Purpose The use of low-frequency high-definition power Doppler in assessing and defining pulmonary venous connections was investigated.Methods Study A included 260 fetuses at gestational age ranging from 18 weeks to 36 weeks.Pulmonary veins were assessed by performing two-dimensional B-mode , color Doppler flow imaging (CDFI) and low-frequency high-definition power Doppler.A score of 1 was assigned if 1 pulmonary vein was visualized, 2 if 2 pulmonary veins were visualized, 3 if 3 pulmonary veins were visualized, and 4 if 4 pulmonary veins were visualized.Compare the detection rate between Exam-1 and Exam-2 (Intra-observer variability)and between Exam-1 and Exam-3 (inter-observer variability).In study B, 5 cases with abnormal pulmonary venous connection were diagnosed and compared to their anatomical examination Results Study A, there was significant difference between CDFI and low-frequency high-definition power Doppler for the four pulmonary veins was observed (P <0.05).The detection rate of each pulmonary vein employing low-frequency high-definition power Doppler was higher than that employing two-dimensional B-mode images, CDFI.There was no significant difference between the intraand inter-observer variabilities using low-frequency high-definition power Doppler display of pulmonary veins was observed (P>0.05), the coefficient correlation between Exam-1 and Exam-2was 0.844, and the coefficient correlation between Exam-1 and Exam-3 was 0.821.Study B, one case of total anomalous pulmonary venous return and four cases of partialanomalous pulmonary venous return were diagnoses by low-frequency high-definition power Doppler, and confirmed by autopsy.Conclusions The assessment of pulmonary venous connections by low-frequency high-definition power Doppler is advantageous.Pulmonary venous anatomy can and should be monitored during fetal heart examination.