Intra and interobserver variability of intrapartum transperineal ultrasound measurements with contraction and pushing

For Peer Review Only INTRA AND INTEROBSERVER VARIABILITY OF INTRAPARTUM TRANSPERINEAL ULTRASOUND MEASUREMENTS WITH CONTRACTION AND PUSHING Journal: Journal of Obstetrics and Gynaecology Manuscript ID CJOG-2017-0145.R2 Manuscript Type: Original Article Date Submitted by the Author: n/a Complete List of Authors: Sainz, Jose; Hospital Universitario Valme, Fetal Medicine Fernández Palacín, Ana; University Sevilla borrero, carlota; H.U.VAlme, Obstetricia Aquise Pino, Adriana; Hospital Universitario Valme, Fetal Medicine Ramos Vega, Zenaida; Hospital Universitario Valme, Fetal Medicine Garcia Mejido, José Antonio; H.U.VAlme, Obstetricia Keywords: Intrapartum ultrasound, labor, pushing, translabial ultrasound, transperineal ultrasound URL: http:/mc.manuscriptcentral.com/cjog Email: [email protected] Journal of Obstetrics and Gynaecology For Peer Review Only 1 INTRA AND INTEROBSERVER VARIABILITY OF INTRAPARTUM TRANSPERINEAL ULTRASOUND MEASUREMENTS WITH CONTRACTION AND PUSHING Authors: José A Sainz (1,2) Ana Fernández-Palacín (3) Carlota Borrero (1) Adriana Aquise (1,4) Zenaida Ramos (1) José A García-Mejido (1). Affiliation: (1). Department of Obstetrics and Gynaecology, Valme University Hospital, Seville, Spain. (2). Department of Obstetrics and Gynaecology, University of Seville, Spain. (3). Biostatistics Unit, Department of Preventive Medicine and Public Health, University of Seville, Spain. (4). Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London, UK. Running Title: EVALUATION OF THE INTER- AND INTRAVARIABILITY OF INTRAPARTUM TRANSPERINEAL ULTRASOUND WITH PUSHING Corresponding author: José Antonio Sainz Bueno, MD, Department of Obstetrics and Gynaecology Valme University Hospital, Seville, Spain. Phone: 0034 630132948 Email: [email protected] Conflict of interest. It doesn't exist any conflict of interest. Page 1 of 25 URL: http:/mc.manuscriptcentral.com/cjog Email: [email protected] Journal of Obstetrics and Gynaecology 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 For Peer Review Only 2 Abstract: Our aim is to evaluate the the inter- and intraobserver correlation of the different intrapartum-transperineal-ultrasound-parameters (ITU) (angle of progression (AoP), progression-distance (PD), head-direction (HD), midline-angle (MLA) and head-perineum distance (HPD)) with contraction and pushing. We evaluated 28 nulliparous women at full dilatation under epidural analgesia. There are no cases without epidural analgesia. We performed a transperineal ultrasound evaluating AoP and PD in the longitudinal plane, and MLA and HPD in the transverse plane. Interclass correlation coefficients (ICC) with 95% CIs and Bland-Altman analysis were used to assess intra- and interobserver measurement’s repeatability. The ICC of the ITU for the same observer was adequate for all the parameters (P<.005) AoP 0.98 (95%CI,0.96-0.99), PD 0.98 (95%CI,0.97-0.99), MLA 0.99 (95%CI,0.97- 0.99), HPD 0.96 (95%CI,0.88-0.99). The ICC of the ITU for interobserver was: AoP 0.93 (95%CI,0.79-0.98), PD 0.92 (95%CI,0.76-0.97), MLA 0.77 (95%CI,0.42-0.92), HPD 0.47 (95%CI,-0.12-0.8). The HD had an interobserver correlation of 0.53 (95%CI,0.1-0.9) (Kappa C). The mean difference of the AoP was 2.42º, of the PD 1mm and 0.28º MLA (Bland-Altman test). ITU has an adequate intra and interobserver correlation for its use with contraction and pushing under epidural analgesia Keywords: Intrapartum ultrasound, labor, pushing, translabial ultrasound, transperineal ultrasound Impact Statement ITU may be used to evaluate the difficulty of instrumental delivery/to evaluate the difficulty of instrumentation in vaginal operative deliveries and this