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European Journal of Obstetrics & Gynecology and
Reproductive Biology 123 (2005) 193–197
www.elsevier.com/locate/ejogrb

Fetal head position during the second stage of labor:
Comparison of digital vaginal examination and
transabdominal ultrasonographic examination
Olivier Dupuis a,*, Silveira Ruimark b, Dupont Corinne c,
Thevenet Simone d, Dittmar Andre´ b, Rudigoz Rene´-Charles a
a

Unite´ de Gyne´cologie Obste´trique, Hoˆpital de la Croix Rousse, 103 Grande-Rue de la Croix Rousse, 69317 Lyon Cedex 04, France
Laboratoire de Physique de la matie`re, Baˆtiment Blaise Pascal, INSA, 7 Avenue Jean Capelle, 69621 Villeurbanne Cedex, France
c
Service de Biostatistique Hospices Civils de Lyon, Lyon, France
d
Cellule des transferts pe´rinataux de la re´gion Rhoˆne-Alpes, Hoˆpital Edouard Herriot, 5 Place d’Arsonval, 69437 Lyon Cedex 03, France
b

Received 24 July 2004; received in revised form 14 February 2005; accepted 19 April 2005

Abstract
Objective: To study the correlation between digital vaginal and transabdominal ultrasonographic examination of the fetal head position
during the second stage of labor.
Methods: Patients (n = 110) carrying a singleton fetus in a vertex position were included. Every patient had ruptured membranes and a fully
dilated cervix. Transvaginal examination was randomly performed either by a senior resident or an attending consultant. Immediately
afterwards, transabdominal ultrasonography was performed by the same sonographer (OD). Both examiners were blind to each other’s results.
Sample size was determined by power analysis. Confidence intervals around observed rates were compared using chi-square analysis and
Cohen’s Kappa test. Logistic regression analysis was performed.
Results: In 70% of cases, both clinical and ultrasound examinations indicated the same position of the fetal head (95% confidence interval,
66–78). Agreement between the two methods reached 80% (95% CI, 71.3–87) when allowing a difference of up to 458 in the head rotation.
Logistic regression analysis revealed that gestational age, parity, birth weight, pelvic station and examiner’s experience did not significantly
affect the accuracy of the examination. Caput succedaneum tended to diminish ( p = 0.09) the accuracy of clinical examination. The type of
fetal head position significantly affected the results. Occiput posterior and transverse head locations were associated with a significantly
higher rate of clinical error ( p = 0.001).
Conclusion: In 20% of the cases, ultrasonographic and clinical results differed significantly (i.e., >458). This rate reached 50% for occiput
posterior and transverse locations. Transabdominal ultrasonography is a simple, quick and efficient way of increasing the accuracy of the
assessment of fetal head position during the second stage of labor.
# 2005 Published by Elsevier Ireland Ltd.
Keywords: Fetal head position; Ultrasonography; Quality control; Safety

1. Introduction
Assessing fetal head location during labor is of
paramount importance. Knowledge of the position of the
head can help to predict the course of labor. Persistent
occiput posterior presentation is associated with higher rates
* Corresponding author. Tel.: +33 4 72 07 16 38; fax: +33 4 72 07 16 65.
E-mail address: olivier.dupuis@chu-lyon.fr (O. Dupuis).
0301-2115/$ – see front matter # 2005 Published by Elsevier Ireland Ltd.
doi:10.1016/j.ejogrb.2005.04.009

of maternal and neonatal complications [1,2–4]. Thus,
knowing the exact position of the fetal head might prevent
some of these complications. Furthermore, the exact
position of the fetal head must be known for appropriate
cephalic forceps application [5].
Clinicians traditionally use palpation of the sagittal
suture and of the anterior and posterior fontanels to
determine the fetal head position. Nevertheless, clinical
examination is highly subjective. Two situations can lead to

194

O. Dupuis et al. / European Journal of Obstetrics & Gynecology and Reproductive Biology 123 (2005) 193–197

misdiagnosis. (1) Large caput succedaneum can mask the
fetal sutures and fontanels making it very difficult to identify
the head position clinically. (2) Asynclitism can lead to an
asymmetric location of the classical anatomical landmarks
(i.e., fontanels and sutures) and increase the difficulty of the
diagnosis. If unrecognized, these situations are potentially
dangerous. Indeed, in cases of forceps application, such
errors can lead to eye or brachial plexus trauma [6,7].
Recent studies suggest that ultrasound assessment during
labor can help to assess the fetal head position correctly [8–
11]. Nevertheless, only two studies have specifically
commented upon the correlation between clinical and
ultrasound examination according to head position [9,10].
The aim of our study was to assess the correlation between
these two examinations in occiput anterior and occiput
posterior or transverse positions.

