Transperineal ultrasound imaging in prolonged second stage of labor with occipitoanterior presenting fetuses: how well does the 'angle of progression' predict the mode of delivery?

Comparison of different methods of measuring angle of progression in prediction of labor outcome

OBJECTIVES

First, to compare the manual sagittal and parasagittal and automated parasagittal methods of measuring the angle of progression (AoP) by transperineal ultrasound during labor, and, second, to develop models for the prediction of time to delivery and need for Cesarean section (CS) for failure to progress (FTP) in a population of patients undergoing induction of labor.

METHODS

This was a prospective observational study of transperineal ultrasound in a cohort of 512 women with a singleton pregnancy undergoing induction of labor. A random selection of 50 stored images was assessed for inter- and intraobserver reliability of AoP measurements using the manual sagittal and parasagittal and automated parasagittal methods. In cases of vaginal delivery, univariate linear, multiple linear and quantile regression analyses were performed to predict time to delivery. Univariate and multivariate binomial logistic regression analyses were performed to predict CS for FTP in the first stage of labor.

RESULTS

The intraclass correlation coefficient (ICC) for the manual parasagittal method for a single observer was 0.97 (95% CI, 0.95-0.98) and for two observers it was 0.96 (95% CI, 0.93-0.98), indicating good reliability. The ICC for the sagittal method for a single observer was 0.93 (95% CI, 0.88-0.96) and for two observers it was 0.74 (95% CI, 0.58-0.84), indicating moderate reliability for a single observer and poor reliability between two observers. Bland-Altman analysis demonstrated narrower limits of agreement for the manual parasagittal approach than for the sagittal approach for both a single and two observers. The automated parasagittal method failed to capture an image in 19% of cases. The mean difference in AoP measurements between the sagittal and manual parasagittal methods was 11°. In pregnancies resulting in vaginal delivery, 54% of the variation in time to delivery was explained in a model combining parity, epidural and syntocinon use during labor and the sonographic findings of fetal head position and AoP. In the prediction of CS for FTP in the first stage of labor, a model which combined maternal factors with the sonographic measurements of AoP and estimated fetal weight was superior to one utilizing maternal factors alone (area under the receiver-operating-characteristics curve, 0.80 vs 0.76).

CONCLUSIONS

First, the method of measuring AoP with the greatest reliability is the manual parasagittal technique and future research should focus on this technique. Second, over half of the variation in time to vaginal delivery can be explained by a model that combines maternal factors, pregnancy characteristics and ultrasound findings. Third, the ability of AoP to provide clinically useful prediction of CS for FTP in the first stage of labor is limited. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Using transperineal ultrasound to predict labor onset

Background

Accurate diagnosis of labor onset is especially important for the counseling about elective induction of labor. The study aimed to evaluate whether transperineal ultrasound could better predict the timing and likelihood of spontaneous labor at term.

Methods

This single-center study was conducted between 2018 and 2019.Data on singleton pregnant women after 39 weeks and before labor onset were retrospectively reviewed.

Results

All the transperineal ultrasound parameters were well reproducible between the two doctors [intraclass correlation coefficient (ICC) for progression distance(PD) was 0.892, P<0.001], [ICC for angle of progression (AoP) was 0.881, P<0.001], [ICC for subpubic arch angle (SPA) was 0.766, P<0.001], [ICC for width of symphysis pubis (WSP) was 0.803, P<0.001]. For the pregnant women before 40 weeks, the width of symphysis pubis changed gradually with the of spontaneous labor (WSP) (r=0.33, P<0.05). For all included women, the SPA correlated with the time of spontaneous labor (SPA) (r=0.31, P<0.05).

Conclusions

The antepartum transperineal ultrasound is a simple and objective technique that better observes the initiation of labor. And with the WSP and SPA we were able to predict labor onset and help in counseling about elective induction of labor.

Prediction of spontaneous vaginal delivery in nulliparous women with a prolonged second stage of labor: the value of intrapartum ultrasound

BACKGROUND

A limited number of studies have addressed the role of intrapartum ultrasound in the prediction of the mode of delivery in women with prolonged second stage of labor.

OBJECTIVE

The objective of the study was to evaluate the role of transabdominal and transperineal sonographic findings in the prediction of spontaneous vaginal delivery among nulliparous women with prolonged second stage of labor.

STUDY DESIGN

This was a 2-center prospective study conducted at 2 tertiary maternity units. Nulliparous women with a prolonged active second stage of labor, as defined by active pushing lasting more than 120 minutes, were eligible for inclusion. Transabdominal ultrasound to evaluate the fetal head position and transperineal ultrasound for the measurement of the midline angle, the head-perineum distance, and the head-symphysis distance were performed in between uterine contractions and maternal pushes. At transperineal ultrasound the angle of progression was measured at rest and at the peak of maternal pushing effort. The delta angle of progression was defined as the difference between the angle of progression measured during active pushing at the peak of maternal effort and the angle of progression at rest. The sonographic findings of women who had spontaneous vaginal delivery vs those who required obstetric intervention, either vacuum extraction or cesarean delivery, were evaluated and compared.

RESULTS

Overall, 109 were women included. Spontaneous vaginal delivery and obstetric intervention were recorded in 40 (36.7%) and 69 (63.3%) patients, respectively. Spontaneous vaginal delivery was associated with a higher rate of occiput anterior position (90% vs 53.2%, P < .0001), lower head-perineum distance and head-symphysis distance (33.2 ± 7.8 mm vs 40.1 ± 9.5 mm, P = .001, and 13.1 ± 4.6 mm vs 19.5 ± 8.4 mm, P < .001, respectively), narrower midline angle (29.6° ± 15.3° vs 54.2° ± 23.6°, P < .001) and wider angle of progression at the acme of the pushing effort (153.3° ± 19.8° vs 141.8° ± 25.7°, P = .02) and delta-angle of progression (17.3° ± 12.9° vs 12.5° ± 11.0°, P = .04). At logistic regression analysis, only the midline angle and the head-symphysis distance proved to be independent predictors of spontaneous vaginal delivery. More specifically, the area under the curve for the prediction of spontaneous vaginal delivery was 0.80, 95% confidence interval (0.69-0.92), P < .001, and 0.74, 95% confidence interval (0.65-0.83), P = .002, for the midline angle and for the head-symphysis distance, respectively.

CONCLUSION

Transabdominal and transperineal intrapartum ultrasound parameters can predict the likelihood of spontaneous vaginal delivery in nulliparous women with prolonged second stage of labor.

Reliability of transperineal ultrasound for the assessment of the angle of progression in labor using parasagittal approach versus midsagittal approach

OBJECTIVE

To assess the inter-method agreement between midsagittal (msAoP) and parasagittal (psAoP) measurements of the angle of progression (AoP) during labor. In addition, we aimed to evaluate the correlation between AoP measurements by both midsagittal and parasagittal approaches with the mode of delivery.

METHODS

We recruited a nonconsecutive series of women in active labor with a singleton uncomplicated term pregnancy with fetuses in vertex presentation. Women underwent transperineal ultrasound in the absence of uterine contractions or maternal pushing to measure both msAoP and psAoP. The inter-method agreement between the two acquisitions was then assessed. Lastly, both measurements were compared between women who had a vaginal delivery versus those who underwent cesarean section (CS).

