Definition and symptoms How far does the ureter have to be dilated to be considered a giant ureter? The upper limit of the ureter is between 5 mm and 6.5 mm from a newborn baby to a child of 12 years of age. Thus, the definition of a giant ureter is those ureters that are more than 7 mm in diameter. Imaging 1. Ultrasound should be repeated in all babies after birth. A series of ultrasounds at different times is more meaningful. 2. voiding cystourethrogram (VCUG, voiding cystourethrogram): all boys should have a cystogram to rule out posterior urethral valves. All children with giant ureter with hydronephrosis should also have a cystogram to rule out vesicoureteral reflux. This test is a little uncomfortable for the child. A small tube is inserted through the urethra, some contrast is injected into the bladder, the tube is removed, the child is allowed to urinate, and x-rays are taken. 3. Nuclear medicine nephrogram (MAG-3): If there is no posterior urethral valve or no vesicoureteral reflux, these children should have a nephrogram. Those with ureters larger than 10 mm in diameter should also have a nuclear nephrogram to rule out obstruction of the vesicoureteral excuse. This test requires a microinjection of radioisotope from a vein. The isotope is absorbed by the kidney and then excreted. The amount of radiation is lower than an x-ray, so parents do not need to talk about “nuclear”. A nuclear nephrogram can measure both kidney function and the rate of isotope elimination to determine whether there is an obstruction. A normal person has about 50% (45-55%) of the kidney function on each side. An obstruction is indicated if the renal function on one side is below 40%, or if there is a 5% decrease from the previous function. It is important to confirm the diagnosis before treatment. I saw a baby last week with a dilated ureter and renal pelvis on ultrasound, and after four CTs and an MRI there was still no correct diagnosis. Following the above guidelines and examination system, I performed a voiding cystourethrography and a nuclear medicine nephrogram, which revealed a vesicoureteral reflux, no congenital obstructive megaureter, and no posterior urethral valves. Treatment A ten-year follow-up study found that three-quarters (73%) of patients with giant ureter did not require any surgery, so today’s concept focuses on conservative treatment. Prenatal ultrasound reveals hydronephrosis, and prophylactic antibiotics are usually recommended for 6-12 months before diagnosis is confirmed, because long-term findings show that congenital obstructive megaureter causes many urinary tract infections in babies, and more than one-third of children have at least one hospital admission. In the first six months of life, the use of prophylactic congestin can reduce the infection rate by 83%. The indications for surgery are limited to: 1) the onset of clinical symptoms such as infection, stones and pain, or 2) a decline in renal function, with unilateral renal function below 40%, a 5% decrease, or a worsening effusion. It is very important to grasp this surgical indication: 1. If the baby has complete ureteral obstruction, infection, or nontoxic disease, most doctors will use puncture nephrostomy for drainage. Personally, I have successfully inserted double J tubes through cystoscope as drainage in this case. 2. Stenting: Ureteral reimplantation is very difficult in babies with ureteral obstruction before the age of one year. When I worked in Royal Melbourne, Australia, the first choice of those pediatric urologists was to place a stent of F4,7 or F5,2 diameter through the cystoscope to support the stenosis with a success rate of more than two-thirds (67%). My experience is that it is not easy to place a stent in a male infant under two months of age. This is because the urethra of a boy of this age cannot accommodate a cystoscope, guidewire and stent (double J tube) at the same time, but it is possible with a modified strategy. Stent placement is a common method of managing giant ureters before the age of one year. The double J tube can be in the body for 2-6 months, but of course, the longer it is in place, the higher the chance of complications (infection, stones, stent migration) (up to 31%). The consensus of the British Pediatric Urology Group is that stenting is the preferred method of management in children under one year of age. 3. Balloon dilation of the stented segment. The pediatric urologists in Barcelona, Spain, have the most experience in this area, but only a few centers worldwide use this approach. Except for myself, this method is not yet popular in this country. I consider this method to be non-invasive. The youngest child I have dilated with a balloon (F40, 12-14 atm, 3-5 minutes) was about 6 months old, and for younger infants, especially boys, I think it would be difficult to dilate with a balloon because the urethra is very small and difficult to accommodate so many instruments at the same time. The average success rate at the Barcelona Center is 77% (Garcia-Aparicio, J Pediatr Urol, 2013; 9 (6 Pt B): 1229). 4. ureteral reimplantation, in which the stenotic segment is removed and the ureter of the patent segment is anastomosed to the bladder (Cohen, Politano-Leadbitter et al.) Although some doctors believe that this procedure can be done at any age, the opinion of most pediatric urologists is that it should be done after one year of age. Because of the “giant” ureter, opinions differ as to whether the ureter should be thinned or folded (Kalicinski procedure) and then anastomosed. Direct anastomosis of the giant ureter removes the obstruction, but there will be some reflux. The success rate of ureteral reimplantation is between 94-96%. When I worked at the Royal Children’s Hospital in Melbourne, Professor John Hutson, a urologist, told me that some reflux was fine (refluxing reimplantation) and that it would get better with age. Most centers in the western world do open surgery, but my director at the Prince of Wales Hospital in Hong Kong, Prof. Chongguang Yang, pioneered minimally invasive reimplantation of the gas bladder, and the results are as good as open surgery. The child should have a long-term follow-up after surgery. Conclusion: Treatment of congenital obstructive megaureter according to international standards gives the best protection to the kidney and minimizes complications.