2D versus 3D transabdomenal Sonography for Measurement of Lower Uterine Segment Thickness in Women with Previous Cesarean Section

Abstract

Summary C esarean section rate has been rising continuously over the last few decades. This rise has become a challenge to the obstetricians all over the world as many obstetric complications are getting more and more common due to increased percentage of obstetric population with previous Cesarean sections including uterine rupture and abnormal placentation. On the other hand, the rate of Trial of Vaginal Birth after Cesarean Section has been declining due to rising concerns about safety of this mode of delivery. The recent literature has suggested association between VBAC and potential catastrophic complications, including uterine rupture and fetal death, leading to less clinicians offering, and less patients accepting the option of VBAC. Safe utilization of VBAC is an important strategy to decrease Cesarean section rates, however, due to the possible complications, proper patient selection is mandatory. Evaluating the integrity of the previous Cesarean section scar and trying to predict possible scar rupture can be an important step in the process of patient selection. However, at present, there is no reliable method for predicting the risk of uterine rupture in women attempting VBAC. Many researchers have used ultrasonography in measuring the thickness and assessing the integrity of the lower uterine segment in patients with previous Cesarean sections. Although it has been shown that the risk of scar defect is inversely correlated to the LUS thickness, yet, the techniques of measurement remains controversial. Some investigators have used transabdominal ultrasound, while others used transvaginal ultrasound in measuring LUS thickness. The full thickness of LUS was considered by some authors to be the best predictor for uterine rupture, while others have shown that the muscular layer thickness is more predictive. The use of three dimensional ultrasound technology has widely expanded in the field of obstetrics and gynaecology.Recently, the use of three dimensional ultrasound in measuring the lower uterine segment thickness has been investigated. However the main focus of research was to compare the interobserver and intermethod variability, in relation to two dimensional ultrasound. In this study, we demonstrated how much the measurements of LUS obtained by ultrasonography can predict the presence of asymptomatic scar dehiscence.We also demonstrated how superior is 3-D ultrasound over 2-D ultrasound in prediction of scar dehiscence.We measured the full LUS thickness and myometrial thickness via the transabdominal route by 2 observers. This policy if proved to be reliable can help the physician in making decision about safety of VBAC. This study was conducted at Ain Shams Maternity Hospital during the period from January 2015 to September 2015. A total 66 women were recruited in the study. All included women were pregnant at 37 to40 weeks gestation at recruitment, having one previous Cesarean sections.2-D and 3-D ultrasound measurement of the full LUS thicknessand myometrial thickness were done transabdominally by 2 observers.