spontaneous kidney rupture could develop in the course of posterior urethral valve ( puv ) , the most common cause of outflow urinary tract obstruction in male infants . our case report presents diagnostic difficulties connected with spontaneous kidney rupture due to puv in a 6 week - old infant . due to not equivocal images , thundery course of disease and rapid deterioration in the infant 's condition , the patient required an urgent laparatomy . this case showed that the investigation of renal abnormalities during early neonatal period , is very important specifically in puv that can lead to kidney rupture . kidney rupture in developmental age most often takes place in the aftermath of multiorgan trauma , especially when urinary abnormalities or urolithiasis are present . rarely spontaneous rupture of kidney is described due to hydronephrosis caused by ureteropelvic and vesicoureteric junction obstruction . also polycystic kidney disease , neoplasmatic lesions due to renal cell carcinoma , renal angiomyolipoma and transitional cell tumor could be predisposing factors . additionally , spontaneous kidney rupture could develop in the course of posterior urethral valve ( puv ) . however , urinary extravasation is a rare complication among this group of children . our report presents diagnostic difficulties connected with spontaneous kidney rupture due to puv in a 6-week old male . previously healthy 6-week - old boy , born to a giii piii , birth weight 2900 g , was admitted to the district hospital with fever , vomiting and oliguria persisting for several hours . family history was of no significance . on admission , infant 's general condition was poor . a distended abdomen , tense and tender on palpation , was noted . laboratory investigations revealed : wbc 3.7 k / u , hb 8.4 g / dl , urea 70 mg / dl , crp 132.3 mg / l , procalcitonine > 200 ng / ml , and uncompensated metabolic acidosis . ultrasound examination showed a left kidney measuring 70 mm in length with a dilated pelvi - calyceal system and an enlarged hydronephrotic right kidney measuring 90 mm in length . the infant 's general condition improved , but crp continued to rise ( 281.5 mg / l ) . serum urea , creatinine and procalcitonine were 98.0 mg / dl , 1.0 mg / dl and 180.74 ng / ml , respectively . on the 2 day of hospitalization the infant was transferred to our department . a distended abdomen with a right sided large palpable mass was found . laboratory tests showed crp 309.4 mg / l , urea 116 mg / dl , creatinine 1.81 mg / dl , hb 10.5 g / dl and compensated metabolic acidosis . abdominal ultrasound demonstrated left kidney 72.8 cm , with mild pelvic dilatation , and right kidney 116.6 cm with a dilated and deformed collecting system . the upper and middle calyces seemed mostly dilated with a total volume of about 216 ml , pelvic volume 3 ml . hydronephrosis was considered , but a suspicion of kidney compression by an extraneous cystic structure was also raised . due to worsening of the infant 's condition and equivocal ultrasound images , he was qualified for an urgent laparotomy . during surgery a huge cyst was found in the peritoneal cavity , encircling almost the whole right kidney and connected to the renal capsule by its capsule . the cyst contained about 500 ml of watery bright fluid which was resected revealing that its wall was a fragment of the anterior wall of the renal capsule . additionally , the bladder was noted to have a thick and hard wall . in the following 24-hours renal function improved ( urea 47 mg / dl , creatinine 0.95 mg / dl ) , crp decreased to 65 mg / dl . bright yellow draining fluid , about 20 ml / h , was noted to have similar biochemical properties to urine : urea 496 mg / dl , urea nitrogen 231.8 mg / dl , creatinine 9 mg / dl . follow up abdominal ultrasound reported a slightly wider right pelvi - calyceal system , with a small fluid collection near the upper pole ( fig . histopathologically the wall of the resected cyst turned out to be the right kidney capsule and was reported as pseudocystis in inflammatione chronica . retrospectively spontaneous kidney rupture due to posterior urethral valves was diagnosed . a ultrasound image of fluid encircled right kidney 's parenchyma after 21 days of treatment , inflammatory markers and renal function normalized . renoscintigraphy performed 6 weeks post surgery revealed cumulative renogram curves of both kidneys , the right kidney ( operated ) contributing 81.5% of renal function and the left kidney 18.5% . at 20 months the case of our 6 week - old infant does not blend with the symptomatology - diagnostic scheme typical for puv . postnatally this abnormality reveals as a general rule in the neonatal period , most often as a pelvis dilation and urinary tract infection . in our case the boy was born to a healthy mother at term , in good condition and was discharged from the neonatal unit without suspicion of any anomaly . on admission to hospital patient 's clinical condition suggested acute kidney injury caused by urosepsis due to bilateral hydronephrosis . ultrasound performed after few hours revealed an acutely increasing fluid collection in the right side of the abdominal cavity . the image was ambiguous and required differential diagnosis from multilocular cystic nephroma , cystic nephroblastoma , cyst with septum and adrenal hemorrhage . absent visible marks of ruptured kidney 's parenchyma did not allow to recognise intraoperatively a urinoma ( i.e. the development of a perirenal extravasation of urine ) . later retrospective analysis of full clinical picture made us diagnose spontaneous kidney rupture in the course of puv and subcapsular urine collection . finnish authors published results of retrospective analysis of 17 boys with puv and urinary extravasation . nine children had a perirenal urinoma , six urinary ascites and two patients urinothorax . in all cases underlying diagnosis included obstruction of the ureteropelvic junction in 3 children and puv in 7 children . it is not known if urinoma is correlated with severity of obstruction . in our patient difficulty with urethral catheterization , thickened bladder wall described in diagnostic imaging and confirmed intraoperatively , argued for a pronounced subvesical barrier . we opted for laparotomy in our patient because of equivocal images , thundery course of disease and rapid deterioration of the infant 's condition . it is still under discussion whether urinoma could be a protective mechanism in obstructive uropathy . claahsen - van der grinten 's et al analysis revealed a better function of ruptured kidney in renal scintigraphy compared to the other side . the right kidney function ( with urinoma ) was estimated as 81.5% and the left kidney 18.5% in renoscintigraphy . in turn patil et al study did not confirm protective role of urinoma for the ruptured kidney function . on the contrary they observed deterioration of its function . once again , retrospective study by finnish authors reported that urinoma had neither harmful nor protective influence on kidney function . the above described case is an example how important is investigation of renal abnormalities during early neonatal period , realizing the fact that in some cases puv can lead to kidney rupture .
backgroundspontaneous kidney rupture could develop in the course of posterior urethral valve ( puv ) , the most common cause of outflow urinary tract obstruction in male infants . however , urinary extravasation is a rare complication among this group of children.case presentationour case report presents diagnostic difficulties connected with spontaneous kidney rupture due to puv in a 6 week - old infant . 
 due to not equivocal images , thundery course of disease and rapid deterioration in the infant 's condition , the patient required an urgent laparatomy.conclusionthis case showed that the investigation of renal abnormalities during early neonatal period , is very important specifically in puv that can lead to kidney rupture .