Postgrad MedJ3 1995; 71: 409-412 i) The Fellowship of Postgraduate Medicine, 1995

Diagnostic dilemmas

Giant hydronephrosis in adults: the great mimic.Early diagnosis with ultrasound

WT Yang, C Metreweli

Department ofRadiology, Prince ofWales Hospital,Chinese University ofHong Kong, Shatin,NT, Hong KongWT YangC Metreweli

Accepted 2 March 1995

SummaryGiant hydronephrosis in adults is uncom-mon and often misdiagnosed clinically.We present three cases of giant hyd-ronephrosis in adults secondary to uret-eric calculous obstruction, two of whompresented with an acute abdomen and onewith an indirect inguinal hernia. Allpatients were diagnosed promptly withultrasound.

Keywords: giant hydronephrosis, ultrasound

Most reported cases of giant hydronephrosisoccur in infants and children, and are con-genital in origin. Giant hydronephrosis inadults secondary to calculous obstruction isuncommon and often misdiagnosed clinically.Patients may present with asymptomaticabdominal distension of long standing, anasymptomatic abdominal mass or an acuteabdomen. Plain abdominal radiographs maynot always provide an accurate diagnosis due toobscuration of radio-opaque urinary calculi bybowel shadows, or overlap with the spine.Ultrasound in such patients is a quick, non-invasive and sensitive method for confirmingthe diagnosis in order that the appropriatemanagement may be instituted promptly.

Case 1

A 58-year-old hypertensive Chinese woman onanti-hypertensive medication complained ofintermittent abdominal pain and abdominalswelling for six days, with no precipitating orrelieving factors. The pain was associated withconstipation and a decrease in appetite. Shesubsequently developed fever and dysuria.Examination revealed fever, a distended abdo-men with no palpable masses, and no shiftingdullness. Laboratory investigations were nor-mal. The clinical impression was possiblebiliary sepsis. Plain abdominal radiographrevealed a 1-cm rounded radio-opacitysuperimposed over the right L4 transverseprocess (figure 1A). Ultrasound revealed agrossly distended right pelvicalyceal systemcontaining echogenic material with no recog-nisable renal parenchyma. Multiple obstruc-ting calculi were seen at the right pelvi-uretericjunction (PUJ) (figure 1B) with multiple calculialso noted in the lower pole calyx. A rightpercutaneous nephrostomy yielded a total of141 of turbid urine and showed completehold-up of contrast by the right PUJ calculus

(figure 1C). The differential renal function ofthe right kidney was 12% and left kidney 88%by technetium-99 m dimercapto-succinate(DMSA) scan.The patient subsequently underwent a right

nephrectomy. Histology confirmed hydrone-phrosis, chronic pyelonephritis with severalsmall renal stones present in the lower polecalyx. The patient recovered well postopera-tively and is currently asymptomatic.

Case 2

A 73-year-old Chinese woman complained ofsudden onset of dull right upper quadrant painfor two days associated with nausea, vomitingand fever, but no urinary symptoms. Physicalexamination showed that the patient was feb-rile, with a distended abdomen and tendernessin the right upper quadrant. There were nopalpable abdominal masses. The clinical im-pression was acute cholecystitis. The white cellcount was raised to 17.5 x 109/1. Urinalysisshowed a large number of white and red cells,with no bacterial growth from urine culture.

Plain abdominal radiograph showed a leftstaghorn calculus but failed to demonstrate anyright urinary calculi due to bowel obscuration(figure 2A). Ultrasound of the abdomenrevealed a massively dilated right pelvicalycealsystem (30 cm in length) and proximal ureterwith echogenic debris in the collecting system.A 1.5 cm proximal right ureteric calculus wasseen as the cause of obstruction (figure 2B).Incidental finding of gallstones and a leftstaghorn calculus was also noted. A rightpercutaneous nephrostomy demonstrated amassively hydronephrotic right collecting sys-tem with complete obstruction by the uretericcalculus. A total of 1.6 1 of urine was drained,and the patient subsequently recovered fromher clinical symptoms. DMSA scintigramshowed a differential function of 91% for theleft kidney and 9% for the right kidney as wellas diffuse parenchymal loss on the right andpatchy focal defects on the left.The patient is currently being managed

conservatively with a view to possible nephrec-tomy should symptoms arise. Extracorporealshock wave lithotripsy and a double J stentinsertion for the left staghorn calculus havebeen scheduled.

