Original Article
Can Ultrasound Performed in Prolonged Second Stage of Labor Predict the Difficulty and Success Rates of Operative Vaginal Delivery?
Authors
Y. Gilboa, O. Moran, Z. Kivilevitch, S. Kees, T. Borkowsky, R. Achiron, A. Weissmann-Brenner
Affiliation
Obstetrics and Gynecology, Chaim Sheba medical center, Ramat Gan, Israel
Key words
Abstract
Zusammenfassung
"
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Objective: To evaluate different sonographic methods for the prediction of the difficulty and the success of operative vaginal delivery (OPD). Materials and Methods: A prospective study was performed on 45 term singleton uncomplicated pregnancies with prolonged 2nd stage of delivery with cephalic presentation. Measurements of the fetal head, relations between the fetal head and maternal pelvic parameters during rest and during maternal pushing were taken using translabial ultrasound. Results: 29 cases of OPD were successful and 4 cases failed ending in cesarean section. The passage of the biparietal diameter (BPD) of the infrapubic line (IPL) was statistically correlated with the success of OPD. Head station, passage of the BPD of the IPL, percentage of head after the IPL, circumference of head after IPL were all correlated with the difficulty of OPD. When the distance between the widest diameter of the head and the IPL is < 1.2 cm, there is a 90 % probability of success of OPD. When that distance is > 3.3 cm, there is 90 % probability of cesarean section. When the percentage of head beyond the IPL was > 54 %, there was 90 % probability of successful OPD. Discussion: Translabial ultrasound is useful in the prediction of the difficulty and the success of OPD. The higher the extent of head that passed the IPL, the less difficult the OPD and the greater the success rate of the OPD.
Ziel: Bewertung verschiedener sonografischen Methoden zur Vorhersage von Schwierigkeiten und Erfolg der vaginal-operative Entbindung (OPD). Material und Methoden: Eine prospektive Studie wurde bei 45 voll ausgetragenen, komplikationslosen Einlingsschwangerschaften durchgeführt, die sich in der protrahierten Austreibungsperiode mit Eintritt des Kopfes befanden. Die Messungen des fetalen Kopfes und die Verhältnisse der Parameter von fetalem Kopf und mütterlichem Becken wurden während der Wehenpause und der mütterlichen Pressphase durch translabiale Sonografie ermittelt. Ergebnisse: Die OPD war bei 29 Fällen erfolgreich und bei 4 Fällen erfolglos und endete mit Kaiserschnitt. Die Passage des biparietalen Durchmessers (BPD) durch die infrapubische Linie (IPL) zeigte eine statistisch-signifikante Korrelation zum Erfolg der OPD. Die Kopfhöhe, die Passage des BPD durch die IPL und der der prozentuale Anteil des Kopfes nach der IPL, der Kopfumfang nach der IPL korrelierten allesamt mit Schwierigkeiten bei der OPD. Wenn der Abstand zwischen dem größten Kopfdurchmesser und der IPL < 1,2 cm betrug, war der Wahrscheinlichkeit für das Gelingen der OPD 90 %. Bei einem Abstand von > 3,3 cm betrug die Wahrscheinlichkeit einer Schnittentbindung 90 %. Wenn der Anteil des Kopfes nach der IPL > 54 % war so hatte die OPD eine 90 % Erfolgsmöglichkeit. Schlussfolgerung: Der translabiale Ultraschall unterstützt die Vorhersage von Schwierigkeiten und Erfolg der OPD. Je größer der Umfang des Kopfes ist, der die IPL passiert hat, desto weniger schwierig gestaltet sich die OPD und umso größer ist deren Gelingen.
● translabial ultrasound ● operative vaginal delivery ● infrapubic line " "
received accepted
4.7.2013 20.11.2014
Bibliography DOI http://dx.doi.org/ 10.1055/s-0034-1398831 Published online: 2015 Ultraschall in Med © Georg Thieme Verlag KG Stuttgart · New York · ISSN 0172-4614 Correspondence Dr. Alina Weissmann-Brenner Obstetrics and Gynecology, Chaim Sheba medical center Tel HaShomer 53621 Ramat Gan Israel Tel.: 9 72/3/5 30 81 16 Fax: 9 72/3/5 30 21 87 [email protected]
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Ist der in der protrahierten Austreibungsperiode durchgeführte Ultraschall ein prädiktiver Marker für Schwierigkeiten und Erfolgsraten einer vaginal-operativen Entbindung?
Introduction !
Successful operative vaginal delivery is safer for the fetus than cesarean section following a failed instrumental delivery. The incidence of intracranial hemorrhage is 1:1900 in spontaneous vaginal delivery, 1:860 in vacuum deliveries and 1:334 in cesarean sections following failed operative vaginal delivery [1]. Maternal risks of second stage cesarean section include major hemorrhage, risk of bladder trauma, and extension tears of the uterus [2]. The ability to predict which women in the second stage of labor have increased risks of cesarean section or whether operative vaginal delivery is easy or difficult affects the obstetrical management of labor. The clinical assessment of fetal head station in the second stage of delivery may vary among different examiners, especially when caput succedaneum and molding are present, causing the presenting part to be low, while the widest part of the skull is actually high [3 – 5]. The use of ultrasound (US) during pregnancy is common and routine. In recent years several studies examined its added value in the management of labor, particularly in the second stage of labor [6, 7]. Several models were analyzed to predict the success rate of vaginal delivery including operative vaginal delivery [8 – 10]. Dietz et al. quantified fetal head descent by measuring the minimum distance between the fetal head and a line positioned at a 900 angle from the central axis of pubic symphysis in the midsagittal plane [11]. Henrich et al. demonstrated that when the widest part of the fetal head crossed the infrapubic line (IPL) operative vaginal delivery had a favorable outcome [12]. Kalache et al. and Barbera et al. measured the angle between a line placed through the midline of the symphysis pubis and a line running from the inferior apex of the symphysis tangentially to the fetal skull (the angle of progression). They found that when this angle was 1200 the probability of successful vacuum extraction or spontaneous vaginal delivery was 90 % [13, 14]. At the Chaim Sheba Medical center there are about 10 500 deliveries annually, 7 % of them are operative vaginal deliveries. The rate of failure of operative vaginal delivery is 7 %. The objective of our study was to compare the different sonographic methods and to assess the best method for the prediction of the difficulty and the success of operative vaginal delivery in prolonged 2nd stage pregnancies.
