Intrapartum translabial ultrasound with pushing used to predict the difficulty in vacuum-assisted delivery of fetuses in non-occiput posterior position

Depósi o de in es igación de la Uni e sidad de Se illa h ps://idus.us.es/ Es a es la e sión acep ada del a ículo publicado en: This is a accep ed manusc ip o a pape published in: The Jou nal o Ma e nal-Fe al & Neona al Medicine (2016) DOI: 10.3109/14767058.2015.1130816 Copy igh : El acceso a la e sión publicada del a ículo puede eque i la susc ipción de la e is a. Access o he published e sion may equi e subsc ip ion. “This is an Accep ed Manusc ip o an a icle published by Taylo & F ancis in [The Jou nal o Ma e nal-Fe al & Neona al Medicine] on [2016], a ailable a : h ps://doi.o g/[10.3109/14767058.2015.1130816].” The Jou nal o Ma e nal-Fe al & Neona al Medicine In apa um anslabial ul asound wi h pushing used o p edic he di icul y in acuum-assis ed deli e y o e uses in non-occipu pos e io posi ion José An onio Sainz, Ca lo a Bo e o, Ad iana Aquise, José An onio Ga cía- Mejido, Lau a Gu ie ez & Ana Fe nández-Palacín To ci e his a icle: José An onio Sainz, Ca lo a Bo e o, Ad iana Aquise, José An onio Ga cía- Mejido, Lau a Gu ie ez & Ana Fe nández-Palacín (2016) In apa um anslabial ul asound wi h pushing used o p edic he di icul y in acuum-assis ed deli e y o e uses in non- occipu pos e io posi ion, The Jou nal o Ma e nal-Fe al & Neona al Medicine, 29:20, 3400-3405, DOI: 10.3109/14767058.2015.1130816 ORIGINAL ARTICLE In apa um anslabial ul asound wi h pushing used o p edic he di icul y in acuum-assis ed deli e y o e uses in non-occipu pos e io posi ion Jose´ An onio Sainz1,2, Ca lo a Bo e o1, Ad iana Aquise1, Jose´ An onio Ga c´ıa-Mejido1, Lau a Gu ie ez1, and Ana Fe na´ndez-Palac´ın3 1 Depa men o Obs e ics and Gynecology, Valme Uni e si y Hospi al, Se ille, Spain, 2 Depa men o Obs e ics and Gynecology, Uni e si y o Se ille, Spain, and 3 Bios a is ics Uni , Depa men o P e en i e Medicine and Public Heal h, Uni e si y o Se ille, Spain Keywo ds In apa um ul asound, labo , pushing, anspe ineal ul asound, acuum deli e y Abs ac Objec i e: Ou aim is o e alua e he capaci y o in apa um anslabial ul asound (ITU) wi h pushing in he p edic ion o di icul y o e al ex ac ion in acuum assis ed deli e ies. P ospec i e, obse a ional s udy pe o med (2/2015–8/2015) on 75 nullipa ous women, ≥37 weeks wi h single on p egnancies a ull dila a ion who had ITU-wi h-pushing pe o med, p e ious o acuum-placemen o e al ex ac ion. Wo king on he anslabial sagi al-plane, we assessed: Angle-P og ession (AoP), P og ession-Dis ance (PD) and Head-Di ec ion (HD); in he axial plane we e alua ed: Midline-Angle (MLA) and Head-Pe ineum-Dis ance (HPD). Vacuum ex ac ions we e classi ied as easy-di icul y (ED) (≤3 acuum-pulls), di icul -unsuccess ul (DD) (43 acuum-pulls). We did no assess occipi o-pos e io -p esen a ions. Resul s: Se en y nullipa ous we e s udied (44-ED,26-DD). We obse ed no di e ences in obs e ic, neona al o in apa um cha ac e is ics be ween he wo s udy g oups, wi h he ollowing excep ions: newbo n weigh (3272 ± 438 g e sus 3540 ± 372 g; p ¼ 0.011) and numbe o acuum-pulls (1.4-ED- s-4.4-DD; p50.0005). AoP-pushing was 143.9◦ ± 14.6◦ in ED and 115.1 ◦ ± 12.9 ◦ in DD (p 5 0.0005); Head-Up was 79.5% e sus 38.4% (p 5 0.0005); PD-Pushing was 42.7 ± 11.3 mm e sus 30.4 ± 9.8 mm (p50.0005); MLA-Pushing was 27.6◦± 26.6◦ e sus 57.5◦±26.5◦(p¼0.025); HPD-Pushing was 40.8 ± 10.0 mm e sus 47.4 ± 10.9 mm (p ¼ 0.039). Conclusion: We iden i ied ha