A nephrostogram is a specialized X-ray imaging procedure used to examine the drainage system of the kidney after a percutaneous nephrostomy tube has been placed. This diagnostic test involves introducing a radiopaque contrast agent (dye) directly into the kidney through the existing tube. The primary purpose is to gain a clear, visual assessment of internal structures, particularly the renal pelvis and the ureter, which connects the kidney to the bladder. The nephrostogram is a focused tool that provides specific information about the functionality of the kidney’s drainage pathway.
Why the Test is Necessary
The nephrostogram evaluates the functionality of the indwelling nephrostomy tube and assesses the health of the upper urinary tract. A primary reason for the test is to identify any obstruction in the flow of urine toward the bladder. The contrast dye allows physicians to visually track the fluid path and pinpoint the location and severity of a blockage, such as a stricture or scar tissue.
The procedure also confirms the precise placement of the nephrostomy tube, ensuring the tip is correctly positioned within the renal pelvis. If the tube is displaced or not draining effectively, the contrast agent reveals this misplacement on the X-ray images. Additionally, the test helps evaluate conditions that necessitated the original tube placement, such as monitoring kidney stone clearance or confirming fistula healing.
What to Expect During the Procedure
The nephrostogram is generally performed in a hospital’s interventional radiology suite or a dedicated X-ray department. You will be positioned on an examination table, usually lying on your back or side, depending on the tube location. The area around the tube site is cleaned with an antiseptic solution to maintain a sterile environment during the examination.
The medical team temporarily disconnects the drainage bag from the nephrostomy tube. A small amount of diluted iodinated contrast medium is then slowly injected directly into the tube using a syringe. This injection is performed carefully to ensure the dye flows into the kidney’s collecting system. The volume of contrast used is typically small, about 5 to 10 milliliters, to avoid excessive pressure.
As the contrast agent enters the kidney, you may feel pressure or fullness in your back or flank area, which is a normal response to the fluid filling the renal pelvis. If you experience sharp or severe pain, immediately inform the technician or physician, as this may indicate excessive pressure or a significant blockage. The physician uses a fluoroscope, a specialized X-ray unit that captures real-time images, to watch the dye travel through the kidney and ureter.
Multiple still images are taken from various angles as the dye progresses down the urinary tract. You may be asked to hold your breath briefly or shift your position slightly on the table for optimal visualization of the structures. In some cases, to encourage the dye to pass through a slow or partially blocked ureter, you might be asked to stand up and walk around briefly. The entire imaging process typically lasts between 30 and 60 minutes, depending on how quickly the contrast drains.
Preparing and Recovering from the Nephrostogram
Preparation for a nephrostogram is often minimal, but you should always follow your healthcare team’s instructions. In most cases, you can eat, drink, and take your regular medications before the test. It is important to inform the staff if you have known allergies, especially to contrast materials used in other imaging tests, or if there is any possibility of pregnancy, as X-rays are involved.
Recovery is usually straightforward, as the procedure is not invasive and does not require sedation. Immediately following the test, the contrast material is drained out of the tube, and the drainage bag is reattached or replaced. You will be monitored briefly to ensure there is no excessive bleeding or leakage from the tube site before you are cleared to leave.
You can generally resume your normal diet and activity level immediately after the nephrostogram. Watch for specific signs that may indicate a complication requiring prompt medical attention, such as fever or chills, which could signal an infection. Severe pain at the tube site that does not subside, or a significant change in the amount or color of urine draining into the bag, are also reasons to contact your doctor.