'ligamentous,'in' the' pelvic' floor.' These' lesions' could' contribute' in' the' development' of' urinary' incontinence' and' pelvic' organ' prolapse1.' LAM’s' avulsion' is' the' most' frequent' muscular' injury' found' after' vaginal' delivery.' Avulsion' is' defined' as' a' discontinuity' between' puborectalis' muscle' and' the' inferior' pubic' rami' as' consequence' of' its' maximum'stretch'during'the'2nd'stage'of'labor2,'3.' Currently,'the'diagnosis'of'LAM'avulsion'is'based'on'3D/4D'ultrasound'assessment'or' MRI2,'4,'5.' It'has'been'established'that'10M36%'of'primiparous'women'will'present'LAM'trauma' during'delivery6,'7.'Multiple'risk'factors'have'been'related8.'The'objective'of'this'study' is'to' assess'the' most'relevant' risk' factors'related' to'LAM' lesions'in'natural' vaginal' delivery.'' '' Method( ( A'prospective' observational'study'was' conducted'involving' 74'primiparous'women' with' natural' vaginal' delivery' at' term' (37M42' gestational' weeks)' between' October' 2013'and'January'2014'at'Hospital'Universitario'Virgen'de'Valme'–'Seville.'' ' None'of'the'patients'had'history'of'pelvic'floor'surgical'interventions.'The'totally'of' deliveries' initiated' spontaneously,' terminated' in' vaginal' natural' delivery' and' were' conducted'by'proven'experienced'midwives.'All'women'who'request'analgesia'were' provided' with' epidural' anesthesia' (6ml' 0,2%' ropivacaine' bolus' and' 0,125%' ropivacaine' plus' fentanyl' 1mcg/ml' for' maintenance' at' 12ml/h).' The' delivery' was' assisted'in'a'dorsal'lithotomy'position.'Episiotomy'was'used'in'a'restrictive'fashion' when' maximum' perineum' distention' was' reached.' All' the' patients' included' were' required'to'sign'an'informed'consent.'Pregnancies'with'maternalMfetal'pathology'were' excluded.'' ' The' obstetric' parameters' included' were:' maternal' age,' gestational' age' at' delivery,' body'mass'index,'weight'gain'during'pregnancy,'type'of'analgesia,'time'for'epidural' anesthesia,' length' of' second' stage' of' labor,' perineum' tears,' episiotomy,' fetal' head' circumference'and'fetal'weight.'' ' Ultrasound'study'was'achieved'6'months'post'delivery'using'a'Toshiba'Aplio'500®' (Toshiba'Medical'Systems'Corp.,'Tokyo,'Japan)'with'3D'abdominal'PVTM675MV'(90º' angle).' An' experienced' explorer,' who' had' no' knowledge' of' the' deliveries' characteristics,'performed'the'ultrasound'evaluation.'Images'were'obtained'while'in' dorsal'lithotomy'and'empty'bladder9,10.'Ultrasound'analysis''assessed'the'pelvic'floor' at'rest,'during'valsalva'and'at'maximal'contraction.'' ' Avulsion'injury'was'defined'as'the'abnormal'insertion'of'LAM,'which'was'identified' using' a' minimal' dimension' axial' plane'(MDP)' with' double' 2,5mm' slice' interval' above11'(image'1).'The'urogenital'hiatus'area'was'calculated'according'to'MDP'during' rest,'valsalva'and'maximal'pelvic'floor'contraction12.' ' Quantitative' variables' were' resumed' evaluating' means,' standard' deviations' and' qualitative'variables'with'percentages.'T'student'and'U'MannMWhitney'test'(ShapiroM Wilk' test)' were' used' to' evaluate' independent' samples' and' samples' with' asymmetrical'distribution'respectively.'' Qualitative' variables' were' evaluated' by' contingency' tables,' ChiMsquare' test' and' not' asymptotic'methods'as'Monte'Carlo'and'Exact'test.'Statistical'analysis'was'performed' using'IBM'SPSS'22'program.' ' Results( 74' women' were' studied.' 3' were' excluded' because' of' absenteeism' to' ultrasound' evaluation.'62'cases'(87,3%)'did'not'show'avulsion.'9'cases'(12,7%)'revealed'avulsion,' 5'of'these'were'unilateral'and'4'bilateral.'' ' Table(1(demonstrates' the' different' obstetric' parameters' evaluated' according' to' the' presence'or'not'of'avulsion.'No'significant'differences'were'found'between'groups.'' Table(2'collects' data' related' to' the' studied' patients.'Neonatal' weight' was' the' only' parameter'that'demonstrated'statistically'significant'difference'comparing'deliveries' with'or'without'avulsion.'Mean'newborn'weight'was'3193gr'in'the'no'avulsion'group' in' contrast' to' 3470gr' found' in' the' avulsion' group.' Our' data' shows' that' cases' with' avulsion' presented' an' enlarged' 2nd' stage' of' labor' (>110' minutes),' although,' no' significant'differences'have'been'able'to'establish'this'as'a'risk'factor'for'pubovisceral' muscle'lesions.'' Table( 3'contrasts' “avulsion' group”' versus' “no'avulsion' group”' according' to' the' urogenital'hiatus'area.'The'avulsion'group'showed'an'increased'urogenital'hiatus'area' and'anteroMposterior'and'lateroMlateral'distance'compared'to'the'no'avulsion'group.' Such'differences'emphasize'during'valsalva'or'maximal'pelvic'floor'contraction.'' ' Discussion( ( Avulsion' of' the' levator' ani' muscle' entails' several' future' dysfunctions' of' the' pelvic' floor' in' women.' 