RESULTS

Overall, 151 women were included in the study. We found an excellent agreement between msAoP and psAoP (ICC 0.935; 95% CI 0.912-0.953, p < .001). On the other hand, psAoP overestimated the measurements in comparison with msAoP (101.2 ± 15.6 versus 98.2 ± 16.0, p < .001). There was a significant correlation between both methods of AoP assessment and duration of the active second stage of labor and AoP measured by either method was significantly wider in patients who delivered vaginally compared to those who had a CS.

CONCLUSIONS

Our data showed a significant difference in the measured angle between the psAoP and the originally described msAoP. The automated measurements of AoP that have been introduced are designed using the parasagittal visualization of the more echogenic pubic arch, rather than the hypoechogenic pubic symphysis. We think that in the light of our data, care should be taken before applying data from midsagittal measurement in centers using the parasagittal automated approach.

Can the Progression Angle before Labor Help to Predict Cesarean Section?

OBJECTIVE

The aim of this study was to predict cesarean section on a single visit at term using a combination of maternal history and ultrasound markers, including some new markers such as the progression angle used to assess intrapartum progress.

STUDY DESIGN

This was an observational prospective cohort study of singleton term pregnancies that included 575 women. The maternal history and ultrasound markers were obtained on a single visit at 37-38 weeks' gestation. Multivariable logistic regression was used for prediction of cesarean section.

RESULTS

Five hundred and seventy-five women were examined at a median gestational age of 38.3 weeks (range: 35.6-41.6) and a cesarean section was performed on 104 women (18%) - 24 for a fetal indication and 80 for a maternal indication. The risk of cesarean section increased with a previous cesarean section, assisted reproduction techniques, a higher estimated fetal weight, and a greater cervical length, and decreased with a greater maternal height, multiparity, and a wider progression angle. The detection rate for a 20% false positive rate was 69.9% for all cesarean sections, 54.2% for those with a fetal indication, and 77.2% for those with a maternal indication.

CONCLUSIONS

Assessment at 37-38 weeks' gestation of ultrasound markers such as the cervical length, progression angle, and estimated fetal weight, in combination with the maternal history, can predict a cesarean section in labor. Cesarean section for a maternal indication is better predicted than cesarean section for a fetal indication.

Assessment of the angle of progression and distance perineum-head in the prediction of type of delivery and duration of labor using intrapartum ultrasonography

OBJECTIVE

To evaluate the relevance of the angle of progression (AOP) and head-perineum distance (HPD) for predicting the type of delivery and duration of the second stage of labor using intrapartum ultrasonography.

METHODS

In total, 221 women in labor with a single gestational sac at ≥37 weeks of gestation and fetuses in cephalic presentation underwent two-dimensional ultrasonography by transperineal route for measurements of AOP and HPD. Correlations between the type of delivery (vaginal or surgical (cesarean section and forceps)), duration of the second stage of labor, and fetal and maternal characteristics were assessed. AOP and HPD variables were separately studied in the first and second stages of labor. Multivariate logistic regression was followed in stages to identify the predictors for the surgical delivery outcome - stepwise forward method.

RESULTS

In total, 153 (69.2%) women underwent vaginal deliveries, 7 (3.2%) underwent forceps deliveries, and 61 (27.6%) underwent cesarean deliveries. AOP was a statistically significant parameter in first and second stages of labor (107.8 ± 12.1° versus 100.8 ± 13.7°; p = .017), with an inverse correlation with the occurrence of vaginal delivery. HPD was a statistically significant parameter in the second stage of labor (3.42 ± 0.84 cm versus 4.17 ± 0.54 cm; p < .003), with a direct correlation with the occurrence of surgical delivery. The value of AOP that optimized the curve was 129.9° with 85% specificity and 63% sensitivity for the vaginal delivery endpoint. The value of HPD that optimized the curve was 4.3 cm with 69% specificity and 89% sensitivity for the surgical delivery endpoint. In the first phase, the variables defining the type of delivery were the following: height, body mass index, and AOP. In the second phase, the variables defining were the following: height, labor analgesia, HPD, and position of the fetal occiput.

CONCLUSION

AOP and HPD determined by intrapartum ultrasonography were associated with duration of labor, which may aid in predicting the type of delivery in association with clinical parameters.

Dynamic changes of fetal head descent at term before the onset of labor correlate with labor outcome and can be improved by ultrasound visual feedback

OBJECTIVE

The aim of the study was to evaluate the dynamic changes of angle of progression (AoP) before the onset of labor and their correlation with labor outcome and to investigate the effect of visual feedback using transperineal ultrasound on maternal pushing.

METHODS

We recruited a group of low-risk nulliparous women with singleton pregnancy at term. We measured AoP at rest, during pelvic floor contraction and Valsalva maneuver (before and after visual feedback). We compared AoP between women who delivered vaginally (VD) and those who underwent a cesarean section (CS). We also assessed the correlation between AoP and labor durations.

RESULTS

Overall, 222 women were included in the study; 129 (58.1%) had spontaneous VD, 35 (15.8%) had instrumental delivery, and 58 (26.1%) underwent CS. In comparison with rest, AoP decreased at PFMC (p < .001) and increased at first Valsalva (p < .001). AoP increased further significantly at Valsalva after visual feedback (p < .001). Women with VD had wider AoP at rest (p = .020), during Valsalva maneuver before (p = .024), and after visual feedback (p = .037). At cox regression analysis, wider AoP was associated with shorter first, second, and active second stages.

CONCLUSION

Wider AoP at rest and under Valsalva is associated with vaginal delivery, the shorter interval to delivery, and shorter labor duration in nulliparous women at term. The accuracy of AoP in the prediction of cesarean delivery is modest and is unlikely to be clinically applicable in isolation for the prediction of the mode of delivery.

A simple sonographic finding is associated with a successful vacuum application: the fetal occiput or forehead sign

BACKGROUND

Intrapartum ultrasound scanning has been proposed as an ancillary tool in the decision-making process of instrumental vaginal delivery.

OBJECTIVE

The purpose of this study was to evaluate the correlation between the sonographic visualization with a transperineal scan of the fetal occiput or forehead distal to the pubic symphysis with anterior or posterior presentation, respectively (fetal occiput or forehead sign), and the outcome of a vacuum delivery.

STUDY DESIGN

We conducted a retrospective cohort study of patients who underwent a vacuum application in our hospital from 2011-2017, excluding outlet applications. In each case, a preliminary transperineal scan was performed to confirm fetal presentation and position and to demonstrate the presence or absence of the fetal occiput or forehead sign. The head direction, angle of progression, and the head perineum distance were also noted. The primary outcome measure was the success of the vacuum. The secondary outcome measures included fetal complications and perineal lacerations.

RESULTS

A total of 196 consecutive patients were enrolled in the study. The occiput or forehead sign was present in 150 and was associated with a successful vaginal extraction in all cases. Of the 46 cases without the sign, 5 babies (10.8%) were delivered by cesarean section after a failed vacuum (P=.0006). The occiput or forehead sign was also associated with fewer grade 3-4 perineal lacerations (10.7% vs 35.7%; P=.0005) and cephalohematomas, although the difference was not statistically significant (1.4% vs 4.3%). There was a good correlation between the occiput or forehead sign and the other sonographic methods that previously had been proposed to predict a successful vacuum extraction, such as head direction, angle of progression, and head perineum distance.

