management options range from nephrectomy to various reconstructive strategies based on the anatomical configuration of the pelvicalyceal system and functional status of the kidney . since the turn of the 21st century , limited literature has emerged regarding the laparoscopic management of such complex conditions . we describe a case of giant hydronephrosis in a solitary functioning kidney managed by robot - assisted tubularized flap pyelovesicostomy along with a brief review of the literature . a 17-year - old girl presented with intermittent , dull , aching right flank pain for 2 months , along with low - grade fever for 5 days . her serum creatinine was 1.4 mg / dl with a total leukocyte count of 10,700 cells / mm . following initial percutaneous nephrostomy ( pcn ) tube placement and resolution of her fever with antibiotics , a computed tomography ( ct ) nephrostogram with 3-dimensional reconstruction revealed giant hydronephrosis on the right side with ureteropelvic junction obstruction as evidenced by significant contrast retention after 30 minutes of study ( fig . she underwent robot - assisted santosh - post graduate institute tubularized flap pyelovesicostomy under general anesthesia by use of the da vinci si system ( intuitive surgical , sunnyvale , ca , usa ) ( fig . a psoas hitch procedure was performed on the ipsilateral side by use of polyglactin 1/0 sutures . cystotomy of around 3 cm in length was made on the anterolateral bladder wall followed by delivery of a supra - pubic catheter into the peritoneal cavity . a gap of 5 to 6 cm was noted between the renal pelvis and the bladder . an anterior trapezoid - shaped renal pelvic flap was created with its base at the most dependent portion of the pelvis . the flap dimensions were as follows : 7 cm length and widths of 5 cm and 3 cm at the base and apex , respectively . the posterior layer of the pyelovesicostomy anastomosis was closed by using vicryl 3 - 0 sutures with a round body needle in an interrupted fashion with mucosato - mucosa approximation . the tip of the 16-fr foley catheter along with the bulb was placed inside the renal pelvis . the anterior layer of the anastomosis was similarly completed followed by tubularization of the flap over the catheter by use of full - thickness mucosa - to - mucosa sutures with vicryl 3 - 0 on a round body needle in a continuous watertight fashion . the drain was removed on day 5 and the patient was discharged with a strapped pcn and foley catheter placed across the flap . follow - up ct nephrostogram after 6 weeks revealed patent anastomosis with prompt drainage of contrast into the bladder ( fig . at the 5-month follow - up , her serum creatinine was 1.3 mg / dl . the earliest description of giant hydronephrosis dates to 1746 when glass ( quoted from ) recorded a hydronephrotic kidney containing 115 l of fluid . in 1939 , stirling defined giant hydronephrosis as a kidney containing more than 1 l of fluid . .   gave radiographic criteria for the diagnosis , which included ( 1 ) kidney occupying the hemi - abdomen , ( 2 ) meeting or crossing the midline , and ( 3 ) about 5 vertebral bodies in length . ureteropelvic junction obstruction is the most common cause ( 33% ) , followed by calculi ( 20% ) , congenital ureteral narrowing , ureteropelvic tumors , trauma , renal ectopia , retroperitoneal fibrosis , obstructive megaureter , ureteric atresia , and obstructive ectopic ureter with or without a duplex system . usually , the patient remains asymptomatic until the late stages because the disease progresses slowly   or may present with flank pain , fever , hematuria , or urinary tract infection . the huge hydronephrotic sac may be confused for hepatobiliary cysts , mesenteric cysts , cystic renal tumor , retroperitoneal tumors , ovarian cysts , or ascites . our patient luckily had consulted a physician at a younger age for her complaint of flank pain and fever ; otherwise , her renal function might have further deteriorated . the therapeutic approach is based on the initial presentation , the functional status of the affected and the contralateral kidney , and the anatomical configuration of the pelvicalyceal system . traditionally , a pcn tube is initially placed if the patient presents with fever , a nonvisualized or poorly delineated moiety on intravenous pyelography , or high serum creatinine . it further helps in assessment of 24-hour urinary creatinine clearance , prevents further renal damage , helps to stabilize renal function , and prevents postoperative acute renal injury secondary to sudden decompression . in our case , the pcn tube was placed in view of suspected infected hydronephrosis , although the results of the culture were sterile . it additionally helped in performance of the ct nephrostogram , which provided precise anatomical details with avoidance of systemic exposure to contrast in the setting of a solitary functioning kidney . preoperative decompression also allows safe placement of laparoscopic trocars without the fear of sac puncture and helps to provide ample space for instrument manipulation . it also allows time to manage