The HSG is an imaging test that allows us to evaluate the inside of the uterine cavity and the fallopian tubes. This test involves injecting a small amount of dye through the cervix while tracking the progress of the dye by X-ray as it fills the uterine cavity and traverses the tubes. The structure of the uterine cavity and tubes is reflected in the pattern of dye. By knowing this structure, appropriate treatment can be recommended. Even with IVF, knowledge of tubal status is important. Research has shown that the presence of even one blocked and dilated fallopian tube, called a “hydrosalpinx”, decreases the pregnancy success rate in an IVF cycle. The hysterosalpingogram (HSG) does not tell us everything about the structure of the pelvic organs. It does not show the muscular wall of the uterus or the ovaries. It is possible to have a normal HSG but still have a significant pelvic factor such as fibroids, adhesions or endometriosis. But, vital information on tubal condition is best obtained through HSG .