According to the textbook, GIFT (Gamete Intra Fallopian Transfer) and ZIFT (Zygote Intra Fallopian Transfer) involve transferring gametes or early zygotes directly into the fallopian tube . Therefore, these methods are not suitable if the fallopian tubes are blocked. IVF (In Vitro Fertilisation) involves fertilisation outside the body followed by Embryo Transfer (ET). If the tubes are blocked, the embryo (typically with more than 8 blastomeres) can be transferred directly into the uterus (Intra Uterine Transfer - IUT), bypassing the fallopian tubes .