Pediatric Ureteropelvic Junction Obstruction Treatment & Management

  • Author: Sang Won Han, MD, PhD; Chief Editor: Marc Cendron, MD   more...
 
Updated: Jan 25, 2010
 

Medical Therapy

The timing of surgical correction of hydronephrosis suggestive of UPJ obstruction in newborns is highly controversial. Those who support delayed management contend that for most newborns with relatively preserved differential renal function (>35% of differential renal function), hydronephrosis is a relatively benign disease without proof of progression. Renal function does not deteriorate; thus, immediate surgery is not necessary. In a study by Koff and associates, approximately 81 out of 104 patients were followed for 5 years; 7 (7%) of those patients ultimately required pyeloplasty, and, even in these cases, pyeloplasty successfully restored the differential renal function to predeterioration levels.

Researchers also observed that in 15 out of 16 patients with severe hydronephrosis (grade 4 hydronephrosis according to the Society for Fetal Urology Guidelines) associated with a differential renal function of less than 40%, spontaneous improvement occurred in the initial obstructive patterns on renal scans, and, for 6 of the patients, it became nonobstructed. Similar results were observed with ultrasonography that hydronephrosis disappeared in 6 kidneys and improved in another 6 kidneys.

Thus, the difficulty in determining the indication of surgical management is 2-fold. First, ultrasonography and diuretic renography to assess hydronephrosis are inaccurate and sometimes misleading. Second, some significant cases of hydronephrosis that are discovered by these modalities may not be obstructive at all. Therefore, Koff redefined obstruction as "any restriction to urinary outflow, which if untreated will injure the kidney" to provide a clinically useful guideline; Koff recommended that most unilateral hydronephrosis actually is nonobstructed and, thus, benign, which can be observed safely nonoperatively.

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Surgical Therapy

In the early 1980s, sonographic identification of obstruction in many infants resulted in a dramatic increase in the number of neonatal pyeloplasties performed. Initially, newborn pyeloplasty had a reported reoperation rate of 20%, which improved with the experience. The relative ease and safety of newborn pyeloplasty stimulated discussion about the necessity of intervention.

Physiologically, the newborn kidney is quite different than the adult kidney, particularly in the response to stimulation by the renin-angiotensin system. Renal function could be preserved by relieving the obstruction, achieving maximal benefit in the youngest of kidneys. Because renal failure caused by obstructive uropathy is a definite clinical dilemma, it may be appropriate to perform immediate pyeloplasty at the time of presentation, even in the asymptomatic infant.

Unilateral pyeloplasty not only improves hydronephrosis but also significantly increases creatinine clearance (as calculated by the Schwartz formula) and somatic growth. The implication is that unilateral obstruction has negative effects on renal function and on somatic growth.

The most compelling supporting data on early surgical correction come from animal experiments suggesting that prolonged partial ureteral obstruction is deleterious to the newborn kidney and can be reversed by early relief of the obstruction. Spontaneous resolution of hydronephrosis is not as benign as proposed by Koff and Campbell, that is 15-33% of patients with asymptomatic neonatal hydronephrosis show progressive ipsilateral renal deterioration, and about one half of them never regain the lost function by pyeloplasty.

There are 2 well-designed longitudinal studies that provide valuable information against initial observation and delayed management. According to a study by Ransley and associates, of 100 infants with differential renal function of hydronephrotic kidney higher than 40% who were followed nonoperatively, 23 eventually underwent pyeloplasty during 6 years of follow-up care. Among these patients, 5 (36%) completely recovered renal function, 4 (29%) partially recovered, 3 (21%) had no change, and 1 (7%) further deteriorated after pyeloplasty. Thus, 8 of 100 initially well-functioning kidneys sustained permanent deterioration with this approach. Similar results were observed by Cartwright and Duckett, which included the results with 39 infants with a cut-off value of 35% of differential renal function. Six patients (15%) underwent pyeloplasty because of decreasing renal function, UTI, or pain.

The observation approach allows the physician to avoid risks associated with surgery and anesthesia, but there is a definite percentage of patients who sustain irreversible renal damage that could have been prevented by early pyeloplasty. Furthermore, after a short learning period, the pyeloplasty in infants is not demanding and is associated with little perioperative morbidity.

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Preoperative Details

When the diagnosis of a UPJ obstruction has been made, prompt intervention is appropriate to prevent or minimize renal damage. First, prophylactic antibiotic therapy is warranted in cases of moderate to severe dilatations because any UTI, especially in neonatal period, dramatically increases the chance of fibrosis and parenchymal damage.

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Intraoperative Details

Conventional techniques

The technique of complete ureteral transection followed by reanastomosis to the renal pelvis was first described in the management of a retrocaval ureter, but it was easily adapted for reconstructing the UPJ obstruction. Many different approaches have been tried, such as lumbotomy, flank, or anterior extraperitoneal incision, but the essence of repair consists of excision of the narrowed segment, spatulation, and anastomosis to the most dependent portion of the renal pelvis. Foley YV-plasty, a nondismembered type of repair, is useful in the repair of a kidney with high ureteral insertion and most cases of horseshoe kidneys; however, the Anderson-Hynes pyeloplasty, the most commonly used type of repair, has a high success rate with few complications in most cases.

