A mixed-methods evaluation of the implementation of IOTA-ADNEX ultrasound triage in NHS secondary care ovarian diagnostic one-stop clinics

Objectives

Robust evidence supports IOTA-ADNEX ultrasound triage at 10% threshold for ovarian cancer (OC) diagnosis to identify women for referral to tertiary gynaecological cancer centres for further management. The IOTA-ADNEX risk prediction model has superior sensitivity compared to the current standard of care triage, Risk of Malignancy Index (RMI-1), yet NHS adoption is limited. In our survey of British Gynaecological Cancer Society clinicians only 30% (24/79) currently follow an IOTA model, despite 80% (63/79) supporting implementation. We evaluated IOTA-ADNEX implementation within two NHS one-stop clinics (OSC) for suspected OC, examining clinical outcomes alongside implementation barriers and facilitators.

Methods

Mixed-methods study conducted across two UK NHS hospitals between June 2023-June 2025. Implementation outcomes were surgical intervention rates comparing IOTA-ADNEX-guided and retrospectively calculated RMI-based management using NICE/RCOG thresholds and patient process metrics. 11 qualitative semi-structured interviews were conducted with NHS staff involved in OSC implementation and thematic analysis performed.

Results

Of 334 patients, 42% (139) underwent same-day discharge. Using IOTA-ADNEX at a 10% threshold, 10% (32/334) of patients underwent surgery under the general gynaecology and cancer unit team. In comparison, 30% (94/334) would have undergone surgery under the same teams if RMI-based triage had been used. Five themes identified from qualitative analysis: organisational infrastructure, clinical decision-making, communication and pathway definition, professional collaboration and training support, and patient experience. Key facilitators included dedicated clinical leadership, timely decision-making capabilities and quality assurance sessions. Barriers included lack of standardised post-clinic pathways and insufficient staff communication about pathway changes.

Conclusions

IOTA-ADNEX implementation in one-stop clinics offer high same-day discharge rates and reduction in surgical rates compared to RMI triage. To ensure success, implementation should be supported by adequate infrastructure, training, and clear pathways. It requires leadership, comprehensive staff training, and robust communication strategies. These findings provide practical guidance for healthcare systems for wider implementation of IOTA-ADNEX.

Key messages

The IOTA-ADNEX ultrasound risk-assessment model to triage adnexal masses has demonstrated superior diagnostic accuracy over RMI which remains the standard tool in UK ovarian cancer pathways, even when applied by certified non-expert sonographers, but implementation within UK NHS pathways remains limited.

This mixed-method evaluation shows IOTA-ADNEX ultrasound triage can be successfully implemented in NHS one-stop clinics, reducing unnecessary benign surgeries compared to RMI and enabling high same-day discharge rates without missing invasive cancers.

Findings on key facilitators and barriers highlight the need for infrastructure, training, and pathway clarity and will inform wider NHS adoption of IOTA-ADNEX.