he p esence o an AoP-Pushing4128◦ p edic s an Easy-Vacuum- Deli e y (≤3 Vacuum-Pulls) in 485% o cases (Sen 80%–FPR 9.3%). In oduc ion Digi al examina ion is subjec i e and un eliable in he e alua ion o he deg ee o engagemen and posi ion o he e al head du ing labo [1]. In apa um anslabial ul asound (ITU) has p o ed o be an objec i e ool o p edic he ype o deli e y ha will ake place when used in second s age o labo . ITU has also begun o be used wi h he aim o p edic ing he di icul y o ins umen a ion in e al ex ac ion, since ins umen al deli e ies a e associa ed wi h an inc ease in ma e nal and neona al mo bidi y [2–9]. Achie ing a success ul ins umen a ion will esul in a educ ion o his inc eased mo bidi y (subdu al o ce eb al hemo hage, con- ulsions, mechanical en ila ion) [10–12]. Ou g oup [13] assessed he capaci y o ITU in he p edic ion o di icul y o e al ex ac ion in acuum assis ed deli e ies. I p e ious o acuum placemen , an angle o p og ession ≤120◦, a ho izon al o downwa ds head di ec ion, and a midline angle ≥35◦ was iden i ied, he p obabili y o a ‘‘di icul ’’ deli e y, hus mo e han 3 pulls needed o achie e e al ex ac ion, is o 85% [13]. Now, we aim o e alua e his ITU’s p edic i e capaci y o ins umen a ion di icul y wi h acuum, in he expulsion s age wi h pushing (angle o p og ession, p og ession dis ance, head di ec ion, midline angle and head pe ineum dis ance). Ma e ial and me hod P ospec i e, obse a ional s udy was ca ied ou be ween Feb ua y 2015 and Augus 2015, a Valme’s Uni e sis y Hospi al in Se ille, on 75 p egnan women a e m, admi ed o ou deli e y uni du ing second s age o labo , and who equi ed ins umen a ion o comple e e al ex ac ion. Th oughou hese 7 mon hs (Feb ua y–Augus 2015) a Valme’s Hospi al we ha e had a o al o 2625 deli e ies, wi h a win a e o 1.8% (47 cases), a cesa ean sec ion a e o 20.1% (527 cases) and a 15.1% o ins umen al deli e ies (398 cases, 320 acuum-assis ed deli e ies (80.4%) and 78 o ceps-assis ed deli e ies (19.5%)). All 75 pa ien s sha ed he ollowing cha ac e is ics: low isk, a e m single on p egnancy (37–42), in nullipa ous, du ing ac i e second s age o labo , wi h up u ed memb anes and e us in cephalic p esen a ion and including bo h spon- aneous and induced ini ia ion o labo cases. P egnancies in ol ing se ious ma e nal o e al pa hology we e excluded om he s udy. A acuum was used o e al ex ac ion, al hough deli e y could ha e been comple ed ei he aginally o abdominally (cesa ean sec ion). P io o ins umen al deli e y, once in ac i e second s age o labo , up u ed memb anes and ull dila a ion, ITU was used o pe o m an e alua ion o e al head posi ion [14]. The ITU was pe o med wi h he p egnan woman in li ho omy posi ion and unde emp y bladde condi ions. Cap u e was ob ained by placing he ansduce wi h a anslabial insona ion a a anspe ineal le el. Since he pubic symphisis would be used as he e e ence longi u- dinal axis, we ensu ed i s whole leng h was included in he cap u e. Angle o p og ession (AoP) was used as he angle be ween he longi udinal axis o he pubic symphysis and he angen line o e al skull’s con ou [15]. Pubis middle line can be iden i ied by he p esence o he ib o- ca ilaginous disk and capsule [16] (Figu e 1); p og ession dis ance (PD) – as he dis ance (mm) be ween he in apubic symphisis and he lowes edge o e al skull [17] (Figu e 2); and Head Di ec ion (HD) – as he angle esul ing om he union o a pe pendicula line o pubic’s bone majo axis and a pe pendicula line o e al’s head wides ans e se diame e ; angles ≥30◦ co espond o ‘‘upwa d’’ di ec ions, ≤0◦ co espond o ‘‘downwa d’’ di ec ions, and angles be ween 0◦ and 30◦ co espond o ho izon al di ec ions [18]; we e he sonog aphic pa ame e s e alua ed, which we e measu ed bo h in es and wi h pushing du ing ma e nal con ac ion. We hen u ned ou ansduce o swi ch om he midsagi al o an axial plane, allowing us o iden i y e al’s b ain midline. We used his iew o e alua e he midline angle (MLA; de ined as he angle be ween he an e opos e io axis o he pel is and he e al’s b ain midline) [19], bo h a es and wi h pushing. To assess hese pa ame e s, we used a Toshiba Famio 8 (Tokyo, Japan) ul asound machine wi h a 3.75 MHz con ex p obe. In apa um ul asound e alua ion was ca ied ou by wo senio obs e icians, wi h mo e han 5 yea s o expe ience in obs e ic ul asonog aphy. Once his in apa um ul asound assessmen was com- ple ed, e al ex ac ion was pe o med by o he wo senio obs e icians, wi h mo e han 15 yea s o expe ience in ope a i e deli e ies. In all cases, a me al acuum (Bi d’s cup 50 mm, 80 KPa) was used o inalize aginal deli e y, wi hou aking in o accoun he p e iously eco ded ul asound da a obs e icians pe o ming e al ex ac ion had no in o ma ion abou ITU esul s p e iously eco ded. In all cases, a me al acuum (Bi d’s cup 50 mm, 80 KPa) was used o inalize aginal deli e y, wi hou aking in o accoun he p e iously eco ded ul asound da a as obs e icians pe o ming e al ex ac ion had no in o ma ion abou ITU esul s p e iously eco ded. Placemen o he suc ion cup o e he lexion poin was conside ed a oiding capu succedaneum and apid nega i e p essu e (o e 2 minu es) applica ion o he acuum (un il 0.6–0.8 kg/cm2). Vacuum ac ion is pe o med in he momen o con ac ion along wi h ma e nal push, a a a e o 2–3 acuum ac ions pe con ac ion and wi hou associa ing K is elle maneu e [20,21]. The p ocedu e was abandoned a e 3 cup slides o 15 minu es wi hou achie ing e al ex ac ion [22]. Acco ding o he numbe o acuum pulls needed o comple e he deli e y, ins umen a ion was classi ied as ‘‘easy’’ (3 o less pulls), di icul (mo e 3 pulls) o impossible ( aginal e al ex ac ion was no achie ed and a cesa ean sec ion had o be pe o med) [18,23]. All cases o occipi o- pos e io posi ion we e excluded om ou e alua ion. The s udy was app o ed by local e hics and esea ch commi ees, and all pa icipan s we e p e iously asked o sign an in o med consen . A e deli e y, bo h ma e nal and neona al mo bidi y and mo ali y da a we e collec ed. P esence o pe ineal ea s, u e ine a ony, bleeding deg ee and need o pos pa um su ge y we e he ma e nal pa ame e s eco ded. New bo n da a egis e ed we e: e al weigh , Apga es esul (a 1 and 5 min), e al pH a bi h, p esence o neona al mo bidi y (cephalohaema oma, b achial plexus palsy, e c.), admission o neona alogy and neona al mo ali y. S a is ical analysis was pe o med using IBM SPSS S a is ics so wa e e sion 22 (A monk, NY). We de e mined means and s anda d de ia ion o nume ic a iables, and pe cen ages o quali a i e a iables. Compa isons o nume ic a iables be ween ins umen a ion di icul y g oups (easy, di icul and impossible) we e ca ied ou using S uden ’s - es . The compa isons o he quali a i e a iables be ween he g oups we e ca ied ou using he Chi- squa e es . We de e mined a eas unde he ROC cu es o he ul asound a iables s udied and hei 95% con idence in e als, and we iden i ied he cu o poin s ha p edic ed an a leas 85% chance o easy deli e y. Figu e 1. (A) Angle o P og ession a es . (B) Angle o P og ession wi h pushing. Figu