Endourological techniques

Endourologic methods applied on UPJ obstruction include balloon dilatations, percutaneous antegrade endopyelotomy, and retrograde ureteroscopic endopyelotomy. In 1983, Wickham and Kellet established access to a hydronephrotic kidney and performed the first percutaneous pyelolysis. The concept was attractive and the technology was available. Soon, a large series of endopyelotomies in adults was reported with fairly good short- and long-term success rates of 70-85%. If an initial attempt of endopyelotomy fails, subsequent open pyeloplasty is still a viable option with a high success rate.

Laceration of the lower pole vessel, which is in anatomic relationship with the ureter in 40% of cases, must be avoided. Angiograms, endoluminal ultrasound, helical CT scans, and Doppler ultrasound have been used to identify the lower pole vessels. The best recommendation is to make sure that all incisions in the ureteral narrowing are directed laterally to minimize the chance for damage to the lower pole vessel.

Retrograde treatment of UPJ obstructions has been applied to children because of the technical advancements. This technique carries risk of significant stricture of the lower ureter. Balloon dilatations are most appropriate in pediatric populations because they are the least invasive approach and associated with the lowest risk of hemorrhage. However, the results generally do not match the open pyeloplasty, and most pediatric urologists continue to recommend open repair of primary UPJ obstruction.

This technique may be more useful in children older than 4 years with a failed pyeloplasty, where only a small dilation of the anastomosis may be required to produce good renal decompression. The technique involves a UPJ bridge with an endopyelotomy stent to drain the kidney and prevent the excessive scar formation that can occur with extensive urinary extravasation. The stent is removed after 6 weeks. Favorable factors include older age, secondary UPJ obstruction, low-grade hydronephrosis, and good renal function.

Laparoscopic techniques

Laparoscopic dismembered pyeloplasty, first introduced in 1993 by Schuessler, yields results that are comparable with those of open pyeloplasty, with success rates reported to be as high as 96-98% while still maintaining the benefits of endoscopic approaches, including less postoperative pain, short hospitalization, and reduced postoperative recovery time. However, the technical skills required for intracorporeal suturing and the lengthy operation time due to the degree of difficulty make it a costly procedure. Robot-assisted laparoscopic dismembered pyeloplasty is another recently introduced surgical treatment option.

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Postoperative Details

No specific guidelines exist for the stents and nephrostomy tubes in the postoperative period. In many instances, there is a chance of delayed opening of the anastomosis, thereby requiring the need for the nephrostomy tube. Another option is to stent the anastomosis with a double J catheter, but the stent is not commonly used in children because the procedure requires anesthesia. Many pediatric urologists tend to use neither stents nor nephrostomy tubes.

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Follow-up

Postoperative evaluation is performed by a renal scan or excretory pyelography at 2-3 months. A further evaluation with ultrasound is recommended at 12-24 months, but, beyond that, late problems are uncommon in the absence of symptoms. A successful outcome does not always mean an improvement in the differential renal function as measured by renography. In most cases, the dismembered pyeloplasty improves the degree of hydronephrosis and washout on the renogram. The symptoms of pain, infection, and hematuria, if present before surgery, resolve along with the improvement of hydronephrosis.

For excellent patient education resources, visit eMedicine's Kidneys and Urinary System Center. Also, see eMedicine's patient education article Intravenous Pyelogram.

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Complications

Postoperative obstruction is a difficult problem, and, faced with these circumstances, ureterocalicostomy may be performed as salvage procedure. The key features of the ureterocalicostomy technique consist of anastomosis of the ureter directly to the dependent portion of the lower pole calyx and trimming of the overlying renal parenchyma to prevent postoperative obstruction. This technique may require clamping of the renal artery. The difficulty of open reoperative surgery in patients with failed pyeloplasty makes the minimally invasive aspects of endopyelotomy seem attractive.

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Outcome and Prognosis

The overall success rate with the dismembered repair is quite satisfactory; most series report a success rate of higher than 90-95%. Long-term obstruction at the anastomosis can occur; but reoperation for this is low, occurring in 2-5% of cases.

Bleeding and infection are uncommon following pyeloplasty. Probably because of significant compliant capacity growing tissue, many cases of fetal hydronephrosis resolve before birth. Of those with hydronephrosis and preserved renal function at neonatal evaluation, 23% presented for delayed surgery in one series. On the other hand, some propose delaying surgical correction because newborn hydronephrosis is a relatively benign condition and a definite proportion of patients have spontaneous improvement.

The common early complications are prolonged urinary extravasation and delayed opening of the anastomosis. Urinary extravasation usually stops spontaneously, generally within 2 weeks. Delay in opening of the anastomosis is observed most often with the use of a nephrostomy tube without a stent across the anastomosis. Within 3 months of surgery, 80% of obstructed anastomoses eventually open.

