Early second trimester transvaginal ultrasound anomaly scan does not cause adverse perinatal outcome

During an early second-trimester transvaginal ultrasound anomaly scan, pressure is applied to the uterus, and the fetus is often rotated manually to allow scanning of its various organs. This study was designed to determine if performing a transvaginal ultrasound anomaly scan during the early second trimester of pregnancy is associated with adverse perinatal outcome or cord entanglement.

During the 4.5year study period we prospectively collected cases of routine ultrasound scans at 14-17weeks gestation performed as anomaly screening, together with perinatal outcome. The study population consisted of 164 women who underwent a transvaginal approach, and the control population consisted of 224 women in which a transabdominal approach was used. Data on perinatal parameters was collected from delivery charts from the four local hospitals.

There were more operative deliveries (vaginal or Cesarean) in the transvaginal scan group (32% vs. 23%, p=0.05). However, on multiple logistic regression analysis vaginal scans were not associated with increased operative delivery rates with an adjusted odds ratio of 1.47 and a 95% confidence interval of 0.85-2.54. There were no other clinically significant differences in perinatal outcomes, or in cord entanglement.

Transvaginal ultrasound anomaly scan conducted in the early second trimester of pregnancy is a safe procedure for the fetus.