e 2. (A) P og ession dis ance a es . (B) P og ession dis ance wi h pushing. Resul s We analyzed 75 p egnan women in labo wi hou p e ious his o y o aginal deli e y. 5 cases we e excluded om he analysis: 2 due o occipi o pos e io e al posi ion iden i ied in he in apa um ul asound e alua ion, 2 due o e al ex ac ion using a di e en ins umen o he han acuum ex ac o and 1 case because o incomple e ul asound da a collec ion. Table 1 displays bo h ma e nal and labo cha ac e is ics, and neona al esul s o ou s udy popula ion (70 p egnan women), di ided acco ding o ins umen a ion di icul y (easy, di icul -impossible ins umen a ion). All pa ien s had epidu al analgesia adminis e ed and e al ex ac ion was comple ed by acuum-assis ed deli e y. Two new-bo ns we e admi ed o Neona ology uni : he i s one due o jaundice, ecei ing 48 h o ligh he apy, while he second one p esen ed mild espi a o y dis ess, and was discha ged in he i s 24 h. Fi e cases o ailed acuum-assis ed deli e y a e included in he ‘‘di icul -impossible ins u- men a ion’’ g oup, equi ing c-sec ion o comple e e al ex ac ion. A e age ma e nal age o his g oup was 29.1 ± 6.5 yea s, wi h a mean ges a ional age o 39.2 ± 1.5 weeks, 4.6 ± 1.4 acuum pulls and a mean bi h weigh o 3620 ± 390 g ams. No cases o neona al mo bidi y we e egis e ed in his g oup. In apa um ul asound pa ame e s a e displayed in Table 2, desc ibing gene al and indi idual s udy g oup (easy and di icul -impossible ins umen a ion) esul s. In Figu es 3 and 4, we display he ROC cu es o he angle o p og ession and p og ession dis ance wi h pushing, in o de o p edic he di icul y o aginal deli e y wi h acuum. The pa ame e s used in p edic ing he di icul y o ope a i e deli e y wi h acuum using ITU, bo h a es and wi h pushing, we e: angle o p og ession 120.5◦ and 128◦, p og ession dis ance 35.5 mm and 37.5 mm and midline angle 43◦ and 28◦ espec i ely (Table 3). Table 1. Ma e nal and neona al cha ac e is ics in 70 p egnancies equi ing acuum deli e y. Easy acuum Di icul -Impossible acuum deli e y To al (n ¼ 70) deli e y (n ¼ 44) (n ¼ 26) p Ma e nal age (yea s) 29.7 ± 5.9 29.7 ± 6.6 29.6 ± 5.0 0.9 Ma e nal BMI (kg/m2) 25.07 ± 5.0 25.03 ± 4.4 25.35 ± 8.0 0.8 Ma e nal smoking (≥1 ciga e e/day) 3 (4.2%) 2 (4.5%) 1 (3.8%) 0.64 Ges a ional pa hology 9 (12.9%) 6 (13.6%) 3 (11.5%) 0.8 Ges a ional age a bi h (weeks) 39.4 ± 1.4 39.2 ± 1.5 39.8 ± 1.4 0.1 Numbe o induced labo s 17 (24.6%) 8 (18.6%) 9 (34.6%) 0.16 Es ima ed e al weigh (g) 3386.4 ± 364.2 3251.1 ± 351.0 3563.0 ± 305.8 0.001 Cause o ins umen a ion 0.9 P olonged second s age 55 (78.6%) 34 (77.4%) 20 (77.0% Ma e nal exhaus ion 6 (8.5%) 4 (9.0%) 3 (11.5%) Fe al dis ess 9 (12.8%) 6 (13.6%) 3 (11.5%) Du a ion o 1s s age o labo (hou s) 7.8 ± 3.2 7.4 ± 3.2 8.4 ± 3.1 0.18 Du a ion o 2nd s age o labo (hou s) 2.3 ± 0.7 2.2 ± 0.7 2.4 ± 0.7 0.07 Numbe C-sec ions o comple e deli e y 5 (7.1%) 0 (0%) 5 (19.2%) 0.005 Numbe o acuum pulls 2.4 ± 1.6 1.4 ± 0.5 4.4 ± 1.1 50.0005 Ma e nal mo bidi y 1 (1.4%) 0 (0%) 1 (3.8%) 1 U e ine a ony 1 (1.4%) 0 (0%) 1 (3.8%) 1 O he s 0 (0%) 0 (0%) 0 (0%) Sex o newbo n ( emales) 34 (48.5%) 21 (47.7%) 13 (50%) 0.9 Newbo n Weigh (g) 3372 ± 432 3272 ± 438 3540 ± 372 0.011 APGAR 1 minu e 8.8 ± 1.0 8.9 ± 1.0 8.5 ± 1.1 0.07 APGAR 5 minu es 9.9 ± 0.2 10 ± 0 9.9 ± 0.4 0.06 Umbilical co d a e y pH 7.25 ± 0.7 7.26 ± 0.6 7.23 ± 0.5 0.525 Pe ina al mo ali y 0 (0%) 0 (0%) 0 (0%) – Pe ina al mo bili y 2 (2.9%) 0 (0%) 2 (7.7%) 0.135 Con ol o he in ensi e ca e neona ology uni 2 (2.9%) 0 (0%) 2 (7.7%) 