Objective: To evaluate the application effect of contrast-enhanced transthoracic echocardiography (c-TTE) in detecting right to left shunt (RLS) in patent foramen ovale (PFO) under different states. Methods: Forty-five patients with suspected PFO who visited the hospital from January 2021 to June 2025 were selected. All of them underwent c-TTE and transesophageal echocardiography (TEE) after admission. The diameter of PFO was measured. With the diagnostic results of TEE as the standard, the diagnostic value of c-TTE in PFO under cough motion (CM), Valsalva motion (VM) and modified VM was comparatively analyzed. The differences in cardiac cycle distribution and grading of RLS microbubble initially appearing under above states were analyzed. Results: A total of 29 patients were diagnosed with PFO by TEE. For c-TTE, the diagnostic accuracy under modified VM was slightly higher than that under CM and VM (P>0.05). Initial appearance of RLS microbubbles in fewer than 3 cardiac cycles was more common under modified VM than under CM and VM (P<0.05). Moreover, RLS at level 4 was also more common under modified VM than under CM and VM (P<0.05). Conclusion: C-TTE has good diagnostic efficacy for PFO under different states, and its diagnostic value is higher under modified VM.