CONCLUSION

In our hands, the fetal occiput or forehead sign was associated strongly with successful vacuum application and with a very low rate of maternal and fetal complications.

Intrapartum ultrasound monitoring of malposition and malrotation during labor neuraxial analgesia: maternal outcomes

Objective: This study analyzes the important role of ultrasonography (IUS) related to the maternal outcomes in women with fetal persistent occiput posterior position (POPP) and asynclitism (A) in labor neuraxial analgesia (LNA).Study design: Prospective assessment of 148 primiparous women diagnosed with the prolonged second stage of labor. Transabdominal and transperineal IUS were used to detect fetal head position and to evaluate the angle of progression (AOP) and pubic arch angle (PAA). Statistical data about maternal aspects, modalities of delivery and maternal outcomes were observed.Results: In all parturients included in the study, the operative delivery rate was 73%. In patients delivered via cesarean section, the PAA was ≤ of 96.5°. There was statistical correlation between doses of LNA and Apgar score at first minute (r0.8).Conclusions: There is a greater frequency of Fetal POPP and asynclitism related with maternal complications. The results of our study confirmed the importance of determination of angle of progression (AoP) and PAA in the prolonged second stage of labor. Unfavorable AoP and PAA, in presence of POPP and A, are related with high percentage of operative delivery. If the prolonged labor and delivery in these patients exceed time limit proposed by American College of Obstetricians and Gynecologists guidelines, it may be viewed as a possible malpractice. In cases of POPP with asynclitism, in the second stage of labor detected by IUS it is advisable to discontinue the anesthetic drugs administration in LNA; because the labor pain is related to the dystocia, an operative delivery is necessary to avoid maternal and fetal complications.

"Strategies to increase the accuracy and safety of OVD" (Clinical assessment skills and role of ultrasound, simulation training and new technologies to enhance instrument application)

Operative vaginal delivery (OVD) is commonly performed in the UK and Ireland. With skillful practice, the risks to mothers and babies are low. Caesarean section at full dilatation, particularly after failed OVD, can be more hazardous for mothers and babies. It is important to maintain and develop skills in OVD in order to provide it as a safe delivery option when the benefits outweigh the risks. As ultrasound machines have become more readily available on the labour ward, ultrasound assessment has been used to help clinicians diagnose the fetal head position and station, and also to try predict the success of the delivery. Simulation training has successfully been used in the setting of obstetric emergencies and is being developed to teach both technical and communication skills in OVD in order to improve maternal and neonatal outcomes. In this chapter we will discuss strategies to improve the accuracy and safety of OVD in more details.

A simple model to predict the complicated operative vaginal deliveries using vacuum or forceps

BACKGROUND

Complicated operative vaginal deliveries are associated with high neonatal morbidity and maternal trauma, especially if the procedure is unsuccessful and a cesarean delivery is needed. The decision to perform an operative vaginal delivery has traditionally been based on a subjective assessment by digital vaginal examination combined with the clinical expertise of the obstetrician. Currently there is no method for objectively quantifying the likelihood of successful delivery. Intrapartum ultrasound has been introduced in clinical practice to help predict the progression and final method of delivery.

OBJECTIVE

The aim of this study was to compare predictive models for identifying complicated operative vaginal deliveries (vacuum or forceps) based on intrapartum transperineal ultrasound in nulliparous women.

STUDY DESIGN

We performed a prospective cohort study in nulliparous women at term with singleton pregnancies and full dilatation who underwent intrapartum transperineal ultrasound evaluation prior to operative vaginal delivery. Managing obstetricians were blinded to the ultrasound data. Intrapartum transperineal ultrasound (angle of progression, progression distance, and midline angle) was performed immediately before instrument application, both at rest and concurrently with pushing. Intrapartum evaluation of fetal biometric parameters (estimated fetal weight, head circumference, and biparietal diameter) was also carried out. An operative vaginal delivery was classified as complicated when 1 or more of the following complications occurred: ≥3 tractions needed; third- to fourth-degree perineal tear; severe bleeding during episiotomy repair (decrease of ≥2.5 g/dL in the hemoglobin level); or significant traumatic neonatal lesion (subdural-intracerebral hemorrhage, epicranial subaponeurotic hemorrhage, skeletal injuries, injuries to spine and spinal cord, or peripheral and cranial nerve injuries). Six predictive models were evaluated (information available in Table 2).

RESULTS

We recruited 84 nulliparous patients, of whom 5 were excluded because of the difficulty of adequately evaluating the biparietal diameter and head circumference. A total of 79 nulliparous patients were studied (47 vacuum deliveries, 32 forceps deliveries) with 13 cases in the occiput-posterior position. We identified 31 cases of complicated operative vaginal deliveries (19 vacuum deliveries and 12 forceps deliveries). No differences were identified in obstetric, neonatal, or intrapartum characteristics between the 2 study groups (operative uncomplicated vaginal delivery vs operative complicated vaginal delivery), with the following exceptions: estimated fetal weight (3243 ± 425 g vs 3565 ± 330 g; P = .001), biparietal diameter (93.2 ± 2.1 vs 95.2 ± 2.3 mm; P = .001), head circumference (336 ± 12 vs 348 ± 6.4 mm; P = .001), sex (female 62.5% vs 29.0%; P = .010), newborn weight (3258 ± 472 g vs 3499 ± 383 g; P = .027), and number of tractions (median, interquartile range) (1 [1-2] vs 4 [3-5]; P < .0005). To predict complicated operative deliveries, all 6 of the studied models presented an area under the receiver-operating characteristics curve between 0.863 and 0.876 (95% confidence intervals, 0.775-0.950 and 0.790-0.963; P < .0005). The results of the study met the criteria of interpretability and parsimony (simplicity), allowing us to identify a binary logistic regression model based on the angle of progression and head circumference; this model has an area under the receiver-operating characteristics curve of 0.876 (95% confidence interval, 0.790-0.963; P < .0005) and a calibration slope B of 0.984 (95% confidence interval, 0.0.726-1.243; P < .0005).

CONCLUSION

The combination of the angle of progression and the head circumference can predict 87% of complicated operative vaginal deliveries and can be performed in the delivery room.

Ultrasound in labor: impact of a theoretical and practical course on caregiver's perspective and accuracy

Objective: The aim of the present study was two-fold; first is to assess the impact of a theoretical and practical course on the caregiver's perspective on the use of ultrasound in labor. Second is to evaluate the impact of the course on the measurement of the angle of progression.Materials and methods: Obstetricians participating in the course responded twice to a questionnaire addressing the caregiver's perspective on the use of ultrasound in labor, before and at the end of the course. In addition, all participants measured the angle of progression on a digital simulation software once following the theoretical part and a second time after the conclusion of both the theoretical and practical sessions. All answers to the questionnaire were compared before versus after the course. The angle of progression assessments after the theoretical part and those after the course were compared with those performed by an expert operator.Results: Overall, data from 51 participants were analyzed. In comparison with the pre-course questionnaire, more participants after the course believed ultrasound can be a useful instrument for fetal occiput presentation diagnosis (45; 88.2% versus 26; 51%, p < .001) and for fetal head progression evaluation (37; 72.5% versus 19; 37.3%; p < .001). Although before the course, most participants (32; 62.7%) thought that the transperineal parameters were too complex to be applied, only 19 (37.3%) still considered the complexity of the ultrasound indices, an obstacle against their application in clinical practice after the course (p = .002). Regarding the angle of progression, precourse measurements showed a systematic overestimation in comparison with the gold standard. Furthermore, the coefficient of variation, more than halved following the practical simulation reflecting at least a doubling of the angle of progression (AoP) measurement precision (14.2 versus 5.5%).Conclusions: A theoretical and practical course conducted by expert operators may positively change obstetricians' perspective on the use of ultrasound in labor. Moreover, a practical session seems to improve the participants' accuracy and precision in the assessment of fetal head descent by transperineal ultrasound.