0.135 O he s 0 (0%) 0 (0%) 0 (0%) Table 2. In apa um anspe ineal ul asound da a in 70 p egnancies equi ing acuum deli e y. Va iable To al (n ¼ 70) Easy acuum deli e y (n ¼ 44) Di icul -Impossible acuum deli e y (n ¼ 26) p Angle o P og ession a es (◦) 123.8 ± 16.5 132.5 ± 11.6 109.2 ± 12.7 0.0005 ≥120◦ 55.7% (39) 84% (37) 7.6% (2) 0.0005 5120 ◦ 44.3% (31) 15.9% (7) 92.3% (24) 0.0005 Angle o P og ession wi h pushing (◦) 133.5 ± 19.7 143.9 ± 14.6 115.1 ± 12.9 0.0005 ≥120◦ 72.5% (50) 95.4% (42) 30.7% (8) 0.0005 5120 ◦ 27.5% (19) 4.6% (2) 65.3% (17) 0.0005 Head di ec ion a es Up 62.8% (44) 81.3% (35) 34.6% (9) 0.0005 Ho izon al-down 36.2% (25) 18.7% (8) 65.3% (17) 0.0005 Head di ec ion wi h pushing Up 45 (66.2%) 83.3% (35) 38.4% (10) 0.0005 Ho izon al-down 23 (33.8%) 16.7% (7) 61.5% (16) 0.0005 P og ession dis ance a es (mm) 34.3 ± 16.4 36.9 ± 12.3 30.0 ± 21.1 0.002 P og ession dis ance wi h pushing (mm) 38.2 ± 12.3 42.7 ± 11.3 30.4 ± 9.8 0.0005 Midline angle a es (◦) 45.6 ± 26.8 37.6 ± 24.6 57 ± 26.3 0.0001 ≤45◦ 59.1% (39) 71.4% (30) 34.6% (9) 0.0005 445 ◦ 40.9% (27) 28.6% (112) 55.6% (15) 0.0005 Midline angle wi h pushing (◦) 37.2 ± 26.7 27.6 ± 26.6 57.5 ± 26.5 0.025 ≤45◦ 66.7% (37) 73% (27) 34.6% (9) 0.34 445 ◦ 33.3% (23) 26% (9) 63.4% (17) 0.34 Numbe o acuum pulls 2.4 ± 1.6 1.4 ± 0.5 4.4 ± 1.1 0.0005 Figu e 3.Angle o P og ession ROC cu e o p edic he di icul y o aginal deli e y wi h acuum ex ac ion. Figu e 4.The p og ession dis ance ROC cu e o p edic he di icul y o aginal deli e y wi h acuum ex ac ion. Table 3. P edic i e abili y o he di icul y o ins umen al deli e y wi h acuum using in apa um anspe ineal ul asound a es and wi h pushing. ITU a es Cu o s Sensi i i y (%) False-posi i e a e (%) ITU wi h pushing Cu o s Sensi i i y (%) False-posi i e a e (%) AoP 120.5◦ 92.3 11.6 AoP 128◦ 84 9.3 P og ession dis ance 35.5 mm 84.6 39.5 P og ession dis ance 37.5 mm 76.9 32.6 Midline angle 43◦ 70.8 31.7 Midline angle 28◦ 91.7 33.3 Discussion Using ‘‘ma e nal push’’ be o e an ins umen al-assis ed deli e y is a usual p ac ice ca ied ou by obs e icians in o de o de e mine he le el o he e al p esen a ion (ACOG e al s a ion) and i s deg ee o engagemen [24]. Dupuis e al. [1] epo s ha , when aginal examina ion was ca ied ou , we o en ail in he co ec e alua ion o hese pa ame e s. Fo his eason, in apa um anspe ineal ul a- sound has been in oduced as an a emp o imp o e he assessmen o he deli e y p og ession [24]. The Food and D ug Adminis a ion (FDA) wa ned o he use o acuum and po en ial e al complica ions, such as in ac anial hema oma and subgaleal hemo hage [25]. Popula ion s udies la e epo ed ha in ac anial hemo hage occu ed in one pe : 1900 spon aneous aginal bi hs, 860 ope a i e deli e ies wi h acuum, 664 ope a i e deli e ies wi h o ceps and 333 cesa ean sec ions a e a ailed ins umen al deli e y [9]. Fu he mo e, an inc ease in ma e - nal mo bidi y is desc ibed in ope a i e deli e ies when compa ed wi h spon aneous ones, exis ing a signi ican associa ion be ween an inc ease in III and IV deg ee ea s in acuum and o ceps assis ed deli e ies [2]. Cu en ly we can use ITU o e alua e he p og ession o he second s age o labo , as well as p edic he ype o deli e y ha will ake place (spon aneous, ins umen al o cesa ean). Ba be a e al. [15] and Kalache e al. [25] epo ha an angle o p og ession ≥120◦ is associa ed wi h spon aneous aginal deli e y in 90% o cases. Ghi e al. [19] and To kildsen e al. [26] desc ibe ha an upwa ds di ec ion o he head, accompanied by an angle o o a