Methodological Concerns Regarding Levels of Vascular Endothelial Growth Factor (VEGF) in Serum of Women with Endometriosis

We read with interest the manuscript entitled "Serum and peritoneal fluid levels of vascular endothelial growth factor in women with endometriosis" recently published in the International Journal of Fertility and Sterility (1). The authors measured the levels of vascular endothelial growth factor in serum and peritoneal fluid of 179 women, 90 of whom were diagnosed with endometriosis, and observed that serum VEGF levels were similar in both study groups while women with endometriosis had higher levels of VEGF in peritoneal fluid compared with controls. Thus, the authors have concluded that endometriosis "is not related to the change of VEGF level in circulation". We believe that the methodology used in the study was not adequate to establish levels of "circulating" VEGF at the time of sampling thus invalidating the results of the study.