Blocked Fallopian tubes are the cause of about 20% of female infertility cases. The tubes are delicate, dynamic structures that link the ovaries to the womb, and are easily damaged. Natural pregnancy relies on the Fallopian tubes to support and transport an embryo to the womb, and mucus or scar tissue prevents or delays this vital journey.
Women need at least one patent (open and functional) tube for a natural pregnancy, and if one tube is blocked, it doubles the expected time to get pregnant. If both tubes are blocked, conceiving is impossible without help, and any tubal abnormalities increase the risk of ectopic pregnancies.
Seven causes of Tubal Blockage
Pelvic inflammatory disease (PID)
PID is the main cause of blocked Fallopian tubes, and the inflammation can create scar tissue and adhesions which distort tubes. While PID is usually due to sexually transmitted infections the causes include:
- Sexually transmitted infections by bacteria, viruses, fungi or parasites
- A miscarriage or termination
- Endometritis (inflammation of the endometrial lining of the womb)
- Abdominal infections such as peritonitis or appendicitis
- Salpingitis (inflammation of the Fallopian tubes)
PID is often symptom-free, or the symptoms are mild, with slight lower abdominal pain and tenderness that’s worse with pressure and possibly a low-grade fever. Laparoscopy that shows clear evidence of PID comes as a complete surprise to about two-thirds of the women involved, and PID infections gradually reduce fertility by making the tubes less functional:
- 12% are infertile after one infection
- 23% are infertile after two infections
- 53% are infertile after three infections
Mucus obstructing the Fallopian tubes
Excess mucus is usually due to problems with the “peg” cells (uterus and fallopian tubes) that line the tubes. The peg cells release nutrient-rich fluids that are essential to nourish sperm or embryos in the tubes. But if the secretions are too thick (or too much) they can accumulate and form a sticky plug that blocks the tube, which Fluids PFP women are particularly vulnerable to.
Alternatively, tubes can get blocked if the “cilia” cells (they have hair-like structures that beat to transport fluids (or an embryo) to the womb) fail to move fluids enough to keep the tube open, and this lack of movement tends to affect Flow PFP women most. It can of course be a combination of factors, but the tubes become blocked as a result of the person’s dynamics, rather than an infection.
Tubal ligation operations that sterilize the woman are the usual cause; however, any lower abdominal surgery can trigger adhesion’s that block Fallopian tubes.
After IUD use
The insertion of intrauterine devices (IUDs) such as the Merina coil into the womb can trigger inflammation which can spread from the womb into the delicate tissue of the tubes. This can distort the tube structure and disturb peg and cilia cell function.
Endometriosis usually consists of connective or vascular tissue, and one of the most common sites for the lesions is at the ends of the Fallopian tubes or around the ovary. The endometriosis lesions can cause the finger-like ends of the tubes to clump together or create adhesions in the tubes.
Torsion is the twisting (and blocking) of a Fallopian tube and the usual cause is an ovary becomes too heavy for the ligaments to hold it in place. The heavy ovary drags the tubes out of position, distorting their shape and closing the space within them. Large “functional cysts” are the prime suspects, but IVF stimulation drugs dramatically increase the number of large follicles in ovaries and significantly raise the risk of this happening.
A hydrosalpinx can form after infections, and they grossly distort a Fallopian tube. They dramatically reduce the possibility of embryos reaching the womb and reduce natural and IVF fertility. The presence of a hydrosalpinx usually requires surgery to tie the tube before IVF proceeds to prevent the fluid in them from draining into the womb and stopping implantation.