Pelviureteric Junction Obstruction
The kidneys filter blood to eliminate waste products and excess water that are excreted in the urine. A drainage system carries urine from each kidney to the bladder where it is stored until emptying is appropriate. Each kidney drains into a renal pelvis, which funnels urine into a ureter, the long, narrow muscular tube that conducts urine to the bladder.
A Pelviureteric junction obstruction is a partial blockage of the connection of a renal pelvis with the ureter, the pelviureteric junction (PUJ). This impedes drainage and causes urine to back up in the kidney leading to increased pressure, flank pain and, in some cases, kidney damage.
Most often, this blockage is the result of an abnormality of kidney development occurring prior to birth (congenital). The muscle of the obstructed PUJ is poorly developed and, sometimes, replaced with scar tissue. Both kidneys are involved in 10% of cases. In some, the obstruction may have occurred after an injury or inflammation related to a kidney stone. Occasionally, a blood vessel crossing over the PUJ can contribute to blockage.
PUJ obstruction may be diagnosed at any age. Routine ultrasound during pregnancy can detect fullness of the fetal renal pelvis (hydronephrosis). Some infants are found to have PUJ obstruction when abnormal swelling in the abdomen or flank is discovered or urinary infection develops. In adults, it may be identified during the investigation of intermittent flank or abdominal pain often made worse by drinking large volumes of fluid. Some patients develop bloody urine or stones in the affected kidney.
Once PUJ obstruction is suspected, investigations are required to determine the exact site and severity of the blockage. Blood and urine tests assess overall kidney function and the possibility of infection.
Imaging studies are used to clarify the drainage system anatomy and assess the degree of obstruction. Ultrasound or CT scan will show fullness in the renal pelvis and any loss of functioning kidney tissue. An injection of contrast material into a vein followed by the CT scan allows the "dye" to be excreted by the kidneys outlining the drainage system and gives an indication of function.
A nuclear renal (MAG-3) scan can evaluate kidney function more accurately. In some cases, a diuretic is given during the scan to promote increased urine production. The scanner will show increasing nuclear marker build up in the kidney in the presence of obstruction while the marker washes rapidly out of a normal drainage system.
A urologist may recommend a Cystoscopy and retrograde pyelography. This involves passing a narrow visualizing instrument (scope) through the urine passage (urethra) into the bladder. The kidney drainage system is then filled from below with x-ray dye to allow detailed x-ray imaging.
The degree of blockage may vary from minimal to severe and, occasionally, it may come and go.
In some cases, particularly in infants, PUJ obstruction may be mild and not require any treatment, however, for these patients you should consult a Pediatric Urologist. A small daily dose of antibiotic may be advised in newborns to prevent urinary infection that could damage the kidney.
Unless very severe, PUJ obstruction found in newborns often can be safely observed without treatment because, frequently, the blockage will resolve on its own as the child matures. A urologist might recommend periodic monitoring with lab tests, ultrasound and nuclear kidney scans.
In adults, treatment may be required when symptoms are bothersome or kidney function is impaired by the obstruction.
In some, temporary kidney drainage can be obtained with an internal or external drainage tube. A ureteric stent is an internal drain running from the renal pelvis to the bladder within the ureter, while a nephrostomy tube drains from the renal pelvis out through the flank into a bag. This can allow treatment of infection, preservation of kidney function or relief of pain while corrective surgery is being planned.
Surgery aims to reconstruct a gradual tapering of the pelviureteric junction to allow unobstructed flow from the renal pelvis to the ureter. Various surgical techniques are available to correct PUJ obstruction. Your urologist will recommend the procedure most suitable to your specific circumstances.
Traditionally, PUJ obstruction has been repaired with an operation called a pyeloplasty. In the past under general anaesthesia, an incision was made in the flank through which the renal pelvis and ureter are exposed. The narrow PUJ is cut out or cut open after which a wider connection is constructed. A temporary stent or nephrostomy tube may be placed. Patients stayed in hospital for up to seven days and able to resume their usual activities within four to six weeks. This operation was successful in about 90% of cases.
Today, we perform a laparoscopic pyeloplasty. A series of 3-4 "keyhole" incisions or via "single-port" in very slim patients are made in the abdomen through which a narrow video camera and operating instruments are used to reconstruct the PUJ. This operation, although technically challenging, may allow a shorter hospital stay (2-3 days) and recovery time (5-7 days) with excellent results identical of those of open surgery regarding drainage but much better regarding convalescence time and post-op pain control.
Another alternative in adults is endopyelotomy, which involves making a cut through the area of obstruction in the PUJ using a scalpel, electric current or laser passed into the drainage system through a "scope". In a percutaneousendopyelotomy, a small incision is made in the flank through which a scope is advanced through the kidney into the renal pelvis to incise the UPJ. Ureteroscopic endopyelotomy involves passing a scope through the urethra, bladder and ureter to incise the PUJ. With either approach, a stent is required for several weeks postoperatively. These techniques may not be possible in all cases and have a success rate of over 70-80%.
If the kidney has very poor function, your urologist may recommend its removal (nephrectomy) rather than repair. This can be performed laparoscopically or via an open incision.
After PUJ obstruction is treated, follow-up can ensure that the affected kidney is functioning properly. This may involve periodic blood and urine tests, ultrasound and nuclear renal scans until it is clear that the problem has been corrected.
Usually the adult patient undergoes a MAG3 test at 3 months and another MAG3 and Intravenous Urography at 12 months post-op.