study concludes that ITU is reproducible during uterine contraction with pushing. Therefore, ITU could be used without difficulty with an adequate intra and interobserver correlation for the prediction of instrumentation difficulty in operative vaginal deliveries. Page 2 of 25 URL: http:/mc.manuscriptcentral.com/cjog Email: [email protected] Journal of Obstetrics and Gynaecology 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 For Peer Review Only 3 Introduction. There is clear evidence that digital vaginal examination has a high error rate in the correct identification of the fetal head position and its degree of engagement in vaginal delivery (Sherer et al. 2002; Sherer et al. 2002; Dupuis et al. 2005). This aspect results in major difficulties in terms of safety in delivery instrumentation (Bird et al. 1976; Vacca et al. 1989; Sultan et al. 1993; Chadwick et al. 1996; Towner et al. 1999; Eason et al 2000; Murphy et al. 2001; Mola et al. 2002; Contag et al. 2010; Johanson et al. 2010; Majoko et al. 2012). Intrapartum transperineal ultrasound (ITU) has proved to be useful in the evaluation of the evolution and engagement of the fetal head during delivery (Mola et al. 2002; Dietz and Lanzarone. 2005; Eggebo et al. 2006; Henrich et al. 2006; Barbera et al. 2009; Ghi et al. 2009; Kalache et al. 2009; Duckelmann et al. 2010; Torkildsen et al. 2011; Torkildsen et al. 2012; Tutschek et al. 2012; Youssef et al. 2012; Ghi et al. 2013; Gilboa et al. 2013; Tutschek et al. 2013; Youssef et al. 2013; Youssef et al. 2013). Through several studies, our group has even been able to demonstrate ITU’s usefulness in the prediction of instrumentation difficulty in operative vaginal deliveries (Cunningham et al. 2001; Sainz et al. 2015). Using ‘maternal push’ before an instrumental assisted delivery is a usual practice carried out by obstetricians in order to determine the level of the fetal presentation and its degree of engagement (Cuerva et al. 2013). This will provide us information about the difficulty of instrumentation we can expect when facing an operative delivery. Intrapartum transperineal ultrasound has already proved to have an adequate reproducibility both in its clinical use and in the evaluation of the second stage of labor (Dietz and Lanzarone. 2005; Barbera et al. 2009; Duckelmann et al. 2010; Molina et al. 2010 ; Tutschek et al. 2011;) . Our aim now is to evaluate the inter- and intraobserver correlation of the different intrapartum transperineal ultrasound parameters (angel of progression, progression distance, head direction, midline angle and head-perineum distance) with pushing, before assessing their usefulness in clinical practice. Materials and Methods. Page 3 of 25 URL: http:/mc.manuscriptcentral.com/cjog Email: [email protected] Journal of Obstetrics and Gynaecology 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 For Peer Review Only 4 We performed an evaluation of 28 pregnant women at term under epidural analgesia, admitted to the delivery unit of Valme’s Universisty Hospital in Seville, between April 2013 and July 2013, during active second stage of labor, and who required instrumentation to complete the delivery. The pregnant women included in the study were: at term, singleton pregnancies (37-42 weeks), without a history of vaginal delivery (nulliparous or multiparous without previous vaginal delivery), in active second stage of labor, with fetus in a longitudinal lie and cephalic presentation and including both spontaneous or induced labor initiation. Delivery was completed using a vacuum (Malmström's vacuum extractor), being a prolonged second stage of labor (more than 2 hours without epidural analgesia and more than 3 hours with epidural analgesia) the indication for instrumental fetal extraction