Case 3

A 62-year-old Chinese man complained of areducible right groin lump which was intermit-

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Yang, Metreweli

A

Figure 1 (A) Plain abdominal radiograph shows asmall rounded opacity superimposed over the right L4transverse process (arrow). (B) Longitudinal ultrasoundscan through the right kidney shows a dilated pel-vicalyceal system containing echogenic material, and theobstructing PUJ calculus (long arrow). (C) Right per-cutaneous nephrostomy shows a massively dilated col-lecting system due to complete obstruction by the rightPUJ calculus (short arrow)

C

tently painful and had been increasing in sizeover six months. He denied any loin pain,haematuria or abdominal distension. Physicalexamination revealed a reducible right inguinalmass with a cough impulse. The patient wasobese and no abdominal masses were palpable.The clinical diagnosis was a right indirectinguinal hernia. Laboratory investigationswere normal. Plain abdominal radiographshowed a large soft tissue opacity filling the lefthemi-abdomen, with an ovoid radio-opacityprojected over the right L4 transverse process,and smaller rounded radio-opacities in the leftlower quadrant (figure 3A).Ultrasound of the abdomen showed gross

left hydronephrosis (more than 30 cm) exten-ding from the left flank to the right iliac fossa. A2.5 cm calculus was demonstrated in the prox-imal left ureter (figure 3B), corresponding tothe radio-opacity seen over the right L4 trans-verse process. Multiple small calculi were seenin the lower pole calyx with no residual leftrenal parenchyma seen (figure 3C). A DMSAscan showed differential renal function of100% on the right.A left nephrectomy was performed in view of

the left giant hydronephrosis causing increased

intra-abdominal pressure and a subsequentright inguinal hernia. The patient had anuneventful postoperative recovery.

Discussion

Giant hydronephrosis has been defined as akidney containing more than 1000 ml offluid inits collecting system.' The radiological diag-nostic criteria are a hydronephrotic renal pelvisthat meets or crosses the midline, occupies ahemi-abdomen and extends for a length of fivevertebrae or more.2 Since the first descriptionof giant hydronephrosis in 1746,3 more than180 cases have been described.4 With higherstandards of medical care giant hydronephrosisis now a rare urological entity, occurringpredominantly in children. The commonestcause is congenital PUJ obstruction whichoccurs in 80% of cases.",5 Other causes includeflap-like mucosal folds, polar or aberrantvessels, ureteric kinks and high pelvic inser-tions of the ureter. Giant hydronephrosis hasbeen reported in the literature,6-9 but little hasappeared regarding its occurrence in adultssecondary to calculous obstruction.Giant hydronephrosis is a slowly progressive

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Giant hydronephrosis

A A

I:B B

Figure 2 (A) Plain abdominal radiograph shows a leftstaghorn calculus (arrow) but no visible right urinarycalculi. (B) Longitudinal ultrasound scan of the rightkidney demonstrates a dilated pelvicalyceal system(arrowheads) containing echogenic debris, and an ob-structing right PUJ calculus (long arrow)

disease, and a huge abdominal mass ordistended abdomen may be the only sign. Theclinical features include an asymptomaticenlargement of the abdomen of long-standing,which may be preceded by a mass in eitherflank. The patient may present after minimaltrauma with flank pain, haematuria and some-times shock. It does not always progress, butmay increase in size rapidly and without warn-ing in adults. When this occurs, an underlyingrenal or pelvic carcinoma with haemorrhageinto the obstructed renal pelvis should beconsidered.2 Infrequently, it may present withrespiratory distress or intraperitoneal urinaryextravasation, particularly in infants withprimary obstructive mega-ureter.i0 Gross bi-lateral disease may cause uraemia. Giant hy-dronephrosis may fill the entire abdomen anddifferentiation of the condition from ascitesmay be clinically difficult. Erroneous diagnosis

Figure 3 (A) Plain abdominal radiograph shows alarge soft tissue opacity occupying the left hemi-abdomen. An ovoid radio-opacity is seen overlying theright L4 transverse process (arrow) with multiplerounded radio-opacities in the left lower quadrant(arrowheads). (B,C) Longitudinal ultrasound scans ofthe left kidney demonstate left hydronephrosis with theobstructing left PUJ stone (arrow), and multiple calculiin the left lower pole calyx (arrowheads)

may lead to paracentesis with the possibleconsequence of pyelonephrosis, urinoma, sep-sis or shock. The differential diagnosis

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412 Yang, Metreweli

Giant hydronephrosis: differentialdiagnosis

* ascites* intraperitoneal cysts (mesenteric or

choledochal)* retroperitoneal cysts (renal or adrenal or

pancreatic pseudocysts)* ovarian cysts/tumours

clinically includes intraperitoneal, and retro-peritoneal cysts, pancreatic pseudocysts, andovarian cysts/tumours (see box). Giant hyd-ronephrosis tends to be a flabby tumour, whilecysts generally maintain tension clinically.The most important aspect ofmanagement is

early diagnosis with accurate pre-operativedelineation of anatomy of the affected kidney.Historically, the correct pre-operative diag-nosis has been made in less than 5000 of cases."Tombari et al" reviewed 61 cases of surgicallyproven giant hydronephrosis and showed thatthe initial diagnosis was erroneous in 5400. Theinitial clinical diagnosis in our three patientswas also inaccurate. Ultrasound promptlyconfirmed the diagnosis in all patients whilstthe calculi were not readily apparent on plainradiographs in cases 1 and 2. Awareness of thiscondition by the clinician and radiologistwould enable prompt diagnosis and appropri-ate therapy.

