MHRA Issues RF Safety Information for Wireless CTG Monitoring (September 2026): Co-Channel Crosstalk Can Display Fetal Heart Rate on the Wrong Monitor

Event Overview

On 17 September 2026, the UK Medicines and Healthcare products Regulatory Agency (MHRA) published Device Safety Information DSI/2026/012, entitled “Radiofrequency (RF) Safety Considerations for Wireless Cardiotocography (CTG) Monitoring Systems.” The document addresses wireless CTG monitoring systems that use radiofrequency (RF) telemetry channels and identifies three categories of risk: signal crosstalk, incorrect CTG traces, and signal loss. It requires healthcare organisations and clinical engineering staff to take specific measures.

The information was subsequently included in the “MHRA Safety Roundup: September 2026,” published on 29 September 2026.

What Wireless CTG Is and What Channel Crosstalk Means

CTG assesses fetal condition by recording the fetal heart rate and uterine contractions; conventionally this is done with wired ultrasound and pressure transducers. Wireless CTG makes this measurement wireless, allowing the mother to move freely during labour. Some wireless systems share a limited number of RF telemetry channels. When co-channel devices are within range of one another, signal crosstalk or interference can occur — for example, between different rooms on the same floor, between different floors, during patient transport, or when devices are moved between clinical areas.

Risks Stated by the MHRA

Based on adverse event reports and stakeholder feedback, the MHRA lists the following risks:

• Signal crosstalk — a device captures the fetal heart rate of another device;
• Incorrect or inconsistent readings — the displayed value differs from the actual fetal heart rate;
• Signal persistence — recording continues after the transducer has been removed;
• Environmental factors — building structure and layout affect RF interference;
• Use and maintenance factors — including transducers not being correctly returned to their designated position, inadequate cleaning after use, or misconfiguration.

In extreme cases, the fetal heart rate displayed on one monitor may originate from another monitor, leading to misinterpretation of the trace and inappropriate clinical decisions.

Specific Requirements for Healthcare Organisations

The MHRA requires clinical staff and clinical engineering staff to ensure, at the operational level, that two or more wireless CTG devices do not operate on the same RF channel unless the separation distance is sufficient to avoid crosstalk. In the absence of obstacles, approximately 100 m of separation between co-channel devices may be needed; walls are not necessarily sufficient, and crosstalk across floors is also possible.

Clinical verification of the trace must be performed at the start of monitoring and throughout the monitoring period to confirm that the fetal heart rate belongs to the correct patient, and a wired CTG system must be available as a backup in the event of signal loss or crosstalk.

Procurement, Installation and Governance

At the procurement stage, clinical teams should work with clinical engineering teams to fully assess the physical environment, the local RF environment and the number of available channels; purchasing more devices than there are available channels directly creates a risk of crosstalk.

Installation should involve obstetrics, clinical engineering (EBME), digital teams, the clinical safety officer and manufacturer representatives. Organisations should also establish and maintain a register recording wireless CTG systems, RF channels, frequencies, bandwidth allocation, deployment locations and paired devices, and should monitor the RF environment periodically.

Reporting and Scope of Application

The MHRA recommends that clinicians report suspected related adverse events through the Yellow Card scheme (in Scotland, through IRIC). This DSI applies to wireless CTG systems that use classic ISM-band telemetry channels, and the manufacturer is listed as “multiple manufacturers”; it is not directed at a single brand or model. The document focuses on risk control at the level of use and configuration, rather than a recall or withdrawal of any particular product.

Sources and Notes

Sources: Medicines and Healthcare products Regulatory Agency (MHRA) — Radiofrequency (RF) Safety Considerations for Wireless Cardiotocography (CTG) Monitoring Systems (DSI/2026/012), published 17 September 2026, https://www.gov.uk/drug-device-alerts/radiofrequency-rf-safety-considerations-for-wireless-cardiotocography-ctg-monitoring-systems-dsi-slash-2026-slash-012 ; MHRA Safety Roundup: September 2026, published 29 September 2026, https://www.gov.uk/drug-device-alerts/mhra-safety-roundup-september-2026 ; DSI source PDF, https://assets.publishing.service.gov.uk/media/6aaabad244ec1aa417346b9d/Radiofrequency__RF__Safety_Considerations_for_Wireless_Cardiotocography__CTG__Monitoring_Systems__DSI-2026-012_.pdf .

Verification scope and access date: this review accessed the MHRA DSI/2026/012 page on GOV.UK, the September 2026 Safety Roundup page and the source DSI PDF on 8 October 2026; the risk descriptions and corrective requirements in those pages are consistent with one another.

Applicability note: this article is an interpretation of publicly available regulatory information and does not constitute a conclusion or commitment regarding any specific product, company or registration application. The specific channel configuration, separation distances and operating requirements for wireless CTG should follow the device instructions for use, manufacturer guidance and institutional procedures. The information may change with subsequent official updates; the official original text prevails.

AIMEILI Regulatory Interpretation and Business Impact

Regulatory Interpretation

DSI/2026/012 is a post-market field safety communication that is primarily directed at healthcare organisations, but it carries clear implications for manufacturers of wireless CTG systems and for their regulatory documentation. Three points stand out.

• Use-environment risk is now on the record. The MHRA attributes crosstalk risk to shared, limited ISM-band telemetry channels and to site-level deployment decisions. Manufacturers can expect purchasers to ask for documented channel plans, maximum device density and coexistence guidance, and to reference this DSI in tenders and safety cases.
• Risk management and IFU expectations increase. The scenarios described — a fetal heart rate appearing on another monitor, incorrect or inconsistent readings, signal persistence after transducer removal, and configuration or maintenance errors — map directly to ISO 14971 risk analysis and to the residual-risk communication expected in labelling. Manufacturers should review whether their instructions for use adequately describe co-channel separation distances, channel assignment, transducer storage and cleaning, and backup procedures.
• Wireless coexistence evidence matters. Documents such as ANSI C63.27 for wireless coexistence evaluation, together with IEC 60601-1-2 electromagnetic compatibility requirements, become more relevant in pre- and post-market submissions. For UK registration and for EU MDR technical documentation, coexistence and interference testing can be expected to face closer scrutiny, and post-market surveillance should include crosstalk-related complaints and near misses as a defined signal.

Business Impact

• Procurement and tender requirements. Buyers are likely to require channel-count disclosure, deployment guidance and site-survey support. Vendors unable to supply a documented channel plan may be disadvantaged in obstetric monitoring tenders.
• Service and training revenue. Installation and configuration services, RF environment surveys, channel registries and clinician training on trace verification and wired backup become part of the commercial offering rather than optional add-ons.
• Installed-base management. Manufacturers may need to notify existing customers, issue supplementary guidance and support customers in building channel and pairing registries, even where no product change is required.
• Product design roadmap. Systems with automatic channel selection, pairing confirmation, transducer-removal detection or alternative wireless technologies are better positioned against crosstalk concerns.
• Distributors and CROs. Distributors should be prepared to relay the MHRA expectations locally, and CROs supporting CTG or obstetric monitoring studies should align site set-up with channel planning and trace verification requirements.

Sources

• Medicines and Healthcare products Regulatory Agency (MHRA) — Device Safety Information (DSI/2026/012), 17 September 2026
• Medicines and Healthcare products Regulatory Agency (MHRA) — MHRA Safety Roundup: September 2026, 29 September 2026
• Medicines and Healthcare products Regulatory Agency (MHRA) — DSI/2026/012 source PDF