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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.
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