Letter to The Editor Methodological Concerns Regarding Levels of Vascular Endothelial Growth Factor (VEGF) in Serum of Women with

We read with interest the manuscript entitled "Serum and peritoneal fluid levels of vascular en-dothelial growth factor in women with endometrio-sis " 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 endometrio-sis 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 ad-