This test is done to evaluate the level of obstruction in the ureters and to see if contrast drains into the urinary bladder. This test will also confirm the position of the PCN if it is displaced outside the kidney.
No. There is also no need to be on empty stomach. But if you have fever, then this test will be deferred. You will be told to empty the bladder at the start of the study.
You will be asked to lie down on an x-ray table. After taking aseptic precautions, the urine bag will be disconnected from PCN tube. About 5-10ml diluted contrast will be instilled into the nephrostomy tube by the urologist/urology specialist nurse, so that contrast flows by gravity. Usually one immediate erect X-ray is taken. After this you may be asked to walk for with PCN tube blocked and fixed on your back. Another x-ray is taken at 20 minutes and during this interval you should not pass urine. This delayed film is to see whether contrast has drained into the bladder.
The test is not painful. However, there may be mild discomfort. If there is obstruction to the flow of contrast and you have severe pain, you can inform your doctor/nurse/radiographer who will unclamp the PCN immediately.
Usually, this test is safe. There is a rare chance of infection, which will manifest as fever and vomiting. If this occurs you may require admission and treatment with antibiotics.