their legs flexed at their hips and knees. Translabial US examination was performed during pushing, with an empty bladder, by a specialized US expert blinded to the digital examination. Measurements were carried out using a Voluson-e ultrasound machine equipped with a 2 – 5 MHz convex transducer. The data observed, except the head position, was not revealed to the obstetrical staff nor influenced the clinical management. The following data was analyzed: age, body mass index (BMI), gestational age, birth weight, sonographic estimation of fetal head circumference, head circumference measured immediately after delivery by a midwife, head circumference measured by the pediatricians, infrapubic angle, passage of biparietal diameter (BPD) beyond the IPL, head station, mode of delivery and subjective difficulty of operative vaginal delivery. We measured the angle of progression as defined by Kalache et al. and Barbera et al. [13, 14], the head progression distance as defined by Dietz et al. [11] and the head direction, head descent during pushing and the widest fetal head diameter below the IPL as defined by Henrich et al. [12]. We assessed additional new parameters: ▶ Head widest part distance (HWPD): the distance between the " Fig. 1). widest diameter of the head and the IPL (● ▶ Head ratio distance (HRD): percentage of head beyond the IPL " Fig. 2). (● In all cases of operative vaginal delivery, a senior attending physician either performs or supervises the procedure. Only two attempts to perform VE and one attempt at forceps extraction were allowed before cesarean section was performed. Only physicians with experience from more than ten previous operative vaginal deliveries performed the procedure. Statistical analysis was performed using Stata/SE version 11.1. Linear regression was performed with continuous parameters. Logistic regression was performed with categorical parameters. Comparison between more than two parameters was done using the ANOVA test.
Materials and Methods !
A prospective study was performed from January 2010 to September 2010 on 45 pregnant women in prolonged 2nd stage of labor at the Chaim Sheba Medical Center. The inclusion criteria were uncomplicated, term (gestational age of more than 37 completed weeks), live singleton pregnancies with cephalic presentation with failure to progress in the second stage of labor. Failure to progress was defined as more than 3 hours if regional anesthesia was administered or 2 hours in the absence of regional anesthesia in nulliparous women and more than 2 hours and 1 hour, respectively, in parous women. The study was approved by the institutional review board of the Chaim Sheba Medical center. All women signed informed consent prior to performance of US. Patients were examined in their labor rooms by an expert sonographer. Women were placed in a semi-recumbent position with
Gilboa Y et al. Can Ultrasound Performed … Ultraschall in Med
Fig. 1 Head Widest Part Distance – The distance between the widest head diameter from the IPL created along the vertical line to the lowest head part Abb. 1 Größter Kopf-Teilabstand – Der Abstand vom dem größten Kopfdurchmesser zur IPL wird entlang der vertikalen Linie zum untersten Bereich des Kopfes bestimmt.
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Original Article
Original Article
NVD
CS
operative
failed operative
n=4
n=8
delivery
delivery
n = 29
n=4
p-value
age
26 ± 3
30 ± 4.5
31 ± 4.7
33 ± 3
BMI
26 ± 4.6
29 ± 4.4
26 ± 3.6
28 ± 3.7
NS
parity
0 (0 – 2)
0 (0 – 2)
0 (0 – 0)
0 (0 – 2)
NS
height (m)
1.6 ± 0.06
1.6 ± 0.04
1.6 ± 0.07
1.6 ± 0.08
NS
birth weight
3188 ± 513
3357 ± 525
3327 ± 500
3277 ± 498
NS
gestational age
38 ± 0.6
39 ± 1.7
39 ± 1.5
40 ± 1.1
NS
Table 1 Characteristics of the study population.
NS
NVD: normal vaginal delivery; CS: cesarean section; BMI: body mass index.
Outcome of delivery.
outcome
number
NVD
4 (8.9 %)
operative vaginal delivery
29 (64.4 %)
– vacuum extraction
26 (57.8 %)
– forceps delivery
3 (6.7 %)
failed operative delivery
4 (8.9 %)
– failed vacuum extraction
3 (6.7 %)
– failed forceps
1 (2.2 %)
CS
8 (17.8 %)
total
45 (100 %)
NVD: normal vaginal delivery; CS: cesarean section.
Table 3
Fig. 2
Head ratio distance – Percentage of the fetal head beyond the IPL
Abb. 2 Kopf-Ratio-Abstand – prozentualer Anteil des fetalen Kopfes nach der IPL
Fig. 3
Probability of success vs. failure of operative vaginal delivery.
Abb. 3 Probabilität von Erfolg versus Misslingen der vaginal-operativen Entbindung.
Results !
45 women were included in the study. In all cases fetal head and pubic symphsis were clearly visualized and adequate measurements preformed. The characteristics of the study population " Table 1. 28 (62.2 %) women were nulliparous, are presented in ●
Difficulty of operative vaginal delivery.
difficulty
number
easy
16 (48.4 %)
medium
7 (21.2 %)
hard
6 (18.2 %)
failure
4 (12.1 %)
total
33 (100 %)
7 (15.6 %) had delivered once previously and 10 (22.2 %) had two previous deliveries, (range of parity, 0 – 2; median, 0). 4 women (8.8 %) had undergone a previous cesarean section. There were 29 cases of successful operative vaginal delivery. The outcome of " Table 2, 3. the deliveries is summarized in ● Logistic regression was performed in order to examine how different parameters including the different sonographic methods of assessment of the fetal station predict the success of operative " Table 4). Passage of BPD is the only variable vaginal delivery (● that was found to be statistically correlated to the success of operative vaginal delivery with a p-value of 0.05. The percentage of head after the IPL was found to have a borderline statistical significance with a p-value of 0.08. Linear regression was performed to correlate between the different modes of measurements and the difficulty of operative vagi" Table 5 demonstrates that the methods of Dietz nal delivery. ● et al. and Henrich et al. along with the passage of the BPD, station of the head, descent of the head, percentage of head after the IPL, circumference of the head after the IPL were all statistically correlated with the difficulty of the operative vaginal delivery. The method of Kalache et al. had a borderline statistical significance with a p-value of 0.06. Logistic regression was performed in order to examine the influence of the success or failure of operative vaginal delivery on Apgar scores, PH, base excess and hematocrit of the newborns. No
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Table 2
Original Article
Table 4
Logistic regression comparing of the influence on success of operative vaginal delivery.
method
coef.
std. err.
