|Year : 2020 | Volume
| Issue : 2 | Page : 474-479
Role of intrapartum transperineal ultrasound in predicting mode of delivery in primigravida women
Mohamed M Fahmy1, Alaa Eldin F. Elhalaby1, Haitham A Hamza1, Ibrahim S Elnasr1, Noha M. T. Elshaikh2
1 Department of Obstetrics and Gynecology, Faculty of Medicine, Menoufia University, Menoufia, Egypt
2 Department of Obstetrics and Gynecology, Shebin Al-Kom Teaching Hospital, Menoufia, Egypt
|Date of Submission||16-Jul-2019|
|Date of Decision||29-Aug-2019|
|Date of Acceptance||06-Sep-2019|
|Date of Web Publication||27-Jun-2020|
Noha M. T. Elshaikh
Shebin El-Kom, Menoufia
Source of Support: None, Conflict of Interest: None
To evaluate if the different intrapartum transperineal ultrasound (ITU) parameters [angel of progression (AOP), head direction (HD), and head progression distance (HPD)] are significant indicators to predict mode of delivery and discuss the role of ITU parameters in the prediction of mode of delivery in primigravida women.
Spontaneous vaginal delivery without obstetric intervention is the suitable outcome for most pregnancies. However, some women fail to progress in the second stage of labor and so require operative delivery.
Patients and methods
In this cross-sectional study, a transperineal ultrasound examination was performed in 70 nulliparous women aged from 18 to 40 years old with single live fetus in cephalic presentation, at term (≥37 weeks), in the active phase of labor. Data were collected and tabulated.
There were good correlations between ITU parameters and delivery mode using a cutoff of more than or equal to 120° for the AOP and a cutoff of less than or equal to 45 mm for the HPD. The HD was divided into three categories of more than 30°, 0–30°, and less than 0°.
The sonographic parameters AOP, HPD, and HD can be used to predict the mode of delivery in primigravida women.
Keywords: angel of progression, head direction, head progression distance, intrapartum transperineal ultrasound
|How to cite this article:|
Fahmy MM, Elhalaby AE, Hamza HA, Elnasr IS, Elshaikh NM. Role of intrapartum transperineal ultrasound in predicting mode of delivery in primigravida women. Menoufia Med J 2020;33:474-9
|How to cite this URL:|
Fahmy MM, Elhalaby AE, Hamza HA, Elnasr IS, Elshaikh NM. Role of intrapartum transperineal ultrasound in predicting mode of delivery in primigravida women. Menoufia Med J [serial online] 2020 [cited 2020 Jul 15];33:474-9. Available from: http://www.mmj.eg.net/text.asp?2020/33/2/474/287759
| Introduction|| |
Spontaneous vaginal delivery without obstetric intervention is the suitable outcome for most pregnancies. Progression failure and fetal distress are considered the two leading causes of increased rates of cesarean section with potential complications.
However, women who fail to progress to labor require operative delivery whether instrumental delivery (forceps or vacuum), cesarean section after failed instrumental delivery, or primary cesarean section. As one of the main causes of cesarean section is failure to progress to labor, reliable prediction of failure to progress will lead to a reduction in unplanned emergency cesarean. The American College of Obstetricians and Gynecologists released a DVD entitled 'Assessment of fetal head descent in labor with transperineal ultrasound,' which suggested that fetal head descent could be assessed by angle measurements of progressive head deflection.
Recent studies have shown that ultrasound measurements of head descent in labor correlate with birth progress and outcome. Different parameters have been proposed and evaluated for their reproducibility, including intrapartum transperineal ultrasound (ITU) for measurement of angel of progression (AOP), head progression distance (HPD), and head direction (HD).
AOP is the angle between a line through the midline of the symphysis pubis and another line from the anterior margin of the symphysis pubis to the leading edge of the fetal head. HPD is the distance between the infrapubic line (the line through the inferior margin of the symphysis pubis perpendicular to the long axis of the symphysis) and a parallel line through the deepest bony part of the fetal head. HD is the angle between a line perpendicular to the widest diameter of the fetal head and a line parallel to the line through the midline of the symphysis pubis.
The objective of this study is to investigate the role of ITU parameters in prediction of the mode of delivery in primigravida women.
| Patients and Methods|| |
In this cross-sectional study, we evaluated and analyzed 70 nulliparous women aged from 18 to 40 years old, at term (≥37 weeks) during labor, between the periods from November 2017 to November 2018, who were attending the emergency labor ward in Menoufia University Hospital. The study protocol was approved by the Medical Ethical Committee of Faculty of Medicine, Menoufia University. A detailed menstrual and medical history was taken first. An informed consent was taken from each participant before being enrolled in the study.
The inclusion criteria were nulliparous women, gestational age from 37 to 40 weeks, singleton fetus, and cephalic presentation during the active phase of labor.
