HealthTech NHS AI Cervical Screening Platform -- MHRA Class IIb

MHRA Class IIb SaMD

AI that performs primary screening (first-pass analysis before cytologist) is Class IIb (higher clinical risk than decision support Class IIa -- AI is performing the screening step).

Class IIb requirements above Class IIa

• 1UK Notified Body full Quality Management System audit (ISO 13485 QMS audit by BSI Assurance UK -- not just technical file review),
• 2IEC 62304 Class C (highest software class -- all functions with clinical safety implications require full traceability),
• 3clinical investigation (prospective clinical investigation -- not just validation study -- MHRA clinical investigation authorisation required),
• 4post-market clinical follow-up (PMCF -- ongoing clinical evidence collection post-launch).

Clinical investigation

ClickMasters supported MHRA CIV1 clinical investigation authorisation application -- 8-week MHRA review before investigation start.

LBC AI model

deep learning (ResNet-50 fine-tuned on NHSCSP LBC training data) performing primary screening of cervical cytology slides.

Clinical workflow integration

• 1digital slide scanner (Hamamatsu NanoZoomer -- digitises LBC slide at 40x magnification),
• 2AI primary screening (AI analyses digital slide -- confidence score per region, overall slide classification: normal/abnormal/inadequate),
• 3normal triage (AI high-confidence normal slides set aside -- still reviewed by cytologist but deprioritised),
• 4abnormal escalation (AI flags abnormal slides -- immediately reviewed by cytologist),
• 5inadequate classification (AI flags inadequate samples -- laboratory recall process).

NHSCSP sensitivity requirement

AI sensitivity for CIN2+ (pre-cancerous change Grade 2+) must be above 95% -- clinical validation required.

Training data

280,000 NHSCSP LBC slides (10-year dataset).

DCB0129 for Class IIb AI screening

higher clinical risk requires more extensive clinical safety case.

Primary hazard

AI misclassifying a CIN2+ sample as normal (false negative -- patient not recalled).

Mitigation

• 1AI cannot classify a slide as normal with 100% confidence -- all slides reviewed by cytologist (AI triage, not AI diagnosis),
• 2double-read protocol (AI abnormal + cytologist abnormal: immediate referral; AI normal + cytologist abnormal: immediate referral; AI abnormal + cytologist normal: second cytologist review -- discordance protocol),
• 3AI sensitivity monitoring (weekly -- AI sensitivity must stay above 95% CIN2+ -- automated alert if sensitivity drops below threshold),
• 4cytologist override (cytologist can override AI classification -- all overrides reviewed monthly by Lead Cytologist).

Clinical Safety Officer

Consultant Cytopathologist.

NHSCSP Programme Integration

NHSCSP (NHS Cervical Screening Programme): national programme run by NHS England.

Programme integration

• 1NCSP-is (Cervical Screening call-recall system -- GP patient lists, invitation management, result notification),
• 2HL7 v2.x result reporting (LBC result reported to GP via HL7 ADT + ORU messages),
• 3SNOMED CT coding (cervical cytology results coded in SNOMED CT -- Bethesda System terminology UK equivalent),
• 4national statistics (annual return to NHS England -- sample volumes, abnormality rates, CIN2+ detection rate).

PHE target

CIN2+ detection rate above national average -- AI primary screening expected to improve detection rate by 12-18%.