Cold Knife Conization of the Cervix

Anatomy and Physiology

The cervix is a short cylindrical structure in the lower uterine segment that provides a connected opening from the internal uterine cavity to the external upper portion of the vaginal canal. The part of the cervix that protrudes into the vagina is termed the ectocervix; its surface is lined by nonkeratinized squamous epithelium. The opening of the ectocervix from the vaginal canal into the endocervical canal is called the external cervical os. The endocervical canal traverses the length of the cervix and connects the uterine endometrial cavity with the vagina. The endocervical canal is lined with columnar glandular epithelium. The squamous to glandular epithelium transition occurs in the squamocolumnar junction (SCJ) or transformation zone.[4] 

Due to the acidic external environment of the vagina that the ectocervix is exposed to, the everted columnar glandular epithelium is continually physiologically replaced by squamous epithelium at the SCJ, where the transition occurs. During this squamous metaplasia process, premalignant and malignant transformation can occur within this junction. The SCJ may be visible on the ectocervix or contained within the endocervical canal. The SCJ is the cervical tissue most susceptible to the human papillomavirus (HPV) attachment and infection, which can lead to cervical dysplasia and malignant transformation.[4]

The uterine cervix's primary vascular supply is the uterine vessels' cervical branches, which enter the cervix laterally at the 3 o'clock and 9 o'clock positions. The uterus and cervix receive sympathetic nerve supply from the hypogastric plexus and the parasympathetic innervation from S2 to S4. The cervix is insensitive to cutting and burning and frequently can be cauterized or excised with minimal anesthesia during therapeutic procedures. However, the uterus and cervix are sensitive to stretch (eg, distension or dilation).[4]

Indications

Diagnostic excisional procedures like CKC are primarily performed when a specimen is needed for histologic examination.[5] Indications for an excisional procedure in patients of any age include:

• The SCJ can not be adequately visualized.
• Cytologic results show cervical intraepithelial neoplasia (CIN) 2+, CIN 3+, or adenocarcinoma in situ (AIS).
• There is discordance between the initial cytology screening test and biopsy histology.
• The colposcopic evaluation reveals a cervical dysplastic lesion that extends into the endocervical canal, and the entire lesion cannot be wholly visualized.[1]

An excisional procedure is also acceptable in patients older than 25 years for the following cases:

• Persistent atypical squamous cells cannot exclude high-grade squamous intraepithelial lesions (HSIL) or CIN 1 on cytology for 2 years
• Persistent high-grade squamous intraepithelial lesion for 1 to 2 years on cytology
• The patient has positive margins for CIN 2+ on a specimen from a previous diagnostic excisional procedure
• An endocervical curettage demonstrates CIN 2+[1]

A CKC procedure may be preferred over other modalities for patients with a high cervical cancer risk in whom the specimen margins must be maintained. Fragmentation of a specimen should be avoided and has been associated with higher rates of indeterminate margins.[6] Positive specimen margins are abnormal cells extending to the tissue sample's edges. Recent data suggest that positive endocervical margins are associated with an increased risk of recurrence; therefore, follow-up is recommended with cytology, HPV testing, and colposcopy for positive or indeterminate margins.[7][8] There is some evidence that in patients desiring to retain their reproductive capability, cervical conization may be used to treat Stage IA1 squamous cell cervical carcinoma, in addition to accompanying lymph node assessment.[9][10]

Contraindications

Contraindications to CKC include the following:

• Severe cervicitis
• Pelvic inflammatory disease
• Uncorrected anticoagulation

Pregnancy is a relative contraindication to the CKC procedure and should only be considered when there is a strong suspicion of invasive cancer. Only an experienced clinician should carry out conization during pregnancy due to the increased risk of blood loss and pregnancy complications. If there is too little cervix to excise for any reason, then a CKC procedure may not be possible. A recommended approach for a poor surgical candidate would involve an office-based excisional procedure without the need for general anesthesia.[11]

Equipment

The CKC procedure is performed in the operating room, usually under general or regional anesthesia. Other equipment may include:

• Candy cane or Allen stirrups
• Colposcope, with 5% acetic acid or Lugol solution 
• Straight catheter for bladder drainage 
• Weighted speculum and right-angle retractor to visualize the cervix
• Single-tooth tenaculum
• Vasoconstrictive solution (eg, vasopressin) in patients without contraindications (eg, heart disease)
• Scalpel mounted on a 45-degree angled handle or a long-handled 11-blade
• Long-handled or Allis forceps
• Long-handled Mayo scissors 
• Delayed absorbable suture with Heaney needle driver
• Bovie cautery tool
• Monsel's solution
• Endocervical curette if endocervical curettage is performed [12][13][14]

Personnel

The personnel indicated for CKC procedures typically are as follows:

• Primary surgeon
• Anesthesia personnel
• Operating room surgical technician
• Operating room nurse circulator

Preparation

CKC procedures are typically performed under regional or general anesthesia, after which the patient is placed in the dorsal lithotomy position using candy cane or Allen stirrups. The vagina is prepped using either Hibiclens antimicrobial scrub or povidone-iodine. The patient is draped in the usual sterile fashion.[13] The bladder may be drained with straight catheterization, though some clinicians prefer to keep the bladder full.