2. Patients and methods
This prospective, randomized study included patients that
delivered in a teaching maternity hospital between May and
December 2003. Informed consent was obtained from every
participant.
Fully dilated women with cephalic-presenting fetuses
were included. All patients had ruptured membranes. Eligible
patients were randomly assigned to either the ‘‘senior
resident’’ group (digital vaginal examination performed by
the senior resident) or the ‘‘attending physician’’ group
(digital vaginal examination performed by the attending
physician) in a ratio of 1:1 by means of computer-generated
random numbers. Randomization was performed using
blocks of four and opaque sealed envelopes.
Operators were free to use their own clinical criteria to
identify the fetal head position. The level of the descent of
the presenting part in the birth canal was determined
accordingly to the 1988 ACOG classification in 11 levels
( 5 to +5), and the presence of caput succedaneum was
recorded. Head position was classified as one of the
following eight categories: occiput anterior (OA; 08), left
occiput anterior (LOA; i.e., 458), left occiput transverse
(LOT; i.e., 908), left occiput posterior (LOP; i.e., 1358),
occiput posterior (OP; i.e., 1808), right occiput posterior
(ROP; i.e., 2258), right occiput transverse (ROT; i.e., 2708),
right occiput anterior (ROA; i.e., 3158). In cases that did not
exactly match one of those eight locations the clinician was
asked to give the nearest location.
Immediately after the clinical examination was performed, the fetal head position was determined sonographically by the same sonographer (OD) who was unaware of
the clinical findings. The ultrasonographic examination was
performed using a Hitachi EUB-415-CFM machine with a
3.5 MHz abdominal probe. All examinations were performed in the supine position. We routinely used an
‘‘ultrasound algorithm’’ to locate the fetal head. This
algorithm uses the fetal orbital region and the fetal cervical

spine to locate the head 12 and takes into account the fact
that less than 20% of deliveries occur in a persistent occiput
posterior position [2–4,12–15]. The ultrasound transducer
was placed longitudinally, tangentially to the skin and used
to look for the cervical fetal spine and occipital bone. In
cases of OA, LOA and ROA, the cervical spine and occipital
bone appears, respectively, on the midline of the maternal
abdomen, half way between the left anterosuperior iliac
spine and the pubis, and half way between the right
anterosuperior iliac spine and the pubis. If the fetal cervical
spine and occipital bone could not be found at one of these
three locations, the sonographer looked for an ROT or LOT
location. In such cases, the cervical spine is located at the
level of the right or left anterosuperior iliac spine. The
transducer was placed transversely in the suprapubic region
of the maternal abdomen and the fetal head position was
confirmed using the position of the midline cerebral echo
and that of the cerebellum [10,16]. Finally, the sonographer
looked for a posterior head location (OP, LOP, ROP). In case
of OP, fetal orbits are symmetrically located on each side of
the maternal pubic bone. In case of ROP, the orbits are
located on the left side, and in case of LOP, orbits are located
on the right side. The location was then confirmed using the
method already described [10,16].
Power analyses were performed with a pre-requisite of a
95% confidence interval (CI) around an estimated fraction of
error of no more than 10%. This indicated that 100 subjects
were required. We assumed that attending consultants were
three times more likely than senior residents to determine the
correct head position by transvaginal digital examination.
With an alpha value of 0.05 and a power of 80%, at least 49
subjects were required in each group.
Confidence intervals around all observed rates and
proportions were compared using chi-square analysis.
Cohen’s Kappa test of concordance was used to assess
the relationship between clinical transvaginal and ultrasonographical abdominal examinations.
Multivariate regression analysis was performed to identify
variables that could predict a risk of error higher than a
458 arc. p < 0.05 was considered statistically significant.
Statistical tests were carried out using Excel 1998
(Microsoft Office 1998, Microsoft corporation, Redmont,
WA, USA) and SPSS statistical package (version 11.5, SPSS
Inc., Chicago, IL, USA).