ion545◦ and a pe ineum-head dis ance ≤40 mm p edic s spon aneous aginal deli e y in 90% o cases. Yousse e al in 2012 in oduced he e alua ion o he e al head-symphysis dis ance in he second s age o Labo , desc ibing he ease o i s assessmen and i s use ulness o p edic he mode o deli e y [27]. Ghi e al. epo ha in spon aneous aginal bi h cases, he angle o p og ession, p og ession dis ance and head–symphysis dis ance show a signi ican imp o emen when e alua ed in he second s age o labo , p edic ing an adequa e deli e y e olu ion [28,29]. In he app aisal o ITU’s capaci y o p edic di icul y o e al ex ac ion in an ope a i e deli e y wi h acuum, we iden i ied ha , i p e ious o acuum placemen , an angle o p og ession ≤120◦, a ho izon al o downwa ds head di ec ion, and a midline angle ≥35◦ was iden i ied, he p obabili y o a ‘‘di icul ’’ deli e y, hus mo e han 3 pulls needed o achie e e al ex ac ion, is o 85% [13]. In an a emp o imp o e ITU’s p edic i e capaci y, we e alua ed hese sonog aphic pa ame e s (angle o p og ession, p og ession dis ance, head di ec ion, midline angle and head-pe ineum dis ance) wi h pushing, obse ing an adequa e in a- (0.99–0.98) and in e - (0.93–0.77) obse e co ela ion [30], enabling i o be applied o clinical p ac ice. Rega ding his, Hen ich e al. [18] e alua ed ITU wi h pushing, obse ing ha all ‘‘di icul ’’ cases in his se ies (5 cases) had a ho izon al o downwa ds head di ec ion and 60% (3/5 cases) exceeded he in apubic line. Simila ly, Lau e al. [31] desc ibed how hose cases which ended in aginal ope a i e deli e y wi h acuum p esen ed highe p og ession angles, han hose which equi ed cesa ean sec ion o comple e e al ex ac ion. Fu he mo e, Cue a e al. [20] compa ed ITU’s pa ame e s a es and wi h pushing o p edic he di icul y in o ceps-assis ed deli e ies, obse ing ha he bes sonog aphic p edic o s a e angle o p og ession and head di ec ion, bo h wi h pushing, and concluding ha an angle o p og ession4138◦ wi h pushing is a eliable indica o o easy aginal deli e y wi h o ceps. Compa ing ITU’s pa ame e s o he p edic ion o easy deli e y wi h acuum, we obse ed ha hese a y i ealized in es and wi h pushing: angle o p og ession and midline angle a y by a mean o 10◦, p og ession dis ance by 6 mm and head- pe ineum dis ance by 2 mm. Howe e , only he angle o p og ession, head di ec ion and p og ession dis ance, all h ee o hem e alua ed wi h pushing, ha e p o ed o be adequa e p edic o s o he di icul y o e al ex ac ion wi h acuum (P50.0005), unlike midline angle and head-pe i- neum dis ance, ha do no me he c i e ia o be conside ed eliable indica o s. I , as men ioned p e iously, an angle o p og ession4120◦, an upwa ds head di ec ion and a midline angle535◦ we e iden i ied in an ITU e alua ion pe o med a es be o e acuum applica ion, he p obabili y o acing an easy acuum deli e y (≤ 3 pulls) was485% [13]. As main s eng hs o ou s udy, a p ospec i e analysis has been highligh ed, he ac ha in apa um ul asound assess- men was pe o med by wo senio obs e icians wi h g ea expe ience in sonog aphic e alua ion, and ha deli e ies we e assis ed by obs e icians who we e blinded o da a collec ed in he in apa um ul asound e alua ion pe o med p io o he ins umen a ion wi h acuum. Fu he mo e, we can now s a e ha he sole iden i ica ion o an angle o p og ession wi h pushing4128◦ aduces a p obabili y o 485% o easy acuum deli e y, wi h a alse posi i e a e o 9.3%. No e ha by using his 128◦ as he cu o o he angle o p og ession wi h pushing o iden i y cases o di icul ins umen a