The American College of Obstetricians and Gynecologists has recommended a single dose of prophylactic antibiotics before procedures to prevent infection; however, a Cochran review found no benefit to perioperative antibiotics for diagnostic excisional procedures.[15] Colposcopy with 5% acetic acid or Lugol solution may be performed in the operating room to facilitate visualization of the cervical lesion according to the surgeon's preference.[13] Vasopressin may be injected into the cervix as a vasoconstrictor solution, reducing blood loss during the procedure.[16]

Technique or Treatment

The first step in performing a CKC is similar to other diagnostic excisional procedures— obtaining a clear view of the cervix. This is achieved by placing a weighted speculum in the vagina. Elevate the anterior vaginal wall with a right-angle retractor to visualize the cervix. Grasp the anterior lip of the cervix with a single-toothed tenaculum. According to the clinician's preference, lateral hemostatic sutures, sometimes called stay sutures, may be placed at the 3 o'clock and 9 o'clock positions at the cervicovaginal junction. However, some studies have demonstrated that these sutures do not provide a hemostatic benefit.[16][17] If the clinician desires to use vasopressin in patients without contraindications, 10 to 15 mL of dilute solution is injected at the 2, 4, 8, and 10 o'clock positions until blanching is seen.[13] 

The cervix is then circumferentially incised, angling the blade toward the endocervical canal, typically beginning at the posterior aspect of the cervix to avoid obscuring visualization of the operating field with blood. A saw-cutting technique is used to excise the cervical cone, carefully including the entire cervical lesion and transformation zone within the circumferential incision. Counteraction can be provided with toothed or Allis forceps, elevating the cone bed while cautioning not to damage the epithelium. Then, the base of the cone is excised with Mayo scissors. The remainder of the endocervical canal may then be sharply curetted due to the benefit of detecting residual pathology (eg, AIS); however, routine curettage of the endometrium is not necessary unless the patient is at higher risk for endometrial pathology (eg, postmenopausal age, AIS cytology, or abnormal bleeding).[18][1][19] Hemostasis of the remaining cervix should be ensured using the clinician's preferred technique (eg, cautery, interrupted sutures, Monsel's solution).[16][17] Place a suture at the 12 o'clock position of the cervical cone specimen as a reference mark for the pathologist.

Complications

The most significant complication of a CKC procedure is bleeding, either intraoperatively or within the first 2 weeks of the postoperative period. Multiple techniques can manage intraoperative bleeding, including Monsel paste, silver nitrate, packing, or suturing. Major postoperative bleeding occurs in 2% to 17% of patients, depending on the study referenced. Occasionally, a return to the operating room to recauterize or suture the cone bed is required to obtain hemostasis.[20][13]

Infections following a CKC procedure are rare, occurring in only 1% of patients; typically, they can be treated with oral antibiotics. Cervical stenosis and cervical insufficiency are late complications associated with this procedure. Cervical stenosis should be evaluated postoperatively if aggressive cauterization was performed or a deep cervical cone specimen was obtained. Cervical stenosis can be treated with dilation of the endocervical canal. Cervical stenosis is more common in postmenopausal women.[20]

Data is mixed regarding the risk of preterm delivery and perinatal mortality associated with excisional conization procedures; no randomized controlled trials exist. Most studies indicate that the CKC procedure is associated with a greater risk of preterm delivery and intraamniotic infection than the LEEP procedure because of the greater depth of cervical excision. A recent study found that conization depths of ≥18 mm increased the risk for early-onset neonatal sepsis and intraamniotic infection; however, most other studies have also found that increased conization length was associated with a higher incidence of preterm labor. Additionally, undergoing more conization procedures is linked to an increased risk of preterm birth.[21][22][19][18][13][23] Therefore, limiting the amount of excised cervical tissue is especially important for patients with future pregnancy plans.  

Clinical Significance

The recurrence risk of CIN 2 or 3 after CKC varies by age, disease severity at initial treatment, and margin status but is, on average, 1.4%[20]. The CKC procedure has the lowest recurrence rate of conization techniques.[24] While the CKC procedure necessitates using an operating room, it yields a histological specimen with the most intact margins.[25] Positive margin status after cervical conization is associated with higher recurrence rates with endocervical involvement.[26] Vaccination against HPV after cervical conization may also protect from recurrent disease. In a 2020 study, vaccination against HPV was associated with a marked decrease in recurrent or persistent HSIL.[27]

Enhancing Healthcare Team Outcomes

CKC is a procedure that involves several members of the healthcare team. CKC is usually performed by a general gynecologist or occasionally a gynecologic oncologist in a hospital operating room or surgical facility. Therefore, anesthesiology clinicians, operating room nurses and technicians, presurgical and postsurgical nurses, and pathologists all have essential roles in caring for a patient undergoing a CKC.

Interprofessional communication and care coordination are critical from the planning to the performance of the procedure to ensure optimal patient outcomes. Furthermore, adequate patient education and follow-up by the gynecology and primary care clinicians should provide the patient with a thorough understanding of the risks and benefits of the procedure, including future fertility risks, the prevention of cervical cancer with condom use and HPV vaccination, and adhering to the recommended cervical cancer screening guidelines.

Nursing, Allied Health, and Interprofessional Team Interventions

Nurses, nurse practitioners, and physician assistants are essential to inform and counsel patients before, during, and after a conization procedure. Nursing is important in the care and support of patients with cervical dysplasia. Nurses provide education, counseling, and assistance throughout the diagnostic, treatment, and follow-up processes. The role of allied health care includes supportive care, pre and postprocedure care, and follow-up monitoring. Nursing responsibilities and scope of practice may vary depending on the healthcare setting, including local protocols and level of training and expertise. Collaborating with the healthcare team and being updated on evidence-based practices are essential. This collaboration will provide optimal care to individuals with cervical dysplasia and conization treatments.[28]