Patients with lower percentages of elastin in the renal pelvis, UPJ proper, or ureter tended to show better resolution of hydronephrosis 6 months after pyeloplasty. Increased elastin of the renal pelvis and ureter might result in inelasticity and low compliance, which delays hydronephrosis improvement after pyeloplasty.

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Future and Controversies

Disruption of proximal tubular integrity leads to increased urinary concentrations of B2M, which normally is resorbed from the tubular lumen via phagocytosis and lysosomal digestion. An increase in urinary concentrations of B2M may indicate tubular dysfunction as a result of the obstructive insult. Functionally significant obstruction and recovery from obstruction may be determined by following the urinary concentration of B2M.

The potential for B2M to be a marker for significant obstruction is quite appealing; however, the determination of its levels in obstructed kidneys is not routine, and many different insults other than UPJ obstruction can lead to increased levels of B2M in the urine. In addition, the immaturity of the nephron and the high fractional excretion of water in neonates contribute to elevated B2M levels in the absence of any identifiable renal stress. Further observations of the concentration of this protein in urinary obstruction are necessary before its assessment can have practical application.

NAG is a tubular lysosomal enzyme present in the urine of children who have various renal diseases. In rats with experimental partial ureteral obstruction, the urinary concentration of NAG increases in the first 2 weeks of obstruction and decreases with the relief of obstruction. In a clinical study, NAG levels in kidneys at the time of pyeloplasty were 7 times higher than those in bladder urine from healthy control patients. In addition, enzyme levels in the bladder of patients 6 weeks after surgery suggested normalization of NAG excretion. Urinary biochemical markers of renal damage someday may aid the diagnosis of clinically significant urinary obstruction.

As described previously, many biologic modulators of glomerular dynamics and renal histology have been identified. The assessment of urine for growth factors (EGF, PDGF, TGF β), cytokines, and vasoactive substances may be an important adjunct in evaluating obstructive uropathy in the future.

Furthermore, detailed knowledge of the cytokine responses in the urothelium is necessary for a better understanding of the role of urothelial cellular reactions in congenital UPJO. This may provide the basis for early intervention to prevent exacerbation of congenital hydronephrosis in the future.

Lastly, the widespread use of modern imaging techniques has not led to an increase in the number of pyeloplasties that are performed. In a multi-institutional study that investigated the total number of pyeloplasties performed in a well-defined region, it was found that the total number of operations has remained constant since the late 1970s. The authors found that the number of pyeloplasties conducted in children aged 1-6 years increased, whereas the number of pyeloplasties in children aged 7-12 years decreased; yet, the total number performed per year remained the same. In other words, the degree of hydronephrosis, impaired isotope washout, or even reduced differential renal function neither helps to define significant obstruction nor predicts deterioration.

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Contributor Information and Disclosures
Author

Sang Won Han, MD, PhD  Professor, Department of Urology, Yonsei University College of Medicine, Korea

Sang Won Han, MD, PhD is a member of the following medical societies: European Society for Paediatric Urology, International Continence Society, Korean Medical Association, and Korean Urological Association

Disclosure: Nothing to disclose.

Coauthor(s)

Koon Ho Rha, MD, PhD  Fellow, Instructor, Department of Urology, Yonsei University and Severance Hospital, Seoul, Korea

Disclosure: Nothing to disclose.

Hye-young Lee, MD  Clinical Research Assistant Professor, Department of Urology, Yonsei University College of Medicine/Severance Hospital

Hye-young Lee, MD is a member of the following medical societies: Korean Medical Association and Korean Urological Association

Disclosure: Nothing to disclose.

Specialty Editor Board

Bartley G Cilento, Jr, MD  Instructor, Department of Surgery, Division of Urology, Children's Hospital of Boston and Harvard Medical School

Bartley G Cilento, Jr, MD is a member of the following medical societies: American Academy of Pediatrics, American Urological Association, and Massachusetts Medical Society

Disclosure: Nothing to disclose.

Mary L Windle, PharmD  Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Harry P Koo, MD  Chairman of Urology Division and Director of Pediatric Urology, Professor of Surgery, Virginia Commonwealth University School of Medicine, Medical College of Virginia; Director of Urology, Children's Hospital of Richmond

Harry P Koo, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Surgeons, and American Urological Association

Disclosure: Nothing to disclose.

Daniel Rauch, MD, FAAP  Director, Pediatric Hospitalist Program, Associate Professor, Department of Pediatrics, New York University School of Medicine

Daniel Rauch, MD, FAAP is a member of the following medical societies: Ambulatory Pediatric Association, American Academy of Pediatrics, and Society of Hospital Medicine

Disclosure: Baxter Honoraria Consulting

Chief Editor

Marc Cendron, MD  Associate Professor of Surgery, Harvard School of Medicine; Consulting Staff, Department of Urological Surgery, Children's Hospital Boston

Marc Cendron, MD is a member of the following medical societies: American Academy of Pediatrics, American Urological Association, European Society for Paediatric Urology, Johns Hopkins Medical and Surgical Association, New Hampshire Medical Society, Society for Fetal Urology, and Society for Pediatric Urology

Disclosure: Nothing to disclose.

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