Z
p-value|
lower 95 %
upper 95 %
conf. interval
conf. interval
significance
Kalashe 7
0.05
0.04
1.27
0.21
–0.03
0.14
Dietz 4
0.66
0.44
1.5
0.13
–0.20
1.53
no
–0.89
0.79
–1.12
0.26
–2.44
0.66
no
BPD pass
1.07
0.54
1.98
0.05
0.01
2.13
yes
head direction
0.08
0.82
0.09
0.92
–1.53
1.68
no
Henrich 6 up down
no
station
1.15
0.71
1.62
0.11
–0.24
2.54
no
descent
–0.05
1.29
–0.04
0.97
–2.57
2.47
no
angle pubic
–0.02
0.05
–0.33
0.74
–0.11
0.08
no
0.07
0.09
0.64
0.53
–0.12
0.24
no no
caput mm
–0.03
0.03
–0.57
0.57
–0.09
0.05
circumference after the line
0.03
0.02
1.48
0.14
–0.01
0.07
no
percentage head after the line
0.16
0.09
1.75
0.08
–0.02
0.34
borderline no
head circumference us
HC measured after delivery
0.02
0.06
0.4
0.69
–0.09
0.13
HC measured by pediatrician
0.02
0.05
0.34
0.74
–0.08
0.11
no
height
1.37
8.43
0.16
0.871
–15.16
17.91
no
–0.01
0.17
–0.04
0.971
–0.34
0.33
no
BMI
Table 5
Linear regression examining the influence on the difficulty of operative vaginal delivery.
coef.
std. err.
t
p-value
lower 95 %
upper 95 %
conf. interval
conf. interval
significance
Kalashe 7
–0.02
0.01
–1.97
0.06
–0.04
Dietz 4
–0.27
0.121
–2.26
0.03
–0.52
–0.03
yes
0.24
2.22
0.03
0.04
1.03
yes
–0.38
0.12
–3.32
0.002
–0.62
–0.15
yes
0.08
0.24
0.34
0.74
–0.40
0.56
no
station
–0.53
0.22
–2.44
0.02
–0.97
–0.09
yes
descent
–0.79
0.36
–2.22
0.03
–1.52
–0.06
yes
0.01
0.02
0.51
0.62
–0.02
0.04
no
caput mm
–0.01
0.03
–0.32
0.75
–0.06
0.05
no
head circumference US
–0.001
0.01
–0.14
0.89
–0.02
0.02
no
circumference after the line
–0.01
0.01
–2.49
0.02
–0.029
–0.002
yes
percentage head after the line
–0.05
0.02
–2.68
0.01
–0.09
–0.01
yes
HC measured after delivery
–0.01
0.02
–0.35
0.73
–0.06
0.05
no
0.01
0.02
0.33
0.74
–0.03
0.04
no
Henrich 6 BPD pass head direction
angle pubic
HC measured by pediatrician
0.546
0.0007
borderline
height
1.68
2.51
0.67
0.51
–3.45
6.80
no
BMI
0.05
0.05
1.02
0.32
–0.06
0.16
no
BPD: biparietal diameter; US: ultrasound; BMI: body mass index.
variable was found to be statistically correlated to the success or failure of the procedure. When linear regression was performed to assess the difficulty of the operative vaginal delivery, Apgar scores at 1 and 5 minutes were statistically influenced by the difficulty of the procedure (p = 0.009 and 0.013, respectively). Logistic regression was performed to analyze the influence of HWPD and HRD on the success or failure of operative vaginal delivery. When the HWPD is longer than 1.2 cm, there is a more than 90 % probability of success of operative vaginal delivery " Fig. 3). When the HWPD is greater than 3.3 cm, there is a (● more than 90 % probability of success of vaginal delivery " Fig. 4). No vaginal delivery occurred when less than 52 % of (● the head passed the IPL. There was a > 90 % probability of success " Fig. 5). of operative vaginal delivery if the HRD was > 54 % (● Comparison of the different sonographic methods with the mode " Table 6. HWPD and HRD were found of delivery is presented in ●
Gilboa Y et al. Can Ultrasound Performed … Ultraschall in Med
to be statistically associated with the success rate of spontaneous and operative vaginal delivery.
Discussion !
Our study demonstrated that the non-quantitative parameter that predicted mode of delivery was the descent of the fetal head during pushing. The quantitative parameter that statistically predicted mode of delivery was the distance between the widest diameter of the head and the IPL. Measurements of the percentage of head beyond the IPL differ significantly between vacuum failure and success and should be considered before operative delivery. The success of operative vaginal delivery is increased when HWPD> 1.2 cm and when HRD> 54 %. These results support previous studies in emphasizing the important role of US in obstetrical decision making in the second
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BPD: biparietal diameter; HC: head circumference; BMI: body mass index.
Original Article
NVD
CS
vacuum
failed vacuum
p-value
angle of progression-Sheba
143 ± 21
± 137 13
143 ± 15
20 ± 127
NS
angle of progression-Kalache
174 ± 34
104 ± 9
130 ± 18
head progression distance (cm)
6.5 ± 1.2
6.5 ± 1.4
6.8 ± 1.2
5 ± 1.3
NS
HWPD (cm)
1.8 ± 2.0
2.1 ± 1.3
2.2 ± 1.2
1.2 ± 0.25
< 0.05
HRD (%)
62 ± 6
59 ± 10
60 ± 10
50 ± 4
0.08
0.008
Table 6 Comparison of sonographic assessment of the fetus during labor to mode of delivery.
Fig. 4 Probability of the need for cesarean section depending on the HWPD Abb. 4 Wahrscheinlichkeit der Notwendigkeit zur Sectio caesarae in Abhängigkeit vom HWPD.
