What Is Conization, How Is It Performed, and What Is Its History?

What Is Conization?

Conization is the removal of a cone-shaped section from the neck of the uterus, the cervix uteri. Cone biopsy is another name for this procedure. A scalpel, laser blade, or thin wire loop heated by electric current removes the tissue, which is then examined microscopically for disease. Conization can check for cervical cancer or treat certain cervical conditions. 

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Sometimes cells sampled from the cervix look abnormal without being cancerous. They may nonetheless represent the beginning of changes leading to cancer. Such abnormal cells are called precancerous (more likely to become cancerous), and their severity is graded using terms such as squamous intraepithelial lesion, dysplasia, cervical intraepithelial neoplasia (CIN), or carcinoma in situ.

Precancerous lesions remain confined to the epithelium lining the cervix. When abnormal cells change and begin invading deeper cervical layers, cervical cancer develops.

Conization investigates such conditions when smear test results show abnormal cervical cell changes or when a smear indicating high-grade pathology does not match colposcopy or biopsy findings. It may also be used for preventive treatment of cervical intraepithelial neoplasia (CIN).

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What Are the Types of Conization?

The procedure has different names depending on the method. With a scalpel, it is called cold knife conization; with a laser, laser conizationand with an electrically heated loop, LEEP (loop electrosurgical excision procedure). Conization takes approximately 30 minutes and may be performed under local or general anesthesia.

Each approach has advantages and disadvantages.

Cold Knife Conizationprovides the cleanest specimen margins and may permit more histological assessment. However, it generally causes more bleeding than laser or LEEP and usually requires general anesthesia.

Laser Procedures take longer and may burn tissue edges, particularly at low power density, interfering with histological diagnosis. Their main advantage is precise delineation of margins, although their high cost can overshadow this benefit.

LEEP Procedureshave advantages including speed, preservation of margins for histological evaluation, and minimal bleeding. They can also be performed in an office or another outpatient setting.

The figure belowillustrates how conization is performed.

The History of Conization

This procedure dates to the early 19th century, when conization-like techniques were used to resect cervical cancers. In the second half of the 20th century, conization became important for diagnosing positive cervical cytology in women without visible lesions and later for treating CIN. Widespread use of colposcopically directed cervical biopsies, sometimes combined with endocervical curettage, reduced diagnostic cold knife conization. It remains an important diagnostic tool in selected circumstances and became an accepted CIN treatment following rigorous Scandinavian and Austrian studies. Its precise historical origins remain uncertain.

Although conization techniques have not changed recently, in 2006 a quadrivalent HPV (human papillomavirus types 6, 11, 16, 18) vaccine, Gardasil, was introduced. Widespread vaccination is expected to reduce abnormal cervical cell growth and consequently the need for surgery.

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Conization frequency can be estimated from confirmed or suspected CIN cases. Although most HPV infections—up to 90%—regress spontaneously within 2 years, detected cases require colposcopy and sometimes conization for definitive diagnosis or treatment. Cervical cancer remains the 2nd most common gynecological cancer worldwide and a major cause of death among women, especially in developing regions lacking effective cancer screening programs.

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Cervical cancer incidence and mortality have fallen by approximately 300% across much of North America and Europe since the 1930s. The sharpest decline followed the introduction of Pap smear screeningin the 1950s. Because cytology rarely provides a definitive diagnosis, conization became an important tool for accurately diagnosing abnormal clinical or colposcopic lesions. It is also an important treatment for cervical intraepithelial lesions.

What Is Colposcopy?

Diagnosis generally begins with a pelvic examination of the vagina and reproductive organs—uterus, ovaries, and cervix—and a Pap smear. Suspicious lesions are preferably biopsied under colposcopic guidance. Colposcopy allows close examination of the cervix, vagina, or vulva. A lighted instrument called a colposcope magnifies the cervix for better examination and visualization. If colposcopic biopsies require further evaluation, conization is performed for diagnosis. If cervical intraepithelial lesions are found, it may be used for treatment.

When Is Conization Preferred?

Diagnostic Conization

• When cervical epithelial abnormalities are present, particularly high-grade squamous intraepithelial lesions (HSIL) or low-grade squamous intraepithelial lesions (LSIL);
• When colposcopy is unsatisfactory because the entire transformation zone, including the squamocolumnar junction, cannot be seen in women with epithelial abnormalities;
• When a biopsy diagnoses CIN but uncertainty remains about the presence or absence of microinvasion or invasion;
• When CIN or microinvasive cancer is found during endocervical curettage;
• When cytological or tissue evidence suggests malignant or premalignant glandular epithelium;
• When histological biopsy findings and cytological findings disagree, it may be performed diagnostically.

Therapeutic Conization

Conization is currently preferred for treating CIN grades 2 and 3. Authorities consider all described approaches—cold knife, laser, and LEEP—equally effective.

CIN Grades

• Cervical intraepithelial neoplasia, grade 1, CIN-1: mild dysplasia
• Cervical intraepithelial neoplasia, grade 2, CIN-2: moderate dysplasia
• Cervical intraepithelial neoplasia, grade 3, CIN-3: severe dysplasia

When Should Conization Not Be Performed?

Avoid conization during pregnancy because it generally causes more than 500 ml of bleeding. Postoperative bleeding occurred in approximately 30% of pregnant patients who underwent conization, with 10% resulting in miscarriage. It also increases preterm birth risk. A possible invasive cancer identified in the first or second 3-month trimester is a circumstance requiring this procedure. Otherwise, avoid it whenever possible.

What Risks Does Conization Carry?

• Bleeding risk
• Infection risk
• Cervical stenosis
• Cervical insufficiency
• Cervical dystocia (difficult labor)

Bleeding and pain may occur during and after conization. Infection is another important postoperative risk. After cold knife conization, infection occurs in 0,2 to 6,8 percent of cases. Risk is somewhat lower after laser conization or LEEP, at 0 to 2 percent.

Conization may also cause cervical insufficiency or stenosis. Cervical dystocia, or difficult labor, is another possible risk.

Every patient should discuss future childbearing plans. In those who may want pregnancy, determine whether a shallow cone excision will suffice, because conization can cause cervical insufficiency leading to miscarriage or premature birth.

Risks to the operator must also be considered. Both laser conization and LEEP produce smoke, which may be hazardous to inhale because it can contain HPV particles. Smoke evacuation devices are therefore essential, and a mask is recommended during the procedure.

What Should You Watch For After Conization?

Vaginal bleeding may occur within a week after conization. Do not use tampons during this period; use sanitary pads instead. Do not clean the vagina with water, soap, or other products, and avoid intercourse for approximately a month afterward.

Conization—Summary and Recommendations:

• Removing the entire transformation zone through a cone-shaped biopsy is diagnostic and potentially therapeutic in women with cervical neoplasia.
• Standard cone biopsy techniques use a scalpel, laser, or electrosurgery.
• The technique and cone configuration should be individualized to the lesion.
• The most important intraoperative complication is bleeding, occurring in approximately 5% to 10 percent of patients and generally manageable with minor local measures.

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