Figure 2a. (a) Longitudinal transabdominal US image in a 37-year-old woman depicts a small fluid collection with questionable echoes and dependent debris, which possibly represents pelvic hemoperitoneum, in the CDS (arrow). b = bladder, u = uterus. (b) Sagittal transvaginal scan shows that the fluid (arrow) is anechoic, which suggests a physiologic cause. bo = bowel, u = uterus.