A 28-year-old woman undergoes routine cervical screening and is found to have atypical squamous cells of undetermined significance (ASCUS) on Pap smear. She is HPV-negative on reflex testing. What is the most appropriate next investigation?

Explanation

## Management of ASCUS with Negative HPV Reflex Testing **Key Point:** In ASCUS cytology with negative HPV reflex testing, the risk of underlying cervical intraepithelial neoplasia (CIN) or cancer is <1%. Repeat cytology in 12 months is the standard approach; colposcopy is not indicated. ### Clinical Significance of ASCUS + HPV-Negative Status **High-Yield:** HPV negativity in ASCUS essentially "clears" the patient. The cytologic abnormality is likely: - Reactive changes (inflammation, infection, trauma) - Sampling artifact - Benign squamous metaplasia - Very low-grade lesions unlikely to progress ### Management Algorithm for ASCUS ```mermaid flowchart TD A[ASCUS on Pap smear]:::outcome --> B{Reflex HPV testing}:::decision B -->|HPV-positive| C[Colposcopy]:::action B -->|HPV-negative| D[Repeat Pap in 12 months]:::action C --> E{CIN present?}:::decision E -->|Yes| F[Treat based on grade]:::action E -->|No| G[Routine screening]:::action D --> H{Repeat result}:::decision H -->|Normal| I[Routine screening]:::action H -->|Abnormal| J[Colposcopy]:::action ``` ### Why Other Options Are Wrong | Option | Rationale | |---|---| | **Immediate colposcopy** | Unnecessary; HPV-negative ASCUS has <1% risk of CIN3+. Colposcopy is reserved for HPV-positive ASCUS or higher-grade cytology. | | **Cone biopsy** | Excisional procedure reserved for diagnosed CIN or when colposcopy findings are concerning. Not indicated without tissue diagnosis. | | **HPV vaccination + 3-year screening** | HPV vaccine is for prevention in unvaccinated women; does not treat existing infection. Screening interval of 3 years is too long for ASCUS; 12 months is standard. | **Clinical Pearl:** Reflex HPV testing has replaced repeat cytology as the triage method for ASCUS. HPV-negative results are reassuring and allow safe deferral of colposcopy. **Mnemonic:** **ASCUS-HPV algorithm**: - **HPV+** → Colposcopy (risk ~15–25% of CIN2+) - **HPV−** → Repeat Pap in 12 months (risk <1% of CIN2+)