CHAPTER 136 Cervical Stenosis and Cervical Dilation
Cervical stenosis is a stricture or narrowing of the cervix. It is diagnosed by the inability to pass a 2-mm dilator into the uterus. Cervical stenosis can be either congenital or acquired. Acquired stenosis can result from postoperative scarring (from conization, whether it be cold knife, large loop electrosurgery, or laser; cautery; or cryotherapy of the cervix), cancer (endometrial or endocervical), radiation complications, infections, or atrophy from lack of estrogen (most common). In acquired cases the external os is most frequently affected (Fig. 136-1). In congenital cases, seen most often in nulliparous cervices, the stenosis is usually at the internal os.
Narrowing of the cervical canal can impede menstrual flow, causing intrauterine pressure during menses. Premenopausal women with cervical stenosis may have pelvic pain, dysmenorrhea, amenorrhea, infertility, or abnormal bleeding. In some cases retrograde menstrual flow may occur, causing endometriosis. Women may have a soft, slightly tender midpelvic mass as a result of hematometra. Postmenopausal women may have pyometra, which is highly suspect for endometrial carcinoma.
Ultrasonography can assess canal anatomy while evaluating the patient for hematometra and a pyometra. Most often, cervical stenosis is discovered when the physician is attempting to enter the uterus for a Pap smear, hysteroscopy, intrauterine device (IUD) insertion, endometrial biopsy, uterine aspiration for elective or spontaneous abortion, or placement of Essure devices.
Treatment of cervical stenosis consists of dilation by using (1) progressive metal or plastic dilators, (2) osmotic tents, or (3) prostaglandin analogs. Laminaria tents are made from the stems of seaweed, usually Laminaria japonica, that is dried and made into sticks. Self-expanding cervical dilators (Dilateria, Lamicel) that resemble laminaria tents can also be used. Once the tents are placed into the endocervical canal, they rehydrate and expand, thereby causing dilation of the cervical canal (Figs. 136-2 and 136-3). Laminaria tents should not be used if pyometra is present or infection is suspected. The os and canal must be patent enough to admit the tents, which are available in several diameters. Some mechanical dilation may be necessary to allow their placement. Another option for the treatment of external os stenosis is the use of the carbon dioxide laser or a small radiofrequency loop excision. The latter two methods can remove a stricture that is readily visible externally.
Recently, clinicians have come to depend on the administration of misoprostol for softening and dilating the cervix. Misoprostol is most effective on the pregnant uterus, and very small doses are used to soften the cervix for labor. Documentation of efficacy is best in the pregnant uterus. In nonpregnant uteri, efficacy has been shown clearly in women of reproductive age. Studies of misoprostol use on postmenopausal women are conflicting regarding its effectiveness. In nonpregnant uteri or in the first trimester, two to four 200-µg tablets administered vaginally, buccally, or sublingually 1 to 2 hours before the procedure is usually effective.