| ORIGINAL REPORTS |
Department of Urology
Indiana University Medical Center
Georgetown Medical Center
Washington D.C.
ABSTRACT
A large cystic abdominal mass was identified on a prenatalultrasound in a 37 gestational week female fetus. Antenatal fluid aspirationfrom the cyst was consistent with fetal urine. The cyst fluid rapidly reaccumulated,prompting induction of labor. Following vaginal delivery, radiographicevaluation revealed giant hydronephrosis with ureteropelvic junction (UPJ)obstruction. This anomaly was associated with a unusual variation of intrarenalanatomy, which prevented classic dismembered pyeloplasty. We report a caseof in-utero detected giant UPJ obstruction and the unique reconstructionutilizing the concept of dismembered ureteroinfundibuloplasty.
CASE REPORT
A 36 year-old female had an abnormal antenatal sonogramin the 37th week of preganancy revealing a female fetus with a large cysticabdominal mass (9.8x8x6 cm). Both kidneys were identified lateral to themass, and neither collecting system was dilated. In-utero aspiration anddrainage of the cystic mass yielded clear fluid with electrolytes consistentwith fetal urine (Na 35 meq/L, C1 36 meq/L, 96 mOsm/kg). Amniotic fluidvolume was normal and amniocentesis revealed 46 XX kariotype without abnormalities.
Repeat sonogram three days later demonstrated reaccumulationof the fluid within the cystic abdominal mass. Because of the persistentabdominal mass, labor was induced at 38 weeks gestation. Following uncomplicatedvaginal delivery, physical exam revealed a smooth but firm, mid-abdominalmass. Genitalia were normal female. Postnatal abdominal ultrasound demonstratedthat the right kidney was displaced posteriorly and malrotated. There wasmild caliectasis in the right kidney, and no hydronephrosis on the left.A voiding cystourethrogram revealed anterior displacement of the bladderwithout evidence of vesicoureteral reflux. MRI scan with gadolinium (Figure1) showed a large mid-abdominal ovoid cystic mass compressing the bladder,posterior and superior displacement of the left kidney, and posterior displacementof the right kidney. There were no renal parenchymal abnormalities or significanthydronephrosis. Delayed images demonstrated a communication between thecystic mass and the urinary tract.
An intravenous urogram(Figure2) confirmed malrotation of the right kidney with accumulation of contrastin the adjacent cystic mass, which appeared to be retroperineal in location.Prior to surgical exploration, a right retrograde ureterogram verifiedthe presence of the right ureter, and demonstrated continuity between theureter and cystic mass (consistent with giant UPJ). Right flank exporationrevealed a malrotated, non-hydronephrotic kidney and massively distendedright renal pelvis anterior to the kidney. The dilated pelvis communicatedwith the intrarenal collecting system via four markedly attenuated infundibulae(Figure3). The ureter entered the posterior mid-portion of the renal pelvis.The entire renal pelvis was excised, leaving the proximal ureter and twocuffs of renal pelvis, each subtending two infundibulae. Infundibuloplastywas conducted by joining the superior and inferior cuffs and ureteroinfundibuloplastywas then accomplished by anastomosing the ureter to the dependent portionof the lower infundibulum(Figure4) with 6-0 PDS.
Following a three week period of urinary diversion witha ureteral stent and nephrostomy tube, an intravenous pyelogram demonstratedprompt renal function and a nondilated neopelvis and ureter(Figure5).
DISCUSSION
Giant hydronephrosis is a rarely encountered entity. Approximately200 cases have been reported, but none have been identified antenatally.Giant hydronephrosis is defined when the adult renal pelvis contains morethan one liter of urine 1or, in childhood, more than one day of urine volume 2.Pfister et al 3 usethe following radiographic criteria: the kidney occupies a hemiabdomen,meets or crosses the midline and is at least 5 vertebral bodies in length.
The most common cause of giant hydronephrosis is a highinsertion of the ureter resulting in ureteopelvic junction obstruction.Approximately two thirds of these kidneys have preserved renal functionand are amenable to repair 3.This unexpectedly high salvage rate may be due to the "protective" effectof the compliant, overdistended pelvis on the renal parenchyma 4.In this case, the diagnosis was unclear prior to exploration. A nonurologicretroperitoneal mass (mesenteric cyst, teratoma. etc.) was considered,with iatrogenic communication between the right kidney (MRI and IVP demonstratedcommunication between the right collecting system and the mass). The disparitybetween mild calyceal dilation and the marked size of the cystic mass mitigatedagainst the diagnosis of hydronephrosis. The unique anatomy of the collectingsystem (i.e. four attenuated infundibulae preventing complete transmissionof renal pelvic pressure into the intrarenal collecting system) accountedfor the minimal dilation of the calyces. The true renal pelvis was dramaticallydilated due to a UPJ obstructrion secondary to a high insertion of theureter. Reconstruction required complete resection of the renal pelvisand ureteroinfundibuloplasty to allow close approximation of the attenuatedinfundibulae.
Antenatal diagnosis was inaccurate in providing a preciseetiology for the cystic abdominal mass. This variant of giant hydronephrosishad an unusual anatomic relationship between the intrarenal collectingsystem and renal pelvis, obscuring the diagnosis and making the reconstructionchallenging. A previously undescribed procedure, ureteroinfundibuloplasty,was required to create a neopelvis. Ureteroinfundibuloplasty provided amethod of i) reconstruction of the neopelvis, ii) avoiding reconstructiveproblems associated with the overdistended native renal pelvis, and iii)providing dependent ureteral drainage. This technique should be consideredand applied in variations of ureteropelvic obstruction that are associatedwith giant hydronephrosis.
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