Fig. 5 Comparison of sonographic parameters – probability of success vs. failure of operative vaginal delivery. Abb. 5 Vergleich der sonografischen Parameter – Probabilität von Erfolg versus Misslingen der vaginal-operativen Entbindung.
stage of labor [6, 7]. Similar to the methods of Henrich et al. [12] and Dietz et al. [11], we found that the greater the percentage of head passing the IPL, the greater the chances for successful operative vaginal delivery. The definition of the IPL differs between the different studies. Dietz et al. quantified fetal head descent in 139 women by measuring the minimum distance between the
fetal head and the IPL which was positioned vertical to the central axis of the symphysis pubis in the midsagittal plane. They found a correlation between the head station and the clinical measures of head engagement: the lower the presenting part, the greater the head progression distance [11]. Similarly, Eggebo et al. measured the shortest distance from the outer bony limit of the fetal skull to the skin surface of the perineum in 152 women before the onset of labor. They found that the lower values of these measurements were associated with quick labor without obstetric interventions [15]. The main limitation of these studies was that they were not performed during the second stage of labor. Henrich et al. performed US in 20 patients immediately before vacuum extraction to predict the success of the VE. They demonstrated that when the widest part of the fetal head crossed the IPL, and especially if the head was up, an operative vaginal delivery had a favorable outcome. They defined the IPL as the line perpendicular to the long axis of the symphysis pubis, originating from the caudal end of the symphysis and extending to the dorsal part of the birth canal. The main limitations of this study were that the posterior skull was not always well visualized. Therefore, there was some subjectivity in the determination of the widest fetal head diameter [12]. We also agree that HWPD measurement may be of some limitation due to its subjective impression as mentioned above as the widest part depiction of the fetal skull is not a fixed landmark which can produce some variation of the measurement. On the other hand, we feel that HRD, which is based on the ratio of the skull that is beyond the prominent IPL, might be a more objective parameter. Previous studies evaluated the location of the presenting part of the fetal head in the birth canal which can be low although the wide part of the skull is actually high [11 – 13]. This is especially pronounced in prolonged labor with fetal head molding. The main advantage of the HRD is the information is provides regarding the spatial location of the skull in the birth canal which may have an advantage in obstructed labor. Another method studied by Kalache et al. and Barbera et al. measured the angle between a line placed through the midline of the symphysis pubis and a line running from the inferior apex of the symphysis tangentially to the fetal skull (the angle of progression). When this angle was 1200 the probability of successful vacuum extraction or spontaneous vaginal delivery was 90 % [13, 14]. Indeed, Bamberg et al. tried to validate the measurements of the angle of progression using open MRI, and demonstrated a significant correlation between the angle of progression determined by US and the distance between the presenting fetal part at the level of the maternal ischial spines [16, 17]. Open MRI is considered the gold standard for measuring the fetal head station [16]. The limitation of these studies was that they were not performed during labor. A recent study performed by Cuerva et al. demonstrated that the angle of progression measured during labor between contractions may predict a difficult forceps delivery [18].
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NVD: normal vaginal delivery; CS: cesarean section; HWPD: head widest part distance; HRD: head ratio distance
However, the angle of progression in our center did not predict the success or failure of operative vaginal delivery. The advantages of the present study were the performance of ultrasound during the second stage of labor just prior to operative delivery, including both vacuum extraction and forceps deliveries. The suggested measurements in our study, i. e. the HWPD and the HRD, overcome the possible limitation of the pressure of translabial US. The success or failure of operative vaginal delivery did not influence the Apgar score, although the more difficult the operative vaginal delivery was, the lower the Apgar score. The PH and the hematocrit were not influenced by the difficulty of the procedure, maybe because Apgar scores reflect immediate influence on the newborn. We acknowledge the disadvantage when reporting the subjective impression of several physicians on the difficulty of the delivery. To overcome this, future studies may use more objective and quantitative parameters such as measuring the timing and traction of the fetal head during operative delivery. In summary, the clinical significance of our findings influences the management of the 2nd stage of labor, the explanation given to the patient by the obstetricians, and the place where the procedure is performed. When a difficult operative vaginal delivery is expected, it can be performed in the operation room in a double setup arrangement. This way time is saved in cases of failure of the procedure when the staff is ready for immediate cesarean section.
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06
07
08 09 10
11
12
13
14
15
16
References 01 Towner D, Castro MA, Eby-Wilkens E et al. Effects of mode of delivery in nulliparous women on neonatal intracranial injury. NEJM 1999; 341: 1709 – 1714 02 Murphy DJ, Liebling RE, Verity L et al. Early maternal and neonatal morbidity associated with operative delivery in second stage of labour: a cohort study. Lancet 2001; 358: 1203 – 1207 03 Dupuis O, Silveira R, Zentner A et al. Birth simulator: reliability of transvaginal assessment of fetal head station as defined by the American College of Obstetricians and Gynecologists classification. Am J Obstet Gynecol 2005; 192: 868 – 874 04 Akmal S, Kametas N, Tsoi E et al. Comparison of transvaginal digital examination with intrapartum sonography to determine fetal head posi-
