Third trimester ultrasound has long been in obstetrics a topic of debate. This issue is framed in a historical debate on the effectiveness of routine obstetrical ultrasound and two opposing trends originated in America and Europe, respectively. Primary function of this ultrasound has been to detect fetal growth restriction, but no study has shown evidence of improving perinatal outcomes. Other secondary functions are detection of fetal abnormalities or evaluation of fetal presentation, and they have also shown no evidence. Despite the continuous appearance of works in this regard, health policies of both american and european trends have not been modified. Future seems to show a prolongation of the stalemate. Those health systems with a universal third trimester policy should propose an optimization of the test, in order to improve the benefits and obtain data for future studies that could resolve this longstanding debate.