Uterorectal fossa fluid is not pregnancy, it is medically called pelvic fluid, this is because the female pelvis is in the lowest position and when there is fluid it gathers in this. The common causes of pelvic effusion are after ovulation, as a small amount of follicular fluid is discharged after ovulation, there will be fluid accumulation in the rectal fossa of the uterus. Such symptoms can also occur when there is pelvic inflammatory disease, which is caused by the exudation of inflammatory cells inside the pelvis. So if there is pelvic fluid and it is found to be more than 20mm, most of them should be considered pathological. Pregnancy is normally inside the uterine cavity and not inside the rectal fossa of the uterus.