FEATURE

Pyonephrosis: is the always doomed?

BY CLAUDIU COZMAN, STEPHANIE SMITH AND STEPHEN KEOGHANE

yonephrosis (Greek pyon ‘pus’ Investigations Aspiration of the collecting system under + nephros ‘kidney’) is defined in Initial work-up includes a complete ultrasound or CT scan guidance followed Campbell-Walsh Urology [1] as an full blood count, serum chemistry and by Gram staining and culture of the fluid Pinfected hydro- associated creatinine, urinalysis with culture, provides a definitive microbiological with suppurative destruction of the renal coagulation profile and blood cultures if diagnosis. The culture should be tested parenchyma which results in total or near there is a high suspicion of pyonephrosis or for aerobic, anaerobic, acid-fast bacilli (if total loss of renal function. the patient is septic [11]. suspicious) and fungal pathogens. The The true incidence of pyonephrosis is A urine culture of the fluid above most common organisms involved are E. unknown but is an uncommon condition in the obstruction must be obtained in coli followed by Enterococcus, Klebsiella, adults and rarer but described in children order to guide antibiotic therapy either Proteus and Pseudomonas [14]. and neonates [2]. by aspiration from the ureteric stent Clinically it can be difficult to determine at the time of retrograde drainage or Imaging the difference between an infected from the percutaneous tube following Ultrasonography offers a sensitivity of 90% and a true pyonephrosis nephrostomy placement. and a specificity of 97% in differentiating and prompt diagnosis and treatment are Bacteriuria, fever, pain, and leukocytosis hydronephrosis from pyonephrosis required to prevent sepsis, extravasation can be absent in 30% of patients with [15]; the presence of hydronephrosis in and parenchymal loss [3]. pyonephrosis; leukocytosis and bacteriuria, conjunction with hyperechoic debris in The risk of pyonephrosis is increased even if present, are therefore not specific the collecting system being suggestive for in patients with upper urinary tract for pyonephrosis and may be due to pyonephrosis [16,17]. obstruction secondary to various causes other causes such as or Computer tomography (CT) is superior (stones, tumours, ureteropelvic junction an uncomplicated urinary tract infection. to ultrasonography in diagnosing obstruction) [4,5]. Predictors of developing Pyuria is of course non-specific and a pyonephrosis; the advantages include a pyonephrosis include a long duration normal urinalysis could be secondary definitive delineation of the obstruction, of symptoms, abnormal anatomy and to complete obstruction of the infected a crude assessment of the function of critically the presence of renal calculi portion of the collecting system. the kidney, an assessment of the severity [6,7]. Immunosuppression due to drugs C-reactive protein (CRP) value has been of hydronephrosis, as well as revealing or disease (diabetes mellitus, acquired shown to be an important marker for other abdominal pathology, including immunodeficiency syndrome and pyonephrosis. In a study of 110 patients metastatic cancer, retroperitoneal fibrosis lymphoproliferative disorders) can increase with renal colic [12], CRP levels greater than the risk of pyonephrosis. and renal stones that are not visible on 28mg/l indicated the need for emergency the sonogram [18]. Treatment is rapid drainage by either drainage with a sensitivity and specificity of Fultz et al. reviewed the CT images retrograde stenting or percutaneous 75.8% and 88.9%. In a systematic review by of 17 pyonephrotic and 20 non-infected nephrostomy insertion with appropriate Shaikh et al. in 2015 [13], the evidence for antimicrobial therapy. In severe cases that hydronephrotic kidneys [19]. CT findings use of CRP to differentiate pyelonephritis do not respond to conservative therapy, suggesting pyonephrosis as opposed to from cystitis in children with urinary tract nephrectomy may be necessary [8]. hydronephrosis were increased infections did not however support its wall thickness of ≥2mm, the presence of routine use in clinical practice. Clinical