OBJECTIVE: Unilateral obstruction of the proximal fallopian tube is identified in 10-24% of patients undergoing hysterosalpingography for evaluation of infertility. Upon further testing, this obstruction spontaneously resolves 16-80% of the time. We hypothesized that patient rotation during hysterosalpingography might resolve proximal tubal obstruction in some cases by altering either the location of intrauterine air bubbles or the spatial relationship of the tube to the uterine fundus. METHODS: In patients in whom unilateral proximal tubal obstruction was detected during hysterosalpingography performed for standard clinical indications, the patient was rotated on her hip approximately 45° such that the obstructed tube was first superior (ventral) to the patent tube, and dye was reinjected. If obstruction did not resolve, the patient was rotated in the opposite direction so that the obstructed tube was inferior (dorsal) to the patent tube and dye reinjected. RESULTS: Unilateral tubal obstruction was found in 15% of cases (24 of 156). Rotating the patient with obstructed tube superior to the patent tube never resulted in tubal patency, whereas rotating the patient with the obstructed tube inferior resulted in resolution of tubal patency in 63% of cases (15 of 24). CONCLUSION: Unilateral cornual obstruction during hysterosalpingography is often resolved by rotating the patient such that the obstructed tube is more inferior. Although this observation may be the result of dislodging smaller air bubbles, from a fluid dynamics perspective a more likely explanation is unkinking of the more inferior tube. © 2003 by The American College of Obstetricians and Gynecologists.