Cervical Length Screening in Asymptomatic Women at High Risk and Low Risk for Spontaneous Preterm Birth.

Cervical length (CL) screening should be offered to singletons because there are interventions for those with a short CL. A transvaginal ultrasound (TVU) is the "gold standard" for CL. In singletons with prior spontaneous preterm birth, serial TVU CL screening is recommended between 16 and 23 6/7 weeks. Universal TVU CL screening between 18 and 24 weeks may be considered for low-risk singletons with the administration of vaginal progesterone for TVU CL≤20 mm; alternatively, transabdominal ultrasound CL screening may be considered with reflux to TVU CL screening for a transabdominal ultrasound CL<35 mm or inadequate visualization. CL screening is not recommended in multiples.