An interesting phenomenon, in this female

Observing the bladder and pelvic structures including uterus, I found this interesting phenomenon.

That streak of color from the posterior wall of the bladder is a ureteral jet. They come alternately from either side. 

Here are some facts about ureteral jets. 

• Ultrasound imaging of the urinary bladder may reveal a "ureteral jet".
• A ureteral jet appears as a small, pulsatile stream of urine entering the bladder.
• It indicates the presence of normal, unobstructed flow from the ureter to the bladder.
• The absence of a ureteral jet may suggest obstruction or other urinary tract abnormalities.
• Ureteral jets can be visualized using color or spectral Doppler ultrasound.

For more on this visit:

Sonography of ureteral jets in the bladder