Measuring angle of progression by transperineal ultrasonography to predict successful instrumental and cesarean deliveries during prolonged second stage of labor

OBJECTIVE

To compare the angle of progression (AoP) measured by transperineal ultrasonography before indicating an instrumental delivery or cesarean delivery.

METHODS

A prospective observational study was conducted among women with singleton term pregnancies with prolonged second stage of labor at Kwong Wah Hospital, Hong Kong, China, between May 16, 2011, and May 25, 2016. Transabdominal and transperineal ultrasonography were performed to determine fetal head position and AoP, respectively, both at rest and during uterine contraction with pushing. Mode of delivery was decided after vaginal examination without relying on ultrasonography.

RESULTS

Of 143 women, 116 underwent successful instrumental delivery and 27 underwent cesarean delivery. Median AoP was 153.0° in the instrumental group versus 139.0° in the cesarean group at rest (P<0.001), and 182.5° in the instrumental group versus 156.5° in the cesarean group during contraction (P<0.001). The best predictive cutoff AoP for successful instrumental delivery was 138.7° at rest (sensitivity 86.2%, specificity 51.9%) and 160.9° during contraction (sensitivity 87.1%, specificity 74.1%). No between-group differences in AoP were found for ease of vacuum extraction at rest (P=0.457) or during contraction with pushing (P=0.095).

CONCLUSION

The AoP predicted approximately 80% of successful instrumental deliveries performed for prolonged second stage of labor.

Head progression distance during the first stage of labor as a predictor for delivery outcome

Objectives: To assess if measurement of the head progression distance (PD) during the first stage of labor in nulliparous women can predict the delivery method.Methods: A prospective study was conducted on consecutive nulliparous women beyond 37 week's gestation during the first stage of labor. Transperineal ultrasound was performed to assess the PD. Analysis was performed on the relationships between PD during rest and during voluntary pushing and the fetal and maternal characteristics, delivery mode, and immediate postnatal outcomes.Results: Eighty seven suitable nulliparous women were suitable for analysis. PD was found to be significantly longer in women who delivered vaginally (VD) compared to those who underwent a cesarean section (CS) for obstructed labor: PD at rest was 2.51 ± 1.71 cm in women who delivered vaginally compared to 1.48 ± 1.9 cm in women who delivered by CS (p = .01). The PD during pushing was 3.43 ± 1.8 cm for a VD compared to 1.5 ± 2.1 cm for CS (p = .015). Logistic regression and receiver-operating characteristics curve analysis demonstrated a moderate predictive value of PD with respect to the mode of delivery (area under the curve was 0.67 during both resting and pushing period).Conclusion: PD measurements during the first stage of labor among nulliparous women differ significantly both in rest and during pushing between patients who delivered vaginally compared to CS and can therefore assist in predicting the mode of delivery.

ISUOG Practice Guidelines: intrapartum ultrasound

The purpose of these Guidelines is to review the published techniques of ultrasound in labor and their practical applications, to summarize the level of evidence regarding the use of ultrasound in labor and to provide guidance to practitioners on when ultrasound in labor is clinically indicated and how the sonographic findings may affect labor management. We do not imply or suggest that ultrasound in labor is a necessary standard of care.

Can we predict levator ani muscle avulsion in instrumental deliveries through intrapartum transperineal ultrasound?

Introduction: To determine whether intrapartum translabial ultrasound (ITU) is useful for the prediction of levator ani muscle (LAM) avulsions in instrumental deliveries (vacuum and forceps). Materials and methods: Prospective, observational study, including (1/2016 - 5/2016) 77 nulliparous women, with singleton pregnancies of ≥37 weeks of gestation and with cephalic presentation, who required vacuum or forceps instrumentation to complete the delivery. The ITU parameters evaluated were Angle of Progression (AoP), Progression Distance (PD), Head Direction (HD), and Midline Angle (MLA), both at rest and with maternal push. Evaluation of LAM avulsion was performed at 6 months postpartum with 3-4D transperineal ultrasound. Complete avulsion was defined as an abnormal insertion of LAM in the lower pubic branch identified in all three central slices. Results: Data from 48 nulliparous women were finally included in the study (34 vacuum and 14 forceps). We observed no difference in obstetric parameters between the two study groups (group with avulsion of LAM -14 cases, 29.2% - and group without avulsion of LAM -34 cases, 70.8%). The "LAM avulsion group" had an AoP and a PD of 136.7 ± 22.4 and 43.5 ± 15.6, respectively, versus 141.6 ± 21.3 and 47.2 ± 16.8 recorded in the group without avulsion (NS), respectively. We obtained a ROC curve for AoP and PD with a push of 0.66 (95% CI, 0.28-1.00) and 0.57 (95% CI, 0.39-0.75), respectively. Conclusions: ITU is not a useful technique to predict the occurrence of LAM avulsion in instrumental deliveries with vacuum or forceps.

Ultrasonographic evaluation of the second stage of labor. Predictive parameters for a successful vaginal delivery with or without neuraxial analgesia: a pilot study

PURPOSE

The aim of the study was to evaluate the progression and rotation of the fetal head during the second stage of labor using translabial ultrasound and to compare ultrasonographic data obtained in nulliparous women both receiving and not receiving neuraxial analgesia.

METHODS

The 49 patients enrolled in the study were divided into two groups according to receiving or not receiving neuraxial analgesia. Every half hour from full dilation to delivery, the ultrasonographic translabial parameters of Angle of Progression, Head Symphysis Distance, and Midline Angle were obtained and recorded by a single operator. Then, these records were compared between the two groups of patients.

RESULTS

Patients that underwent neuraxial analgesia presented with increased duration of the second stage of labor, with mean values of Angle of Progression significantly higher and of Midline Angle significantly lower for each time interval studied compared to patients without analgesia. A borderline significant relationship was found between administration of neuraxial analgesia and Head Symphysis Distance.

CONCLUSIONS

In this study, we demonstrated that combined spinal-epidural analgesia influences the duration of the second stage of labor and the initial progression and rotation of the fetal head through the birth canal, but not the kind of delivery. A correlation between Angle of Progression values and success in the application of a vacuum has been reported by other authors and confirmed in our study.

Automatic ultrasound technique to measure angle of progression during labor

OBJECTIVE

To evaluate the accuracy and reliability of an automatic ultrasound technique for assessment of the angle of progression (AoP) during labor.

METHODS

Thirty-nine pregnant women in the second stage of labor, with fetus in cephalic presentation, underwent conventional labor management with additional translabial sonographic examination. AoP was measured in a total of 95 acquisition sessions, both automatically by an innovative algorithm and manually by an experienced sonographer, who was blinded to the algorithm outcome. The results obtained from the manual measurement were used as the reference against which the performance of the algorithm was assessed. In order to overcome the common difficulties encountered when visualizing by sonography the pubic symphysis, the AoP was measured by considering as the symphysis landmark its centroid rather than its distal point, thereby assuring high measurement reliability and reproducibility, while maintaining objectivity and accuracy in the evaluation of progression of labor.

