Which ultrasound is more accurate in measuring cervical length in pregnancy transvaginal or transabdominal? Because according to transabdominal ultrasound my cervical length is 2.7cm and internal os open and told me I have cervical incompetancy .on next day for second opinion I did transvaginal ultrasound at some other place radiologist told me my length is 3.8cm and internal os closed no cervical incompetancy