Fallopian tubes are necessary for the retrieval of the egg at the time of ovulation and for the ability of a living embryo to reach the uterus, where a pregnancy is carried until labor and delivery.
The fallopian tubes, long structures which resemble straight brass horns, play a critical role in reproduction. They have a very complex and delicate structure designed to retrieve an egg at the time of ovulation, conduct sperm to the end of the tube near the ovary, where fertilization is to occur, nourish the new embryo and conduct it to the uterus. That is a huge responsibility.
Let’s begin with packing up the egg. The end of the fallopian tube next to the ovary consists of a large array of delicate finger like projections called fimbriae. The fimbriae are anchored to the bell shaped end of the tube called the ampulla. It is the ampulla where fertilization takes place. The remainder of the fallopian tube, called the isthmus, has a very narrow channel or lumen. The lining of the tubal lumen consist of 2 cell types. The secreto ry cells provide the nutrients for the embryo resulting from fertilization of the egg. The other cells have microscopic hair-like projections called cilia. The cilia beat in rhythmic fashion and propel the embryo to the uterus. A number of agents can damage the cells and structures and impair tubal function.
There are 2 infections, which are epidemic that can damage fallopian tubes. Both Chlamydia and gonorrhea infect the lining of fallopian tubes causing scarring. The fimbriae scar together, so that they will not function to pick up an egg. As the infection progresses, scarring of the fimbriae can totally block the end of the tube near the ovary. When the tube is blocked at the fimbriated end, the nutrient secretions from cells of the tubal lining collect. If the infection is not adequately treated in a timely manner, the infection in the closed space of the blocked tube becomes an abscess. Even if no abscess forms, the cilia of the tubal lining are damaged and cannot propel an embryo to the uterus. In the circumstance that cilia are damaged a pregnancy will attach to the tube and produce a tubal pregnancy. Tubal pregnancy can require emergency treatment, or can become fatal.
There are other forms of tubal blockage. One form of tubal blockage can usually be easily remedied. Cells which cover surfaces are continually produced and the replaced cells are shed. The portion of the fallopian tube which traverses the uterine wall, the intramural portion, has a lumen about the size of the tear duct you can see at the inner corner of your eye, near your nose. It seems as though shed cells sometimes block the channel in the intramural segment of the tube. That is easy to fix. The other tubal blockage can be difficult to identify. It is called salpingitis isthmica nodosa (S.I.N.). The best way to describe it is like a sieve partially blocking the lumen of the isthmic portion of the fallopian tube. During studies to determine if the tube is open, the dye can go through to give the appearance that the tube is OK. Sperm can get through to the egg, but the embryo cannot traverse the tube to the uterus. The result is a tubal pregnancy. Instead of having a baby, a woman with a tubal pregnancy must have treatment to destroy the pregnancy in the fallopian tube. A tubal pregnancy is life threatening. If an examiner knows what to look for, salpingitis isthmica nodosa can usually be identified, and disaster averted.
OK, there is a self inflicted tubal problem. It is tubal sterilization. At one time it was only accomplished by cutting out a section of each fallopian tube and tying the stumps. Although a few programs, mostly OB-GYN generalists, try to reopen tubes after “tubal ligation”, today, it is probably better to by-pass the tubes with in vitro fertilization (IVF).
Tubal problems are a fairly common finding when evaluating an infertile couple. Today, in stead of surgery, we have much better and more effective tools to deal with tubal infertility. If fallopian tubes are badly damaged, we can bypass them. Today, we do not even need fallopian tubes. We have in vitro fertilization (IVF).
Dr. Jacobs is a Reproductive Endocrinologist, practicing in Carrollton, Texas, a northern suburb of Dallas. He completed his residency training in obstetrics and gynecology at Baylor College of Medicine in Houston, and remained at that institution to become its first fellow once Baylor achieved accreditation for an advanced training program in Reproductive Endocrinology and Infertility. Dr. Jacobs has served on the faculty of several medical schools and was director of Reproductive Endocrinology at Texas Tech Health Science Center in Amarillo. Currently, in addition to his clinical activities caring for infertile patients and those with recurrent pregnancy loss, he is Chairman of the IVF committee at Baylor Medical Center in Carrollton. Barry Jacobs, M.D., 4323 M. Josey Lane, Suite #201, Carrollton, TX 75010www.texasfertility.comPhone: 972-394-9590 Fax: 972-394-9597
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