3. Results
One hundred and ten patients were included. Mean
maternal age was 30.7 5.3 years, 62% (n = 68) were
nulliparous, mean gestational age was 39.8 1.2 weeks,
and mean birth weight was 3420 471 g. All women had
epidural analgesia. Characteristics of the 110 patients are
given in Table 1.
Digital vaginal examinations were performed by senior
residents in 50% (n = 55) of cases and by attending

O. Dupuis et al. / European Journal of Obstetrics & Gynecology and Reproductive Biology 123 (2005) 193–197

195

Table 1
Characteristics of the 110 women included

Age (years)
Nulliparous (%)
Gestational age at delivery (week)
Birth weight (g)
Ischial spine station higher than zero level ( 1, 2,
Occiput anterior positions (OA, ROA, LOA) (%)
Presence of caput succedaneum (%)

3) (%)

Senior resident (n = 55)

Attending consultant (n = 55)

p

30.2 5.2
63.6
39.81 1.23
3417 460
12.7
78.2
25.5

31.3 5.3
60
39.84 1.22
3422 486
9.1
85.5
36.4

0.27
0.69
0.89
0.95
0.54
0.32
0.21

OA = occiput anterior; ROA = right occiput anterior; LOA = left occiput anterior.

consultants in 50% (n = 55) of the cases. The frequencies of
the various fetal head positions determined by ultrasound
were 81.8, 17.3 and 0.9% for anterior, posterior and
transverse fetal head locations, respectively. All transabdominal ultrasound examinations lasted less than 3 min. In
cases of OA, ROA and LOA, the examination lasted less
than 30 s. The incidences of the various pelvic stations were
1.8, 5.5, 3.6, 28.2, 34.5, 19.1 and 7.3% for stations 3, 2,
1, 0, +1, +2 and +3, respectively. In 70% of cases (n = 77),
digital vaginal examinations indicated a similar head
position (95% CI 66.5–78.4). Cohen’s Kappa test indicated
a concordance of 0.66 (with a correct assessment rate
attributed to chance alone of 0.27). When accounting for a
diagnosis within 458 arc fetal head position determinations
by transvaginal digital examinations were similar to those
obtained by transabdominal ultrasound (95% CI: 71.3–87)
in 80% of cases (n = 88). In this case, Cohen’s Kappa test
indicated a concordance of 0.74 (with a correct assessment
rate attributed to chance alone of 0.26).
Ranges of errors are given in Table 2. In seven cases, the
operator was unable to determine fetal head location by
clinical assessment alone.
Logistic regression analysis revealed that only the type of
head position significantly affected the accuracy of
transvaginal examination; errors were significantly more
frequent for occiput posterior (OP, ROP, LOP) and
transverse locations than for occiput anterior locations
( p < 0.001) (Table 3).
Gestational age ( p = 0.2), parity ( p = 0.6), birth weight
( p = 0.4), higher ischial spine station ( p = 0.2) and
examiner experience ( p = 0.2) did not significantly affect
Table 2
Range of error of the clinical digital vaginal examination
Range of error (8 arc)
0
45
90
135
180
225
Not availablea
Total
a

N
77
11
6
1
7
1
7
110

%
70
10
5.5
0.9
6.4
0.9
6.4
100

Clinical examination failed to give any fetal head position.

the accuracy of the examination. The presence of caput
succedaneum tended to decrease the accuracy of the clinical
examination ( p = 0.09).

4. Discussion
Ultrasonographic determination of fetal head position is
of paramount importance before instrumental delivery.
Furthermore, when instrumental delivery is required to
expedite delivery for an abnormal CTG rate, identification of
the head position should not delay the delivery. In our
cohort, 81.9% of the fetal heads were in an occiput anterior
location. Studies by Akmal and Sherer confirmed that
anterior position of the occiput is the most common category
of head positions during the second stage of labor in 66 and
54% of cases, respectively [8,10]. Therefore, we believe that
the sonographer should first look for an anterior location
(OA, ROA, LOA) using a longitudinal view. A transverse
view is required only in occiput posterior and in occiput
transverse cases. This procedure will save time and might
increase the feasibility of this technique.
Our results suggest that clinical digital vaginal examination is inaccurate in defining the fetal head location during
the second stage of labor in up to 20% of the cases. Sherer
et al. examined 112 patients during the second stage of labor
and reported that the findings of digital vaginal examination
differed from those of sonography by >458 in rotation in
39% of cases [8]. Akmal et al. studied 64 patients
immediately before instrumental delivery and found that
the difference was >458 in 19% of cases [10]. Finally,
Kreiser et al. studied 44 cases during the second stage of
Table 3
Relationship between head location and digital vaginal examination error