The exclusion criteria were multipara women, gestational age at 36 weeks or before, multiple pregnancies such as twins, and fetal presentation other than cephalic presentation. The women were not in labor or scheduled for induction of labor or scheduled for elective cesarean section for any cause or with previous cesarean delivery or had any contraindication of normal delivery, for examples, cord prolapse, abnormal placentation, abnormality in fetal heart rate patterns, and medical and obstetric complications.
All women were assessed by the physician on duty, including general, abdominal, and local examination and investigation. The study was explained to them, and an informed consent was obtained before a transperineal ultrasound examination. The ultrasound assessment was performed by the same experienced operator. The examination was conducted with IBE Sonata plus ultrasound systems equipped with a 3–5 MHz transabdominal two-dimensional convex transducer.
A conventional abdominal obstetrical ultrasound was first performed for fetal well-being and biometry. The transducer was then positioned at the suprapubic area to identify the fetal presenting part (head) and position as determined by locating the fetal occiput and/or spine.
Before switching to transperineal acquisition, care was taken to utilize the widest angle and the lowest output frequency together with the maximum depth to visualize the whole infrapubic plane (vide infra) as much as possible.
Then the abdominal probe was enclosed in a latex glove covered with ultrasound gel and then placed between the labia below the pubic symphysis. The sagittal view, in which the long axis of the pubic symphysis could be ascertained, was obtained by gently rocking the transducer upward. While in this same plane, the leading portion of the fetal head could easily be discerned. On the sagittal image, a line was drawn on the screen between calipers placed at the two points identifying the long axis of the pubic symphysis. A second caliper line then was created on the frozen image that extends from the most inferior portion of the pubic symphysis tangentially to the fetal skull contour. The AOP was the angle between the constructed lines and was measured electronically [Figure 1]. On the same frozen image, we measured the HD which is defined as the angle between the infrapubic line (a line perpendicular to the longer diameter of the pubis starting from its inferior border) and another line drawn perpendicular to the widest transverse diameter of the fetal head. Using this technique, three types of HD were described: head down, horizontal, and head up [Figure 1]. HPD was measured also as a minimal distance from the infrapubic line and the leading edge of the fetal skull [Figure 1].
|Figure 1: Ultrasound image and diagram from the study material demonstrating (a) the AOP of the fetal head, (b) the HD angle of the fetal head, and (c) the HPD of the fetal head. AOP, angel of progression; HD, head direction; HPD, head progression distance.|
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Vaginal examinations, as well as translabial ultrasound parameters, were taken both at same session by two different well-trained obstetric operators.
From the previous studies, there was a difference in the angle between women who delivered vaginal delivery and cesarean section, with SD of nearly ±25.2.
The data were analyzed with IBM SPSS 20.0 (IBM Corp., Armonk, New York, USA). The univariate descriptive analysis of the mean, the interval, and the SD for continuous variables and of absolute frequency and percentages for the categorical variables was performed. The results among groups (vaginal birth or cesarean section) were correlated by Student t test (continuous variables) and the χ2 test (categorical variables), establishing as a statistical significance if P value less than 0.0.5.
Data were collected and entered to the computer using statistical package for social science program for statistical analysis. Data from questionnaires were entered as numerical or categorical, as appropriate.
The following are the analytical statistics tests used in this study:
- χ2 test was used to measure association between qualitative variables
- Fisher exact test was used for 2 × 2 qualitative variables when more than 25% of the cells have expected count less than 5
- Student t test was used to compare mean and SD of two sets of quantitative normally distributed data, whereas Mann–Whitney test was used when these data were not normally distributed
- The receiver operating characteristic curve was done to detect the cutoff value with highest sensitivity and specificity
- Sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy were calculated
- Sensitivity = ability of the test to correctly identify those who have the disease
- Specificity = ability of the test to correctly identify those who do not have the disease
- Positive predictive value of a test is the likelihood that an individual with a positive test to have the disease
- Negative predictive value of a test is the likelihood that an individual with a negative test does not have the disease
- P value was considered statistically significant when it is less than 0.05.
| Results|| |
A total of 70 primigravida women with a singleton at term pregnancy were recruited for the current study. Approximately 65% of the patients were delivered vaginally (n = 45) as opposed to only 35% who delivered by cesarean section (n = 25). The cutoff values of AOP, HD, and HPD were 120°, 30°, and 40 mm, respectively. The ITU parameters showed a sensitivity of 91.7% and specificity of 84% for AOP, sensitivity of 95.8% and specificity of 92% for HD, and sensitivity of 95.8% and specificity of 84% for HPD in prediction of the occurrence of normal vaginal delivery, with a P value less than or equal to 0.001 for all parameters.
The demographic data of women included in the study did not differ significantly. The clinical data of women included in the study did differ significantly [Table 1].
