I am 4 weeks pg & i had an us done and it showed trace of free fluid in left adnexa? what does that mean? but thick endo lining & right corpus luteum

Early PG ultrasound: This is typical of an early pregnancy ultrasound as a gestational sac can barely be seen if at all. The corpus luteum is a "yellow body" within the ovary that produces the hormone progesterone and sustains the pregnancy until the placenta develops after 12 weeks. Free fluid is just that, a small amount of fluid inside your abdomen that was seen. Endometrium thickness is support for a new pregnancy

Early pregnancy: It is too early to see a gestational sac with fetal pole. Follow up is very important. The thickened lining of the uterus and corpus literal cyst is normal. The free fluid could have been a ruptured cyst but a tubal pregnancy must be ruled out. You did not mention any bleeding or cramping. If not, most likely normal pregnancy but follow up important