RESULTS

There was a strong and statistically significant correlation between AoP values measured by the algorithm and the reference values (r = 0.99, P < 0.001). The high accuracy provided by the automatic method was also highlighted by the corresponding high values of the coefficient of determination (r²  = 0.98) and the low residual errors (root mean square error = 2°27' (2.1%)). The global agreement between the two methods, assessed through Bland-Altman analysis, resulted in a negligible mean difference of 1°1' (limits of agreement, 4°29').

CONCLUSIONS

The proposed automatic algorithm is a reliable technique for measurement of the AoP. Its (relative) operator-independence has the potential to reduce human errors and speed up ultrasound acquisition time, which should facilitate management of women during labor. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Three-dimensional/four-dimensional transperineal ultrasound: clinical utility and future prospects

During the last decade, there has been a huge advancement in the use of transperineal ultrasound (TPU) in the field of obstetrics and gynecology. Its main applications in obstetrics include the monitoring of fetal progression in labor and recently the assessment of maternal pelvic dimensions, whereas in gynecology, TPU is at present widely used for the evaluation of the female pelvic floor, opening new boundaries for the assessment of pelvic floor disorders. The association of volumetric three-dimensional techniques has largely contributed to the remarkable progress that has occurred in the use of TPU. The aim of this paper is to offer an overview of the advantages, challenges and future perspectives of the use of TPU for women’s imaging.

Mueller-Hillis maneuver and angle of progression: Are they correlated?

Objective:

Mueller-Hillis maneuver (MHM) and angle of progression (AOP) measured by transperineal ultrasound have been used to assess fetal head descent during the second stage of labor. We aimed to assess whether AOP correlates with MHM in the second stage of labor.

Method:

A prospective observational study including women with singleton pregnancy in the second stage of labor was performed. The AOP was measured immediately after the Mueller-Hillis maneuver. A receiver-operating characteristics (ROC) curve analysis was performed to determine the best discriminatory AOP cut-off for the identification of a positive MHM. A p-value less than 0.05 was considered statistically significant.

Results:

One hundred and sixty-six (166) women were enrolled in the study and 81.3% (n=135) had a positive MHM. The median AOP was 143º (106º to 210º). The area under the curve for the prediction of a positive maneuver was 0.619 (p=0.040). Derived from the ROC curve, an AOP of 138.5º had the best diagnostic performance for the identification of a positive MHM (specificity of 65% and a sensitivity of 67%).

Conclusion:

An AOP of 138º seems to be associated with a positive MHM in the second stage of labor.

Measurement of retropubic tissue thickness using intrapartum transperineal ultrasound to assess cephalopelvic disproportion

Purpose

First, to describe a new method of assessing cephalopelvic disproportion by measuring the retropubic tissue thickness (RTT), and second, to determine whether RTT was associated with an eventual delivery by cesarean section.

Methods

Three-dimensional transperineal ultrasound scans were performed on 129 laboring nulliparous women to obtain 3-dimensional volume datasets for assessing RTT. RTT was measured off-line by three operators (A, B, and C) as the shortest distance between the capsule of the pubic symphysis and the outer border of the fetal skull. The intraoperator repeatability of operator A and the interoperator reproducibility among A, B, and C were determined. The RTT in women who were delivered by cesarean section due to failure to progress was compared to that of women who had a vaginal delivery.

Results

The intraoperator repeatability for RTT was 1.2 mm. The overall RTT interoperator interclass correlation was 0.97 (0.95-0.98). The RTT in women who had a spontaneous, instrumental, or cesarean delivery was 1.16±0.32 cm, 1.12±0.25 cm, and 0.94±0.25 cm, respectively. Women who were delivered by cesarean section had a significantly smaller RTT than women who had a spontaneous delivery (P=0.008). There was no statistically significant difference in RTT between patients who had a normal vaginal delivery and patients who had an instrumental delivery (P=0.990), or between those who had an instrumental delivery and those who had a cesarean delivery after the Bonferroni correction (P=0.120).

Conclusion

RTT can be measured with satisfactory intraoperator repeatability and interoperator reproducibility. RTT was significantly smaller in women who eventually had a cesarean delivery than in those who had a vaginal delivery.

Sonographic prediction of outcome of vacuum deliveries: a multicenter, prospective cohort study

BACKGROUND

Safe management of the second stage of labor is of great importance. Unnecessary interventions should be avoided and correct timing of interventions should be focused. Ultrasound assessment of fetal position and station has a potential to improve the precision in diagnosing and managing prolonged or arrested labors. The decision to perform vacuum delivery is traditionally based on subjective assessment by digital vaginal examination and clinical expertise and there is currently no method of objectively quantifying the likelihood of successful delivery. Prolonged attempts at vacuum delivery are associated with neonatal morbidity and maternal trauma, especially so if the procedure is unsuccessful and a cesarean is performed.

OBJECTIVE

The aim of the study was to assess if ultrasound measurements of fetal position and station can predict duration of vacuum extractions, mode of delivery, and fetal outcome in nulliparous women with prolonged second stage of labor.

STUDY DESIGN

We performed a prospective cohort study in nulliparous women at term with prolonged second stage of labor in 7 European maternity units from 2013 through 2016. Fetal head position and station were determined using transabdominal and transperineal ultrasound, respectively. Our preliminary clinical experience assessing head-perineum distance prior to vacuum delivery suggested that we should set 25 mm for the power calculation, a level corresponding roughly to +2 below the ischial spines. The main outcome was duration of vacuum extraction in relation to ultrasound measured head-perineum distance with a predefined cut-off of 25 mm, and 220 women were needed to discriminate between groups using a hazard ratio of 1.5 with 80% power and alpha 5%. Secondary outcomes were delivery mode and umbilical artery cord blood samples after birth. The time interval was evaluated using survival analyses, and the outcomes of delivery were evaluated using receiver operating characteristic curves and descriptive statistics. Results were analyzed according to intention to treat.

RESULTS

The study population comprised 222 women. The duration of vacuum extraction was shorter in women with head-perineum distance ≤25 mm (log rank test <0.01). The estimated median duration in women with head-perineum distance ≤25 mm was 6.0 (95% confidence interval, 5.2-6.8) minutes vs 8.0 (95% confidence interval, 7.1-8.9) minutes in women with head-perineum distance >25 mm. The head-perineum distance was associated with spontaneous delivery with area under the curve 83% (95% confidence interval, 77-89%) and associated with cesarean with area under the curve 83% (95% confidence interval, 74-92%). In women with head-perineum distance ≤35 mm, 7/181 (3.9%) were delivered by cesarean vs 9/41 (22.0%) in women with head-perineum distance >35 mm (P <.01). Ultrasound-assessed position was occiput anterior in 73%. Only 3/138 (2.2%) fetuses in occiput anterior position and head-perineum distance ≤35 mm vs 6/17 (35.3%) with nonocciput anterior position and head-perineum distance >35 mm were delivered by cesarean. Umbilical cord arterial pH <7.10 occurred in 2/144 (1.4%) women with head-perineum distance ≤35 mm compared to 8/40 (20.0%) with head-perineum distance >35 mm (P < .01).

