Ureteropelvic Junction Obstruction Workup
- Author: Michael Grasso, III, MD; Chief Editor: Bradley Fields Schwartz, DO, FACS more...
All patients with possible ureteropelvic junction (UPJ) obstruction should be evaluated with the following laboratory studies:
Complete blood cell count (CBC)
Renal function assessment - Blood urea nitrogen (BUN) and serum creatinine levels
Neonates who present with hydronephrosis should be fully evaluated with voiding cystourethrography (VCUG; to rule out vesicoureteral reflux) and renal ultrasonography (see image below) soon after birth. These patients should also be placed on prophylactic antibiotics (amoxicillin 15 mg/kg) to prevent urinary tract infections (UTIs), especially while diagnostic imaging is being performed.
If renal ultrasonography demonstrates hydronephrosis without reflux on VCUG, a diuretic renal scan (mercaptotriglycylglycine [MAG-3], diethylenetriamine [DTPA], or dimercaptosuccinic acid [DMSA]) should be performed to quantify relative renal function and to define the extent of obstruction. Renal ultrasonography and VCUG are performed in children with suspected UPJ obstruction.
Historically, intravenous pyelography (IVP) was used to evaluate patients with possible UPJ obstruction. However, in the evaluation of a child with a hydronephrotic kidney, diuretic renography has taken the place of IVP. The benefits of diuretic renography are that iodine-based intravenous contrast is not used, radiation exposure is minimal, and renal function can be better quantified. The disadvantage of the nuclear medicine scan is that insight into renal anatomy is not obtained.
In 1992, the Society for Fetal Urology and the Pediatric Nuclear Medicine Council published guidelines for the "Well-Tempered Diuresis Renogram." Standardized protocols for hydration, radiopharmaceuticals, bladder catheterization, diuretic dose, timing of diuretic, and determination of clearance half-time (T 1/2) have been established.
Functionally significant obstruction is often diagnosed with diuretic renal scanning. The conventional renographic criteria include a flat or rising washout curve after diuretic with T 1/2 of greater than 20 minutes and differential function of less than 40. The differential function is important in determining the need for intervention, especially in asymptomatic patients, and in selecting the appropriate treatment (pyeloplasty vs nephrectomy). Poorly functioning kidneys (< 10%) are often best treated with nephrectomy. Nuclear medicine scanning is also used to assess outcomes after surgical intervention.
The evaluation of ureteral anatomy is difficult with nuclear medicine renal scanning. In adult patients, IVP is more commonly used to outline this anatomy and can often replace nuclear medicine scanning altogether. See the images below.
Multidetector computed tomography (CT) scanning with three-dimensional reconstruction may be used to help establish the anatomy of UPJ obstruction and associated vessels. In children, retrograde ureteropyelography is sometimes performed to define the entire ureter just prior to surgical repair. Contrast-enhanced color Doppler imaging is recommended by some as a useful imaging modality for the detection of crossing vessels in patients with UPJ obstruction.
Dynamic contrast-enhanced magnetic resonance urography (MRU) is the latest imaging modality used in assessing UPJ obstruction. In children, this study offers the advantages of no radiation exposure and excellent anatomical and functional details with a single study. The study also provides details of renal vasculature, renal pelvis anatomy, location of crossing vessels, renal cortical scarring, and ureteral fetal folds in the proximal ureter.
Recent criteria for diagnosis of UPJ obstruction on MRU include fluid levels on delayed contrast-enhanced scans and the presence of swirling contrast material on the dynamic images. MRU using a time-resolved, data-sharing three-dimensional contrast-enhanced technique can demonstrate ureteral peristalsis and permits quantification of ureteral peristaltic frequency.
Contrast-enhanced magnetic resonance angiography (MRA) had a sensitivity of 85%, a specificity of 80%, and a positive predictive value of 0.8 for the diagnosis of aberrant and obstructing renal arteries in a retrospective study of 19 pediatric patients with UPJ obstruction.
When the workup results are equivocal, a Whitaker antegrade pressure-flow study may be performed to further evaluate for UPJ obstruction. This test begins with the placement of a small-diameter nephrostomy tube through the back and directly into the kidney. Dilute contrast medium is instilled, and the intrarenal collecting system is pressure-monitored. Under fluoroscopy, the UPJ is assessed and drainage through this segment is defined.
While function cannot be assessed, relative resistance and pressure within the renal pelvis can be measured. High intrarenal pressures define obstruction, while low pressures in the presence of hydronephrosis are consistent with normal variance. This is particularly useful in large dilated systems in which the renal pelvis must be completely full prior to drainage assessment. In this setting, nuclear medicine scanning can yield false-positive results.
Symons SJ, Bhirud PS, Jain V, Shetty AS, Desai MR. Laparoscopic pyeloplasty: our new gold standard. J Endourol. 2009 Mar. 23(3):463-7. [Medline].
El-Nahas AR, Abou-El-Ghar M, Shoma AM, Eraky I, El-Kenawy MR, El-Kappany H. Role of multiphasic helical computed tomography in planning surgical treatment for pelvi-ureteric junction obstruction. BJU Int. 2004 Sep. 94(4):582-7. [Medline].
