About Your Cervix
To understand how cervical stenosis can cause infertility, you need to understand the cervix. Your cervix is the doorway and passage from your vagina up to your uterus. At the end of the vaginal canal is the external os or cervical opening. When you have a pap smear, the cells are sampled from here. You can feel this part of your cervix with your fingers. In fact, some women track cervical changes as a way of detecting ovulation. This, however, is only the outer section of the cervix. The cervical canal continues past the external os, creating a sort of tunnel from the vagina up to the uterus. The “tunnel” of the cervix is known as the endocervical canal. At the end of the endocervical canal is the internal os, or internal opening of the cervix. This is where your cervix ends and your uterus begins. Cervical stenosis can occur at any of these areas, or even at all of them at once. Most commonly, though, the problem is found at the external os. The cervix plays a few key roles in fertility and pregnancy:
During menstruation, endometrial tissue exits the uterus through the cervix. It is the passageway for sperm to swim from the vagina up into the reproductive system. It contains mucus-producing tissue; cervical mucus is needed to help sperm move effectively up into the cervix during ovulation and helps to prevent infection and keep unwanted microorganisms out. During pregnancy, the cervix creates a mucus plug to protect the fetus. It also remains tightly closed, acting as a seal, until the time of birth.
How Cervical Stenosis Impacts Fertility
Cervical stenosis can negatively impact fertility, directly and indirectly.
Sperm passage blocked or limited: If the cervical opening is blocked or narrower than it should be, sperm can’t travel up to the fallopian tubes (where they meet and fertilize the egg). Uterine inflammation and endometriosis risk: Menstrual bleeding can be blocked completely (in severe cases) or held back and not able to easily flow outward. This can cause the uterus to fill up with blood, causing pain and inflammation. This is known as a hematometra.
If infection occurs, the uterus can become filled with pus. The medical term for this is pyometra. Even if the cervix is slightly open and blood can flow outward, menstrual blood may occasionally backwash up through the fallopian tubes, which can lead to endometrial lesions and endometriosis.
Less fertile cervical mucus: Cervical stenosis is most commonly caused by scar tissue. The scar tissue can interfere with the production of cervical mucus. Sometimes, the surgery that caused the scar tissue involved the removal of cervical tissue, and that further limits cervical mucus production. Without adequate cervical mucus, sperm may have trouble moving and surviving. Complications during fertility treatment: Both IUI and IVF treatment require a catheter to be placed inside the cervix. With IUI, the catheter transports specially washed sperm. With IVF, the catheter carries embryos.
In either case, if the cervical opening is blocked or too narrow for the catheter to pass through, treatment can become complicated. It’s not possible (or advised) to force the catheter through. There are, however, options for creating a pathway. (More on this below.) Cervical stenosis treatment may also weaken the cervix or cause cervical tissue damage. Later, during pregnancy, this may lead to what is known as incompetent cervix. It may lead to a second-trimester pregnancy loss or premature birth. There are options to reduce this risk, however. (See more below.)
What Causes Cervical Stenosis?
The most common cause of cervical stenosis is from prior surgery on the cervix. If a pap smear finds abnormal cells, your doctor may need to remove a slice of tissue from your cervix. This may be done as a cone biopsy or loop electrocautery excision procedure (commonly known as LEEP). When your body is healing from the biopsy, scar tissue can form over the cervical opening. This can lead to cervical stenosis. Other possible causes of cervical stenosis include:
Asherman’s syndromeCervical dysplasia (precancerous cells)Cervical or endometrial cancerCongenital (born with a closed or narrow cervix)Endometrial ablation surgery (treatment done to reduce heavy periods, not recommended for those who plan to have children in the future)Infection of the uterus or cervixMenopauseRadiation therapy to the cervical area
Diagnosis and Symptoms
Depending on the severity, cervical stenosis may be discovered when investigating symptoms, or it may not be apparent until fertility testing or treatment. Possible symptoms include abnormal menstrual bleeding, intense menstrual cramps, and no period or very light spotting. Infertility is also a possible symptom of cervical stenosis. During fertility testing, cervical stenosis may be suspected if there is difficulty completing an HSG. An HSG is a specialized x-ray that involves transferring a dye via the cervix up into the female reproductive system. Usually, a catheter is placed inside the external os of the cervix. A dye is released, and then, the doctor takes x-rays. The x-rays should show whether the fallopian tubes are open and look at the shape of the uterine cavity. However, if the catheter can’t be placed, is very painful, or the dye doesn’t make it past the cervix, cervical stenosis may be an issue. If this happens, a hysteroscopy is usually ordered next. This fertility test can also be used to possibly correct cervical stenosis. It is also possible for cervical stenosis to be discovered during fertility treatment itself. (If you’re wondering how it could be missed during testing, it is possible for corrected cervical stenosis to reoccur after treatment). During IUI or IVF, if there is trouble placing the catheter for insemination or embryo transfer, cervical stenosis may be an issue.
Treatment Options
Cervical stenosis can be treated, though there is a risk that scar tissue will re-close the opening. There are options to reduce the possibility of re-narrowing. One method of treatment involves the use of dilators. The dilators come as a set of thin rods, which slowly increase in size. Sometimes even the smallest dilator is too large, in which case a wire may be used. This can be done in the doctor’s office. A paracervical block is used, which is a kind of anesthetic, to reduce pain during the procedure. Your doctor starts with the thinnest of dilators, and carefully introduces the next size up, until the desired opening is achieved. Sometimes, a stent is placed to keep the cervix open and prevent scar tissue from reforming and closing the opening back up. A stent is a tube-like object. The stent would be removed after several weeks. If dilators are not successful or not appropriate, hysterscoptic shaving is an option. This is a surgical procedure completed during a hysteroscopy. Laser treatment—where the scar tissue is vaporized with medical laser—is another possible option. In women who are not trying to get pregnant, an IUD may be placed after treating the cervical stenosis. The IUD is meant to prevent scar tissue from reforming. If you want to get pregnant in the future, the IUD can be removed then. There are potential risks to cervical stenosis treatment. The chances will depend on what treatment method is used, but some of those risks include uterine puncture, infection, and incompetent cervix (during future pregnancy).
Conceiving After Treatment
Sometimes, cervical stenosis is the primary cause of infertility, in which case, you may be able to conceive on your own after treatment. Your doctor will suggest a timeframe for trying to conceive on your own, most likely 6 months. If you don’t get pregnant, further fertility treatment options can be considered.
IVF and IUI Treatment
If cervical stenosis is discovered during an IUI treatment and prevents the procedure, your doctor may place the pre-washed semen as close to the cervix as possible instead of inter-cervically. Pregnancy success would be less likely to occur, but may still be possible. However, after cervical stenosis has been discovered, your doctor should be able to treat it and reschedule another IUI. What happens if cervical stenosis is discovered during an IVF cycle, at the actual embryo transfer? Your doctor may decide to attempt cervical dilation and then proceed with the transfer. Research is mixed, however, on whether this reduced pregnancy success rates or not.
Reducing Pregnancy Risks
As mentioned above, treating cervical stenosis can increase your risk of incompetent cervix or premature birth. One possible treatment to reduce the risk of pre-term birth is known as cerclage. A cerclage is when your doctor sews the cervix closed early in pregnancy. The sutures are removed after you reach 36 weeks, so they don’t interfere with regular cervical dilatation and childbirth.
