OB Dating Atlas - Week 25 - Abdominal Circumference (AC)
Caption
A 19-year-old G0 with an unknown LMP presents for a missed period and light vaginal bleeding. UPT is positive and on abdominal ultrasound, abdominal circumference measures 21.4 cm confirming a 25w6d IUP. General Rules: Measure the in the transverse section around the skin line making sure to be in the same plane as the stomach, umbilical vein, and portal sinus It is important to take multiple measurements here, as measurements can be altered due to fetal breathing motion. Accuracy [3]: ± 7-17 days