in 100% of cases. No cases of fetal distress were evaluated. During active second stage of labor, previous to instrumental delivery and under full dilatation and ruptured membranes conditions, an intrapartum transperineal ultrasound assessment, including angle of progression, progression distance, head direction, midline angle and head-perineum distance, was carried out. These parameters were evaluated both at rest and after pushing. This evaluation was carried out using a Toshiba Famio 5 ultrasound machine (Tokyo, Japan) with a 3.5 mHZ probe. The ultrasound was performed by two senior obstetricians with over 10 years experience in operative deliveries and obstetric ultrasonography. Both sonographers carried out their transperineal ultrasound separately and without any knowledge of their partner’s results. The study was approved by local ethics and research committees, and all participants were previously asked to sign an informed consent. In order to perform our intrapartum ultrasound evaluation, with the pregnant woman in lithotomy position and under empty bladder conditions, we placed the transducer at a transperineal level applying a translabial insonation to obtain the capture. The pubic symphysis was identified and used as the reference line for the longitudinal axis. The following sonographic parameters were measured, both in rest and with pushing (figure 1): 1. Angle of Progression (AoP; defined by Barbera (Barbera et al. 2009) as the angle between the longitudinal axis of the pubic symphysis the tangent line to fetal skull’s contour); 2. Progression Distance (PD; defined by Dietz (Dietz and Lanzarone, 2005) as Page 4 of 25 URL: http:/mc.manuscriptcentral.com/cjog Email: [email protected] Journal of Obstetrics and Gynaecology 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 For Peer Review Only 5 the distance (mm) between the infrapubic symphisis and the lowest edge of fetal skull it should be the distance from the lower part of the fetal skull and the perpendicular line from the lower edge of the symphysis pubis ; 3. Head Direction (HD; as the angle resulting of the union of a perpendicular line to pubic’s bone major axis and a perpendicular line to fetal’s head widest transverse diameter; as according to Henrich (Henrich et al. 2006), angles ≥ 30º correspond to ‘upward’ directions, ≤ 0º correspond to ‘downward’ directions, and angles between 0º-30º correspond to horizontal directions). We then turned our transducer to switch from the midsagittal to an axial plane, allowing us to identify fetal’s brain midline. We used this capture to evaluate the midline angle (figure 2) (Ghi et al. 2009) (MLA; defined as the angle between the anteroposterior axis of the pelvis and the fetal’s brain midline) and the perineum-head distance (figure 2) (the distance between foetal skull and maternal perineum), both at rest and with contraction and pushing. All measurements were performed on screen and the images for the intraobserver variability were captured in 2 different contractions Statistical analysis: The quantitative variables were summarised with means and standard deviations or, in the case of asymmetrical distributions, with medians and percentiles (P 25 and P 75 ) while qualitative variables were done with percentages. The intraobserver and interobserver concordance was analysed using intraclass correlation coefficients and their 95% confidence intervals and Bland- Altman graphs, including the mean and confidence interval for the differences of the intraobserver and interobserver measurements. For qualitative variables, we used Cohen’s Kappa concordance coefficients and their 95% confidence intervals (Bartko, 1966; Shrout and Fleiss, 1079; Bland and Altman, 1986; Bland and Altman, 2003; ACOG, 2007; Lau et