Tweetable abstract
Simple models based on maternal height and ultrasound findings can
predict the delivery mode and internal fetal head rotation.
INTRODUCTION
Operative deliveries are associated with increased maternal (obstetric
hemorrhage, perineal injuries, wound infection) 1, 2and neonatal morbidity (neonatal seizures, and intracranial hemorrhage)2-6. It is important to monitor labor progress to
prevent these maternal and neonatal complications 7.
The conventional assessment currently relies on a serial digital
examination, which has been demonstrated to be subjective, imprecise,
and poorly reproducible 8, 9. Furthermore, digital
vaginal examinations can also cause discomfort 10 and
may introduce infection 9. Intrapartum
ultrasonographic examinations have been introduced to complement
assessments of labor progress 11.
Occiput posterior (OP) and occiput transverse (OT) positions account for
15 to 49% at the onset of labor 12-15, and in most
cases, the fetal head will rotate spontaneously to the occiput anterior
(OA) positions. Accumulating evidence implicates the persistent OP or OT
position is associated with obstetric complications, including prolonged
labor, operative delivery, postpartum hemorrhage and third or
fourth-degree perineal lacerations16-18. The
spontaneous internal rotation of the fetal occiput from the transverse
or posterior position to the anterior position is associated with
multiparity, a maternal age of fewer than 35 years, maternal stature,
BMI, and newborn birth weight (<4000 g) 14,
19, 20. However, there is still no model, which can help predict
successful fetal head rotation during the delivery.
In the last decade, various sonographic parameters have been proposed,
including the angle of progression (AoP)21,
head-perineum distance (HPD)22 and
midline
angle (MLA) 23.
Several studies have reported that
intrapartum ultrasonography is a reliable and noninvasive approach for
determining fetal head position, station and
descent 24-27. The
AoP has been used to assess fetal head station and be predictive of
spontaneous vaginal delivery or successful instrumental vaginal delivery28-31, and the MLA was associated with the fetal head
station and rotation11.
In the majority of studies, a single assessment of
sonographic
parameters was performed in either the first or second labor phase30, 32-35. Moreover, few studies have developed
predictive models associated with successful internal rotation and
vaginal delivery. Therefore, the primary aim of the present study was to
assess
serial intrapartum ultrasound measurements at different time points
during delivery for the prediction of the delivery mode in nulliparous
women. A secondary aim was to develop a model to predict successful
internal fetal occiput rotation.