Overview

This is an aftermarket-compatible cordless Toco transducer offered by IPR Medical as a direct replacement for the M2725A wireless Toco fetal transducer used in the Philips Avalon Cordless Transducer System (CTS). It is intended to function as part of the Avalon cordless monitoring chain together with the Avalon CTS base station (M2720A) and a host Avalon fetal monitor — the FM20 (M2702A), FM30 (M2703A), FM40 (M2704A), or FM50 (M2705A). Like the part it replaces, this transducer measures uterine activity externally by evaluating the hardness of the mother’s abdomen during contractions, then transmits the signal wirelessly to the CTS base station so the host monitor can render a continuous Toco trace on the integrated recorder. The cordless form factor is intended to support patient mobility during labor and delivery while keeping continuous CTG documentation in place. This is a compatible aftermarket part sold and supported by IPR Medical and is not manufactured by, affiliated with, or endorsed by Philips.

Display and User Interface

The compatible M2725A-style transducer has no display of its own; all numeric values, waveforms, alarms, and trace recording are presented on the host Avalon fetal monitor’s touchscreen and integrated thermal recorder. The transducer carries on-board status indicators that show pairing, battery charge state, and bed-identifier assignment so clinicians at the bedside can confirm the cordless link is active. When the transducer is removed from the CTS base station, the Avalon host monitor automatically reconfigures its on-screen layout to show cordless Toco data on the appropriate channel; redocking the transducer in the base station — or putting the base station into Stand-by — returns the host monitor to wired-transducer operation. Bed-label assignment and other configuration steps are performed at the host monitor and propagate to the cordless transducer through the CTS base station.

Strain-Gauge Operation and Wireless Transmission

External tocodynamometry detects uterine contractions indirectly. As the uterus tightens during a contraction, the abdominal wall stiffens and pushes outward against the Toco transducer; inside the transducer, that mechanical force deflects a movable base plate against a pressure-sensitive resistor bridge — a strain-gauge (DMS) element. AC excitation is applied to the bridge, and the resulting differential output is amplified and synchronously rectified to produce a pressure-proportional DC signal. That signal is digitized and transmitted to the CTS base station over a digital subcarrier together with the transducer’s serial number, bed label, fetal movement data (where supported by the host monitor), and battery status. The base station forwards the data to the host Avalon monitor, which displays the result as a relative-pressure Toco channel and prints it to the trace alongside FHR data from a paired cordless or wired ultrasound transducer. As with any wired Toco transducer, the displayed value is relative rather than calibrated absolute pressure, so the operator zeroes the trace between contractions using the host monitor’s Toco baseline control.

Compatibility with the Philips Avalon Family

The compatible M2725A-style cordless Toco transducer is designed to be used with the Philips Avalon FM20 (M2702A), Avalon FM30 (M2703A), Avalon FM40 (M2704A), and Avalon FM50 (M2705A) fetal/maternal monitors. All four monitors share the same cordless transducer ecosystem and are compatible with the Avalon CTS Cordless Fetal Transducer System base station (M2720A). Two operational rules apply across the Avalon family. First, only one CTS base station can be connected to a host monitor at a time. Second, wired and cordless transducers cannot be mixed during a single monitoring session; the operator selects either the wired chain or the cordless chain by docking or undocking the cordless transducers in the CTS base station and uses one chain at a time. Cordless monitoring of twins or triplets is not supported by the CTS architecture, so multi-pregnancy patients should be moved to wired transducers. If sufficient signal quality cannot be achieved on the cordless link — for example, in a labor room with significant RF interference or with a patient who has moved outside the CTS coverage radius — switching to wired transducers is the appropriate fallback documented in the host system’s instructions for use.

Patient Mobility, Belts, and Workflow

The cordless form factor’s primary clinical benefit is freedom of movement during labor. The transducer attaches to a fetal monitoring belt with a snap-clip belt fixing identical in interface to the wired Avalon transducers, so existing belts in a Labor and Delivery unit’s circulating stock continue to work. Compatible belts include reusable washable fetal belts (e.g., M1562A), waterproof washable fetal belts (e.g., M1562B) for showering and tub labor, and disposable abdominal belts (e.g., M2208A) for single-patient use. Because the transducer housing is waterproof, it can remain in place during showering and bathing without removing the patient from continuous CTG monitoring, provided the host monitor and CTS base station coverage area extend to the bathing location. After each patient, the transducer is wiped clean of skin oils and lotions, surface-disinfected per the host system’s care and cleaning instructions, and returned to the CTS base station to recharge between uses; it should not be steam-sterilized.

Service and Maintenance Considerations

Because the compatible M2725A-style transducer participates in a wireless, battery-operated monitoring chain, its failure modes are different from a wired Toco transducer. Common service-related issues include reduced battery runtime as the internal cell ages, intermittent radio link quality in environments with significant 2.4 GHz interference or after structural changes to a Labor and Delivery floor (new walls, new equipment, new wireless networks), drift of the strain-gauge baseline that cannot be zeroed at the host monitor, and damage to the housing seal that compromises the waterproof rating after drops or rough handling. Performance verification after any repair or maintenance event should follow the same performance and safety test sequence the host system’s service guide defines for the wired Toco channel, with the addition of cordless link verification at the CTS base station. Telemetry should not be used as the primary monitoring chain when momentary loss of the Toco signal would be unacceptable; in those cases the patient should be returned to a hard-wired transducer chain. IPR Medical’s biomed team can support facilities that need bench testing, evaluation, or replacement of compatible cordless Toco transducers as part of fleet maintenance on Avalon fetal monitors.

IPR Medical — Buy, Sell, Repair, and Parts

IPR Medical buys, sells, repairs, and stocks parts and accessories for the Philips Avalon fetal monitor family and the Avalon Cordless Transducer System (CTS), including aftermarket-compatible wireless Toco transducers offered as direct replacements for the M2725A. Whether your facility needs a single replacement cordless Toco transducer to bring an Avalon CTS chain back into service, additional cordless transducers to expand cordless monitoring across more Labor and Delivery beds, or evaluation and repair of an existing cordless transducer that is producing baseline drift, intermittent radio link, or short battery runtime, IPR Medical’s biomed team can support the request. We also buy back surplus Avalon monitors, CTS base stations, and cordless transducers from facilities upgrading their fetal monitoring fleet. Reach out for compatibility verification against your specific Avalon host monitor software revision, fleet sourcing for multi-bed deployments, and service questions on the host monitor or CTS base station.

IPR Medical buys, sells, repairs, and stocks parts for the Philips Avalon Cordless Transducer System (CTS), including aftermarket-compatible wireless Toco transducers for the M2725A. Contact IPR Medical at 855-477-8866 or cs@iprmed.com with service or software questions.