Module 4: Point of care ultrasound in first trimester abortion (POCUS)
5. Equipment – what is required?
There is a wide range of ultrasound equipment available, from high tech machines with multiple probes costing six figure sums to handheld devices with limited functionality.
For the clinical questions this module is designed to answer, cheaper handheld devices with a single abdominal (low frequency, curvilinear) probe are sufficient.
There are multiple devices on the market. Functionality and quality can vary between them. In purchasing a handheld scanner, you should consider the following:
- Does it have its own screen, or does it need to be partnered with a mobile device?
- Is it a suitable size and is it portable?
- Is the user interface design intuitive? (e.g. ease of depth and gain adjustment)
- Is there an image archiving capability? (if required)
- Can it easily be cleaned?
- What is its resolution? Devices with higher resolution give a clearer image
- Does it have an obstetric setting? Without this you will not be able to easily calculate gestational age.
- Is it wired or cordless? Although cordless may be less cumbersome, there is often a trade off with image quality and price.
- What is the battery life/charging time? Can the device be used while charging?
- What is the warranty? And is the service New Zealand based?
- Are there any hidden costs? Some scanners have a yearly subscription in addition to the cost of the machine.
Adjusting Ultrasound Machine Settings: Machine adjustment can improve image quality and diagnostic accuracy. There are four important settings to find on your ultrasound machine:
- Examination type: examination pre-sets optimise the imaging settings for the kinds of structures you are interesting in viewing. Select an obstetric examination type if it is available, abdominal is your next best option.
- Depth: set the depth such that your object of interest is centred on the screen to optimise image quality.
- Gain: adjusts the overall screen brightness of the ultrasound image. In general, the gain should be set at a level where urine in the bladder appears black and there is adequate contrast between structures.
- Probe Indicator Marker (Figure 1): every ultrasound probe has an indicator marker, a mark on the probe the corresponds to a orienting marker on the screen. Apply gel to the transducer or touch one edge of the probe. Look at the ultrasound screen to see match orientation on the screen.
Figure 1. Location of an ultrasound probe orientation marker and an example image demonstrating its location on the ultrasound screen image.
Images provided by Dr Sierra Beck.