Background Recent advances in the superficial circumflex iliac artery (SCIA) perforator flap transfer emphasized the necessity to comprehensively understand the lower abdominal vasculature. This study aimed to clarify the relationship among the superficial inferior epigastric artery (SIEA), the superficial branch (SCIAs), and the deep branch (SCIAd) of the SCIA. Methods Computed tomographic angiography was retrospectively reviewed in 312 hemiabdomens in 161 female patients who underwent abdominal flap breast reconstruction. We assessed the presence, caliber, and branching patterns of the SCIA branches and the SIEA. Results The SIEA-SCIA common trunk was present in 40.1% of the hemiabdomen and was identified in either side of the abdomen in 63.6% of patients. At least one superficial vessel larger than 1.5 mm was found in 61.5% of hemiabdomens. Seven branching patterns of the SCIA-SIEA system were noted: (1) the SCIA and the SIEA originated together (17.0%); (2) the SIEA and the SCIAs shared an origin (22.8%), (3) the SCIA and the SIEA branched separately (17.0%), (4) each artery originated separately (8.0%); (5) the SCIAs and the SCIAd emerged together with the SIEA absent (17.3%); (6) the SCIAs and the SCIAd originated separately with the SIEA absent (13.1%); (7) the SIEA and SCIAd originated separately with the SCIAs absent (3.5%). Conclusion SCIA-SIEA branching patterns were classified into seven distinctive patterns. This novel classification may help surgeons to choose the optimal pedicle when using the hemi-abdomen region as the donor site.