Ureteropelvic Junction Obstruction

Normal Anatomy and Function

The main job for the kidney is to filter the blood in order to remove waste, producing urine in the process. To function normally, the urine must freely drain from the kidney through an internal collecting system that leads first to a funnel-shaped structure called the renal pelvis and then downward into the ureter. The ureter is a tubular structure 10-12 inches long which carries urine produced in the kidney to the bladder. The urine is expelled from the renal pelvis and down the ureter by a process called peristalsis. The site where the renal pelvis connects to the ureter is the ureteropelvic junction (UPJ).

Ureteropelvic junction obstruction is a partial blockage of the connection site. Such obstruction impedes urine drainage and causes urine to back up in the kidney leading to increased pressure, stagnation of urine and intermittent flank pain. Increased pressure inside the kidney causes deterioration of kidney function and, in rare cases, hypertension. Stagnation of urine can lead to kidney stone formation and increases the risk of infection.

Causes

Most often, Ureteropelvic Junction Obstruction is the result of an abnormality of urinary tract development occurring prior to birth (congenital). Often, a blood vessel crossing over the UPJ causes or contributes to the blockage. The muscle of the obstructed ureteropelvic junction is poorly developed and often replaced by scar tissue. Less commonly, the obstruction may have occurred after injury, surgery or passage of a kidney stone.

Signs & Symptoms

Ureteral obstruction can cause flank pain on the affected side. The pain usually is intermittent and often triggered by drinking large volumes of fluids, particularly alcoholic or caffeinated beverages. Some patients develop bloody urine, infection or stones in the affected kidney. When infection occurs in association with obstruction, patients can develop sepsis, characterized by fevers and chills. This serious condition may require hospitalization, emergency drainage of the urine and treatment with intravenous antibiotics. Some patients have UPJ Obstruction incidentally discovered during abdominal imaging to evaluate an unrelated issue. Rarely, hypertension or kidney failure are the first signs present.

How is ureteropelvic junction (UPJ) obstruction diagnosed?

While ultrasound is a very useful screening test, it is not diagnostic of UPJ obstruction. In order to make the diagnosis it is necessary to perform a functional test or one that measures the ability of the kidney to produce and drain urine. Historically, an examination called the intravenous pyelogram (IVP) was used utilized. In this test, a dye is injected into the blood stream and the kidneys remove this substance from the blood. The dye passes into the urine and eventually out of the bladder. The dye is visible on X-ray and the physician can see the shape of the kidney, renal pelvis and ureter. Currently, the imaging modality of choice is a contrasted CT scan; this study can more precisely delineate the pertinent anatomy of the kidney and the adjacent structures. In addition, a renal scan is often obtained: this nuclear medicine study can confirm that obstruction is present and can determine the proportional function of each kidney. In certain circumstances, a ureteral stent is placed endoscopically to relieve the obstruction in order to alleviate symptoms and improve the kidney's function prior to definitive treatment.

Treatments

The traditional treatment for ureteropelvic junction obstruction has been open surgery to cut out the area of scarring and re-connect the ureter to the kidney. This surgery is referred to Pyeloplasty. This surgery requires a significant abdominal incision and typically a multi-day hospitalization. Its long-term effectiveness exceeds 95%.

Over the past several years, newer, less-invasive treatment options have been developed.

Endopyelotomy is a procedure through which an endoscope [ureteroscope] is passed to the level of the kidney. The scar tissue is then cut open from the inside, typically employing a laser. These procedures can be done as an outpatient with less anesthesia and with a much shorter recuperation than with open surgery. Patients will have to keep a temporary internal tube (stent) for six weeks. The radiographic success rate with these procedures is 15%-40% lower than what is obtained with open surgery. Moreover, 40% of patients may still have significant, persistent pain following procedure.

Robotic-assisted Laparoscopic Pyeloplasty has emerged as the new gold-standard treatment for Ureteropelvic Junction Obstruction. Developed in order to give the same high success rate obtained with open pyeloplasty while decreasing the morbidity, Robotic Pyeloplasty is performed in a similar manner as the open surgery without the need for a large incision. Postoperative pain is less, recuperation is significantly quicker and scarring is minimal when compared with open surgery. The procedure requires a general anesthetic and hospitalization (usually 1 night). An internal UPJ stent is also needed for four weeks. Success with this procedure is the same as open surgery (>95%).

Having performed hundreds of robotic /laparoscopic surgeries over the course of the past decade, the surgeons of Central Bucks Urology are considered experts in performing Robotic-assisted Laparoscopic Pyeloplasty.

What can be expected after surgery for UPJ obstruction?

After Robotic Pyeloplasty, most patients can go home from the hospital on the day after surgery. Patients typically recover quickly from any of the procedures, but some have pain for a few days after surgery. Normal diet activities and diet are resumed immediately. Lifting greater than 50 pounds is restricted for 4 weeks. After repair of UPJ obstruction, swelling of the ureter and continued poor drainage of the kidney persists for several weeks, necessitating maintenance of the ureteral stent, which was placed during the surgery. The stent will typically cause irritation of the bladder, resulting in increased urinary frequency and urgency. These symptoms disappear within 24-48 hours after the UPJ stent is removed, typically one month after surgery. Occasionally, an external drainage tube must be left in place for a few days to help drain the kidney area while it heals. The radiographic appearance of the treated kidney will continue to improve for years, but usually never looks completely normal. Once repaired by open or robotic technique, UPJ obstruction rarely recurs. Despite a successful repair, patients retain a somewhat increased risk of developing stones and infection throughout their lives; though most repaired kidney systems significantly improve in function, most do not fully recover to a completely normal level.


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