Blocked fallopian tube. The involvement of “tubal factor” in fertility
The Fallopian tubes are trumpet-shaped structures that begin in the uterine cavity and end up opening by the ovaries. After ovulation, the fallopian tubes collect the released egg that is fertilized on the first portion, which is the closest part to the ovary. For this, the spermatozoa travel through the vagina, the cervix, the uterine cavity, and finally the route to the end of the tube. After fertilization occurs, the embryo (fertilized egg) launches its first divisions and travels through the fallopian tube towards the uterus where implantation occur and thus the establishment of pregnancy.
In some women, the tubes are damaged, so the union of egg and sperm cannot happen. These patients have an inability to get pregnant naturally and therefore the sterility cause is categorized as “tubal factor”. This problem may be responsible for between 10 and 25% of cases of infertility in developed countries.
The most common cause is infectious. In most cases, a past infection is responsible for the injury and subsequent tubal obstruction. These infections are associated with STDs so in patients with a history of gynecological infections (pelvic inflammatory disease) and infertility, we´ll suspect a tubal obstruction as the cause of the problem.
However, in many cases, these infections are asymptomatic, i.e. go unnoticed by women, so the absence of a history of risk does not rule out tubal blockage and this should be dismissed as part of the basic fertility study. When we talk about gynecological infections, we are not referring to the vaginitis, usually thrush and common in women but are not common causes of tubal obstruction.
Other causes of tubal damage are adhesions caused by previous abdominal surgeries or inflammatory diseases such as endometriosis. In these cases the background are usually obvious and high suspicion requires us to determine whether or not the tubes are permeable.
The diagnostic test of choice for diagnosing or ruling out tubal obstruction is Hysterosalpingography (HSG). In this test, contrast agent (especial liquid) is injected into the uterus while a serial of x-rays are taken to appreciate the distribution of contrast agent injected through the tubes and showing patency or blockage. The HSG, along with Seminogram and evaluation of Ovarian Reserve are part of the basic study of couples with problems to gestate.
Another way to evaluate tubal patency is by performing a laparoscopy. This procedure involves the insertion of an optical device within the abdominal cavity by making a hole by the navel. With this we will have a direct view of the tubes and we can assess morphology and permeability after instillation of a colorant into the uterus. This examination is a surgical procedure that requires general anesthesia and is not without complications so it will only be used when needed to solve other problems (surgery fibroids, cysts or endometriosis).
Ultrasound does not allow visualization of the tubes so it is not an examination indicated to assess patency. Only when tubal occlusion is accompanied by a buildup of fluid (hydrosalpinx) this will be noticeable with an ultrasound, being very important for the diagnostic implications of the prognosis for In Vitro Fertilization (IVF).
The restoration of natural fertility through tubal surgery is extremely complex, requires a long time to assess its effectiveness and unfortunately the chances of success are very limited. Therefore IVF treatment is first choice for most patients and allowing fertilization in the laboratory replacing the function of the tubes.
In vitro fertilization as a treatment in cases of tubal factor infertility has an excellent prognosis so currently tubal obstruction or even absent after surgical removal (salpingectomy) is not a serious obstacle to achieving pregnancy.
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