The tube has three sections, the cornu, the isthmus, and the ampulla and fimbria. The cornu, which is the connection to the uterus, is a narrow valve that opens and closes in response to uterine contractions. It measures about half an inch in length, and is lined by glands that make fluids.
The isthmus, the narrowest connecting part of the tube is an intricate and tiny tube lined with cilia, the tiny hair-like projections off of cells that move in waves to pull sperm and embryos along the tube. The walls of the isthmus are thrown up into multiple complex folds. The isthmus is hardly a simple conduit, but rather a complex and active moving pathway.
The ampulla, the funnel-shaped end of the tube, is connected to the fimbria, feathery fingers that reach out to the ovary and pick up the newly released egg. These three portions of the tube work together to carry sperm out to the end of the tube, pick up the egg, and provide a site for fertilization. They then carry the fertilized embryo to its resting spot in the uterus.
The pathway to the egg is an arduous one; only a small proportion of the ejaculated sperm find the egg. At ejaculation, sperm are deposited in the vagina and then swim through the cervix and uterus and into the fallopian tubes. Some reports indicate that sperm can be found in the fallopian tubes within five minutes of ejaculation 51; they are quite speedy. The sperm travel with the motion of their own tails and with assistance from muscular contractions in the uterus and tubes, and with the motion of cilia, tiny hair-like cells that line the inside of the tube. The sperm travel to the end of the tube, where they meet and fertilize the egg. The fertilized egg, or embryo, then moves back down through the tube to the uterus, taking several days to make the journey.
With such a delicate and sophisticated pathway, it is common for problems to develop in the tubal system. Here are a few of these:
Cornual Occlusion: The connection between the uterus and fallopian tube is a fragile area that can become blocked. This is referred to as cornual occlusion or proximal tubal occlusion. Most blockages are actually contractions of the uterine muscle and are not true blockages. The diagnostic test to detect this can irritate the uterus and cause the uterine musculature to contract. This is a temporary condition that has no effect on fertility. Other blockages reflect true problems in this portion of the tube, which can result from infection or inflammation, fibroids or polyps, or use of an IUD. A common example is a condition known as Salpingitis Isthmica Nodosum (SIN), in which the tube becomes inflamed and nodules develop in the glands that line this portion of the tube.
Isthmic Occlusion: This condition occurs only rarely naturally. The isthmus is the smallest and narrowest portion of the tube, but has a thick muscular wall that is not easily damaged. Tuberculosis and other infections and tubal polyps are possible, but rare causes of isthmic occlusion. Most cases are intentional 51; this is the location where a tubal ligation is performed for sterilization.
Hydrosalpinx and Fimbrial Phimosis: The hydrosalpinx refers to a tube that is filled with water ("hydro" = water, "salpinx" = tube). With infection by bacteria, such as gonorrhea or chlamydia, the end of the tube can become inflamed. If the end of the tube becomes blocked, fluids can no longer drain from the tube, and build up under considerable pressure. These fluid filled tubes can become quite large, requiring surgical removal. A hydrosalpinx is unable to pick up eggs, resulting in infertility, and is subject to infection. Milder degrees of injury to the tube can result in loss of or damage to the feathery appendages of the tube, the fimbria. This is known as fimbrial phimosis. This can vary from quite subtle degrees of blockage to nearly complete obstruction of the tubes.
The tubes are quite delicate in their structure and function, and any of this delicate structure can be injured. The ciliary cells that help sperm and embryos move through the tubes can be lost. Studies often show patches of missing cells, probably victims of injury from bacterial infections. This can happen throughout the tubes. The folds that occur in several segments of the tubes can also be injured, resulting in blind cul-de-sacs through which sperm and embryos cannot pass.
Diagnosing these problems usually requires a medical study. The exact tests are determined in association with a fertility specialist, a physician who is board certified in reproductive endocrinology and infertility.
Examples of tests used for diagnosing tubal problems are:
Ultrasound: Most patients will start with an ultrasound, in which uterine and ovarian relationships can be studied. A normal fallopian tube is almost always invisible on ultrasound. A hydrosalpinx may appear as a large fluid filled cyst between the ovary and uterus.
Hysterosalpingogram (HSG): The HSG is a dye study of the uterus. At pelvic exam, a catheter is placed in the cervix and dye flushed into the uterus and tubes with gentle pressure. An X-Ray picture is taken of the uterus and tubes. It may reveal cornual occlusion, or a hydrosalpinx, the most common abnormalities, or more subtle problems like tubal polyps and fimbrial phimosis. Commonly one of the tubes fills and spills dye more easily than the other, a phenomenon known as preferential spill. The HSG can cause cramping, which is usually mild, but can be quite strong in women with a sensitive uterus. Ibuprofen taken 2 hours before the procedure can help reduce the cramps. The procedure carries a small risk of infection, but this is usually only seen when tubal injury is present.
Treating these problems is highly individualized and depends on the patient's age, medical problems, and patient wishes. The available procedures are:
Laparoscopy: Laparoscopy is the classic procedure to evaluate and treat tubal disease. Under anesthesia, an incision is placed in the belly button, and a small television camera is placed through the incision. The doctor can look at the pelvic organs, and introduce some treatment equipment through small ¼ inch incisions. Problems can be treated with scissors, cautery, or a laser.
Tubal cannulation: Devised for the treatment of cornual occlusion, a tiny wire is placed through the cervix and uterus and into the tube. The wire gently opens the tube and may relieve an obstruction in this area. Tubal cannulation can be performed in the X-Ray department under fluoroscopy or via a hysteroscope. A physician who is experienced in the techniques is essential.
Evaluation of these problems can be complex, and devising a treatment plan requires a close relationship with a physician with experience in these areas. A few common scenarios follow:
Hydrosalpinx: A hydrosalpinx carries risk of infection and very low pregnancy rates even after treatment. Hydrosalpinx can be treated laparoscopically, a procedure known as neosalpingostomy. In neosalpingostomy, an incision is made in the end of the hydrosalpinx and the edges of the incision are folded or flowered back, leaving an open tube. The best outcomes occur in young women with a small hydrosalpinx. Unfortunately, the tube often closes back up, and pregnancy rates are relatively low. Even when the fallopian tubes are bypassed, via techniques such as in vitro fertilization, a hydrosalpinx can have adverse effects on pregnancy rates. Basically a small hydrosalpinx in a young woman might be repaired, with the understanding that further surgery might be necessary if the repair is unsuccessful; a larger hydrosalpinx should be removed.
Bipolar Disease: Bipolar disease refers to the situation in which there exists injury to both the cornual and the ampullary or fimbrial portion of the tube. It is very difficult to get a satisfactory repair when problems are present at both ends of the fallopian tubes. Most patients with bipolar disease should proceed to in vitro fertilization.
Tubal adhesions: Some patients with an otherwise normal evaluation, including a normal Hysterosalpingogram, can have subtle adhesions over the fallopian tube and ovaries. These adhesions appear like cobwebs over the surface of these organs, and can prevent eggs successful ovulation, prevent the tubes from picking up eggs, and limit the mobility of the tubes. Patients at special risk for these problems include those who have used IUDs, had abdominal problems, such as appendicitis or an ovarian cyst removal. Limited adhesions benefit from laparoscopy. The adhesions can be removed with scissors, cautery, or a laser. Age is a significant factor in who will respond to these procedures 51; younger women benefit more than older women.