Radiologically, there is displacement ofabdominal viscera to one side on the plainabdominal film or upper gastrointestinal series.Although the radiological hallmark has been alarge radiodense homogenous mass in theregion of the kidney that fails to registercontrast medium on an excretory urogram, wefind ultrasound to be a quick and sensitivemethod of establishing the diagnosis. Theclassical ultrasound features are a multi-septated cystic lesion with the 'cysts' com-municating with one another. The diagnosiscan be confidently made when communicationbetween the dilated calyces and pelvis is dem-onstrated, and the cause of obstruction, oftenan ureteric calculus, is shown on ultrasound, asin our patients. The potential pitfall duringultrasound is misdiagnosis as a multicysticdysplastic kidney, which is distinctly uncom-mon in adults, and more often diagnosed in thepaediatric population. The cystic spaces in thiscondition do not communicate with one an-other, producing the 'cluster of grapes' sign,and there is often contralateral renal abnor-mality.'2 Other less common misdiagnoses atimaging include retroperitoneal and ovarian

Giant hydronephrosis: features

Clinical* non specific.* huge abdominal mass or abdominal

distension, usually of long standing.* flank pain and/or haematuria after mild

trauma.Radiological* displacement of abdominal viscera to one side on

plain abdominal film, may visualise radio-opaqueurinary calculi as cause ofobstruction.

* large dense homogenous mass in the region of thekidney that fails to register contrast medium onan excretory urogram

* ultrasound shows a large multi-septated cysticlesion with communication demonstratedbetween dilated calyces and pelvis.

Giant hydronephrosis: summarypoints

* definition: a kidney containing more than 1 1offluid in its collecting system.

* radiological criteria: hydronephrotic renalpelvis that meets or crosses the midline,occupies a hemi-abdomen, and extends for alength of five vertebrae or more.

* in adults, often misdiagnosed clinically whensecondary to calculous obstruction

* plain radiographs may not provide an accuratediagnosis when there is obscuration ofradio-opaque urinary calculi by bowelshadows or overlap with the spine.

* ultrasound is a quick and sensitive method ofestablishing the diagnosis.

tumours, and dilated fluid-filled bowel loops.Once the suspicion of giant hydronephrosis

secondary to calculous obstruction has beenraised on ultrasound, isotope (DMSA) scan-ning is essential in the determination ofdifferential renal function. Management ofgiant hydronephrosis is surgical. Nephrectomyis the usual method of treatment, as there isoften very poorly functioning renal tissue.Nephrectomy rates, however, vary from30-7O/ .1,3 A two-stage procedure withgradual pre-operative decompression isadvocated to prevent possible cardiopul-monary collapse and alimentary tract dysfunc-tion which might be caused by sudden decreasein intra-abdominal pressure. A more conser-vative approach involving reconstructivesurgery (pyeloplasty) is generally reserved forthe younger patient, patients with bilateraldisease, or for kidneys with salvageable residualfunction.

1 Crooks KK, Hendren WH, Pfister RC. Giant hydroneph-rosis in children. J Pediatr Surg 1979; 14: 844-50.

2 Friedland GW, Filly R, Goris M, et al. (eds) Congenitalanomalies of the urinary tract. In: Uroradiology: an inte-grated approach. Vol 2. Edinburgh: Churchill Livingstone,1983, pp 1386-91.

3 Ochsner MG, Fuselier HA, Brannan W, et al. Congenitalgiant hydronephrosis in adults. Urology 1977; 10: 422.

4 Macksood MJ, James RE. Giant hydronephrosis in ectopickidney in a child. Urology 1983; 22: 532-5.

5 Uson AC, Levitt SB, Lattimer JK. Giant hydronephrosis inchildren. Paediatrics 1969; 44: 209-16.

6 Talukder BC, Chatterjee SC, Agarwal TN. Giant hy-dronephrosis. Br J Urol 1979; 51: 322-3.

7 Livine PM, Huben RP, Pontes JE. Transitional cell car-cinoma in a solitary giant hydronephrotic kidney. BrJt Urol1986; 58: 727-8.

8 Al Saleh BMS, Hadi AQ, Abdin MW. Giant hydro-nephrosis. Br J Urol 1992; 70: 686-7.

9 Morris SB, Dick JA. Ureteric obstruction secondary tocontralateral hydronephrosis. Br J7 Radiol 1994; 67: 100- 1.

10 Krane RJ, Retik AB. Neonatal perirenal extravasation. JUrol 1974; 111: 96.

11 Tombari AA, Power RF, Harper JM, et al. Giant hydro-nephrosis - a case report with review of the literature. J Urol1968; 100: 120-3.

12 Sanders RC, Hartman DS. The sonographic distinctionbetween neonatal multicystic kidney and hydronephrosis.Radiology 1984; 151: 621.

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