Conway JJ, Maizels M. The "well tempered" diuretic renogram: a standard method to examine the asymptomatic neonate with hydronephrosis or hydroureteronephrosis. A report from combined meetings of The Society for Fetal Urology and members of The Pediatric Nuclear Medicine C. J Nucl Med. 1992 Nov. 33(11):2047-51. [Medline].
Kim S, Jacob JS, Kim DC, Rivera R, Lim RP, Lee VS. Time-resolved dynamic contrast-enhanced MR urography for the evaluation of ureteral peristalsis: initial experience. J Magn Reson Imaging. 2008 Nov. 28(5):1293-8. [Medline].
Ritter L, Götz G, Sorge I, Lehnert T, Hirsch FW, Bühligen U, et al. Significance of MR Angiography in the Diagnosis of Aberrant Renal Arteries as the Cause of Ureteropelvic Junction Obstruction in Children. Rofo. 2015 Jan. 187(1):42-48. [Medline].
Gill IS, Desai MM, Kaouk JH, Wani K, Desai MR. Percutaneous endopyeloplasty: description of new technique. J Urol. 2002 Nov. 168(5):2097-102. [Medline].
Shapiro EY, Cho JS, Srinivasan A, Seideman CA, Huckabay CP, Andonian S, et al. Long-term follow-up for salvage laparoscopic pyeloplasty after failed open pyeloplasty. Urology. 2009 Jan. 73(1):115-8. [Medline].
Singh V, Sinha RJ, Gupta DK, Kumar V, Pandey M, Akhtar A. Prospective randomized comparison between transperitoneal laparoscopic pyeloplasty and retroperitoneoscopic pyeloplasty for primary ureteropelvic junction obstruction. JSLS. 2014 Jul. 18(3):[Medline]. [Full Text].
Casale P. Robotic pyeloplasty in the pediatric population. Curr Urol Rep. 2009 Jan. 10(1):55-9. [Medline].
Casale P. Robotic pyeloplasty in the pediatric population. Curr Opin Urol. 2009 Jan. 19(1):97-101. [Medline].
Tugcu V, Sönmezay E, Ilbey YO, Polat H, Tasci AI. Transperitoneal laparoendoscopic single-site pyeloplasty: initial experiences. J Endourol. 2010 Dec. 24(12):2023-7. [Medline].
Stein RJ, Berger AK, Brandina R, et al. Laparoendoscopic single-site pyeloplasty: a comparison with the standard laparoscopic technique. BJU Int. 2011 Mar. 107(5):811-5. [Medline].
Seideman CA, Tan YK, Faddegon S, Park SK, Best SL, Cadeddu JA, et al. Robot-assisted laparoendoscopic single-site pyeloplasty: technique using the da Vinci Si robotic platform. J Endourol. 2012 Aug. 26(8):971-4. [Medline].
Bagley DH, Liu JB. Endoureteral sonography to define the anatomy of the obstructed ureteropelvic junction. Urol Clin North Am. 1998 May. 25(2):271-9. [Medline].
Baniel J, Livne PM, Savir A. Dismembered pyeloplasty in children with and without stents. Eur Urol. 1996. 30(3):400-2. [Medline].
Bartoli F, Penza R, Aceto G, et al. Urinary epidermal growth factor, monocyte chemotactic protein-1, and ß2-microglobulin in children with ureteropelvic junction obstruction. J Pediatr Surg. 2011 Mar. 46(3):530-6. [Medline].
Boylu U, Oommen M, Lee BR, Thomas R. Ureteropelvic junction obstruction secondary to crossing vessels-to transpose or not? The robotic experience. J Urol. 2009 Apr. 181(4):1751-5. [Medline].
Casale P, Grady RW, Joyner BD, Zeltser IS, Figueroa TE, Mitchell ME. Comparison of dismembered and nondismembered laparoscopic pyeloplasty in the pediatric patient. J Endourol. 2004 Nov. 18(9):875-8. [Medline].
Chow GK, Geisinger MA, Streem SB. Endopyelotomy outcome as a function of high versus dependent ureteral insertion. Urology. 1999 Dec. 54(6):999-1002. [Medline].
el-Nahas AR, Shoma AM, Eraky I, el-Kenawy MR, el-Kappany HA. Prospective, randomized comparison of ureteroscopic endopyelotomy using holmium:YAG laser and balloon catheter. J Urol. 2006 Feb. 175(2):614-8; discussion 618. [Medline].
El-Sherbiny MT, Mousa OM, Shokeir AA, Ghoneim MA. Role of urinary transforming growth factor-beta1 concentration in the diagnosis of upper urinary tract obstruction in children. J Urol. 2002 Oct. 168(4 Pt 2):1798-800. [Medline].
Figenshau RS, Clayman RV. Endourologic options for management of ureteropelvic junction obstruction in the pediatric patient. Urol Clin North Am. 1998 May. 25(2):199-209. [Medline].
