The intravesical ureteral jets, or the bladder jets represent the sonographic appearance of discrete boluses of urine entering the bladder, better detected using color Doppler. They are thought to result from autonomic and pressure dependent calyceal and ureteral peristalses.
Most healthy people have a ureteric jet frequency of 2 or more per minute on either side. Absence of ureteric jets during 10 minutes of observation in the steady diuresis phase may indicate complete ureteral obstruction, and the ureteric jet frequency of less than 2 per minute may indicate partial obstruction. In addition, jets may be absent in cases with poor renal plasma flow, or impaired unilateral renal circulation, such as in the case of renal cell carcinoma complicated with renal vein occlusion from tumor invasion or tumor thromboembolism.
However, their practical utility is not well established. In one study, urologists and radiologists disagreed on both the necessity for evaluating ureteral jets and their clinical relevance. In summary, if you see strong jets on both sides, it’s good and if you don’t, it doesn’t mean much unless you have suspicion for unilateral ureteral obstruction and there is no jet on that side after you ‘patiently’ monitored for at least 10 minutes.
Sometimes, these jets can also be seen on greyscale images. Particularly happens when there is debris in the bladder though its not a requirement. Depends on machine settings as well. Examples: