On colposcopy of a patient with high-grade CIN3, the transformation zone (TZ) is not fully visualized as it extends into the endocervical canal. Directed biopsy confirms CIN3. What is the PREFERRED treatment modality?
- A Knife cone biopsy (cold knife conization) ✓
- B Cryotherapy
- C Large loop excision of the transformation zone (LLETZ)
- D Laser ablation
Correct answer: A. Knife cone biopsy (cold knife conization)
Explanation
When the TZ is not fully visible (extends into the endocervical canal — Type 3 or unsatisfactory colposcopy), cold knife conization is the preferred management for CIN3. It removes the entire transformation zone including the endocervical component and provides an adequate specimen with clear margins for histological assessment. LLETZ may be used for visible TZ (Type 1 or 2), but when the lesion extends endocervically, cone biopsy is required. Ablative techniques (cryotherapy, laser) are inappropriate when the TZ cannot be fully visualized.
Reference: Shaw's Textbook of Gynaecology, 17th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.