What makes an incompetent cervix?
Losing a baby in the second trimester can be a devastating experience, as we read in Paul’s story. One of the especially sad facts about cervical incompetent is that these women have been losing pregnancies regularly, often at the same week in each pregnancy. Not only is any miscarriage a harrowing experience, but to find yourself repeatedly losing healthy, normal, babies—who, if you could see or hold, look like miniature newborns—then the experience can obviously lead a woman, and her husband, to despair. Later in this chapter we will hare the story of Laura, who has indeed gone through just this type of experience. This is unfortunately a very common problem. But, with new techniques we can now offer much more hope for successful treatment.
The actual incidence of incompetent cervix is unknown but is thought to be about 1 to 2 percent of normal deliveries. It has been estimated that an incompetent cervix is the cause of up to one-fifth of late miscarriages (that is, those following the 12th week).
Technically speaking, a cervix is classified as incompetent if it fails to maintain an intrauterine pregnancy to term. The cervix begins to dilate far too early and easily, the amniotic membranes push through, and, following either a dramatic rupture of the membranes or blood loss, you go into a rapid, short premature labor. The baby is then born too early for independent life. Only recently have doctors understood just what can happen to the cervix. Although the procedure of inserting a stitch to hold the cervix closed has been in practice since 1951, we are now more competent in diagnosing and treating the condition successfully.
Normally, the cervix acts as the plug that holds the pregnancy in place. The cervix is mainly composed of collagen, or connective tissue, and only 10 percent of ut is muscle. When you are not pregnant the cervix is rigid, fibrous as “riprning,” and that is probably caused by the action of the pregnancy hormones. If the cervix ripens too early, the pregnancy can be pushed through a weakened cervix from about the 14th to the 20th week.
All too often the cervix has been affected prior to the pregnancy by trauma, for example, from previous D&C’s or elective terminations of pregnancy. Until recently no one realized how gingerly the cervix should be treated. For example, one method of treatment for painful periods used to be dilating, or overstretching, the cervix, the cervix, which usually tore the muscle fibers and led to incompetence. This treatment is now unnecessary because of the availability of effective medications. With our increased medical knowledge, there is no reason why induced abortions (terminations) should now result in incompetent cervix.
If an abortion is needed after the 10th or 11th week, when the cervix would otherwise have to be opened, or dilated, unduly, your doctor dose not have to use metal dilators that can tear and damage, using laminaria (seaweed) sticks, which are inserted into the cervix and left overnight before the procedure. The risks of mechanical trauma and damage to the cervix can thus be obviated.
The cervix can unfortunately also be damaged in childbirth, torn either by the passage of the infant during delivery or by instruments such as forceps or a vacuum extractor. The other major cause of an incompetent cervix, as we discussed in the previous section of the top of the uterus as the pregnancy grows, force the cervix to open below.
A diagnosis of competent cervix can be made from a combination of your personal medical history, which is most important, and an internal examination. Shortly after your last period ends and you know you’re not pregnant, if you doctor can pass a size 6 Hegar dilator through the cervix into the uterine canal, then he would strongly suspect such a diagnosis.
Hysterography, described in the previous section, can also be used for diagnosis. The dye may spill back around the instrument that hs been placed in the cervix and through which the dye is injected, o show the width of the cervix. Ultrasound, in expert hands, can also be used dor diagnosis of incompetent cervix, especially if you are already pregnant. On the screen, you may be able to see a widely dilated cervix, with membranes and amniotic fluid bulging down. With use of the newly introduced transvaginal ultrasound, more is being learned about diagnosing abnormalities of the cervix.
The main indiction of a weak cervix, however, remains a past history of recurrent miscarriages between 14 and 24 weeks. Usually there will have been little heavy bleeding; the membranes may even have ruptured before any contractions were felt. The contractions that do come are short and usually quite painless. The fetus is often, very sadly, born alive.

Prevention of damage to the cervix
Doctors treat D&C procedures with caution. They are aware that any woman in her productive years should not have her cervix forcibly ripen the cervix the night before, using the seaweed (laminaria) I described earlier, or by placing prostaglandins in the vagina, which also ripen the cervix overnight. They then do not have to do much dilation (the D part of the D&C) because you will already have been dilated.
If you receive word of an abnormal pap smear that may eventually need to be treated, cryosurgery (freezing) or laser therapy may be used, rather than a surgical cone biopsy, where some of the cervix is cut away, which may lead to incompetence. So your doctor now has the alternative of these newer methods that can be used with less trauma to the cervix and which are just effective.
At medical schools, young doctors in training are being taught such methods of prevention of illness, at the same time as they are discussing methods of treatment. This new attitude runs through all areas of medicine.

Cerclage, McDonald suture, or the Shirodkar stitch
The placing of a stitch into the cervix to tighten and close it is the method of treatment fro an incompetent, or weak, cervix. The procedure was described just over thirty years ago. Putting in the stitch is often also called a Shirodkar, but that name, in fact, only applies to one particular method. Professor Shirodkar was an eminent physician to whom many women are gratefuk, as his method has helped maintain so many pregnancies in the uterus.