CI 95%
66.5–78.4
5.1–17.2
2–11.5
0.02–4.9
2.6–12.7
0.02–4.9
2.6–12.7

Head location

Range of error

Total

0–458

>458

Occiput anterior (OA, ROA, LOA)
Occiput posterior
(OP, ROP, LOP) and
occiput transverse

78
10

12*
10*

90
20

Total

88

22

110

*

Difference in error rate between the occiput anterior and the occiput
posterior + occiput transverse group is highly significant: p < 0.001.

196

O. Dupuis et al. / European Journal of Obstetrics & Gynecology and Reproductive Biology 123 (2005) 193–197

Table 4
Rate of error of the clinical digital vaginal examination
Reference

Year

n

Rate of error > 458 (%)

Correlation between error rate and head position

Kreiser et al. [11]
Sherer et al. [8]
Akmal et al. [10]
Present study

2001
2002
2003
2004

44
112
64
110

18
39
19
20

Not studied
Not studied
Significant increase in error rate with occiput lateral or posterior positions
Significant increase in error rate with occiput lateral or posterior positions

labor and found an error rate of 18% [11] (Table 4).
Furthermore, this study showed that clinical examination is
sometimes totally unable to locate the fetal head position (in
seven out of 110 cases). These data strongly suggest that
obstetrical teams should be trained to determine the fetal
head position by transabdominal ultrasound.
To date, instrumental deliveries account for 9.5–11.2% of
all deliveries [17,18]. Therefore, any technique that may
increase the safety of an instrumental delivery should be
promoted. In case of a forceps delivery, an error of 908 will
lead to inappropriate (i.e., fronto occipital) forceps blade
placement and call for potential fetal eye or neck injury
[6,7]. Errors of 1808 might lead to head deflexion and
increase the failure rate of the instrumental delivery [19].
Several studies have shown that paramedian placement of a
vacuum also increases the procedure’s failure rate [20,21].
Thus, knowing the exact position of the fetal head might
help the clinician to decrease the rate of paramedian cup
placement.
Logistic regression analysis found that digital vaginal
examination is significantly less accurate in cases of occiput
posterior locations, confirming the results obtained by
Akmal et al. and by Souka et al. [9,10]. In the occiput
posterior position, the head is driven against the perineum to
a much greater degree than in the anterior occiput position
[22]. Moreover, several authors have performed studies
comparing women with persistent occiput posterior position
and occiput anterior position [3,4]. Those studies have
shown that persistent occiput posterior position is associated
with a significantly higher incidence of anal sphincter
disruption. De Leeuw et al. studied 284,783 deliveries and
showed that mediolateral episiotomy provides strong
protection against damage to the anal sphincter [23].
Therefore, knowing the fetal head position may also help in
deciding whether or not to perform a mediolateral
episiotomy [1,22], and hence, help to prevent anal sphincter
disruption. Fitzpatrick as well as Ponkey studies have also
shown that less than one-third of nulliparas with persistent
occiput posterior position will achieve a spontaneous
vaginal delivery. Therefore, early diagnosis of persistent
occiput position could help obstetricians and midwives to
provide woman with additional information about operative
vaginal as well as abdominal deliveries.
Results related to the experience of the obstetrician in
determining the position of the fetal head are conflicting.
Sherer et al. did not find any significant difference [8],
whereas Akmal et al. suggested that both variables
independently contribute to the accuracy of vaginal

examination [8]. Irrespective of the difference between
junior and senior obstetricians, all studies showed that senior
obstetricians do get the fetal head position wrong in
significant proportion of cases, highlighting the potential
benefits of transabdominal ultrasound examination.
In summary, our data strongly support the use of abdominal
ultrasound to locate the fetal head. This simple and
reliable technique might improve the recognition of occiput
posterior positions and facilitate the decision of whether
or not to perform a mediolateral episiotomy. Finally,
ultrasound identification of the fetal head position might
increase the success rate and safety of instrumental delivery.

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