When the fallopian tubes are blocked or damaged, it is difficult for fertilization to occur and for the fertilized egg to reach the uterus. Irregular fallopian tubes can be caused by:
- Past ectopic pregnancy
- Uterine fibroids (non-cancerous growths in the uterus)
- Pelvic inflammatory disease (PID)
Ectopic pregnancy occurs when the embryo attaches outside of the uterus. 90% of the time this happens in the fallopian tubes, but embryos can also attach to the ovary, cervix, or in the abdomen. These pregnancies are not viable and will be quickly removed when discovered. If the ectopic pregnancy has not caused the tube to burst, the embryo can usually be removed and the tube repaired laparoscopically.
Uterine fibroids are non-cancerous smooth muscle growths in the uterus. Fibroids can cause bleeding, miscarriage, or prevent embryos from attaching, but contribute to infertility in only about 3% of women who develop them.
Scarring from pelvic inflammatory disease can contribute to difficulties conceiving. This frequently affects the fallopian tubes (and may be a factor in ectopic pregnancies) but can also occur in the uterus and ovaries.