presentation debris in the renal pelvis and perirenal Patients with pyonephrosis may present fat stranding. with a variety of clinical symptoms ranging CT attenuation values can be used from asymptomatic bacteruria (15%) to to differentiate hydronephrosis from frank sepsis. The clinician should have a “The clinician should have pyonephrosis. A retrospective review by high index of suspicion when examining a Yuruk et al. showed that having a Hounsfield patient presenting with fever, flank pain, a high index of suspicion Unit (HU) of 9.21 or higher diagnosed urinary tract infection, and obstruction or pyonephrosis accurately with a sensitivity of hydronephrosis. when examining a patient 65.96% and specificity 87.93% [20]. On examination, a palpable presenting with fever, Cova et al. reviewed the use of diffusion- abdominal mass may be associated weighted MRI which can distinguish with the hydronephrotic kidney; rarely flank pain, urinary tract between pyonephrosis and non-infected a pyonephrotic kidney can rupture infection, and obstruction hydronephrosis. In pyonephrosis there into the peritoneal cavity, leading to are marked, hyper-intense signals in the peritonitis [9,10]. or hydronephrosis” collecting system corresponding to pus,

urology news | MARCH/APRIL 2020 | VOL 24 NO 3 | www.urologynews.uk.com FEATURE

while the hydronephrotic kidney without pyonephrosis and resolution of infection urinary tract obstruction or urosepsis. The pus is hypo-intense. is governed by the residual split renal causes of hydronephrosis in a neonate A non-functioning kidney was defined as function. There is however a lack of data in can be classified as obstructive and non- having paper-thin parenchyma on urinary the adult population regarding the interval obstructive. The most common causes ultrasound or CT with no contrast evident to assess split renal function following renal are pelvi-ureteric junction obstruction in the collecting system and having a split decompression and definitive treatment. (50-60%), vesico-ureteric reflux (20-30%), renal function of <10% on nuclear renal Data on outcome following vesico-ureteric junction obstruction, function studies [21]. pyonephrosis is also sparse: traditionally, multicystic kidney and rarely, posterior nephrectomy is considered for a kidney urethral valves. Management and outcome with a split renal function of less than 10% Paediatric urolithiasis has increased Antibiotic therapy should be guided by following decompression. globally over the last few decades and now cultures and local microbiology policy In an observational study on 14 patients represents 2-3% of the total population of and resistance. with pyonephrosis, in 10 cases treatment stone-formers which makes it a significant In the presence of infection and consisted of primary nephrectomy; in risk factor for pyonephrosis even in this obstruction antibiotic penetration and three of these cases primary nephrostomy age group [2]. efficacy can be impaired from the oedema was performed with a positive outcome Kidney-sparing treatment in the and poor blood flow in the area and and in one case of renal failure treated paediatric population should be considered emergency drainage is therefore imperative. with nephrostomy and conservative after early renal decompression even Pearle et al. randomised 42 patients management the patient did not survive with poor split function on a nuclear with an infected obstructed kidney to [25]. The author concluded that the optimal medicine scan [27,28]. nephrostomy or retrograde stent [22]; there management was early detection and was similar efficacy between antegrade treatment of the mechanism of obstruction Pregnancy and retrograde kidney decompression. which was urolithiasis in 71% of the cases Asymptomatic bacteriuria affects 2-10% Their results demonstrated an increased in the series. Conservative treatment was of all pregnant women and approximately incidence of bacterial urinary colonisation suggested in cases with a single kidney and 30% of these will develop pyelonephritis if post-procedure in the nephrostomy group as