CONCLUSION

Ultrasound has the potential to predict labor outcome in women with prolonged second stage of labor. The information obtained could guide whether vacuum delivery should be attempted or if cesarean is preferable, whether senior staff should be in attendance, and if the vacuum attempt should be performed in the operating theater.

Predicting the difficulty of operative vaginal delivery by ultrasound measurement of fetal head station

BACKGROUND

Clinical assessment of fetal head station is difficult and subjective; it is mandatory before attempting operative vaginal delivery.

OBJECTIVE

The principal objective of our study was to assess whether measurement of the perineum-to-skull ultrasound distance was predictive of a difficult operative vaginal delivery. Secondary objectives included evaluation of the interobserver reproducibility of perineum-to-skull ultrasound distance and comparison of this measurement and digital examination in predicting a difficult operative delivery.

STUDY DESIGN

This was a prospective cohort study including all cases of operative vaginal deliveries in singleton pregnancies in cephalic presentation >34 weeks' gestation, from 2012 through 2015. All data were entered prospectively in a medical record system specially devised to meet the requirements of this study.

RESULTS

Of the 659 patients in whom perineum-to-skull ultrasound distance was measured prior to operative vaginal delivery, 120 (18%) met the composite criterion for a difficult extraction. Perineum-to-skull ultrasound distance measurement of ≥40 mm was significantly associated with the occurrence of a difficult extraction based on the composite criterion, after adjustment for parity, presentation type, and fetal macrosomia (odds ratio, 2.38; 95% confidence interval, 1.51-3.74; P = .0002). The intraclass correlation coefficient between the perineum-to-skull ultrasound distance measured by the first operator and that measured by the second operator was 0.96 (95% confidence interval, 0.95-0.97; P < .0001). Based on the receiver operating characteristic curve analyses, perineum-to-skull ultrasound distance was a more accurate predictor of difficult operative delivery than digital vaginal examination (P = .036).

CONCLUSION

Measurement of the perineum-fetal skull ultrasound distance is a reproducible and predictive index of the difficulty of instrumental extraction. Ultrasound is a useful supplementary tool to the usual clinical findings.

Transperineal sonographic assessment of angle of progression as a predictor of successful vaginal delivery following induction of labor

OBJECTIVES

To assess whether measurement of the angle of progression (AOP) before induction of labor (IOL) can predict successful vaginal delivery in nulliparous women.

METHODS

This was a prospective, observational study of nulliparous women with a singleton term pregnancy and an indication for IOL. Transperineal sonography was used to measure the AOP before cervical ripening. Since all women enrolled had a low Bishop score, 98.6% of them were induced with either intracervical extra-amniotic balloon catheter or vaginal prostaglandin E-2. The staff in the labor ward were blinded to the AOP measurements. Clinical data were retrieved from computerized medical records.

RESULTS

Of the 150 women included in the final analysis, 40 (26.7%) delivered by Cesarean section. The median AOP was narrower in women who had a Cesarean delivery than in those who delivered vaginally (90° (interquartile range (IQR), 84-94.5°) vs 98° (IQR, 90.8-105°); P < 0.001). When including only women who underwent Cesarean delivery for non-progression of labor (n = 27) in the analysis, an AOP of > 92° (derived from a receiver-operating characteristics curve) was associated with a successful vaginal delivery in 94.8% of women. Multivariate stepwise logistic regression analysis including maternal age, body mass index, gestational age, estimated fetal weight, fetal head station, indication for IOL and AOP demonstrated that only AOP was independently associated with the prediction of a successful induction.

CONCLUSION

AOP may be a useful sonographic parameter for predicting successful vaginal delivery among nulliparous women at term undergoing IOL; an AOP wider than 92° is associated with a high rate of vaginal delivery. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Computed tomographic study of anatomical relationship between pubic symphysis and ischial spines to improve interpretation of intrapartum translabial ultrasound

OBJECTIVE

To analyze the anatomical relationship between the pubic symphysis and the ischial spines to determine reliable landmarks for the assessment of fetal head descent by intrapartum translabial ultrasound (ITU).

METHODS

All computed tomography (CT) scans performed for breech presentation and for twin delivery between 2006 and 2014 in a tertiary university hospital were obtained for measurement and analysis by two operators. The symphysis-left ischial spine angle (SIA) and the symphysis-left ischial spine distance (SID) were measured on three-dimensional reconstructions from the CT volume dataset. We calculated intra- and interobserver agreements for SIA and SID with 95% prediction intervals, created Bland-Altman plots with 95% limits of agreement and estimated the intraclass correlation coefficient (ICC). A sagittal plane projection from the SIA enabled calculation of a sagittal angle, corresponding to the angle of progression (AoP) on ITU.

RESULTS

SIA and SID were obtained from CT images from 458 women. Reproducibility was good for both SIA (intraobserver ICC, 0.94 (95% CI, 0.88-0.97) and interobserver ICC, 0.81 (95% CI, 0.66-0.92)) and SID (intraobserver ICC, 0.92 (95% CI, 0.82-0.97) and interobserver ICC, 0.83 (95% CI, 0.73-0.92)). The median SIA was 106° (interquartile range (IQR), 105-109°) and median SID was 26.1 (IQR, 23.4-29.5) mm. SIA and SID were not correlated with pelvic diameter or height. The 50^th percentile of AoP was 110°.

CONCLUSION

Knowledge of the anatomical relationship between the pubic symphysis and ischial spines makes it possible to establish a sonographic method for assesssing fetal head descent by taking into account the level of the ischial spines. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Intrapartum transperineal ultrasound for evaluating uterine contraction intensity in the second stage of labor

PURPOSE

To clarify whether intrapartum transperineal ultrasound (ITU) can be used to evaluate uterine contraction intensity, and whether the intensity is associated with the duration of the second stage.

METHODS

A prospective observational study was performed involving 86 women with a normal singleton term fetus and more than three contractions every 10 min. ITU was performed for contractile and non-contractile periods of labor at the beginning of the second stage, and one representative "angle of progression (AoP)" image was selected for each period. The Mann-Whitney U test was used to compare ∆AoP, the difference between the two angles, depending on the duration of the second stage. Receiver operating characteristic curves were used to evaluate the probability of duration of the second stage ≤50 min in nulliparous women.

RESULTS

Among nulliparous women, ΔAoP differed significantly according to the duration of the second stage (52.5° ± 5.0° for ≤50 min vs. 30.9° ± 2.1° for >50 min; P < 0.001). Receiver operating characteristic curve analysis showed that approximately 85% of nulliparous women with ΔAoP greater than 40° delivered within 50 min.

CONCLUSION

These findings could be utilized in the evaluation of uterine contraction intensity, and ∆AoP measurement could be used to predict the duration of the second stage of labor in nulliparous women.

Angle of fetal head progression measured using transperineal ultrasound as a predictive factor of vacuum extraction failure

OBJECTIVE

To evaluate the predictive value of angle of progression (AoP) of the fetal head for a failed vacuum delivery.

METHODS

This was a prospective observational study that included women with a singleton pregnancy of ≥ 37 weeks' gestation, in cephalic presentation requiring vacuum extraction. Transperineal ultrasound was performed immediately before vacuum extraction, although AoP was measured on stored images after delivery. Vacuum extraction was defined as failed when the duration of extraction exceeded 20 min or the vacuum cup detached more than three times. We compared the demographic and ultrasound data of failed vacuum deliveries with those that were successful. The predictive value of AoP for failure of vacuum delivery was calculated.