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tion before instrumental delivery. Ultrasound Obstet Gynecol 2003; 21: 437 – 440 Ghi T, Farina A, Pedrazzi A et al. Diagnosis of station and rotation of the fetal head in the second stage of labor with intrapartum translabial ultrasound. Ultrasound Obstet Gynecol 2009; 33: 331 – 336 Tutschek B, Braun T, Chantraine F et al. A study of progress of labour using intrapartum translabial ultrasound, assessing head station, direction, and angle of descent. BJOG 2011; 118: 62 – 69 Tutschek B, Torkildsen EA, Eggebø TM. Comparison between ultrasound parameters and clinical examination to assess fetal head station in labor. Ultrasound Obstet Gynecol 2013; 41: 425 – 429 Molina FS, Nicolaides KH. Ultrasound in labor and delivery. Fetal Diagn Ther 2010; 27: 61 – 67 Sherer DM. Intrapartum ultrasound. Ultrasound Obstet Gynecol 2007; 30: 123 – 139 Yeo L, Romero R. Sonographic evaluation in the second stage of labor to improve the assessment of labor progress and its outcome. Ultrasound Obstet Gynecol 2009; 33: 253 – 258 Dietz HP, Lanzarone V. Measuring engagement of the fetal head: validity and reproducibility of a new ultrasound technique. Ultrasound Obstet Gynecol 2005; 25: 165 – 168 Henrich W, Dudenhausen J, Fuchs I et al. Intrapartum translabial ultrasound (ITU): sonographic landmarks and correlation with successful vacuum extraction. Ultrasound Obstet Gynecol 2006; 28: 753 – 760 Kalache KD, Duckelmann AM, Michaelis SAM et al. 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? Ultrasound Obstet Gynecol 2009; 33: 326 – 330 Barbera AF, Pombar X, Perugino G et al. A new method to assess fetal head descent in labor with transperineal ultrasound. Ultrasound Obstet Gynecol 2009; 33: 313 – 319 Eggebo TM, Gjessing LK, Heien C et al. Prediction of labor and delivery by transperineal ultrasound in pregnancies with prelabor rupture of membranes at term. Ultrasound Obstet Gynecol 2006; 27: 387 – 391 Bamberg C, Scheuermann S, Slowinski T et al. Relationship between fetal head station established using an open magnetic resonance imaging scanner and the angle of progression determined by transperineal ultrasound. Ultrasound Obstet Gynecol 2011; 37: 712 – 716 Bamberg C, Scheuermann S, Fotopoulou C et al. Angle of progression measurements of fetal head at term: a systematic comparison between open magnetic resonance imaging and transperineal ultrasound. Am J Obstet Gynecol 2012; 206 (2): 161.e1 – 161.e5 Cuerva MJ, Bamberg C, Tobias P et al. Intrapartum ultrasound, a predictive method for complicated operative forceps delivery in non-occiput posterior deliveries. Ultrasound Obstet Gynecol 2013; DOI: 10.1002/ uog.13256 [Epub ahead of print]
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Original Article
Can Ultrasound Performed in Prolonged Second Stage of Labor Predict the Difficulty and Success Rates of Operative Vaginal Delivery?
Authors
Y. Gilboa, O. Moran, Z. Kivilevitch, S. Kees, T. Borkowsky, R. Achiron, A. Weissmann-Brenner
Affiliation
Obstetrics and Gynecology, Chaim Sheba medical center, Ramat Gan, Israel
Key words
Abstract
Zusammenfassung
"
!
!
Objective: To evaluate different sonographic methods for the prediction of the difficulty and the success of operative vaginal delivery (OPD). Materials and Methods: A prospective study was performed on 45 term singleton uncomplicated pregnancies with prolonged 2nd stage of delivery with cephalic presentation. Measurements of the fetal head, relations between the fetal head and maternal pelvic parameters during rest and during maternal pushing were taken using translabial ultrasound. Results: 29 cases of OPD were successful and 4 cases failed ending in cesarean section. The passage of the biparietal diameter (BPD) of the infrapubic line (IPL) was statistically correlated with the success of OPD. Head station, passage of the BPD of the IPL, percentage of head after the IPL, circumference of head after IPL were all correlated with the difficulty of OPD. When the distance between the widest diameter of the head and the IPL is < 1.2 cm, there is a 90 % probability of success of OPD. When that distance is > 3.3 cm, there is 90 % probability of cesarean section. When the percentage of head beyond the IPL was > 54 %, there was 90 % probability of successful OPD. Discussion: Translabial ultrasound is useful in the prediction of the difficulty and the success of OPD. The higher the extent of head that passed the IPL, the less difficult the OPD and the greater the success rate of the OPD.
Ziel: Bewertung verschiedener sonografischen Methoden zur Vorhersage von Schwierigkeiten und Erfolg der vaginal-operative Entbindung (OPD). Material und Methoden: Eine prospektive Studie wurde bei 45 voll ausgetragenen, komplikationslosen Einlingsschwangerschaften durchgeführt, die sich in der protrahierten Austreibungsperiode mit Eintritt des Kopfes befanden. Die Messungen des fetalen Kopfes und die Verhältnisse der Parameter von fetalem Kopf und mütterlichem Becken wurden während der Wehenpause und der mütterlichen Pressphase durch translabiale Sonografie ermittelt. Ergebnisse: Die OPD war bei 29 Fällen erfolgreich und bei 4 Fällen erfolglos und endete mit Kaiserschnitt. Die Passage des biparietalen Durchmessers (BPD) durch die infrapubische Linie (IPL) zeigte eine statistisch-signifikante Korrelation zum Erfolg der OPD. Die Kopfhöhe, die Passage des BPD durch die IPL und der der prozentuale Anteil des Kopfes nach der IPL, der Kopfumfang nach der IPL korrelierten allesamt mit Schwierigkeiten bei der OPD. Wenn der Abstand zwischen dem größten Kopfdurchmesser und der IPL < 1,2 cm betrug, war der Wahrscheinlichkeit für das Gelingen der OPD 90 %. Bei einem Abstand von > 3,3 cm betrug die Wahrscheinlichkeit einer Schnittentbindung 90 %. Wenn der Anteil des Kopfes nach der IPL > 54 % war so hatte die OPD eine 90 % Erfolgsmöglichkeit. Schlussfolgerung: Der translabiale Ultraschall unterstützt die Vorhersage von Schwierigkeiten und Erfolg der OPD. Je größer der Umfang des Kopfes ist, der die IPL passiert hat, desto weniger schwierig gestaltet sich die OPD und umso größer ist deren Gelingen.
● translabial ultrasound ● operative vaginal delivery ● infrapubic line " "
received accepted
4.7.2013 20.11.2014
Bibliography DOI http://dx.doi.org/ 10.1055/s-0034-1398831 Published online: 2015 Ultraschall in Med © Georg Thieme Verlag KG Stuttgart · New York · ISSN 0172-4614 Correspondence Dr. Alina Weissmann-Brenner Obstetrics and Gynecology, Chaim Sheba medical center Tel HaShomer 53621 Ramat Gan Israel Tel.: 9 72/3/5 30 81 16 Fax: 9 72/3/5 30 21 87 [email protected]
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Ist der in der protrahierten Austreibungsperiode durchgeführte Ultraschall ein prädiktiver Marker für Schwierigkeiten und Erfolgsraten einer vaginal-operativen Entbindung?
