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After reading this article, the reader should be able to:
- Identify the causes and potential consequences of ureteropelvic junction (UPJ) obstruction.
- Describe the common presenting symptoms of UPJ obstruction and the imaging study used to confirm the diagnosis.
- Summarize the general management of UPJ obstruction.
- Compare and contrast open, laparoscopic, and robot-assisted laparoscopic pyeloplasty (RALP).
- Discuss the outcomes associated with RALP for UPJ obstruction in children.
Date of original release: October 2014
Date of expiration: October 2015
Note: While it offers CME credits, this activity is not intended to provide extensive training or certification in the field.
Overview of Congenital Ureteropelvic Junction Obstruction
UPJ obstruction is the most common cause of pediatric hydronephrosis, with an incidence of one in 500 live births. Twice as many cases are diagnosed in infant boys as girls, and more than 60 percent involve the left kidney.
“The condition results from lesions or functional abnormalities in the proximal ureter that restrict urinary flow across the UPJ, causing dilation of the ureter and renal pelvis (Figure 1) that may lead to irreversible loss of renal function,” explains Benjamin Whittam, MD, director of minimally invasive robotic pediatric urology at Riley Hospital for Children at Indiana University Health and assistant professor of urology at Indiana University School of Medicine. “Urinary stasis may lead to calculus formation and predispose to infection.”
Intrinsic stenosis, linked to a variety of factors that may have both biochemical and mechanical etiologies, is responsible for the majority of cases and is usually identified antenatally on routine ultrasound. Extrinsic stenosis, in which an aberrant or accessory renal artery or arterial branch or a fibrous band crosses the lower pole of the kidney, compressing the UPJ and blocking the flow of urine, accounts for approximately 25 percent of cases and tends to present later in childhood. Horseshoe or pelvic kidney, duplex collecting systems, and other rotational abnormalities may also cause UPJ obstruction.
A five-year-old boy is seen by his pediatrician for intermittent episodes of left-sided pain, each lasting about two hours and associated with nausea and vomiting. He is diagnosed with constipation, and a stool softener is prescribed. The episodes increase in frequency and are not relieved by resolution of constipation. During a particularly severe attack, his parents bring him to the emergency department of Riley Hospital for Children at Indiana University Health. A renal-bladder ultrasound is obtained and shows a normal right kidney and bladder and severe hydronephrosis of the left kidney. The child is admitted and given intravenous analgesia; a pediatric urology consult is obtained. A diagnosis of left ureteropelvic junction (UPJ) obstruction is made and confirmed by a Lasix renogram demonstrating poor drainage of the left kidney with preserved function.
Presentation and Diagnosis
Periodic abdominal pain with nausea and vomiting are common symptoms of UPJ obstruction and likely indicate intermittent kinking of the UPJ. Children may also present with hematuria, renal calculi, or hypertension.
“The diagnosis is generally suspected when imaging studies—ultrasonography or computed tomography—demonstrate hydronephrosis,” Dr. Whittam says. “Radionuclide diuretic renography, a nuclear medicine examination that measures drainage time from the renal pelvis and assesses the function of each kidney (Figure 2), is used for diagnostic confirmation.”
Other causes of hydronephrosis that must be considered in the differential diagnosis include vesicoureteral reflux, transient or functional hydronephrosis, and other urologic anomalies (e.g., posterior urethral valves, congenital megaureter, ureterocele, multicystic dysplastic kidney).
Improving renal drainage and preserving kidney function are the primary goals in the management of UPJ obstruction. Observational studies from the pediatric literature suggest that a substantial number of cases of “incidental” UPJ obstruction diagnosed by antenatal ultrasonography resolve spontaneously or result in no loss of function. Thus, asymptomatic children are often followed long-term using serial renal ultrasonography and renography.
“Symptomatic patients and those with deteriorating kidney function usually require surgical intervention,” notes Dr. Whittam.
Open pyeloplasty remains the gold standard for the treatment of UPJ obstruction, with 90 to 100 percent of patients experiencing improved or stabilized hydronephrosis.1-3 The procedure, typically performed through a flank incision, involves dismembering the renal pelvis and ureter, excising the narrowed ureteral segment (or transposing it over a crossing renal vessel), and trimming redundant tissue from the dilated renal pelvis and tailoring it to funnel down toward the anastomosis.
“The advantages of open pyeloplasty include excellent exposure of the UPJ, familiar anatomy for virtually all urologists, and the ability to tailor the renal pelvis as needed and perform a watertight anastomosis,” Dr. Whittam summarizes. “Disadvantages include a large surgical incision—2.0 to 6.0 cm in children—with associated postoperative pain and an extended recuperation. Patients are usually hospitalized for one to two days and are sent home with a nephroureteral catheter that exits the back or an internal ureteral stent.”
The laparoscopic approach to pyeloplasty, first reported in 1993,4 has become the standard of care for the repair of adult UPJ obstruction at many US medical centers and is increasingly being done in pediatric patients. The procedure is performed via a transperitoneal or retroperitoneal route, depending on surgeon preference and patient factors, such as obesity and previous abdominal surgery. As with open pyeloplasty, the laparoscopic technique allows for excision of the strictured ureteral segment, reduction pyeloplasty, transposition of the UPJ over crossing vessels, and extraction of renal calculi, if present.
“Patients undergoing laparoscopic pyeloplasty have less postoperative pain, a shorter hospital stay, and a more rapid recovery as compared to open pyeloplasty,” reports Dr. Whittam. “The primary disadvantage of the procedure is the difficulty of the ureteropelvic anastomosis, which is time-consuming and technically demanding.”
Robot-assisted laparoscopic pyeloplasty
The use of surgical robotic systems is enhancing reconstructive laparoscopic techniques and proving useful in UPJ obstruction, particularly in children, according to Dr. Whittam.
