Intraaortic balloon pump (IABP) is used as temporary mechanical assistance in case of cardiovascular diseases, even if different hemodynamic problems and, thus, clinical complications may happen, such as the decrease of visceral perfusion. A computational fluid dynamic (CFD) study was carried out to investigate the effects of different IABP-induced abdominal occlusions on patient-specific aortic flow. Two possible sizes (25 and 34 cm3) and two locations (2 and 3 cm) of the balloon were compared, modeling four abdominal occlusions and numerically reproducing IAB inflation/deflation behavior. The results highlighted that the perfusion in renal, mesenteric, and iliac arteries decreases when the abdominal occlusion increases with balloon inflation. The study illustrates also how the balloon size affects the flow in aorta vessels in both locations, and that the positioning is of little relevance for the 34 cm3 balloon, whereas it influences the aortic flow very much in case of 25 cm3 IAB. This analysis demonstrates how the IAB-induced occlusion may vary the abdominal circulation; therefore, the correct size and positioning are emphasized for patient’s outcome.