poor performance status. not properly treated [30]. Urolithiasis is the compared to the stent group. A retrospective analysis on 53 patients most common non-obstetric complication Goldsmith et al. studied 130 patients who by Zhang et al. demonstrated improved in the gravid patient with a prevalence of underwent decompression for obstructing split renal function following nephrostomy kidney stones in pregnancy of 1:200 [31]. ureteral stone with nephrostomy or stent insertion for ureteropelvic junction The diagnosis of pyonephrosis in placement [23]. Patients who underwent obstruction in 56.6% (30 patients) [26]. pregnancy is similar to non-pregnant nephrostomy placement had a longer Those who had the greatest benefit from women but it is important to remember that hospital stay but other outcomes such pyeloplasty were young adults (aged physiologic hydronephrosis may be as high as time to definitive stone management, between 18 and 35) showing a further as 90% on the right side and 67% on the rates of spontaneous stone passage and improvement of the split renal function left side. [32]. initiation of stone metabolic work-up were without secondary hypertension or urinary Ureteric stents and percutaneous not statistically different. The authors noted tract infection at 12 and 36 months. nephrostomy drainage are considered that the method of initial decompression Wagner at al. showed that the paediatric equally safe and effective in pregnancy. correlated with the eventual approach population benefits from early renal In a study of 26 pregnant women with selected for definitive stone management. decompression and pyeloplasty even if the urolithiasis, 7 out of 15 women with stents Patients treated with nephrostomy were split renal function is less than the 10% [27]. required early induction secondary to stent more likely to undergo percutaneous This was supported by Aziz at al. in a small intolerance [33]. management, while patients managed study of 12 patients (age range 35 days to 11 The risk of stent encrustation is with ureteral stenting were more likely years) with kidney function less than 10% however greater due to the altered urinary to be treated utilising a ureteroscopic which initially had nephrostomy followed by environment, especially the hypercalciuria approach. Larger stones, multiple an Anderson-Hynes pyeloplasty after four seen in the second and third trimester comorbidities and severe sepsis favoured a to six weeks [28]. All subjects demonstrated causing re-obstruction and further nephrostomy as drainage. improvement in renal function at four to complicating surgical management [34]. Mokhmalji et al. prospectively six weeks (more than 10%) after initial Based on this, stents require exchange every randomised 40 patients to receive either nephrostomy insertion. Furthermore, Zhao four to six weeks in the gravid patient. nephrostomy or stent [24]. Sixteen et al. [26] and Fink et al. [29] confirmed on Nephrostomy drainage has similar out of twenty stents were successfully animal models that renal function with complications to a ureteral stent insertion placed while all 20 nephrostomies were complete ureteral obstruction could be including bacterial colonisation and successfully sited. All unsuccessful restored to normal levels in the first week encrustation but the percutaneous tube is stents were successfully managed by after obstruction, which indicates that the also subject to inadvertent dislodgement, nephrostomy insertion. early GFR decrease is reversible. causing more pain and the need for further The results demonstrated that stent intervention. Nephrostomy placement has utilisation was less successful when Children also been associated with an increased risk compared to nephrostomy insertion and The clinical presentation of pyonephrosis in of sepsis [35]. there was a trend for longer antibiotic older children is similar to adults with fever, In a retrospective analysis by Collins therapy due to persistent signs of urinary chills, flank pain and tenderness associated et al. on 30 women who underwent tract infection in patients who underwent with a previous history of urinary tract nephrostomy insertion during pregnancy stent placement. calculi, infection, surgery or malformation. (mean gestational age 25 weeks) 17 patients Further management of the Neonates with hydronephrosis may have required drainage for renal calculi or decompressed kidney following a palpable abdominal mass, features of pyelonephritis [36]. The mean number of

