Inferior epigastric artery arising from the obturator artery as a terminal branch of the internal iliac artery and consideration of its rare occurrence

The origins of the inferior epigastric and obturator arteries and the relationship between these arteries have been determined macroscopically in examinations of 706 body-halves of Japanese subjects. Three very rare inferior epigastric arteries were found to arise from the obturator artery leaving the internal iliac artery. The intimate relationship between these arteries has been documented by the obturator artery arising from the inferior epigastric artery and the anastomosis between them. It is generally interpreted that such anomalies occur as remnant or partial disappearance of the connection between the pubic branches of the inferior epigastric and obturator arteries. The inferior epigastric artery arising from the obturator artery is also thought to be a similar anomaly. Since the obturator artery from the inferior epigastric artery represents one form of extreme anomaly, and the inferior epigastric artery from the obturator artery represents another form, it would seem that these two forms of extreme anomaly should occur at similar frequencies. However, in our research, the incidence of the former was 10.5% while that of the latter was a very low 0.4%. During normal development, the inferior epigastric artery is established at an earlier stage than the obturator artery as a channel for blood supply. We suppose that the difference of blood flow resulting from this time lag is one of the reasons why the inferior epigastric artery from the obturator artery is very rare in comparison to the obturator artery from the inferior epigastric artery.