Does a biochemical pregnancy indicate blocked fallopian tubes?

For women with a biochemical pregnancy, tubal obstruction is usually not the cause. This is because a biochemical pregnancy refers to the successful fertilization of an egg by sperm, forming a zygote that fails to implant and develop within the uterine cavity and is expelled vaginally from the uterus. As a result, hormone levels in the body drop, leading to shedding of the endometrium. However, since sperm and egg can successfully unite within the fallopian tube, this indirectly indicates that the woman's fallopian tubes are patent. If the fallopian tubes were blocked, sperm and egg would generally not be able to unite to form a zygote, or if fertilization did occur, the resulting embryo might implant and grow within the fallopian tube, causing an ectopic pregnancy—this typically does not result in a biochemical pregnancy.