“The difficulty of intracorporeal suturing and lengthy anastomosis times are major impediments to the widespread application of conventional laparoscopic techniques to pediatric reconstructive procedures, such as pyeloplasty and ureteral reimplantation,” he states. “Robot-assisted laparoscopic pyeloplasty (RALP) has the advantages of providing a three-dimensional, magnified image; increased articulation; and multiple degrees of instrument freedom that allow for more precise and efficient suturing compared with conventional laparoscopic techniques.
“Three small incisions, each less than 1.0 cm in length, are made very low on the abdomen or concealed in the umbilicus,” Dr. Whittam continues. “Patients are generally discharged the day of surgery with an internal ureteral stent and can resume normal daily activities within 24 to 48 hours.”
IU Health is the only center in Indiana to offer RALP to pediatric patients with UPJ obstruction.
Case Study (cont.)
Because the child is experiencing recurrent symptoms, surgery to correct the UPJ obstruction is recommended. Three weeks after diagnosis, he undergoes RALP using the da Vinci® Surgical System (Intuitive Surgical). In the operating room, the patient is rotated to a supine position, and pneumoperitoneum is created via insufflation through a Veress needle placed in an infraumbilical location. A trocar and laparoscope are used to permit direct-vision insertion of a robotic working port, a camera port, and an assistant port (Figure 3a). Using the hidden incision endoscopic surgery (HIdES) technique, ports are inserted in the umbilicus and below the underwear line for maximum concealment of scars. A ureteral stent is placed. The duration of the procedure is approximately three hours (Figure 3b).
RALP success rates are comparable to those for open pyeloplasty, ranging from 94 to 100 percent,5-8 with RALP having the added advantages of reduced operative blood loss, lower opioid requirements, and shorter hospitalizations.9 The operative time for RALP decreases with increasing surgical experience and is shorter than that of pure laparoscopic pyeloplasty. In very experienced hands, the operative time for RALP is essentially equivalent to that for open surgery—slightly over three hours.9
“Failure and complication rates following RALP are low,” says Dr. Whittam. “Urine leakage during the early postoperative period occurs in about two percent of cases, and persistent obstruction during followup is identified in fewer than five percent of cases.” Other potential complications include conversion to an open procedure, splenic and liver lacerations, and bowel injuries, all of which are potential complications of any minimally invasive or laparoscopic procedure.
Parent and patient* surveys have shown that satisfaction is greater with RALP than with open pyeloplasty with regard to cosmesis (i.e., scars) (Figure 4) and recovery.10,11
*Completed by children aged seven years and older.
A retrospective, observational, matched cohort study of 146 pediatric patients undergoing open or robot-assisted laparoscopic urologic surgery found that direct costs for the latter were significantly lower.12
Factors reducing the costs of robot-assisted surgery included a consistent and trained robotic surgery team, extensive institutional history of performing urologic robotic surgery, and appropriate patient selection. The higher indirect costs of robot purchase and maintenance may be offset by greater surgical volume and, in the future, competition from other equipment manufacturers.
“The shorter hospital stays and faster recovery associated with RALP also translate to a reduction in lost parental wages,” Dr. Whittam adds.
Case Study (cont.)
The child’s stay in the recovery room is uneventful. Nonsteroidal antiinflammatory drugs successfully control postoperative pain, and he is discharged home in <24 hours. Two weeks after surgery, the ureteral stent is removed. Follow-up renal ultrasound performed six weeks after surgery shows a reduction in swelling of the left kidney. The parents report their son has had no recurrence of the painful episodes.
IU Health to Conduct Pilot Study Comparing Open and Robotic Pyeloplasty for Young Children with UPJ Obstruction
While open pyeloplasty remains effective especially in patients younger than two years of age, many pediatric urologists favor RALP for the surgical correction of congenital UPJ obstruction because of perceived better patient-centered outcomes. Specifically, hospital stays are shorter, pain and analgesia use are reduced, scars are smaller, and patients have a quicker return to daily activities. However, no randomized controlled trials have compared the two surgical approaches with regard to these outcome measures.
“Randomization of varying surgical techniques has always proven challenging because surgeons are unwilling to leave operative decisions to chance,” Dr. Whittam explains. “Such reluctance has resulted in a paucity of high-quality evidence regarding the ideal surgical modality or technique for specific patient conditions.”
To remedy this situation as it pertains to the treatment of primary UPJ obstruction, Dr. Whittam and pediatric colleagues from the department of urology at IU School of Medicine have designed a pilot study seeking to randomize 20 healthy, nonobese children aged two to eight years with primary UPJ obstruction to open or robotic pyeloplasty.
“This study will serve as a proof-of-concept trial to demonstrate the feasibility of randomization, delineate patient-centered outcomes, and provide a framework for a large randomized controlled trial comparing open pyeloplasty with RALP,” says Dr. Whittam, who will serve as the study’s principal investigator. “Primary outcomes will be length of stay, pain medication usage, and 30- and 90-day costs. Secondary outcomes will be pain score, parental return to work, and scar perception.”
The study has received approval from the IU institutional review board, and the investigators are in the process of finalizing funding.
Dr. Whittam received his medical degree from Dartmouth Medical School in Hanover, NH; did his residency training in urology at Vanderbilt University Medical Center in Nashville, TN; completed a fellowship in pediatric urology at Riley Hospital for Children at IU Health; and was awarded a master of science in clinical research from the Indiana Clinical and Translational Sciences Institute in Indianapolis. His primary areas of research are the cost-effectiveness of robotic surgery and collaborative clinical pathways.
The author of several journal articles and textbook chapters, Dr. Whittam has been an invited presenter at professional meetings in the United States and abroad. He is a member of the American Urologic Association.
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