RESULTS

AoP was measured in 235 women. Vacuum extractions failed in 30 (12.8%) women (29/184 nulliparous and 1/51 parous) and resulted in 28 vaginal deliveries by forceps and two Cesarean deliveries. Median AoP was significantly lower in the vacuum failure group compared with those with successful vacuum delivery (136.6° (interquartile range (IQR), 129.8-144.1°) vs 145.9° (IQR, 135.0-158.4°); P < 0.01). As all but one failed vacuum extraction occurred among nulliparous women, the predictive value of AoP was calculated in this subgroup of women. The area under the receiver-operating characteristics curve for prediction of vacuum extraction failure was 0.67 (95% CI, 0.57-0.77) and the optimal AoP cut-off was 145.5°. Above this value, the rate of vacuum extraction failure fell below 5%.

CONCLUSION

AoP is a predictive factor of failed vacuum extraction, especially among nulliparous women whose risk of failure is high. AoP measurement may help in choosing between forceps and vacuum extraction. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Correlation of intrapartum translabial ultrasound parameters with computed tomographic 3D reconstruction of the female pelvis

AIMS

Intrapartum translabial ultrasound [ITU] can be an objective, reproducible and more reliable method than digital vaginal examination when evaluating fetal head position and station in prolonged second stage of labor. However, two-dimensional (2D) ultrasound is not sufficient to demonstrate the ischial spines and other important "landmarks" of the female pelvis. Therefore, the purpose of this study was to evaluate the distance of the interspinous plane as a parallel line to the infrapubic line in 2D ITU with the help of 3D computed tomography and digital reconstruction.

RESULTS

Mean distance between the infrapubic plane and the tip of the ischiadic spine was 32.35 (±4.46) mm. The mean height was 166 (±7) cm; the mean weight was 67.5 (±18.4) kg. Body height and the measured distance were significantly correlated (P=0.025; correlation coefficient of 0.5), whereas body weight was not (P=0.37; correlation coefficient of -0.214).

CONCLUSIONS

With the present results, clinicians were enabled to transfer the reproducible measurements of the "head station" by ITU to the widespread but observer-depending vaginal examination. Furthermore, ITU can be verified as an objective method in comparison to subjective palpation with the ability to optimize the evaluation of the head station according to bony structures as landmarks in a standardized application.

[Are ultrasound measurements of the cervical length and fetal head-perineum distance predictive of delivery outcome in post-term pregnancies?]

OBJECTIVE

Post-term pregnancy is frequently associated with higher fetal and maternal morbidity and mortality. Its management essentially depends on clinical cervical characteristics as evaluated by the Bishop score (BS). However, BS is poorly predictive of the delivery outcome. We sought to demonstrate that ultrasound measurement of cervical length and evaluation of fetal height could predict the outcome in post-term pregnancies.

METHODS

A prospective single center study was undertaken between the 21st of January and the 1st of June 2013. Fetal height was measured using a transperineal technique and cervical length was evaluated by a vaginal ultrasound on patients consulting and their term date. C-section rates were considered to be the primary judgment criteria.

RESULTS

A total of 136 patients were included. C-section rates in this population was 19%. Fetal height and cervical length were not different between the C-section group and the vaginal delivery group.

CONCLUSION

Our study demonstrates that ultrasound measurement of cervical length and fetal height do not show better results than BS in predicting the outcome of post-term pregnancy. Combining these ultrasound measurements has already been suggested in other studies and promising results have been shown. More studies are necessary to further these results.

Prediction of spontaneous vaginal delivery by transperineal ultrasound performed just after full cervical dilatation is determined

PURPOSE

To investigate whether transperineal ultrasound examination just after full cervical dilatation is determined can predict the mode of delivery.

METHODS

This was a prospective observational study of pregnant women. After full cervical dilatation was determined by vaginal examination during labor, transperineal ultrasound was immediately performed, and the head direction (HD), progression distance (PD), and angle of progression (AoP) were measured. The cases were divided into two groups: spontaneous vaginal delivery and operative delivery due to failure of progression. Differences between the groups were statistically analyzed using Student's t test and Fisher's exact test.

RESULTS

Of the 50 women, 42 had spontaneous vaginal deliveries and 8 had vacuum extractions. The spontaneous delivery group had significantly higher HD, PD, and AoP values than the vacuum extraction group. The areas under the receiver-operating characteristic curves for the prediction of spontaneous vaginal delivery were 0.850 for HD, 0.827 for PD, and 0.783 for AoP. The optimum cut-off points and positive predictive values were 83° and 92.9 % for HD, 56 mm and 94.9 % for PD, and 146° and 94.3 % for AoP, respectively.

CONCLUSION

Transperineal ultrasound examination just after full cervical dilatation was determined was useful in predicting spontaneous vaginal delivery.

Association of fetal biparietal diameter with mode of delivery and perinatal outcome

OBJECTIVE

To determine the association between sonographic assessment of fetal biparietal diameter (BPD) and pregnancy outcome.

METHODS

This was a retrospective cohort study of pregnancies at 37-42 weeks of gestation which had antepartum sonographic measurement of BPD within 7 days before delivery. Eligibility was limited to singleton pregnancies with neither known structural or chromosomal abnormalities nor prelabor Cesarean delivery (CD). The association of BPD with outcome was analyzed using multivariate logistic regression, receiver-operating characteristics curves and stratification according to BPD quartiles.

RESULTS

In total, 3229 women were eligible for analysis, of whom 2483 (76.9%) had a spontaneous vaginal delivery (SVD), 418 (12.9%) underwent operative vaginal delivery (OVD) and 328 (10.2%) underwent CD. The mean BPD in the obstetric intervention groups (OVD and CD) was significantly higher than that in the SVD group (P < 0.001). After adjusting for confounders, increased BPD was an independent risk factor such that higher values of BPD were associated with progressively higher risk of obstetric intervention (adjusted odds ratio, 1.05 for each 1-mm increase in BPD (95% CI, 1.02-1.09)), but no clear cut-off value for obstetric intervention was found. The fourth quartile group (BPD ≥ 97 mm) was associated with a significantly lower SVD rate (P < 0.001) and higher OVD rate (P = 0.04), relative to the first (BPD 88-90 mm) and second (BPD 91-93 mm) quartile groups, with no apparent adverse impact on immediate neonatal outcome.

CONCLUSIONS

Increased BPD within the week prior to delivery is an independent risk factor such that higher values of BPD are associated with progressively higher risk of obstetric intervention; however, in our experience, no adverse neonatal outcome resulted from such intervention. Thus, increased BPD should not discourage a trial of vaginal delivery.

Is intrapartum translabial ultrasound examination painless?

OBJECTIVES

To find out whether intrapartum translabial ultrasound examination is painless by comparing pain score of ultrasound-based versus digital vaginal examination of foetal head station.

METHODS

In 94 women carrying uncomplicated-term singleton pregnancies, labour progress was assessed by translabial ultrasound, followed immediately by conventional digital vaginal examination. Pain scores (0-10) using visual analogue pain scale were obtained for both examinations. Forty-eight and forty-six sets of data were obtained in first and second stage of labour, respectively. The difference in pain scores between digital vaginal examination and translabial ultrasound was analysed.

