SOP

Ultrasound Assessment of Bladder Wall Thickness

Moji Balogun (Consultant radiologist, BWH NHSFT)

TO BE USED IN CONJUNCTION WITH TRAINING VIDEO

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 bladderbefore 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.
  • 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 patientshould 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
  • 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
  • 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 anterior-posterior (D) x transverse diameter (W) x0.5233 (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:

  • 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)PVR image 1 WITH callipers

2)PVR image 1 WITHOUT callipers

3)PVR image 2 WITH callipers

4)PVR image 2 WITHOUT callipers

5)Bladder Wall Thickness image 1 WITH callipers

6)Bladder Wall Thickness image 1 WITHOUT callipers

7)Bladder Wall Thickness image 2 (optional) WITH callipers

8)Bladder Wall Thickness image 2 (optional) WITHOUT callipers

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

–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.

1BUS SOP V2 11/11/11