Introduction !
Successful operative vaginal delivery is safer for the fetus than cesarean section following a failed instrumental delivery. The incidence of intracranial hemorrhage is 1:1900 in spontaneous vaginal delivery, 1:860 in vacuum deliveries and 1:334 in cesarean sections following failed operative vaginal delivery [1]. Maternal risks of second stage cesarean section include major hemorrhage, risk of bladder trauma, and extension tears of the uterus [2]. The ability to predict which women in the second stage of labor have increased risks of cesarean section or whether operative vaginal delivery is easy or difficult affects the obstetrical management of labor. The clinical assessment of fetal head station in the second stage of delivery may vary among different examiners, especially when caput succedaneum and molding are present, causing the presenting part to be low, while the widest part of the skull is actually high [3 – 5]. The use of ultrasound (US) during pregnancy is common and routine. In recent years several studies examined its added value in the management of labor, particularly in the second stage of labor [6, 7]. Several models were analyzed to predict the success rate of vaginal delivery including operative vaginal delivery [8 – 10]. Dietz et al. quantified fetal head descent by measuring the minimum distance between the fetal head and a line positioned at a 900 angle from the central axis of pubic symphysis in the midsagittal plane [11]. Henrich et al. demonstrated that when the widest part of the fetal head crossed the infrapubic line (IPL) operative vaginal delivery had a favorable outcome [12]. Kalache et al. and Barbera et al. measured the angle between a line placed through the midline of the symphysis pubis and a line running from the inferior apex of the symphysis tangentially to the fetal skull (the angle of progression). They found that when this angle was 1200 the probability of successful vacuum extraction or spontaneous vaginal delivery was 90 % [13, 14]. At the Chaim Sheba Medical center there are about 10 500 deliveries annually, 7 % of them are operative vaginal deliveries. The rate of failure of operative vaginal delivery is 7 %. The objective of our study was to compare the different sonographic methods and to assess the best method for the prediction of the difficulty and the success of operative vaginal delivery in prolonged 2nd stage pregnancies.
their legs flexed at their hips and knees. Translabial US examination was performed during pushing, with an empty bladder, by a specialized US expert blinded to the digital examination. Measurements were carried out using a Voluson-e ultrasound machine equipped with a 2 – 5 MHz convex transducer. The data observed, except the head position, was not revealed to the obstetrical staff nor influenced the clinical management. The following data was analyzed: age, body mass index (BMI), gestational age, birth weight, sonographic estimation of fetal head circumference, head circumference measured immediately after delivery by a midwife, head circumference measured by the pediatricians, infrapubic angle, passage of biparietal diameter (BPD) beyond the IPL, head station, mode of delivery and subjective difficulty of operative vaginal delivery. We measured the angle of progression as defined by Kalache et al. and Barbera et al. [13, 14], the head progression distance as defined by Dietz et al. [11] and the head direction, head descent during pushing and the widest fetal head diameter below the IPL as defined by Henrich et al. [12]. We assessed additional new parameters: ▶ Head widest part distance (HWPD): the distance between the " Fig. 1). widest diameter of the head and the IPL (● ▶ Head ratio distance (HRD): percentage of head beyond the IPL " Fig. 2). (● In all cases of operative vaginal delivery, a senior attending physician either performs or supervises the procedure. Only two attempts to perform VE and one attempt at forceps extraction were allowed before cesarean section was performed. Only physicians with experience from more than ten previous operative vaginal deliveries performed the procedure. Statistical analysis was performed using Stata/SE version 11.1. Linear regression was performed with continuous parameters. Logistic regression was performed with categorical parameters. Comparison between more than two parameters was done using the ANOVA test.
Materials and Methods !
A prospective study was performed from January 2010 to September 2010 on 45 pregnant women in prolonged 2nd stage of labor at the Chaim Sheba Medical Center. The inclusion criteria were uncomplicated, term (gestational age of more than 37 completed weeks), live singleton pregnancies with cephalic presentation with failure to progress in the second stage of labor. Failure to progress was defined as more than 3 hours if regional anesthesia was administered or 2 hours in the absence of regional anesthesia in nulliparous women and more than 2 hours and 1 hour, respectively, in parous women. The study was approved by the institutional review board of the Chaim Sheba Medical center. All women signed informed consent prior to performance of US. Patients were examined in their labor rooms by an expert sonographer. Women were placed in a semi-recumbent position with
Gilboa Y et al. Can Ultrasound Performed … Ultraschall in Med
Fig. 1 Head Widest Part Distance – The distance between the widest head diameter from the IPL created along the vertical line to the lowest head part Abb. 1 Größter Kopf-Teilabstand – Der Abstand vom dem größten Kopfdurchmesser zur IPL wird entlang der vertikalen Linie zum untersten Bereich des Kopfes bestimmt.
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Original Article
Original Article
NVD
CS
operative
failed operative
n=4
n=8
delivery
delivery
n = 29
n=4
p-value
age
26 ± 3
30 ± 4.5
31 ± 4.7
33 ± 3
BMI
26 ± 4.6
29 ± 4.4
26 ± 3.6
28 ± 3.7
NS
parity
0 (0 – 2)
0 (0 – 2)
0 (0 – 0)
0 (0 – 2)
NS
height (m)
1.6 ± 0.06
1.6 ± 0.04
1.6 ± 0.07
1.6 ± 0.08
NS
birth weight
3188 ± 513
3357 ± 525
3327 ± 500
3277 ± 498
NS
gestational age
38 ± 0.6
39 ± 1.7
39 ± 1.5
40 ± 1.1
NS
Table 1 Characteristics of the study population.
NS
NVD: normal vaginal delivery; CS: cesarean section; BMI: body mass index.
Outcome of delivery.
outcome
number
NVD
4 (8.9 %)
operative vaginal delivery
29 (64.4 %)
– vacuum extraction
26 (57.8 %)
– forceps delivery
3 (6.7 %)
failed operative delivery
4 (8.9 %)
– failed vacuum extraction
3 (6.7 %)
– failed forceps
1 (2.2 %)
CS
8 (17.8 %)
total
45 (100 %)
NVD: normal vaginal delivery; CS: cesarean section.
