- Patient preparation: have the patient empty the bladder before the exam, explain procedure to the patient and parents, to relieve parental anxiety stress to parents the exam has two “worse parts:” first is a child being immobilized throughout the exam usually will not like it and may cry throughout the exam and second that even though we anesthetize the urethra with viscous lidocaine there is still a “rubbing” when the catheter goes in the urethra but that once the catheter is in it does not hurt so that overall any crying the patient exhibits once the catheter is in is not because the child is experiencing pain but because they are angry about being imobilized
- Contrast used: high osmolar water soluble
- Technique:
— The patient must be filled to their Estimated Bladder Capacity, to ensure they are assessed adequately for reflux, using the following formulas: If less than 2 years old = 10 cc x weight in kg and If greater than 2 year old = (age in years +2) x 30 cc up to a maximum of 500 cc
— An alternative calculation for Estimated Bladder Capacity is if less than 1 year old = weight in kg x 7 cc and if greater than 1 year old = (age in years + 2) x 30 cc up to a maximum of 500 cc
— If the patient is less than 2 years old, a cyclic study should be done to increase your sensitivity to detecting reflux. This is done by performing 3 cycles of filling and voiding, before the catheter is finally removed during voiding and the final image of the urethra is obtained
— Place the patient in a frog leg position
— Examine the patient to determine the position of the urethra. In the female, the urethra lies between the clitoris and the vagina and may be difficult to see
— Using sterile technique, prep and drape the patient first with 3 swabs of of an iodinated antibacterial cleaning solution, and then 2 swabs of water to clean off the iodinated antibacterial cleaning solution
— If the patient is a male, use viscous lidocaine to anesthetize the urethra. Fill the urethra with viscous lidocaine and give it 2-3 minutes to take effect before catheterizing the patient
— If the patient is a female, use viscous lidocaine to anesthetize the urethra. Fill the vulva / vagina with viscous lidocaine and give it 2-3 minutes to take effect before catheterizing the patient
— Place the end of the catheter in the specimen bottle and set the bottle on the table
— Insert the 8 French feeding tube into the bladder through the urethra (use a 5 French feeding tube if the patient is a premature infant)
— Tape the catheter to the anterior abdominal wall in the midline and then down to the penis or vagina
— Perform a Crudet maneuver (gentle pressure on the lower abdomen) to empty the bladder of urine before starting
— Obtain a urine specimen and send it to the clinic with the patient
— Take a scout image of the abdomen, to make sure the catheter is in the bladder
— Fill the bladder with contrast
— Once the bladder is filled to Estimated Bladder Capacity, the catheter is removed and the patient is asked to empty their bladder. Many patients cannot comply with this request, due to age or feeling uncomfortable with voiding in front of strangers. In patients who are not yet toilet-trained you may dribble room-temperature water on the perineal area to induce spontaneous voiding. In toilet-trained patients, they may get off the table to void on the toilet and then be brought back immediately to the fluoroscopy table for a final post-void image. - Images to obtain:
— Scout image with the catheter in the bladder
— AP image of abdomen with low volume filled bladder looking for ureterocele
— Lateral urethra voiding image in males, AP urethra voiding image in females
— Post void AP image of bladder to document bladder emptying
— Post void AP image of the kidneys to document any reflux
— Oblique and AP images of any reflux showing ureteral insertion - Looking for: vesicoureteral reflux, duplicated collecting systems, ureteral insertion, bladder diverticula, posterior urethral valves
- Post procedure tasks: explain the results to the patient and parents, explain urine may be pink-tinged for a day or so
Pediatric Imaging 