al. 2009). The sample size was determined in order to estimate the intraclass correlation coefficient as a measure of reliability between measurements performed by different methods on the same subjects. For the calculation of this size we assume an expected intraclass correlation coefficient of 0.95 in the worst case scenario (obtained from previous experience), a confidence level of 95%, an accuracy or amplitude of the range of 0.04 and performance of 2 replicates / observers per measurement. Taking all of this into account, the evaluation of at least 24 cases is needed. Results. Page 5 of 25 URL: http:/mc.manuscriptcentral.com/cjog Email: [email protected] Journal of Obstetrics and Gynaecology 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 For Peer Review Only 6 We evaluated 28 nulliparous women who required instrumentation with vacuum to complete fetal extraction. The mean age of the pregnant women was 31.2 years old with a mean gestational age at delivery of 39 weeks. The mean vacuum pulls necessary for fetal extraction was 2.1 and the mean birth weight of the new-borns was 3,255 grams, with no cases of neonatal morbidity or mortality (Table I). In the evaluation of the intrapartum transperineal ultrasound with pushing we observed (Table II): an increase in the angle of progression of 12º-12.7º and of the progression distance of 5.4-8mm, and a decrease in the midline angle of 0.5º-4.7º and of the headperineum distance of 3.3-4.4mm. We did not identify any change in the head direction with pushing. The intraobserver correlation of the intrapartum transperineal ultrasound parameters at rest and with pushing was adequate (P<.005): measurements at rest: angle of progression of 0.96 (95% CI, 0.89-0.99), progression distance of 0.98 (95% CI, 0.97- 0.99), midline angle of 0.98 (95% CI, 0.96-0.99), head-perineum distance of 0.96 (95% CI, 0.87-0.99); versus measurements with pushing: angle of progression of 0.98 (95% CI, 0.96-0.99), progression distance of 0.98 (95% CI, 0.97-0.99), midline angle of 0.99 (95% CI, 0.97-0.99), head-perineum distance of 0.96 (95% CI, 0.88-0.99) (Table III). The interobserver correlation of the intrapartum transperineal ultrasound parameters at rest were: for the angle of progression 0.71 (95% CI, 0.31-0.9), for the progression distance 0.93 (95% CI, 0.81-0.98), for the midline angle 0.79 (95% CI, 0.47-0.93) and for the head direction 0.66 (95% CI, 0.18-0.89) (Cohen’s Kappa). With pushing, the interobserver correlation was: for the angle of progression 0.93 (95% CI, 0.79-0.98), for the progression distance 0.92 (95% CI, 0.76-0.97), for the midline angle 0.77 (95% CI, 0.42-0.92) and for the head direction 0.53 (95% CI, 0.1-0.9) (Cohen’s Kappa) (Table IV), being a small mean difference between the measurements of: 2.42º in the angle of progression, 1mm in the progression distance and 0.28º in the midline angle (Bland- Altman test) (Table V). Discussion Page 6 of 25 URL: http:/mc.manuscriptcentral.com/cjog Email: [email protected] Journal of Obstetrics and Gynaecology 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 For Peer Review Only 7 We observed that ITU is reproducible during uterine contraction with pushing under epidural analgesia. The ITU has an adequate inter- and intraobserver correlation for the angle of progression, the progression distance, the midline angle and the head-perineum distance (0.96, 0.47). During the last few years, intrapartum transperineal ultrasound (ITU) has been used to predict the type of delivery that will take place in cases of prolonged first or second stage of labor ( Dietz and Lanzarone. 