Bladder Scanner Product

Overview

A bladder scanner measures how much urine is in a patient's bladder without touching it, using three-dimensional ultrasound from the abdominal surface. Its single output number — bladder volume in millilitres — answers a question nurses face constantly: is this patient retaining urine? Before bladder scanners, the answer required an in-and-out catheterization, an invasive procedure carrying roughly a 1–2% risk of introducing a urinary tract infection per insertion. A 3-second scan replaces most of those diagnostic catheterizations, which is why the device lives on a cart in nearly every ward, post-anesthesia unit, and nursing home.

The system divides into a handheld 3D Ultrasound Probe that acquires the 3D data, a console containing the Ultrasound Front End, Processing Unit, and Display Console, a swappable Battery Pack, and the Mobile Cart that carries it all between rooms.

How it works

Unlike a diagnostic ultrasound machine with a multi-element array, the bladder scanner uses one 2.5 MHz Focused Transducer — a single 2.5 MHz piezoceramic element focused around typical bladder depth — and moves it mechanically. Inside the probe, two Servo Motor drives sweep the element through a fan of B-mode planes and rotate that fan about the probe axis, so 12 to 24 planes cover a 120° cone in about three seconds. Each Encoder reports sweep angle so every echo line is tagged with its exact direction. The element scans inside the Oil-Filled Acoustic Dome, an oil-filled dome that couples sound to the skin while the moving parts stay sealed behind it.

For each line, the High-Voltage Pulser excites the element with a bipolar pulse of roughly 100 V; the T/R Switch then isolates the transmitter, and the Receive Analog Front End amplifies the returning echoes with a time-gain ramp that compensates for tissue attenuation before digitizing them at 12 bits. Urine is anechoic — it returns almost no echo — while the bladder wall and surrounding tissue reflect strongly, so the bladder appears in each plane as a dark region with a bright boundary.

The Compute SoC Module in the Processing Unit segments that boundary in every plane, stacks the outlines by their encoder angles into a closed 3D surface, and integrates the enclosed volume. Because the actual shape is measured plane by plane, the method copes with the bladder's irregular, posture-dependent geometry far better than the old two-diameter ellipsoid estimate. Phantom accuracy is typically ±7.5% or ±7.5 mL, whichever is greater.

Using it

The operator applies coupling gel about 3 cm above the pubic bone, aims the probe slightly toward the patient's coccyx, and presses the Scan Trigger Button. After the sweep, the Aiming Indicator shows the bladder's position inside the scan cone as a crosshair; if the organ is clipped at the cone edge, the operator re-aims and rescans rather than accepting an underestimate. The accepted volume appears on the LCD Panel with the B-mode planes available for review via the Touch Digitizer, a Speaker tone confirms completion, and the exam is written to the Exam Storage Flash for export to the patient record.

Typical decision thresholds: post-void residual under 50 mL is normal; over 200–300 mL generally indicates retention needing catheterization. Scanning takes under a minute door to door, so wards scan first and catheterize only on a positive result.

Power and mobility

The console runs from a Battery Pack of four Li-ion Cell, 18650 cells under BMS Board supervision — about 30 exams per charge — and the Battery Pack Case latches out for tool-free swap with the spare kept warm in the Charging Dock. The Mobile Cart rolls on five Wheel Assembly casters with a supplies Supplies Basket for gel and wipes; the console also lifts off by its Carry Handle for bedside use in tight rooms. The Console Shell and Probe Shell are sealed for wipe disinfection between every patient.

Limitations

The scanner assumes the anechoic region it finds is urine. Ascites, ovarian cysts, or an indwelling catheter balloon can be misread as bladder volume, and scarring or obesity degrade the acoustic window. Readings in early pregnancy are unreliable because the uterus overlaps the scan cone. It is a measurement device, not an imaging diagnostic: it reports volume, and anything anatomically ambiguous belongs to formal ultrasound.