postobstructive diuresis ( in case of a solitary kidney or bilateral obstruction ) preoperatively . if the contralateral moiety is normal and previous surgical attempts have failed , nephrectomy may be considered . nephrectomy should also be considered in cases of grossly hydronephrotic infected kidneys with poor function and a normal contralateral moiety . however , nearly two - thirds of cases have preserved renal function and therefore are suitable for reconstruction . reconstructive procedures should be considered in cases with significant residual renal function , a solitary functioning kidney , or bilateral disease . the high salvage rates are probably the result of a hugely dilated , compliant pelvicalyceal system . because the drainage of urine in giant hydronephrosis is dependent on gravitational flow rather than peristalsis , the type of reconstruction procedure is partly based on the anatomical configuration of the pelvicalyceal system . options include reduction pyeloplasty in cases with a large extrarenal redundant pelvis , uretero - calycostomy or boari - flap calycovesicostomy in cases of a grossly dilated inferior calyx with intrarenal pelvis , and pyelovesicostomy in cases of giant hydronephrosis with a dilated extrarenal pelvis reaching up to the bladder . nephroplication and nephropexy are useful adjunctive procedures to reduce pelvicalyceal system stasis and to improve drainage , thereby reducing the risk of subsequent stone formation , infection , and deterioration in renal function . one of the potential disadvantages of uretero - calycostomy is the formation of strictures and kinking of the anastomosis . the boari - flap calycovesicostomy ensures a wide anastomosis ; however , vesicoureteric reflux with its deleterious impact on renal function is a major concern . in a study by danforth et al . , however , no glomerular or tubular functional and histological abnormalities were noted in a canine model or in renal allotransplant patients with vesicopyelostomy or vesicocalycostomy . pyelovesicostomy has been previously described in cases of posttransplant donor ureteral necrosis , renal pelvic carcinoma , and ureteral carcinoma . it has also been described in cases of giant hydronephrosis as well as in a case of a solitary functioning pelvic kidney with ureteropelvic junction obstruction and recurrent renal calculi . as described earlier , the presence of reflux following such reconstructions does not cause significant renal injury because the hugely dilated pelvicalyceal system bears the brunt of the reflux . also , the reflux may not cause harm as long as the cultures are maintained sterile . such refluxing reconstructive procedures can be chosen more freely in females than in males , who with increasing age may be more prone to develop infravesical obstruction owing to prostatic enlargement . the native ureter need not be disturbed , thereby limiting the extent of dissection needed . in an attempt to further dampen the impact of reflux on renal parenchyma in patients planned for pyelovesicostomy , we utilized the redundant renal pelvis to create a tubularized flap that was anastomosed to the urinary bladder instead of a direct anastomosis between the bladder and the most dependent part of the renal pelvis . this technique would also help in reducing the tension at the anastomotic site . compared to a boari - flap pyelovesicostomy or uretero - calycostomy , the creation of a renal pelvic flap is more straightforward without disturbing the native bladder tissue . the use of a foley catheter as a splint ensured construction of a wide - caliber tubularized flap . it could easily be removed during follow - up without additional endoscopic intervention as would be needed for removal of a double - j stent . with the emergence of minimal - access surgery , the morbidity associated with open surgery has been significantly reduced . kumar et al .   described laparoscopic pyelovesicostomy as a salvage procedure for giant hydronephrosis secondary to ureteropelvic junction obstruction . several other reports have described the feasibility and efficacy of complex reconstructive procedures performed laparoscopically . one of the major hurdles in laparoscopic reconstructive techniques is the difficulty in suturing during anastomosis . the ease with which intracorporeal suturing can be performed and the added advantage of 3-dimensional vision aided in successful performance of a complex reconstructive procedure with a good outcome . robot - assisted tubularized flap pyelovesicostomy is a safe and effective reconstructive technique in salvaging renal units having giant hydronephrosis with redundant extrarenal pelvis .
we describe a case of a solitary functioning kidney with giant hydronephrosis secondary to ureteropelvic junction obstruction in a young girl who underwent successful robot - assisted tubularized flap pyelovesicostomy . 
 the aim of this report was to highlight the feasibility and efficacy of this technique in salvaging such renal moieties and to present a brief review of the surgical options available for the management of giant hydronephrosis .