2005; Eggebo et al. 2006; Henrich et al. 2006; Barbera et al. 2009; Ghi et al. 2009; Torkildsen et al. 2012) . Thus, we observed that situations with an angle of progression greater than 110º-120º, an upwards head direction, a headperineum distance of less than 40mm and a midline angle lower than 45º, are associated with spontaneus vaginal deliveries (Ghi et al. 2009; Torkildsen et al. 2011; Tutschek et al. 2011). Furthermore, ITU has proved to be useful in the determination of the degree of engagement of the fetal head. Henrich ( Henrich et al. 2006) reports that for ITU, ischial spines are 3cm more caudal than the parallel line drawn from the pubic symphysis, while Tutschek (Tutschek et al. 2011) observes that head stations 0.0 and +2 are correlated with angles of progression of 116º and 138º respectively. In its evaluation of the second stage of delivery using a 2D ultrasound machine, ITU has shown that it is reproducible with an adequate intra- (0.90) and interobserver (0.86) (Tutschek et al. 2011) correlation. Tutschek (Tutschek et al. 2011) reports that the angle of progression has an intra- and interobserver variability of 13º and 14º respectively. Comparing it to expert obstetrician evaluations (more than 10 years experience), Duckelmann (Duckelmann et al. 2010) reports that ITU’s reproducibility remains to be high even when performed by obstetricians with little experience in this kind of assessment (less than 5 years’ experience). Molina (Molina et al. 2010) demonstrates that ITU evaluated with 3D ultrasound also has an adequate reproducibility. Moreover, Torkinldsen (Torkildsen et al. 2011) observes by using 2 and 3D ultrasound that ITU is also reproducible when carried out in the first stage of labor. ITU has also been introduced in the evaluation of the difficulty of delivery instrumentation. Henrich (Henrich et al. 2006) observed that the assessment of the head direction may be an adequate predictor of the difficulty of fetal extraction with vacuum. Lau (Lau et al. 2009) described how those cases which ended in vaginal delivery with Page 7 of 25 URL: http:/mc.manuscriptcentral.com/cjog Email: [email protected] Journal of Obstetrics and Gynaecology 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 For Peer Review Only 8 vacuum presented higher angles of progression, than those which required caesarean section to complete fetal extraction. Cuerva (Cuerva et al. 2013) describes the usefulness of ITU in the prediction of delivery difficulty with forceps by using the evaluation of the angle of progression and the head direction. We (Sainz et al. 2015) used ITU to quantify the difficulty of vaginal delivery with a vacuum, observing that those cases in which the ITU evaluation revealed an angle of progression ≤120º, a downwards or horizontal head direction, and a midline angle ≥35º, vaginal delivery with vacuum turned out to be difficult, with a mean of 3 or more vacuum pulls needed to complete fetal extraction. In the delivery room, performing digital vaginal examination during uterine contraction and maternal push, is a usual practice carried out by obstetricians in order to determine the level of the fetal presentation and its degree of engagement (Cunningham et al. 2001). In this context, we now need to evaluate the usefulness of ITU for the prediction of instrumentation difficulty in operative deliveries, when carried out during maternal push. In order to do this, and previous to its clinical application, we have evaluated the reproducibility of ITU with pushing. We observed an adequate inter- and intraobserver correlation for the angle of progression (0.98, 0.93 respectively), the progression distance (0.98, 0.92), the midline angle (0.99, 0.77) and the head-perineum distance (0.96, 0.47). We observed a mean difference of only 2.42º in the angle of progression, of 1mm in the progression distance, and of 0.28º in the midline angle. As well as Tutscheck (Tutschek