ion wi h acuum, we s ill ha e a 16% o cases in which despi e we p edic a ‘‘di icul ’’ ins umen a ion (5128◦) we will end up acing an ‘‘easy’’ deli e y. Once again, we p o e ha aginal examina ion ails o iden i y he deg ee o cephalic engagemen , acco ding o Dupuis e al. [1] o 15.9% when ca ied ou by expe ienced obs e icians. In ou s udy we obse ed ha he cases o di icul acuum deli e ies had a mean AoP a es o 109◦, which acco ding Tu chek e al. s udies [32] co espond o a head s a ion o 0.5–1 cm and whe e ope a i e deli e ies should no be pe o med. Recen ly, we ha e published ha he p esence o an AoP wi h pushing less han 100◦ is a e y un a o able si ua ion o a emp a aginal deli e y [33]. This obse a ion ein o ces he u ili y anspe ineal in apa um could ha e in deli e y assis ance, especially in hose cases whe e we suspec a di icul ins umen a ion may be equi ed. We conside he small numbe o cases in ou se ies as a limi a ion o he esul s o ou s udy, and belie e i is necessa y o ca y ou u he s udies o ce i y he u ili y o ITU as a p edic o o he di icul y o e al ex ac ion in acuum-assis ed deli e ies. Decla a ion o in e es The au ho s epo no con lic s o in e es . The au ho s alone a e esponsible o he con en and w i ing o his a icle. Re e ences 1. Dupuis O, Sil ei a R, Zen ne A, e al. Bi h simula o : eliabili y o ans aginal assessmen o e al head s a ion as de ined by he Ame ican College o Obs e icians and Gynecologis s classi ica- ion. Am J Obs e Gynecol 2005;192:868–74. 2. Johanson RB, Menon BKV. Vacuum ex ac ion e sus o ceps o assis ed aginal deli e y. Coch ane Da abase Sys Re 2010;2: CD000224. doi: 10.1002/14651858.CD000224.pub2 3. Majoko F, Ga dene G. T ial o ins umen al deli e y in hea e e sus immedia e caesa ean sec ion o an icipa ed di icul assis ed bi hs. Coch ane Da abase Sys Re 2012;10:CD005545. 4. Mu phy DJ, Liebling RE, Ve i y L, e al. Ea ly ma e nal and neona al mo bidi y associa ed wi h ope a i e deli e y in second s age o labou : a coho s udy. Lance 2001;13:1203–7. 5. Con ag SA, Cli on RG, Bloom SL, e al. Neona al ou comes and ope a i e aginal deli e y e sus cesa ean deli e y. Am J Pe ina ol 2010;27:493– 9. 6. Eason E, Lab ecque M, Wells G, Feldman P. P e en ing pe ineal auma du ing childbi h: A sys ema ic e iew. Obs e Gynecol 2000;95:464–71. 7. Sul an AH, Kamm MA, Ba am CI, Hudson CN. Anal sphinc e auma du ing ins umen al deli e y. In J Gynaecol Obs e 1993; 43:263–70. 8. Chadwick LM, Pembe on PJ, Ku inczuk JJ. Neona al subgaleal haema oma: associa ed isk ac o s, complica ions and ou come. J Paedia Child Heal h 1996;32:228–32. 9. Towne D, Cas o MA, Eby-Wilkens E, Gilbe WM. E ec o mode o deli e y in nullipa ous women on neona al in ac anial inju y. N Engl J Med 1999;341:1709–14. 10. Bi d GC. The impo ance o lexion in acuum ex ac o deli e y. B J Obs e Gynaecol 1976;83:194–200. 11. Vacca A, Kei se MJNC. Ins umen al aginal deli e y. In: Chalme s I, Enkin M, Kei se MJNC, eds. E ec i e ca e in p egnancy and childbi h. Ox o d: Ox o d Uni e si y P ess; 1989:1216–33. 12. Mola GD, Amoa AB, Edilyong J. Fac o s associa ed wi h success o ailu e in ials o acuum ex ac ion. Aus N Z J Obs e Gynaecol 2002;42:35–9. 13. Sainz JA, Bo e o C, Fe na´ndez-Palac´ın A, e al. Ins umen a ion di icul y wi h acuum-assi ed deli e y in p imipa ous womens. J Ma e n Fe al Neona al Med 2014;7:1–7. 14. Akmal S, Tsoi E, Kame as N, e al. In apa um sonog aphy o de e mine he e al head posi ion. J Ma e n Fe al Neona al Med 2002;12:172–7. 