Table 3
Fig. 2
Head ratio distance – Percentage of the fetal head beyond the IPL
Abb. 2 Kopf-Ratio-Abstand – prozentualer Anteil des fetalen Kopfes nach der IPL
Fig. 3
Probability of success vs. failure of operative vaginal delivery.
Abb. 3 Probabilität von Erfolg versus Misslingen der vaginal-operativen Entbindung.
Results !
45 women were included in the study. In all cases fetal head and pubic symphsis were clearly visualized and adequate measurements preformed. The characteristics of the study population " Table 1. 28 (62.2 %) women were nulliparous, are presented in ●
Difficulty of operative vaginal delivery.
difficulty
number
easy
16 (48.4 %)
medium
7 (21.2 %)
hard
6 (18.2 %)
failure
4 (12.1 %)
total
33 (100 %)
7 (15.6 %) had delivered once previously and 10 (22.2 %) had two previous deliveries, (range of parity, 0 – 2; median, 0). 4 women (8.8 %) had undergone a previous cesarean section. There were 29 cases of successful operative vaginal delivery. The outcome of " Table 2, 3. the deliveries is summarized in ● Logistic regression was performed in order to examine how different parameters including the different sonographic methods of assessment of the fetal station predict the success of operative " Table 4). Passage of BPD is the only variable vaginal delivery (● that was found to be statistically correlated to the success of operative vaginal delivery with a p-value of 0.05. The percentage of head after the IPL was found to have a borderline statistical significance with a p-value of 0.08. Linear regression was performed to correlate between the different modes of measurements and the difficulty of operative vagi" Table 5 demonstrates that the methods of Dietz nal delivery. ● et al. and Henrich et al. along with the passage of the BPD, station of the head, descent of the head, percentage of head after the IPL, circumference of the head after the IPL were all statistically correlated with the difficulty of the operative vaginal delivery. The method of Kalache et al. had a borderline statistical significance with a p-value of 0.06. Logistic regression was performed in order to examine the influence of the success or failure of operative vaginal delivery on Apgar scores, PH, base excess and hematocrit of the newborns. No
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Table 2
Original Article
Table 4
Logistic regression comparing of the influence on success of operative vaginal delivery.
method
coef.
std. err.
Z
p-value|
lower 95 %
upper 95 %
conf. interval
conf. interval
significance
Kalashe 7
0.05
0.04
1.27
0.21
–0.03
0.14
Dietz 4
0.66
0.44
1.5
0.13
–0.20
1.53
no
–0.89
0.79
–1.12
0.26
–2.44
0.66
no
BPD pass
1.07
0.54
1.98
0.05
0.01
2.13
yes
head direction
0.08
0.82
0.09
0.92
–1.53
1.68
no
Henrich 6 up down
no
station
1.15
0.71
1.62
0.11
–0.24
2.54
no
descent
–0.05
1.29
–0.04
0.97
–2.57
2.47
no
angle pubic
–0.02
0.05
–0.33
0.74
–0.11
0.08
no
0.07
0.09
0.64
0.53
–0.12
0.24
no no
caput mm
–0.03
0.03
–0.57
0.57
–0.09
0.05
circumference after the line
0.03
0.02
1.48
0.14
–0.01
0.07
no
percentage head after the line
0.16
0.09
1.75
0.08
–0.02
0.34
borderline no
head circumference us
HC measured after delivery
0.02
0.06
0.4
0.69
–0.09
0.13
HC measured by pediatrician
0.02
0.05
0.34
0.74
–0.08
0.11
no
height
1.37
8.43
0.16
0.871
–15.16
17.91
no
–0.01
0.17
–0.04
0.971
–0.34
0.33
no
BMI
Table 5
Linear regression examining the influence on the difficulty of operative vaginal delivery.
coef.
std. err.
t
p-value
lower 95 %
upper 95 %
conf. interval
conf. interval
significance
Kalashe 7
–0.02
0.01
–1.97
0.06
–0.04
Dietz 4
–0.27
0.121
–2.26
0.03
–0.52
–0.03
yes
0.24
2.22
0.03
0.04
1.03
yes
–0.38
0.12
–3.32
0.002
–0.62
–0.15
yes
0.08
0.24
0.34
0.74
–0.40
0.56
no
station
–0.53
0.22
–2.44
0.02
–0.97
–0.09
yes
descent
–0.79
0.36
–2.22
0.03
–1.52
–0.06
yes
0.01
0.02
0.51
0.62
–0.02
0.04
no
caput mm
–0.01
0.03
–0.32
0.75
–0.06
0.05
no
head circumference US
–0.001
0.01
–0.14
0.89
–0.02
0.02
no
circumference after the line
–0.01
0.01
–2.49
0.02
–0.029
–0.002
yes
percentage head after the line
–0.05
0.02
–2.68
0.01
–0.09
–0.01
yes
HC measured after delivery
–0.01
0.02
–0.35
0.73
–0.06
0.05
no
0.01
0.02
0.33
0.74
–0.03
0.04
no
Henrich 6 BPD pass head direction
angle pubic
HC measured by pediatrician
0.546
0.0007
borderline
height
1.68
2.51
0.67
0.51
–3.45
6.80
no
BMI
0.05
0.05
1.02
0.32
–0.06
0.16
no
BPD: biparietal diameter; US: ultrasound; BMI: body mass index.
variable was found to be statistically correlated to the success or failure of the procedure. When linear regression was performed to assess the difficulty of the operative vaginal delivery, Apgar scores at 1 and 5 minutes were statistically influenced by the difficulty of the procedure (p = 0.009 and 0.013, respectively). Logistic regression was performed to analyze the influence of HWPD and HRD on the success or failure of operative vaginal delivery. When the HWPD is longer than 1.2 cm, there is a more than 90 % probability of success of operative vaginal delivery " Fig. 3). When the HWPD is greater than 3.3 cm, there is a (● more than 90 % probability of success of vaginal delivery " Fig. 4). No vaginal delivery occurred when less than 52 % of (● the head passed the IPL. There was a > 90 % probability of success " Fig. 5). of operative vaginal delivery if the HRD was > 54 % (● Comparison of the different sonographic methods with the mode " Table 6. HWPD and HRD were found of delivery is presented in ●
Gilboa Y et al. Can Ultrasound Performed … Ultraschall in Med
to be statistically associated with the success rate of spontaneous and operative vaginal delivery.