The relation of ITU parameters and mode of delivery and their significant difference are shown in [Table 2].
|Table 2: Intrapartum transperineal ultrasound parameters and their significant value among delivery modes|
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Pearson correlation between HPD and AOP index is shown in [Figure 2].
|Figure 2: Pearson correlation between HPD and AOP index in 70 nulliparous women in active stage of labor. AOP more than 120° and HPD less than 40 mm are significant indicators in this cases. AOP, angel of progression; HPD, head progression distance.|
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The receiver operating characteristic curve characteristics of AOP, HD, and HPD are shown in [Table 3].
|Table 3: Receiver operating characteristic curve characteristic of angel of progression, head direction, and head progression distance|
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| Discussion|| |
ITU has been suggested as an objective and reliable method for assessing both fetal head descent and internal rotation.
This is in contrast to other studies, like Cuerva et al., who evaluated the hypothesis that ITU sonographic parameters AOP, HPD, and HD can be used to predict complicated operative forceps delivery in fetuses in nonocciput posterior position. They found that best cutoffs to predict a complicated forceps delivery were an AOP of 138° (sensitivity = 85.7%, specificity = 100%) and a HPD of 4.8 cm (sensitivity = 85.7%, specificity = 100%). The HD measurements were divided into three categories of more than 30°, 0–30°, and less than 0°. They concluded that higher head stations determined by lower AOP or PD measurements and an unfavorable HD during a contraction are more likely to result in complicated forceps delivery. A combination of AOP and HD yielded the best predictive value, and the single parameter AOP was the best predictor. Gillor et al. assessed whether measurement of the AOP before induction of labor can predict successful vaginal delivery in nulliparous women or not. All participants delivered within 1 week of the transperineal ultrasound examination. The rate of cesarean delivery in the study population was 26.7% and 73.3% was delivered vaginally. Of the women who delivered vaginally, 12.7% required vacuum extraction. The cutoff value for AOP was 92°. Eggebø et al. also investigated prospectively if the HPD had a role in prediction of mode of delivery and compare the results with AOP to find which one of both was accurate. They found that HPD in those who delivered vaginally was less than or equal to 40 mm, in 56% women. AOP was more than or equal to 110° in 58% in whom this was available of those who delivered vaginally. Multivariable logistic regression analysis showed that HPD less than or equal to 40 mm, AOP more than or equal to 110°, nonocciput posterior position, and spontaneous onset of labor were independent predictors for vaginal delivery.
Chan et al. measured the AOP by transperineal ultrasonography to predict successful instrumental and cesarean deliveries during prolonged second stage of labor, and they found that the best predictive cutoff AOP for successful instrumental delivery was 138.7° at rest and 160.9° during contraction. They inferred that the AOP predicted ∼80% of successful instrumental deliveries performed for prolonged second stage of labor.
Sainz et al. evaluated the predictive capacity of ITU to predict cases of fetal extraction failure in operative deliveries with vacuum. They observed that the presence of an AOP with pushing less than 105°, a HPD more than 25 mm and a 'head-down' direction are very unfavorable ITU parameters which can be used to identify cases of high risk of fetal extraction failure in vacuum-assisted deliveries.
Yonetani et al. assessed prospectively the role of transperineal sonographic parameters as AOP in women with singleton pregnancy in cephalic presentation to predict the time remaining of the second stage of labor. They found that AOP more than or equal to 160° in nulliparous women and an AOP more than or equal to 150° in multiparous women were significantly associated with the remaining time in labor.
Kameyama et al. investigated whether transperineal ultrasound examination can predict the mode of delivery just after full cervical dilatation was determined by vaginal examination. They enrolled 50 women, comprising 42 who had spontaneous vaginal deliveries and eight had vacuum extractions. The spontaneous delivery group had significantly higher HD, HPD, 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 cutoff 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.
Ghi et al. set guidelines to review the published techniques of ultrasound in labor and their practical applications and how the sonographic findings may affect labor management. They found that ultrasound in active labor is not yet used widely, even though studies have shown that it is more accurate and reproducible than clinical examination. Ultrasound allows objective measurement and precise documentation of findings obtained during the examination. Several sonographic parameters can be used during labor to assess mainly head station and position.
In our study, we included patients during the active phase of the first stage of labor, and we found that the AOP more than 120°, HPD less than 40 mm, and head up direction (>30°) are appropriated ITU measurements which can be used to predict vaginal and instrumental deliveries.
Finally, the fact that the AOP, HD, and HPD in this study were measured during labor like other studies may be the reason why this measurement is close to our study results. ITU provides objective information on the dynamics of the second stage of labor, head station, and HD. However, no specific cutoff for the AOP, HD, and HPD were proposed.
| Conclusion|| |
Ultrasound has become a fundamental tool in all areas of obstetrics. Transperineal ultrasound converted images to measurement of AOP, HD, and HPD to accurately predict the mode of delivery. This, in turn, may improve our understanding of normal and abnormal labor, enable objective measurement of birth progress, and provide a more scientific basis for assessing labor. This study has demonstrated the feasibility of defining a group of women at high risk of operative delivery.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]