Frauscher F, Janetschek G, Helweg G. Crossing vessels at the ureteropelvic junction: detection with contrast- enhanced color Doppler imaging. Radiology. 1999 Mar. 210(3):727-31. [Medline].
Jabbour ME, Goldfischer ER, Klima WJ. Endopyelotomy after failed pyeloplasty: the long-term results. J Urol. 1998 Sep. 160(3 Pt 1):690-2; discussion 692-3. [Medline].
Johnston JH, Evans JP, Glassberg KI. Pelvic hydronephrosis in children: a review of 219 personal cases. J Urol. 1977 Jan. 117(1):97-101. [Medline].
Kajbafzadeh AM, Elmi A, Talab SS, Emami H, Esfahani SA, Saeedi P. Urinary and serum carbohydrate antigen 19-9 as a biomarker in ureteropelvic junction obstruction in children. J Urol. 2010 Jun. 183(6):2353-60. [Medline].
Kumar R, Kapoor R, Mandhani A. Optimum duration of splinting after endopyelotomy. J Endourol. 1999 Mar. 13(2):89-92. [Medline].
Lee RS, Retik AB, Borer JG, Peters CA. Pediatric robot assisted laparoscopic dismembered pyeloplasty: comparison with a cohort of open surgery. J Urol. 2006 Feb. 175(2):683-7; discussion 687. [Medline].
Lopez-Pujals A, Leveillee RJ, Wong C. Application of strict radiologic criteria to define success in laparoscopic pyeloplasty. J Endourol. 2004 Oct. 18(8):756-60. [Medline].
Matlaga BR, Shah OD, Singh D, Streem SB, Assimos DG. Ureterocalicostomy: a contemporary experience. Urology. 2005 Jan. 65(1):42-4. [Medline].
McDaniel BB, Jones RA, Scherz H, Kirsch AJ, Little SB, Grattan-Smith JD. Dynamic contrast-enhanced MR urography in the evaluation of pediatric hydronephrosis: Part 2, anatomic and functional assessment of uteropelvic junction obstruction. AJR Am J Roentgenol. 2005 Dec. 185(6):1608-14. [Medline].
Mitterberger M, Pinggera GM, Neururer R, Peschel R, Colleselli D, Aigner F, et al. Comparison of contrast-enhanced color Doppler imaging (CDI), computed tomography (CT), and magnetic resonance imaging (MRI) for the detection of crossing vessels in patients with ureteropelvic junction obstruction (UPJO). Eur Urol. 2008 Jun. 53(6):1254-60. [Medline].
Murakumo M, Nonomura K, Yamashita T, Ushiki T, Abe K, Koyanagi T. Structural changes of collagen components and diminution of nerves in congenital ureteropelvic junction obstruction. J Urol. 1997 May. 157(5):1963-8. [Medline].
Niemczyk P, Krisch EB, Zeiger L. Use of diuretic renogram in evaluation of patients before and after endopyelotomy. Urology. 1999 Feb. 53(2):271-5. [Medline].
Park JM, Bloom DA. The pathophysiology of UPJ obstruction. Current concepts. Urol Clin North Am. 1998 May. 25(2):161-9. [Medline].
Patel V. Robotic-assisted laparoscopic dismembered pyeloplasty. Urology. 2005 Jul. 66(1):45-9. [Medline].
Reddy PP, Mandell J. Prenatal diagnosis. Therapeutic implications. Urol Clin North Am. 1998 May. 25(2):171-80. [Medline].
Richstone L, Seideman CA, Reggio E, Bluebond-Langner R, Pinto PA, Trock B, et al. Pathologic Findings in Patients With Ureteropelvic Junction Obstruction and Crossing Vessels. Urology. 2009 Feb 2. [Medline].
Rooks VJ, Lebowitz RL. Extrinsic ureteropelvic junction obstruction from a crossing renal vessel: demography and imaging. Pediatr Radiol. 2001 Feb. 31(2):120-4. [Medline].
Shalhav AL, Giusti G, Elbahnasy AM. Adult endopyelotomy: impact of etiology and antegrade versus retrograde approach on outcome. J Urol. 1998 Sep. 160(3 Pt 1):685-9. [Medline].
Siddiq FM, Leveillee RJ, Villicana P, Bird VG. Computer-assisted laparoscopic pyeloplasty: University of Miami experience with the daVinci Surgical System. J Endourol. 2005 Apr. 19(3):387-92. [Medline].
Smith AD, Horgan JD. Endopyelotomy and Pyeloplasty. Clinical Urology. Philadelphia, Pa: JB Lippincott; 1994. 433-43.
Thomas DF. Fetal uropathy. Br J Urol. 1990 Sep. 66(3):225-31. [Medline].
Wang Y, Puri P, Hassan J, Miyakita H, Reen DJ. Abnormal innervation and altered nerve growth factor messenger ribonucleic acid expression in ureteropelvic junction obstruction. J Urol. 1995 Aug. 154(2 Pt 2):679-83. [Medline].
Yurkanin JP, Fuchs GJ. Laparoscopic dismembered pyeloureteroplasty: a single institution's 3-year experience. J Endourol. 2004 Oct. 18(8):765-9. [Medline].