A 28-year-old woman presents with persistent cervical cytology showing atypical squamous cells of undetermined significance (ASCUS). She is HPV-positive on reflex testing. What is the most appropriate next investigation to determine the need for colposcopy?

Explanation

## Investigation of Choice for HPV-Positive ASCUS **Key Point:** In a woman with ASCUS and positive HPV reflex testing, HPV genotyping for high-risk types (HPV-16 and HPV-18) is the most appropriate next step to stratify risk and guide colposcopy referral. ### Rationale HPV genotyping provides critical risk stratification: - **HPV-16/18 positive** → Immediate colposcopy (highest cancer risk) - **Other high-risk HPV positive** → Colposcopy or repeat cytology depending on guidelines - **Low-risk HPV positive** → Routine screening or repeat cytology ### Clinical Context ASCUS with HPV-positive status represents an intermediate-risk scenario. Genotyping distinguishes between: 1. **Oncogenic HPV-16/18** (responsible for ~70% of cervical cancers) 2. **Other high-risk HPV types** (lower but non-zero cancer risk) 3. Low-risk types (minimal malignant potential) **High-Yield:** HPV-16 and HPV-18 are the most oncogenic types and warrant immediate colposcopic evaluation, while other high-risk types may allow for deferred colposcopy or repeat cytology based on institutional protocols. ### Comparison of Investigations | Investigation | Timing | Role | Limitation | |---|---|---|---| | HPV genotyping (16/18) | Immediate | Risk stratification in ASCUS | Does not visualize lesion | | Repeat cytology | 12 months | Acceptable for low-risk HPV | Delays diagnosis if high-risk | | Colposcopy | Immediate if HPV-16/18 | Gold standard visualization | Over-investigates low-risk cases | | Liquid-based cytology | Initial screening | Improved specimen quality | Not a next step after ASCUS | **Clinical Pearl:** Current ASCCP (American Society for Colposcopy and Cervical Pathology) and WHO guidelines recommend HPV-16/18 genotyping as a triage tool for ASCUS to optimize resource allocation and reduce unnecessary colposcopies. **Warning:** Simply repeating cytology without genotyping in an HPV-positive woman delays diagnosis of high-grade lesions and is not standard practice. Immediate colposcopy without genotyping over-investigates low-risk cases.