et al. 2011), we observed an improvement in the following ITU parameters: the angle of progression increased 12º, the progression distance 5.4-8mm, the head-perineum distance 3.3-4.4mm, while the midline angle decreased between 0.5º and 4.7º. Tutscheck (Tutschek et al. 2011) observed that ITU-measured head station decreased between 1 and 2.5cm and that there was an increase of 18º in the head direction. We can therefore conclude that ITU is reproducible during uterine contraction with pushing under epidural analgesia and may be used to evaluate the difficulty of instrumental delivery/to evaluate the difficulty of instrumentation in vaginal operative deliveries. Page 8 of 25 URL: http:/mc.manuscriptcentral.com/cjog Email: [email protected] Journal of Obstetrics and Gynaecology 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 For Peer Review Only 15 Table 2. Intrapartum transperineal ultrasound assessment (progression angle, head direction, progression distance, midline angle and head-perineum distance) at rest and with pushing according explorer. Intrapartum Transperineal Ultrasound Explorer 1 (n 28) Explorer 2 (n 28) Measure 1ª Measure 2ª Measure 1ª Measure 2ª Angle of Progression at rest (º) 127.3 SD 15,1 127.0 SD 13.7 125.5 SD 10.4 126.6 SD 9.5 Angle of Progression with pushing (º) 139.7 SD 20.0 139.7 SD 18.6 137.3 SD 16.6 137.5 SD 13.5 Head direction at rest Up 22 (78.6%) 22 (78.6%) 24 (85.7%) 24 (85.7%) Horizontal-Down 6 (21.4%) 6 (21.4%) 4(14.3%) 4(14.3%) Head direction with pushing Up 22(78.6%) 22(78.6%) 24(85.7%) 24(85.7%) Horizontal-Down 6(21.4%) 6(21.4%) 4 (14.3%) 4 (14.3%) Progression distance at rest (mm) 29.9 SD 12.2 31.0 SD 11.6 31.5 SD 12.3 31.4 SD 11.6 Progression distance with pushing (mm) 37.9 SD 13.8 38.9 SD 13.7 36.9 SD 13.3 37.5 SD 12.5 Midline angle at rest (º) 39.6 SD 18.0 39.9 SD 17.2 36.7 SD 22.9 36.6 SD 20.3 Midline angle with pushing (º) 34.9 SD 20.0 36.9 SD 18.9 34.6 SD 23.8 36.1 SD 23.1 Head-perineum distance at rest (mm) 46.8 SD 6.3 47.5 SD 6.1 44.9 SD 5.1 45.5 SD 5.0 Head-perineum distance with pushing (mm) 43.3 SD 7.6 44.1 SD 6.9 40.5 SD 6.3 41.6 SD 5.4 SD. Standard Deviations Page 15 of 25 URL: http:/mc.manuscriptcentral.com/cjog Email: [email protected] Journal of Obstetrics and Gynaecology 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 For Peer Review Only 16 Table 3. Assessment of intraobserver correlation of the intrapartum translabial ultrasound (progression angle, head direction, progression distance, midline angle and head-perineum distance) at rest and with pushing. Explorer 1 Explorer 2 ICC CI (95%) Significant difference (p) ICC CI (95%) Significant difference (p) Angle of Progression at rest 0.96 0.89-0.99 p<0.0005 0.91 0,75-0,97 p<0.0005 Angle of Progression with pushing 0.98 0.96-0.99 p<0.0005 0.98 0.95-0.99 p<0.0005 Progression distance at rest 0.98 0.97-0.99 p<0.0005 0.98 0.93-0.99 p<0.0005 Progression distance with pushing 0.98 0.94-0.99 p<0.0005 0.95 0.85-0.98 p<0.0005 Midline angle at rest 0.98 0.96-0.99 p<0.0005 0.98 0.94-0.99 p<0.0005 Midline angle with pushing 0.99 0.972-0.997 p<0.0005 0.99 0.968-0.997 p<0.0005 Head-perineum distance at rest 0.96 0.87-0.99 p<0.0005 0.97 0.89-0.99 p<0.0005 Head-perineum distance with pushing 0.96 0.88-0.99 p<0.0005 0.95 0.84-0.99 p<0.0005 ICC. Intraclass correlation coefficient. CI. Confidence intervals. Page 16 of 25 URL: http:/mc.manuscriptcentral.com/cjog Email: [email protected] Journal of Obstetrics and Gynaecology 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 For Peer Review Only 17 Table 4. Assessment of interobserver correlation of the intrapartum translabial ultrasound (progression angle, head direction, progression distance, midline angle and head-perineum distance) at rest and with pushing. ICC CI (95%) Significant difference (p) Angle of Progression at rest 0.71 0.31-0.9 0.002 Angle of Progression with pushing 0.93 0.79-0.98 p<0.0005 Progression distance at rest 0.93 0.81-0.98 p<0.0005 Progression distance with pushing 0.92 0.76-0.97 p<0.0005 Midline angle at rest 0.79 0.47-0.93 p<0.0005 Midline angle with pushing 0.77 0.42-0.92 p<0.0005 Head-perineum distance at rest 0.66 0.18-0.89 0.007 Head-perineum distance with pushing 0.47 -0.12-0.81 0.054 Kappa coefficient CI (95%) Significant difference (p) Head direction at rest 0.53 0.1-0.90 p=0.015 Head direction with pushing 0.53 0.1-0.90 p=0.015 ICC. Intraclass correlation coefficient. CI. Confidence intervals. Page 17 of 25 URL: http:/mc.manuscriptcentral.com/cjog Email: [email protected] Journal of Obstetrics and Gynaecology 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 For Peer Review Only 18 Table 5. Interobserver Bland-Altman analysis of the intrapartum translabial ultrasound with pushing. Mean difference +/- SD CI 95% Angle of Progression with pushing 2.42 +/- 6.95º -1.58-6.44º Progression distance with pushing 1.00 +/- 5.57 mm -2.21-4.21 mm Midline angle with pushing 0.28 +/- 15.00º -8.37-8.94º Head-perineum distance with pushing 1.91 +/- 4.67 mm -1.05-4.89 mm CI. Confidence intervals. Page 18 of 25 URL: http:/mc.manuscriptcentral.com/cjog Email: [email protected] Journal of Obstetrics and Gynaecology 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 For Peer Review Only Table 1. General and intrapartum obstetric characteristics and neonatal outcomes of the study population (N 28) N 28 % Mean maternal age (years) 31.2 SD 4.70 History of cesarean section 2 14.2 % Gestational pathology 3 21.4% Gestational age at birth (weeks) 39.0 SD 1.25 Estimated foetal weight at birth 3,350 SD 337.42 Number of induced labours 8 28.5% Epidural analgesia 28 100% Duration of 1st stage of labour (hours) 7.1 SD 3.47 Duration of 2nd stage of labour (hours) 3.1 SD 0.36 Number of instrumental deliveries 28 100% Type of instrumental delivery: Vacuum 28 100% Number of vacuum pulls 2.1 SD 0.5 Maternal morbidity 1 3.5% Uterine atony Others 1 0 100% 0% Sex of newborn (females) 18 64.2% Newborn weight (grams) 3 , 255 SD 425.25 APGAR 1 minute 8.7 SD 1.10 APGAR 5 minutes 10 SD 0.00 Umbilical cord artery pH 7.23 SD 9.79 Perinatal mortality 0 0% Perinatal morbility 0 0% SD. Standard Deviations Page 19 of 25 URL: http:/mc.manuscriptcentral.com/cjog Email: [email protected] Journal of Obstetrics and Gynaecology 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 For Peer Review Only Table 2. Intrapartum transperineal ultrasound assessment (progression angle, head direction, progression distance, midline angle and head-perineum distance) at rest and with pushing according explorer. Intrapartum Transperineal Ultrasound Explorer 1 (n 28) Explorer 2 (n 28) Measure 1ª Measure 2ª Measure 1ª Measure 2ª Angle of Progression at rest (º) 127.3 SD 15,1 127.0 SD 13.7 125.5 SD 10.4 126.6 SD 9.5 Angle of Progression with pushing (º) 139.7 SD 20.0 139.7 SD 18.6 137.3 SD 16.6 137.5 SD 13.5 Head direction at rest Up 22 (78.6%) 22 (78.6%) 24 (85.7%) 24 (85.7%) Horizontal-Down 6 (21.4%) 6 (21.4%) 4(14.3%) 4(14.3%) Head direction with pushing Up 22(78.6%) 22(78.6%) 24(85.7%) 24(85.7%) Horizontal-Down 6(21.4%) 6(21.4%) 4 (14.3%) 4 (14.3%) Progression distance at rest (mm) 29.9 SD 12.2 31.0 SD 11.6 31.5 SD 12.3 31.4 SD 11.6 Progression distance with pushing (mm) 37.9 SD 13.8 38.9 SD 13.7 36.9 SD 13.3 37.5 SD 12.5 Midline angle at rest (º) 39.6 SD 18.0 39.9 SD 17.2 36.7 SD 22.9 36.6 SD 20.3 Midline angle with pushing (º) 34.9 SD 20.0 36.9 SD 18.9 34.6 SD 23.8 36.1 SD 23.1 Head-perineum distance at rest (mm) 46.8 SD 6.3 47.5 SD 6.1 44.9 SD 5.1 45.5 SD 5.0 Head-perineum distance with pushing (mm) 43.3 SD 