urology news | MARCH/APRIL 2020 | VOL 24 NO 3 | www.urologynews.uk.com FEATURE

tube changes during pregnancy was 4.6 with 12. Angulo JC, Gaspar MJ, Rodríguez N, et al. The value 34. Sefa R, Cetin EH, Gurkan K, Metin K. Are changes of C-reactive protein determination in patients with in urinary parameters during pregnancy clinically 10 patients requiring tube changes at one renal colic to decide urgent urinary diversion. Urology significant?Urol Res 2006;34(4):244-8. to two weeks intervals until delivery. While 2010;76(2):301-6. 35. Khoo L, Anson K, Patel U. Success and short-term three premature births were recorded (12%), 13. Shaikh N, Borrell JL, Evron J, Leeflang MM Procalcitonin, complication rates of percutaneous nephrostomy caesarean section was performed in 14 of 25 C-reactive protein, and erythrocyte sedimentation rate during pregnancy. J Vasc Interv Radiol 2004;15(12):1469- for the diagnosis of acute pyelonephritis in children. 73. (56%) patients. Cochrane Database of Systematic Reviews 2015;20:1. 36. Collins D, Malhotra A, Herr A, et al. Outcomes after The authors concluded that the high rate 14. Gupta R, Gupta S, Choudhary A, Basu S. Giant nephrostomy tube placement in pregnant patients of caesarean section emphasises the need pyonephrosis due to ureteropelvic junction obstruction: with ureteral obstruction. J Vasc Interv Radiol for multidisciplinary care in this patient a case report. J Clin Diagnostic Res 2017;11(8):PD17- 2017;28(2):S142-3. PD18. population and appropriate discussions 37. Scarpa RM, De Lisa A, Usai E. Diagnosis and treatment 15. Subramanyam BR, Raghavendra BN, Bosniak MA, et al. of ureteral calculi during pregnancy with rigid and counselling must take place before Sonography of pyonephrosis: a prospective study. Am J ureteroscopes. J Urol 1996;155(3):875-7. considering nephrostomy tube placement. Roentgenol 1983;140(5):991-3. 38. Fregonesi A, Dias FGF, Saade RD, et al. Challenges on Definite stone treatment with 16. Colemen BG, Arger PH, Mulhern CB, et al. Pyonephrosis: percutaneous nephrolithotomy in pregnancy: supine position approach through ultrasound guidance. Urol ureteroscopy has been known to be safe sonography in the diagnosis and management. Am J Roentgenol 1981;137(5):939-43. Ann 2013;5(3):197-9. and effective in pregnancy [31,37]. SWL and 17. Jeffrey RB, Laing FC, Wing VW, Hoddick W. Sensitivity percutaneous nephrolithotomy (PCNL) of sonography in pyonephrosis: a reevaluation. Am J are not indicated in pregnancy but cases Roentgenol 1985;144(1):71-3. treated with supine PCNL showed good 18. Wyatt SH, Urban BA, Fishman EK. Spiral CT of the outcome in selected patients [38]. Arvind kidneys: role in characterization of renal disease. Part I: Nonneoplastic disease. Critical Reviews in Diagnostic et al. described a case of pyonephrosis Imaging 1995;36(1):1-37. in pregnancy treated with laparoscopic 19. Fultz PJ, Hampton WR, Totterman SMS. Computed AUTHORS nephrectomy as definitive treatment with tomography of pyonephrosis. Abdom Imaging good outcome [8]. 1993;18(1):82-7. 20. Yuruk E, Tuken M, Sulejman S, et al. Computerized tomography attenuation values can be used to Conclusion differentiate hydronephrosis from pyonephrosis.World J Stone disease is the main aetiological factor Urol 2017;35(3):437-42. in up to 70% of patients with pyonephrosis. 