Accuracy of Bladder Ultrasound Study (BUS)
SOP
Ultrasound
Assessment of Bladder
Wall Thickness
Moji Balogun (Consultant radiologist, BWH NHSFT)
TO BE USED IN CONJUNCTION WITH TRAINING VIDEO
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BUS SOP V2 11/11/11
Clinician Preparation
The clinician performing the BUS should be different to the clinician performing the UDS, to
ensure blinding between the two tests.
If, for any reason, this is not possible the BUS should be performed BEFORE the UDS.
Patient Preparation
The patient may be seen in various settings:
–
Clinic (patient may need other assessment)
–
Scan department (may require renal tract assessment and attends with full bladder)
Ensure patient empties bladder before assessment of Bladder Wall Thickness (BWT) and
Post Void Residual (PVR)
Important to stress need to void as completely as possible
Machine & Probe Preparation
Ensure scanner is capable of measurement in millimetres (mm)
Set to the scanner to the Gynae preset
Use a Trans-Vaginal probe (not a rectal probe)
–
Multifrequency – use between 7 & 9 MHz for optimal image (no lower than 5 MHz)
–
Prepare the probe:
Clean
Put gel into probe cover, excluding air
Put gel onto tip of probe
Timescales
The ultrasound scan should ideally be completed in a one-stop clinic with the urodynamics
test.
The two tests should be undertaken by different clinicians to ensure blinding of results.
If it is not possible to hold one-stop clinics, the ultrasound and urodynamics tests should be
undertaken no more than 4 weeks apart.
The second test can be undertaken up to a further 4 weeks after this cut-off (8 weeks in total
from the first test), but the data collected will be classed as a protocol violation.
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BUS SOP V2 11/11/11
If the patient is happy to have one or both tests re-taken (effectively constituting a second
‘set’ of tests), they can do so, as long as they haven’t become ineligible in the interim (i.e.
begun medication).
An interval of more than 8 weeks between the two tests will be designated as breach of
protocol and no per patient payment will be provided for these patients.
Ultrasound Assessment
The patient should be in the supine position (stirrups or pad under pelvis as appropriate)
The TV probe should be inserted into introitus in longitudinal plane
Position should then be assessed on screen
Identify the urethra in sagittal orientation
Position probe such that the VUJ is close to top of screen
Ensure image sizing is appropriate for screen, between 5-7cm depth
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BUS SOP V2 11/11/11
Focal zone positioned at region of interest; multiple focal zones if possible to give good
definition at various levels
PVR and BWT should be measured before any other assessment, as in patients who have filled
their bladder before hand, it may fill during scan:
PVR:
Identify entire bladder in sagittal plane, measure longest AP dimension and then CC
dimension perpendicular to this
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BUS SOP V2 11/11/11
Rotate probe through 90° and measure axial dimension
Most machines are now able to generate volumes automatically (need to select this before
starting with callipers)
If not available, use the following to standardize calculations: cranio-caudal (H) x anteriorposterior (D) x transverse diameter (W) x 0.5233 (prolate ellipsoid) = PVR volume
ELIGIBILITY: Proceeding to BWT measurement:
If PVR <=30mls proceed with BWT measurement.
If PVR >=30ml, ask patient to re-void
If after re-void PVR is >30 ml but <100 ml measure the BWT.
If the PVR is >100 ml exclude patient from BUS
BWT assessment:
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BUS SOP V2 11/11/11
Measurement should be obtained in sagittal plane with VUJ on margin of screen (probe may
need to be introduced slightly further)
3 x measurements: at the dome, anterior wall and trigone need to be obtained
The same image should be stored twice; with and without callipers
Any focal areas of thickening need separate assessment and evaluation
It is not always possible to see the anterior wall or trigone well, as many women with
bladder problems often have irregular bladder outline, but…. It is always possible to see the
dome
If the whole of the bladder is not visible on one image (as is preferable), there may be the
need to angle anteriorly or posteriorly and measure the trigone or anterior wall thickness
Patients with significant cystocoeles may find complete emptying difficult and trigone may
be difficult to visualise adequately
It is important to document any additional findings (diverticuli, cystocoeles, focal masses)
Providing Electronic Images:
Anonymised electronic images for each patient should be provided, labelled clearly with Study ID as
the only identifier. These images should be as follows:
1)
2)
3)
4)
5)
6)
7)
8)
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PVR image 1 WITH callipers
PVR image 1 WITHOUT callipers
PVR image 2 WITH callipers
PVR image 2 WITHOUT callipers
Bladder Wall Thickness image 1 WITH callipers
Bladder Wall Thickness image 1 WITHOUT callipers
Bladder Wall Thickness image 2 (optional) WITH callipers
Bladder Wall Thickness image 2 (optional) WITHOUT callipers
BUS SOP V2 11/11/11
a) For optimal quality these should be sent to Birmingham Clinical Trials Unit on disk or
memory stick in DICOM format ideally.
b) Failing this JPEG images will be accepted.
c) If downloadable images are not possible please supply a print out of each image listed
above, ensuring that the print quality is optimal (what is seen on screen).
SUMMARY
Prepare patient (ensure voiding takes place just prior to scan and measure in supine
position)
Prepare machine (use vaginal probe and frequency 7-9 MHz for optimal image)
USS assessment
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–
Important to obtain good quality images
–
Callipers placed on margin of bladder wall for thickness; within bladder lumen (on
wall) for volumes
–
Store images with and without callipers for cross-referencing and evaluation
–
Measure if PVR is <=30ml, revoid if PVR is >=30ml and measure if PVR is >30 but
<100ml, exclude if PVR is>100ml.
BUS SOP V2 11/11/11