1,'13,'14' Nowadays,' no' screening' method' has' been' proved' to' predict' these'lesions.15'Knowledge'of'the'associated'risk'factors'could'help'to'prevent'LAM' injury.' Forceps' delivery' is' the' most' important' risk' factor' related' to' avulsion.' Using' transperineal' ultrasound,' injuries' have' been' demonstrated' in' 35M64%' of' these' cases8,16,'17,'18,'19.'' 'Among' other' risk' factors,' there' is' evidence' that' an' enlarged' second' stage' of' labor' over' 110' minutes' associates' an' OR' of' 2,27' for' LAM' injuries8,' 17,20.' Fetal' head' circumference' appears' to' be' an' independent' risk' factor.8,' 14' Circumferences' over' 35,5cm'reveals'OR'of'3,34'for'LAM'avulsions8.'Nevertheless,'other'authors'have'not' proved'such' association21.'According'to' our'results,'this' relationship'have' not'been' proven'either.'' Although'several'risk'factors'for'avulsion'have'been'described,'protective'factors,'as' epidural' anesthesia,' have' also' been' proposed17.' This' last' association' has' not' been' proven'by'our'results'either14.'' Other'factors,'such'as'maternal'age'and'body'mass'index'(BMI),'have'been'proposed' to'be'associated'with'LAM'injuries'although'there'is'not'enough'evidence'to'confirm' this.'Several'authors'have'established'that'advanced'maternal'age'is'associated'with' an'increased'risk'of'LAM'injuries'during'their'first'vaginal'delivery21,'24.'Other'authors' have' not' proved' such' relationship13,' 15,' 20.' In' contrast,' it' has' been' proposed' that' women' with' low' BMI' are' less' exposed' to' LAM' injuries,' although' this' has' not' been' proven8.'Our'results'were'not'able'to'demonstrate'these'associations.'' According' to' this' trial,' the' most' important' risk' factor' associated' with' avulsions,' during'vaginal'delivery,'is'estimated'fetal'weight14.'This'fact'does'not'agree'with'other' authors'who'reject'this'relationship13,'17,'25,'26.' Pubovisceral' muscle' injuries' showed' an' increased' urogenital' hiatus' area' at' rest,' valsalva'and'maximal'contraction.'The'increased'area'of'the'hiatus'has'been'described' previously'and'has'demonstrated'an'envidence'level'II14,'19,26M28.' Finally,' this' trial' determines' that' the' most' important' factor' associated' with' LAM' injuries'during'vaginal'delivery'is'the'estimated'fetal'weight'and,'in'case'of'avulsion,' hiatus'area'is'increased'at'rest,'valsalva'and'maximal'contraction.'' ' ' Bibliography( ' 1. Kearney R, Sawhney R, DeLancey JO. Levator ani muscle anatomy evaluated by origin-insertion pairs. Obstet Gynecol. 2004;104(1):168–73. 2. Halban J, Tandler J. Anatomie und aetiologie der genitalprolapse beim weibe. Vienna and Leipzig: Wilhelm Braumuller; 1097. 3. Richardson AC, Lyon JB, Williams NL. A new look at pelvic relaxation. Am J Obstet Gynecol 1976; 126(5): 568-573. 4. Sultan AH, Kamm MA, Hudson CN, Thomas JM, Bartram CI. 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No'statistical'significance'(NS).'Statistical'significance'(*)' ' ' Table(2.'Data'related'to'delivery'according'to'Avulsion.'' ' ! Mean((±TD)(o(%! p! ! Without( Avulsion( (n=62)! (((((((Avulsion( (n=9)! Epidural'analgesia! 54'(87.1%)! 6'(66.7%)! NS! Time'of'epidural'anesthesia' (minutes)! 341.74' (±153.97)! 435.83' (±199.58)! NS! Length'2nd'stage'of'labor' (minutes)! 92.18'(±65.39)! 121.67' (±64.66)! NS! Episiotomy! 23'(37.1%)! 3'(33.3%)! NS! Perineal'tears'(PT)! 30'(48.4%)! 7'(77.8%)! NS! '''''PT'I'grade! 14'(46.7%)! 3'(42.9%)! NS! '''''PT'II'grade! 13'(43.3%)! 3'(42.9%)! NS! '''''PT'III'grade! 3'(10%)! 1'(14.3%)! NS! Head'Circumference'(cm)! 34.29(±1.31)! 34.33(±1.03)! NS! Neonatal'weight'(g)! 3193.47' (±343.62)! 3470.56' (±289.82)! 0.025*! No'statistical'significance'(NS).'Statistical'significance'(*)' Table 3. Urogenital hiatus area according to avulsion. ! Mean((±TD)(! p! ! Without( Avulsion( (n=62)! (((((((Avulsion( (n=9)! Urogenital(hiatus(area((cm2)( ! Rest! 16.24'(±2.93)! 18.23'(±4.24)! NS! Valsalva! 18.51'(±3.94)! 23.16'(±5.24)! 0.002*! Maximum'contraction! 15.47'(±3.08)! 19.05'(±4.62)! 0.003*! No'statistical'significance'(NS).'Statistical'significance'(*)' ' Image 1: LAM'injuries'identified'in'the'three'central'slices'of'multislice'ultrasound' study.' '