Discussion !
Our study demonstrated that the non-quantitative parameter that predicted mode of delivery was the descent of the fetal head during pushing. The quantitative parameter that statistically predicted mode of delivery was the distance between the widest diameter of the head and the IPL. Measurements of the percentage of head beyond the IPL differ significantly between vacuum failure and success and should be considered before operative delivery. The success of operative vaginal delivery is increased when HWPD> 1.2 cm and when HRD> 54 %. These results support previous studies in emphasizing the important role of US in obstetrical decision making in the second
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BPD: biparietal diameter; HC: head circumference; BMI: body mass index.
Original Article
NVD
CS
vacuum
failed vacuum
p-value
angle of progression-Sheba
143 ± 21
± 137 13
143 ± 15
20 ± 127
NS
angle of progression-Kalache
174 ± 34
104 ± 9
130 ± 18
head progression distance (cm)
6.5 ± 1.2
6.5 ± 1.4
6.8 ± 1.2
5 ± 1.3
NS
HWPD (cm)
1.8 ± 2.0
2.1 ± 1.3
2.2 ± 1.2
1.2 ± 0.25
< 0.05
HRD (%)
62 ± 6
59 ± 10
60 ± 10
50 ± 4
0.08
0.008
Table 6 Comparison of sonographic assessment of the fetus during labor to mode of delivery.
Fig. 4 Probability of the need for cesarean section depending on the HWPD Abb. 4 Wahrscheinlichkeit der Notwendigkeit zur Sectio caesarae in Abhängigkeit vom HWPD.
Fig. 5 Comparison of sonographic parameters – probability of success vs. failure of operative vaginal delivery. Abb. 5 Vergleich der sonografischen Parameter – Probabilität von Erfolg versus Misslingen der vaginal-operativen Entbindung.
stage of labor [6, 7]. Similar to the methods of Henrich et al. [12] and Dietz et al. [11], we found that the greater the percentage of head passing the IPL, the greater the chances for successful operative vaginal delivery. The definition of the IPL differs between the different studies. Dietz et al. quantified fetal head descent in 139 women by measuring the minimum distance between the
fetal head and the IPL which was positioned vertical to the central axis of the symphysis pubis in the midsagittal plane. They found a correlation between the head station and the clinical measures of head engagement: the lower the presenting part, the greater the head progression distance [11]. Similarly, Eggebo et al. measured the shortest distance from the outer bony limit of the fetal skull to the skin surface of the perineum in 152 women before the onset of labor. They found that the lower values of these measurements were associated with quick labor without obstetric interventions [15]. The main limitation of these studies was that they were not performed during the second stage of labor. Henrich et al. performed US in 20 patients immediately before vacuum extraction to predict the success of the VE. They demonstrated that when the widest part of the fetal head crossed the IPL, and especially if the head was up, an operative vaginal delivery had a favorable outcome. They defined the IPL as the line perpendicular to the long axis of the symphysis pubis, originating from the caudal end of the symphysis and extending to the dorsal part of the birth canal. The main limitations of this study were that the posterior skull was not always well visualized. Therefore, there was some subjectivity in the determination of the widest fetal head diameter [12]. We also agree that HWPD measurement may be of some limitation due to its subjective impression as mentioned above as the widest part depiction of the fetal skull is not a fixed landmark which can produce some variation of the measurement. On the other hand, we feel that HRD, which is based on the ratio of the skull that is beyond the prominent IPL, might be a more objective parameter. Previous studies evaluated the location of the presenting part of the fetal head in the birth canal which can be low although the wide part of the skull is actually high [11 – 13]. This is especially pronounced in prolonged labor with fetal head molding. The main advantage of the HRD is the information is provides regarding the spatial location of the skull in the birth canal which may have an advantage in obstructed labor. Another method studied by Kalache et al. and Barbera et al. measured the angle between a line placed through the midline of the symphysis pubis and a line running from the inferior apex of the symphysis tangentially to the fetal skull (the angle of progression). When this angle was 1200 the probability of successful vacuum extraction or spontaneous vaginal delivery was 90 % [13, 14]. Indeed, Bamberg et al. tried to validate the measurements of the angle of progression using open MRI, and demonstrated a significant correlation between the angle of progression determined by US and the distance between the presenting fetal part at the level of the maternal ischial spines [16, 17]. Open MRI is considered the gold standard for measuring the fetal head station [16]. The limitation of these studies was that they were not performed during labor. A recent study performed by Cuerva et al. demonstrated that the angle of progression measured during labor between contractions may predict a difficult forceps delivery [18].
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NVD: normal vaginal delivery; CS: cesarean section; HWPD: head widest part distance; HRD: head ratio distance
However, the angle of progression in our center did not predict the success or failure of operative vaginal delivery. The advantages of the present study were the performance of ultrasound during the second stage of labor just prior to operative delivery, including both vacuum extraction and forceps deliveries. The suggested measurements in our study, i. e. the HWPD and the HRD, overcome the possible limitation of the pressure of translabial US. The success or failure of operative vaginal delivery did not influence the Apgar score, although the more difficult the operative vaginal delivery was, the lower the Apgar score. The PH and the hematocrit were not influenced by the difficulty of the procedure, maybe because Apgar scores reflect immediate influence on the newborn. We acknowledge the disadvantage when reporting the subjective impression of several physicians on the difficulty of the delivery. To overcome this, future studies may use more objective and quantitative parameters such as measuring the timing and traction of the fetal head during operative delivery. In summary, the clinical significance of our findings influences the management of the 2nd stage of labor, the explanation given to the patient by the obstetricians, and the place where the procedure is performed. When a difficult operative vaginal delivery is expected, it can be performed in the operation room in a double setup arrangement. This way time is saved in cases of failure of the procedure when the staff is ready for immediate cesarean section.
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Original Article
