Objective: To assess the diagnostic efficiency of transvaginal ultrasound four-dimensional contrast hysterosalpingography (TVS 4D-HyCoSy) in evaluation of fallopian tube patency and analyze the misdiagnosed cases. Methods: Fifty two infertile patients (97 fallopian tubes) underwent TVS 4D-HyCoSy and fallopian tube patency was assessed. The results were divided into obstructed and unobstructed groups (consisting of fully unobstructed and partially obstructed). The results of laparoscopic methylene blue test were used as the golden standard. The results were compared and contrasted with that of laparoscopic methyl blue test. Results: Among the 97 fallopian tubes, TVS 4D-HyCoSy showed 34 unobstructed tubes, 28 partially obstructed tubes, 35 obstructed tubes, resulting in a consistency of 83 tubes and inconsistency of 14 tubes with the findings of laparoscopic methylene blue test. The factors in false positive results included pelvic surgery, endometriosis of pelvis and tubal spasm, and for false negative results included the contrast agent in the unobstructed fallopian tubes diffusing into the diseased side, distal fallopian hydrops and expansion being mistaken for contrast agent diffusion and contrast agent reflux. The sensitivity, specificity, positive predictive value and negative predictive value of TVS 4D-HyCoSy were 78.4%(29/37), 90.0%(54/60), 82.9%（29/35）, 87.1%（54/62）, respectively. Conclusions: TVS 4D-HyCoSy is an effective method for evaluating the fallopian tube patency. If the above-mentioned factors in misdiagnosed cases occur, objective analysis should be conducted to distinguish the false positive and false negative ones. False positive result should be aware of when there is a history of pelvic surgery. Second time contrast imaging could be done if needed.