A teenager of 13 years-old with complaints of abdominal pain is aimed at abdominal US for excluding appendicitis - found mesadenitis, for surgeon this was not enough, and after filling the UB is aimed to pelvis US - the lesion of the endometrium like a complex cyst size of 12mm consisting of 2 round structures, one of them anechoic and second - hypoechoic (polyp? EP? etc.?).