Routine early maternal screening ultrasound is recommended for a variety of reasons, including evaluation of the cause of vaginal bleeding or suspected gestational trophoblastic disease (such as hydatidiform moles), assessment of gestational age, and identification of multiple gestations.[43]American College of Radiology. ACR-ACOG-AIUM-SRU practice parameter for the performance of obstetrical ultrasound. 2018 [internet publication].
http://www.acr.org/~/media/ACR/Documents/PGTS/guidelines/US_Obstetrical.pdf
[49]American College of Radiology. ACR appropriateness criteria®: first trimester vaginal bleeding. 2017 [internet publication].
https://acsearch.acr.org/docs/69460/Narrative