Excerpt from Conization of Cervix

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Conization of the cervix uteri plays a major role in the diagnosis and treatment of intraepithelial neoplasias. Conization of the cervix is defined as excision of a cone-shaped or cylindrical wedge from the cervix uteri that includes the transformation zone and all or a portion of the endocervical canal. It is used for the definitive diagnosis of squamous or glandular intraepithelial lesions, for excluding microinvasive carcinomas, and for conservative treatment of cervical intraepithelial neoplasia (CIN).

While no recent changes have occurred in the technique of conization, a quadrivalent human papillomavirus (types 6, 11, 16, 18) recombinant vaccine (Gardasil) was introduced in 2006. Its widespread use is expected to reduce the number of cervical neoplasias, and, consequently the need for surgical interventions.

Conization can be performed with a scalpel (cold-knife conization), laser, or electrosurgical loop. The latter is called the loop electrosurgical excision procedure (LEEP) or large loop excision of the transformation zone (LLETZ). Combined conization usually refers to a procedure started with a laser and completed with a cold-knife technique. Laser conization can be excisional or destructive (by vaporization). Techniques for diagnostic and therapeutic conization are virtually identical. The extent of excision must be adjusted according to individual needs (see Media file 1).

Each of these approaches has distinct benefits and disadvantages. Cold-knife conization provides the cleanest specimen margins for further histologic study, but it is typically associated with more bleeding than laser or LEEP, and it requires general anesthesia in most cases. Laser procedures are of longer duration and, especially if low-power density is used, may "burn" the margins, thus interfering with histologic diagnosis. The main advantage with this procedure is that dots produced by the laser energy can be used to accurately outline the exocervical margins. However, overall, the benefit of using laser for conization may not justify the high cost of the procedure.

LEEP procedures have several advantages, including rapidity, preservation of the margins for histologic evaluation, and virtual bloodlessness. Moreover, one can perform LEEP procedures in the office or in other outpatient settings.

Procedures that do not yield tissue for pathologic studies, such as electrocoagulation or cryosurgery, are not discussed in this article.

History of the Procedure

The precise origin of cold-knife conization is uncertain. Procedures similar to conization were used in the early 19th century in an attempt to excise gross cervical tumors per vaginam. During the second half of the 20th century, conization evolved as an important tool for diagnosing the cause of positive cervical cytology in women without visible lesions and, later, as treatment of CIN. The diagnostic application of cold-knife conization was reduced following the widespread use of colposcopically directed cervical biopsies combined with endocervical curettage. However, conization remains an important diagnostic tool in selected situations. Therapeutic conization for CIN became an accepted modality in the management of CIN following publication of rigorous studies by Scandinavian and Austrian researchers.^{1, 2, 3, 4}

Problem

The incidence and mortality of carcinoma of the cervix have declined about 300% since the 1930s in most of North America and in Europe. The sharpest decline began in the 1950s, following the introduction of cytologic screening. Since cytology rarely provides precise diagnosis, conization of the cervix became an important tool for the determination of the accurate diagnosis of abnormal, cytologic, clinical, or colposcopic lesions. Additionally, it is a major method for the treatment of intraepithelial cervical lesions.

Frequency

The frequency with which conization procedures are performed depends on the number of suggested or detected cases of CIN and can only be estimated. Approximately 10-20 million cases of human papillomavirus (HPV) infection may be responsible for causing CIN or cervical carcinoma. Although a large proportion of these (an estimated 80%) regress spontaneously, for a definitive diagnosis or treatment, detected cases require colposcopy and, at times, conization. In the United States, 10,370 new cases of cancer of the cervix (uterus) and 3,710 deaths from this disease were estimated for 2005.

Worldwide, cervical carcinoma is the third most common cause of cancer-induced death in women. In 1998, 470,606 new cases and 233,372 deaths were reported. It remains a major cause of mortality in regions without effective universal screening programs, particularly in developing countries, such as some of those in Latin America and Central and Eastern Europe.

Etiology

Intraepithal neoplasia is induced by high-risk human papillomavirus infection. Types 16 and 18 are found in 50-80% of squamous intraepithelial lesions (SIL) and in up to 90% of invasive cancers.⁵

Pathophysiology

Human papillomavirus infection induces proliferation and atypia in the cervical epithelium. Most commonly, these changes occur in the transformation zone, or, at times, directly in the squamous or in the glandular epithelium.

Clinical

The clinical diagnostic process usually begins by a pelvic examination and by taking a Papanicolaou smear. Suspicious lesions are biopsied, preferably under colposcopic control. Diagnostic conizations are performed if colposcopic biopsies require further evaluation. Therapeutic conizations are indicated if SILs (in particular HSIL) are detected. 

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