Blockage in the fallopian tubes negatively affects the chances of natural pregnancy. This is because, in natural conception, the meeting of the egg and sperm, the early development of the embryo, and its subsequent transfer to the uterus all occur within the fallopian tubes. In in vitro fertilization (IVF) treatment, since fertilization takes place outside the body, blocked tubes do not directly alter the chances of pregnancy. However, in some cases, fluid accumulation (hydrosalpinx) in the tubes can reduce the likelihood of the embryo implanting in the uterus. In such a situation, laparoscopic closure or removal of the fallopian tube or tubes may be necessary. Your doctor will provide you with detailed information specific to your condition.