RESULTS

The median pain score for translabial ultrasound was 0 (range 0-8), while that for vaginal examination was 4.5 (range 0-10), p < 0.05. There was no significant difference in pain scores between first and second stages of labour for translabial ultrasound (p = 0.123) and for vaginal examination (p = 0.680). The pain score for vaginal examination was higher than that of translabial ultrasound in 81.9%, similar in 13.8% and lower in 4.3% of cases. There was no statistically significant difference in pain scores obtained for digital vaginal examination by clinicians with different experience (p = 0.941).

CONCLUSIONS

Intrapartum translabial ultrasound is generally better tolerated than digital vaginal examination for assessment of labour progress, making it an acceptable adjunctive assessment tool during labour.

Prediction of delivery mode by ultrasound-assessed fetal position in nulliparous women with prolonged first stage of labor

OBJECTIVES

To ascertain if fetal head position on transabdominal ultrasound is associated with delivery by Cesarean section in nulliparous women with a prolonged first stage of labor.

METHODS

This was a prospective observational study performed at Stavanger University Hospital, Norway, and Addenbrooke's Hospital, Cambridge, UK, between January 2012 and April 2013. Nulliparous pregnant women with a singleton cephalic presentation at term and prolonged labor had fetal head position assessed by ultrasound. The main outcome was Cesarean section vs vaginal delivery, and secondary outcomes were association of fetal head position with operative vaginal delivery and duration of remaining time in labor.

RESULTS

Fetal head position was assessed successfully by ultrasound examination in 142/150 (95%) women. In total, 19/50 (38%) women with a fetus in the occiput posterior (OP) position were delivered by Cesarean section compared with 16/92 (17%) women with a fetus in a non-OP position (P = 0.01). On multivariable logistic regression analysis, the OP position predicted delivery by Cesarean section with an odds ratio (OR) of 2.9 (95% CI, 1.3-6.7; P = 0.01) and induction of labor with an OR of 2.4 (95% CI, 1.0-5.6; P = 0.05). Fetal head position was not associated with operative vaginal delivery or with remaining time in labor. The agreement between a digital and an ultrasound assessment of OP position was poor (Cohen's kappa = 0.19; P = 0.18).

CONCLUSION

OP fetal head position assessed by transabdominal ultrasound was significantly associated with delivery by Cesarean section.

Agreement between transperineal ultrasound measurements and digital examinations of cervical dilatation during labor

Background

To compare 2D transperineal ultrasound assessment of cervical dilatation with vaginal examination and to investigate intra-observer variability of the ultrasound method.

Methods

A prospective observational study was performed at Skane University Hospital, Lund, Sweden between October 2013 and June 2014. Women with one fetus in cephalic presentation at term had the cervical dilatation assessed with ultrasound and digital vaginal examinations during labor. Inter-method agreement between ultrasound and digital examinations and intra-observer repeatability of ultrasound examinations were tested.

Results

Cervical dilatation was successfully assessed with ultrasound in 61/86 (71 %) women. The mean difference between cervical dilatation and ultrasound measurement was 0.9 cm (95 % CI 0.47–1.34). Interclass correlation coefficient (ICC) was 0.83 (95 % CI 0.72–0.90). Intra-observer repeatability was analysed in 26 women. The intra-observer ICC was 0.99 (95 % CI 0.97–0.99). The repeatability coefficient was ± 0.68 (95 % CI 0.45–0.91).

Conclusion

The mean ultrasound measurement of cervical dilatation was approximately 1 cm less than clinical assessment. The intra-observer repeatability of ultrasound measurements was high.

Intrapartum sonographic signs: new diagnostic tools in malposition and malrotation

In the past years, numerous studies have been published on the use of ultrasound during labor, showing this is an effective, accurate and objective tool for the assessment of the fetal head position and station. Literature affirmed that traditional transvaginal digital examination is highly subjective and dependent on the operator's experience. On the contrary, the use of intrapartum suprapubic transabdominal ultrasound can improve accuracy in determination of fetal head position and the precise knowledge of the location of specific fetal head landmarks in relationship to maternal pelvis. Intrapartum ultrasound will assist obstetricians in the diagnosis of normal labor progression, suggesting when medical and or operative intervention should be taken in case of complications. During each fetal head movement, there is a very specific relationship between fetal head landmarks and well-identified maternal structures, so the ultrasound diagnosis is performed step by step. In this review, we summarized the clinical situation of the fetal head in the pelvis and the relative ultrasonographic signs. Moreover, we collected all the ultrasonographic measures to diagnose the fetal head progression and rotations in the birth canal.

Acceptability of Intrapartum Ultrasound Monitoring - Experience from a Romanian Longitudinal Study

OBJECTIVES

To assess the acceptability of intrapartum ultrasound (IPUS) labor monitoring in unselected Romanian women attending a tertiary maternity unit and the patients' experience of the examination (i.e. the perceived difficulty regarding the evaluation protocol).

METHODS

The research was a prospective longitudinal observational study on unselected low-risk women that delivered in our unit. IPUS monitoring of active labor was proposed for observational purposes in low-risk population. Transabdominal and transperineal scans were performed hourly in the first stage of labor and at every 15 minutes in the second stage. The second day after birth, consenting women were invited to take part in a questionnaire survey with features regarding the patient's impression about the ultrasound monitoring scans during labor, and the acceptability of having an IPUS protocol for labor monitoring in the future.

RESULTS

From 200 parturient women questioned, 98% of them agreed to IPUS investigation protocol. The demographic characteristics did not influence the acceptance. However, due to the small number of women declining IPUS we were not able to compare the characteristics and perceptions of women who declined the scan with those who accepted it. Most of the women (93% of accepters and 75% of decliners) had little difficulty deciding whether or not to have the scan protocol. All laboring women who had the IPUS scan found it an acceptable experience; 21% of women without epidural anesthesia rated the perceived difficulty as "mild" or "discomforting". Women rated having the IPUS scan as being significantly less difficult than having a cervical smear, transvaginal scan or having a digital clinical evaluation. 67% of the studied patients expressed increased confidence while being able to follow along the medical personnel the progression of the labor on the ultrasound screen. 97% of the consenting women who had the IPUS scans and all the 4 decliners said they would definitely or probably agree such ultrasound monitoring in a future labor, if this technique is proven useful for the labor outcome.

CONCLUSIONS

IPUS protocol for labor monitoring was overwhelmingly acceptable in our population of women, despite the fact that they were learning about the procedure for the first time. The demographic characteristics did not influence acceptance, but due to the high rate of acceptance, predictors of acceptance could not be analyzed. More than two thirds of the patients expressed increased confidence while being able to follow along the medical personnel the progression of the labor on the ultrasound screen and almost all the participants were willing to have the procedure again in future, further reinforcing their favorable attitude to the procedure.

The Angle of Progression at Station 0 and in Magnetic Resonance and Transperineal Ultrasound Assessment

The transperineal ultrasound (TPU) value of the angle of progression (AOP) during fetal head engagement, at station 0, is a critical cut-off for current obstetrical practice, especially when intrapartum instrumental interventions are required. Still, controversial measurements were reported in previous high resolution imagistic studies. Our TPU and direct “gold-standard” magnetic resonance (MRI) measurements confirm that station 0 corresponds to a 120° AOP, concordantly. Based on these findings, the fact that an AOP of 120° or greater was previously strongly associated with vaginal delivery may be due to the achievement of head engagement in labor.