Reliability of Ultrasound Modalities in Assessment Lower Uterine Segment in Women with Previous Cesarean Section

Abstract

The number of deliveries by caesarean section has been increasing steadily worldwide in recent decades. Although it is often assumed that caesarean section improves neonatal outcomes, there is no hard scientific evidence to support this. The safety of caesarean section, however, has increased owing to improvements in surgical and anaesthetic techniques, increased safety of blood transfusion and routine use of antibiotics and thromboprophylaxis. As the incidence of caesarean deliveries rises,the number of patients who face the decision between a trial of labour (TOL) and repeat caesarean section delivery increases Uterine rupture is an uncommon but potentially catastrophic complication of a trial of VBAC. Several studies have reported the perinatal risks of failed trial of labour and uterine rupture in women attempting VBAC. Studies have shown that the risk of uterine rupture in the presence of a defective scar is directly related to the degree of thinning of the lower uterine segment. Ultrasound also has been used by clinicians to diagnose uterine rupture before the onset of labour, and recently, researchers have tried to predict which women may be at increased risk of uterine rupture. To measure the scar thickness, the most suitable time to perform ultrasonography is from 36-38 weeks gestation, as this allows for adequate lower segment development and avoids problems of diagnosis when the presenting part is deep in the pelvis and when the amniotic fluid is physiologically decreased