21. Zengin K, Tanik S, Sener NC. et al. Incidence of renal carcinoma in non-functioning kidney due to renal pelvic Conservative treatment with antibiotics stone disease. Mol Clin Oncol 2015;3(4):941-3. and prompt drainage of the system is the 22. Pearle MS, Pierce HL, Miller GL, et al. Optimal method standard of care followed by an assessment of urgent decompression of the collecting system for of split renal function when the acute obstruction and infection due to ureteral calculi. J Urol Claudiu Cozman, 1998;160(4):1260-4. problem has settled. Renal function 23. Goldsmith ZG, Oredein-McCoy O, Gerber L, et al. Dept of Urology, West Suffolk Hospital, recovers better in young adults and children. Emergent ureteric stent vs percutaneous nephrostomy Bury St Edmunds. for obstructive urolithiasis with sepsis: patterns of use and outcomes from a 15-year experience. BJU Int References 2013;112(2):E122-8. 1. Wein AJ, Kavoussi LR, et al. Campbell-Walsh Urology, 10th 24. Mokhmalji H, Braun PM, Martinez Portillo FJ, et al. Edition. Elsevier; 2012. Percutaneous nephrostomy versus ureteral stents 2. Sharma S, Mohta A, Sharma P. Neonatal pyonephrosis - a for diversion of hydronephrosis caused by stones: case report. Int Urol Nephrol 2004;36(3):313-15. a prospective, randomized clinical trial. J Urol 3. Davenport M, Shortliffe LMD. Urinary tract infections, 2001;165(4):1088-92. renal abscess, and other complex renal infections. In: 25. Rabii R, Rais H, Sarf I, et al. [Peritonitis caused by Long SS, Prober, Fischer M (Eds.). Principles and Practice of spontaneous rupture of pyonephrosis in pregnancy. Pediatric Infectious Diseases Elsevier; 2017. Report of a case]. Ann Urol (Paris) 1999;33(1):31-5. 4. Wah TM, Weston MJ, Irving HC. Lower moiety pelvic- 26. Zhang S, Zhang Q, Ji C, et al. Improved split renal Stephanie Smith, ureteric junction obstruction (PUJO) of the duplex function after percutaneous nephrostomy in young kidney presenting with pyonephrosis in adults. Br J adults with severe hydronephrosis due to ureteropelvic Dept of Urology, West Suffolk Hospital, Radiol 2003;76(912):909-12. junction obstruction. J Urol 2015;193(1):191-5. Bury St Edmunds. 5. Perimenis P. Pyonephrosis and renal abscess associated 27. Wagner M, Mayr J, Häcker FM. Improvement of renal with kidney tumours. Br. J Urol 1991;68(5):463-5. split function in hydronephrosis with less than 10% 6. Patodia M, Goel A, Singh V, et al. Are there any predictors function. Eur J Pediatr Surg 2008;18(3):156-9. of pyonephrosis in patients with renal calculus disease? 28. Aziz MA, Hossain AZ, Banu T, et al. In hydronephrosis Urolithiasis 2017;45(4):415-20. less than 10% kidney function is not an indication 7. Liang X, Huang J, Xing M, et al. Risk factors and for nephrectomy in children. Eur J Pediatr Surg outcomes of urosepsis in patients with calculous 2002;12(5):304-7. pyonephrosis receiving surgical intervention: A 29. Fink RL, Caridis DT, Chmiel R, Ryan G. Renal impairment single-center retrospective study. BMC Anesthesiol and its reversibility following variable periods 2019;19(1):61. of complete ureteric obstruction. Aust N Z J Surg 8. Arvind NK, Singh O, Gupta SS, et al. Laparoscopic 1980;50(1):77-83. nephrectomy for pyonephrosis during pregnancy: 30. Duarte G, Marcolin AC, Quintana SM, Cavalli RC. [Urinary Stephen Keoghane, case report and review of the literature. Rev Urol tract infection in pregnancy]. Rev Bras Ginecol Obstet 2011;13(2):98-103. 2008;30(2):93-100. Dept of Urology, West Suffolk Hospital, 9. Shifti DM, Bekele K. Generalized peritonitis after 31. Semins MJ, Matlaga BR. Management of urolithiasis Bury St Edmunds. spontaneous rupture of pyonephrosis: a case report. Int in pregnancy. International Journal of Women’s Health Med Case Rep J 2018;11:113-16. 2013;5:599-604. Declaration of competing interests: None declared. 10. Quaresima S, Manzelli A, Ricciardi E, et al. Spontaneous 32. Peake SL, Roxburgh HB, Le Langlois PS. Ultrasonic intraperitoneal rupture of pyonephrosis in a patient with assessment of hydronephrosis of pregnancy. Radiology unknown kidney carcinosarcoma: a case report. World J 1983;146(1):167-70. Surg Oncol 2011;9:39. 33. Rivera ME, McAlvany KL, Brinton TS, et al. Anesthetic 11. St Lezin M, Hofmann R, Stoller ML. Pyonephrosis: exposure in the treatment of symptomatic urinary diagnosis and treatment. Br J Urol 1992;70(4):360-3. calculi in pregnant women. Urology 2014;84(6):1275-8.

urology news | MARCH/APRIL 2020 | VOL 24 NO 3 | www.urologynews.uk.com