7.6 44.1 SD 6.9 40.5 SD 6.3 41.6 SD 5.4 SD. Standard Deviations Page 20 of 25 URL: http:/mc.manuscriptcentral.com/cjog Email: [email protected] Journal of Obstetrics and Gynaecology 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 For Peer Review Only Table 3. Assessment of intraobserver correlation of the intrapartum translabial ultrasound (progression angle, head direction, progression distance, midline angle and head-perineum distance) at rest and with pushing. Explorer 1 Explorer 2 ICC CI (95%) Significant difference (p) ICC CI (95%) Significant difference (p) Angle of Progression at rest 0.96 0.89-0.99 p<0.0005 0.91 0,75-0,97 p<0.0005 Angle of Progression with pushing 0.98 0.96-0.99 p<0.0005 0.98 0.95-0.99 p<0.0005 Progression distance at rest 0.98 0.97-0.99 p<0.0005 0.98 0.93-0.99 p<0.0005 Progression distance with pushing 0.98 0.94-0.99 p<0.0005 0.95 0.85-0.98 p<0.0005 Midline angle at rest 0.98 0.96-0.99 p<0.0005 0.98 0.94-0.99 p<0.0005 Midline angle with pushing 0.99 0.972-0.997 p<0.0005 0.99 0.968-0.997 p<0.0005 Head-perineum distance at rest 0.96 0.87-0.99 p<0.0005 0.97 0.89-0.99 p<0.0005 Head-perineum distance with pushing 0.96 0.88-0.99 p<0.0005 0.95 0.84-0.99 p<0.0005 ICC. Intraclass correlation coefficient. CI. Confidence intervals. Page 21 of 25 URL: http:/mc.manuscriptcentral.com/cjog Email: [email protected] Journal of Obstetrics and Gynaecology 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 For Peer Review Only Table 4. Assessment of interobserver correlation of the intrapartum translabial ultrasound (progression angle, head direction, progression distance, midline angle and head-perineum distance) at rest and with pushing. ICC CI (95%) Significant difference (p) Angle of Progression at rest 0.71 0.31-0.9 0.002 Angle of Progression with pushing 0.93 0.79-0.98 p<0.0005 Progression distance at rest 0.93 0.81-0.98 p<0.0005 Progression distance with pushing 0.92 0.76-0.97 p<0.0005 Midline angle at rest 0.79 0.47-0.93 p<0.0005 Midline angle with pushing 0.77 0.42-0.92 p<0.0005 Head-perineum distance at rest 0.66 0.18-0.89 0.007 Head-perineum distance with pushing 0.47 -0.12-0.81 0.054 Kappa coefficient CI (95%) Significant difference (p) Head direction at rest 0.53 0.1-0.90 p=0.015 Head direction with pushing 0.53 0.1-0.90 p=0.015 ICC. Intraclass correlation coefficient. CI. Confidence intervals. Page 22 of 25 URL: http:/mc.manuscriptcentral.com/cjog Email: [email protected] Journal of Obstetrics and Gynaecology 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 For Peer Review Only Table 5. Interobserver Bland-Altman analysis of the intrapartum translabial ultrasound with pushing. Mean difference +/- SD CI 95% Angle of Progression with pushing 2.42 +/- 6.95º -1.58-6.44º Progression distance with pushing 1.00 +/- 5.57 mm -2.21-4.21 mm Midline angle with pushing 0.28 +/- 15.00º -8.37-8.94º Head-perineum distance with pushing 1.91 +/- 4.67 mm -1.05-4.89 mm CI. Confidence intervals.  Page 23 of 25 URL: http:/mc.manuscriptcentral.com/cjog Email: [email protected] Journal of Obstetrics and Gynaecology 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 For Peer Review Only Figure 1. Angle of Progression: angle between the longitudinal axis of the pubic symphysis the tangent line to fetal skull’s contour (A: Angle of progression at rest. B: Angle of progression with pushing). Progression Distance it should be the distance from the lower part of the fetal skull and the perpendicular line from the lower edge of the symphysis pubis (C: Progression distance at rest. B: Progression distance with pushing). 270x188mm (72 x 72 DPI) Page 24 of 25 URL: http:/mc.manuscriptcentral.com/cjog Email: [email protected] Journal of Obstetrics and Gynaecology 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60