15. Ba be a AF, Pomba X, Pe ugino G, e al. A new me hod o assess e al head descen in labo wi h anspe ineal ul asound. Ul asound Obs e Gynecol 2009;33:313–19. 16. Duckelmann AM, Bambe g C, Michaelis SA, e al. Measu emen o e al head descen using he ’angle o p og ession’ on anspe ineal ul asound imaging is eliable ega dless o e al head s a ion o ul asound expe ise. Ul asound Obs e Gynecol 2010;35: 216–22. 17. Die z HP, Lanza one V. Measu ing engagemen o he e al head: alidi y and ep oducibili y o a new ul asound echnique. Ul asound Obs e Gynecol 2005;25:165–8. 18. Hen ich W, Dudenhausen J, Fuchs I, e al. In apa um anslabial ul asound (ITU): sonog aphic landma ks and co ela ion wi hsuccess ul acuum ex ac ion. Ul asound Obs e Gynecol 2006;28: 753–60. 19. Ghi T, Fa ina A, Ped azzi A, e al. Diagnosis o s a ion and o a ion o he e al head in he second s age o labo wi h in apa um anslabial ul asound. Ul asound Obs e Gynecol 2009;33:331–6. 20. Royal College o Obs e icians and Gynaecologis s. G een- op guideline n 26. Ope a i e Vaginal Deli e y. London: RCOG; 2011 21. Sociedad Espan˜ola de Ginecologia y Obs e icia. P oSEGO. Pa o Ins umen al. Mad id: SEGO; 2013 22. Mu phy DJ, Liebling RE, Pa el R, e al. Coho s udy o ope a i e deli e y in he second s age o labou and s anda d o obs e ic ca e. BJOG 2003;110:610–15. 23. Cue as M, Bambe g C, Tobias P, e al. In apa um ul asound, a p edic i e me hod o complica ed ope a i e o´ ceps deli e y in non- occipu pos e io deli e ies. Ul asound Obs e Gynecol Ul asound Obs e Gynecol 2014;43:687–92. 24. Cunningham FG, Gan NF, Le eno KJ, e al. Mechanisms o no mal labo . In: Cunningham FG, MacDonald PC, Gan NF, e al., eds. Williams obs e ics. 21s ed. New Yo k: McG aw-Hill; 2001:419–39. 25. Kalache KD, Duckelmann AM, Michaelis SA, e al. T anspe ineal ul asound imaging in p olonged second s age o labo wi h occipi oan e io p esen ing e uses: how well does he ‘angle o p og ession’ p edic he mode o deli e y? Ul asound Obs e Gynecol 2009;33:326–30. 26. To kildsen EA, Sal esen KA, Eggebo TM. P edic ion o deli e y mode wi h anspe ineal ul asound in women wi h p olonged i s s age o labo . Ul asound Obs e Gynecol 2011;37:702–8. 27. Yousse A, Ma oni E, Ragusa A, e al. Fe al head–symphysis dis ance: a simple and eliable ul asound index o e al head s a ion in labo . Ul asound Obs e Gynecol 2013;41:419–24. 28. Ghi T, Yousse A, Ma oni E, e al. In apa um anspe ineal ul asound assessmen o e al head p og ession in ac i e second s age o labo and mode o deli e y. Ul asound Obs e Gynecol 2013;41:430–5. 29. Gilboa Y, Ki ile i ch Z, Spi a M, e al. Head p og ession dis ance in p olonged second s age o labo : ela ionship wi h mode o deli e y and e al head s a ion. Ul asound Obs e Gynecol 2013;41: 436–41. 30. Sainz JA, Bo e o C, Fe na´ndez-Palac´ın A, e al. E alua ion o he in e and in a a iabili y o in apa um anspe ineal ul asound wi h pushing. Ul asound e alua ion o he di icul y in ins umen- a ion o acuum-media ed aginal deli e y. J Ul asound Med in p ess. 31. Lau WL, Leung WC, Chin R. Wha is he bes anspe ineal ul asound pa ame e o p edic ing success o acuum ex ac ion? Ul asound Obs e Gynecol 2009;33:735–6. 32. Tu schek B, B aun T, Chan aine F, Hen ich W. A s udy o p og ess o labou using in apa um anslabial ul asound, assessing head s a ion, di ec ion, and angle o descen . BJOG 2011;118:62–9. 33. Sainz JA, Bo e o C, Aquise A, e al. U ili y o in apa um anspe ineal ul asound o p edic cases o ailu e in acuum ex ac ion a emp and need o cesa ean sec ion o comple e deli e y. J Ma e n Fe al Neona al Med 2015;5:1–5.