Ureteropelvic Junction (UPJ) Obstruction
A specific type of kidney obstruction that is seen not uncommonly in the adult population, and is common in the pediatric population, is called a ureteropelvic junction obstruction, or UPJ obstruction. We will not spend too much time here discussing the problem of pediatric UPJ obstruction other than to say it is usually found on pre-natal ultrasound, is the most common cause of a baby having a dilated kidney on such an ultrasound, and often requires surgery to correct it. In the pediatric population, almost always the cause of an UPJ obstruction is that the ureter, or the tube that connects the kidney to the bladder, is malformed where the ureter meets the kidney at an area called the renal pelvis. Since the muscular ureter propels urine towards the bladder with a rhythmic motion called peristalsis, this area of malformed ureter does not squeeze and thus in essence serves to obstruct the normal flow of urine.
The most common situation is that a young adult, perhaps a college student or similar age, will begin to have pain in the back or kidney. This pain is usually worse in situations where a lot of urine is made (such as binge drinking of alcohol), and many such patients will state that they do not drink much alcohol because historically it “makes them feel bad.”
In the adult population, the presentation of an UPJ obstruction is quite different. The most common situation is that a young adult, perhaps a college student or similar age, will begin to have pain in the back or kidney. This pain is usually worse in situations where a lot of urine is made (such as binge drinking of alcohol), and many such patients will state that they do not drink much alcohol because historically it “makes them feel bad.” If the pain becomes worse enough, or if another problem develops such as kidney stones or infection, medical help will be sought. Here, an initial imaging study, most commonly a screening ultrasound, will show a dilated kidney. Kidney dilation is termed hydronephrosis, and this hydronephrosis can be very severe when found. It is usually at this point that a patient is referred to an Urologist.
At the Urologic consultation, the patient must bring their imaging study. Here, we will not only look at the degree of hydronephrosis, but also get a sense as to whether chronic obstruction has led to kidney damage. Sometimes the damage is so severe that a determination must be made if the kidney is worth saving at all. The next study that will be ordered is called a renal scan, a nuclear medicine study that will allow us to quantify the degree of function in the affected kidney, as well as the exact degree of obstruction. Sometimes the degree of function will be borderline, the pain mild, or the kidney without damage. Such patients at times are followed with another renal scan to track the situation. Those where pain is severe, severe obstruction is found, or where the kidney is being damaged, are offered treatment.
Before discussing treatment, it is first important to understand that the cause of UPJ obstruction in the adult population is usually very different than in the pediatric world. Patients that have a section of malformed ureter causing obstruction at the UPJ usually will not make it to adulthood without either being treated already or without severe damage over the years making salvaging the kidney impossible. Rather, in nearly every case of adult UPJ obstruction, the cause is an aberrant blood vessel, usually an artery but at times also a vein or only a vein, that is feeding the lower pole of the kidney directly on its own. This aberrant blood vessel, called a “crossing vessel”, drapes over the ureter right at the ureteropelvic junction. As one enters adulthood their anatomy, and their blood vessels, enlarge. Once large enough, the vessel causes enough obstruction to the ureter to cause the renal pelvis to enlarge, or to get hydronephrotic. Once this happens, the ureter begins to kink, thus setting off a cycle of more obstruction, and more hydronephrosis until symptoms appear.
Treatment of adult UPJ obstruction has evolved over time. 15-20 years ago, the standard treatment was an open operation through a standard flank or similar incision. This provided a 98% success rate, but a very long six week recovery and considerable pain. The first attempts at treating this in a minimally invasive fashion were percutaneous, or via a tube and scope driven directly into the kidney through the back. The UPJ was cut and stented. Long term success rate was perhaps 30%. What replaced this was called the Accusize endopyelotomy. Here, the ureter was cut and stented in a similar fashion, but all through a scope in the bladder getting to the UPJ from below. Incisions were avoided, but long terms success rates were still very poor. Remember that these approaches do not address the fact that a crossing vessel still would exist, and thus the source of obstruction was not taken away. Also noteworthy is the danger involved in blindly cutting the ureter with a crossing vessel just outside of it. Hemorrhage was not uncommon after these procedures.
Laparoscopic pyeloplasty became an excellent substitute to the open operation. Here, the identical operation to the open approach is performed, with identical success rates, but much faster recover times due to the avoidance of the flank incision.
With the advent of laparoscopy, laparoscopic pyeloplasty became an excellent substitute to the open operation. Here, the identical operation to the open approach is performed, with identical success rates, but much faster recover times due to the avoidance of the flank incision. What is done during surgical repair is to dissect out all of the anatomy of the kidney, including the ureter, the UPJ, the renal pelvis, and all blood vessels feeding the kidney. The surgeon must demonstrate the cause of obstruction, usually a crossing vessel, and plan the repair. The ureter is severed from the renal pelvis, both sides widened, and then reconnected over the crossing vessel. The crossing vessel must be preserved, as if taken the lower pole of the kidney would be left without a blood supply. A stent, which in Dr. Engel’s case is previously placed in a separate procedure just before the pyeloplasty, is kept in place to remain for six weeks of healing.
Unfortunately, laparoscopic pyeloplasty was performed during an era where the vast minority of Urologists, such as Dr. Engel, possessed the specialized laparoscopic skill set to perform this operation. Therefore, what needed to occur to make the laparoscopic pyeloplasty the predominant approach was the popularization of robotic instrumentation. Robotic instruments allow for a less experienced surgeon to perform a laparoscopic pyeloplasty by simplifying the reconstruction portions of the procedure such as sewing or knot-tying. Dr. Engel performs all of the dissection for this case laparoscopically, switching to robotic instruments only for the final phase of the case where the reconstruction is performed.
Please see our procedure page for Robotic Pyeloplasty for more specific information on this procedure and actual operative videos of this case, both right and left sided pyeloplasties.