Patient supine with suprapubic area exposed.
Examine the bladder sagitally in the midline. Now angle laterally & sweep the probe both left and right to check the lateral margins.
Rotate 90 degrees into the axial(transverse) plane. Sweep through from the superior dome to the bladder base. Ensure the ultrasound beam is projected as close to perpendicular to the bladder wall as possible.
Look for ureteric jets at the bladder base. This confirms bilateral renal function and ureteric patency. To do this, in transverse angle inferiorly using power doppler (or colour doppler with low PRF & wall filter settings). You may need to be patient to wait for the ureteric jet depending on renal function and degree of hydration.
Document the normal anatomy and any pathology found (including measurements and vascularity if indicated). Measure the bladder volume pre and post micturition. As a rule of thumb, the bladder should empty to approximately 10% of the pre-micturition volume. If the initial post-void volume is greater than 100mL, encourage the patient to try again because a large residual volume may be artefactual following a very full bladder.