Abstract Introduction The transradial approach (TRA) has gained popularity in cardiology procedures. This study aims to evaluate forearm and hand arterial circulation in radial artery (RA) occlusion (RAO) patients after coronary angiography (CAG) and percutaneous coronary interventions (PCI). The ulnar (UA) and anterior interosseous artery (AIA) can compensate for RAO. Methods A prospective, observational study was conducted on 40 RAO patients after CAG/PCI. Ultrasonographic and functional evaluation (Barbeau test) of collateral circulation through AIA or UA were performed. Statistical analyses were applied to evaluate various Doppler ultrasound parameters and the anatomical characteristics of the RAO. Results The RAO group mean age was 71.22 ± 9.99 years, and 45% were male. RA, UA, and AIA showed significant differences in peak systolic velocity, end-diastolic velocity, arterial diameter, total flow volume, and stroke volume (p < 0.01). Pulse quality over RA and UA also differed significantly (p < 0.0001). Blood flow direction in the distal RA segment divided patients into an antegrade flow group (50%) from AIA and a retrograde flow group (50%) from UA. The Barbeau test results varied among RAO patients, with type D being the most common. Anatomical locations of RAO included the anatomical snuffbox (10%), wrist (60%), and forearm (30%). The logistic regression model revealed that the Barbeau test results on Finger 2 (p=0.0006, OR=0.1398) and Finger 4 (p=0.004, OR 0.2843) were significant predictors for the occurrence of antegrade or retrograde blood flow in the distal RA when RAO occurred. Furthermore, when the RA was occluded, the study revealed that a palpable pulse over the RA was still possible in 15% of cases. Conclusion Ultrasonographic evaluation and the Barbeau test can assess collateral circulation and predict blood flow patterns in RAO patients. Further research is needed to validate these findings, explore additional factors influencing collateral circulation and access route selection, and investigate the clinical implications of different RAO anatomical locations in cardiology procedures.Radial Artery OcclusionThe pulse quality over RA/UA with RAO