 Abstract | | |
Megaureter is a developmental anomaly of the ureter, which is associated with significant morbidity in children and frequently requires surgical intervention. I am presenting here a case of massively dilated ureters in a child that occupied almost the entire abdomen and was wrongly misinterpreted as a cystic lymphangioma due to its unusual presentation. Keywords: Megaureter, Cystic lymphangioma, Hydroureteronephrosis
How to cite this article:
Rastogi R. Giant Megaureters Presenting as a Multicystic Abdominal Mass. Saudi J Kidney Dis Transpl 2008;19:431-4 |
| Introduction | |  |
Developmental abnormalities of the ureter encompass a wide range of disorders. Ureteral anomalies are a common cause of morbidity in children and frequently require surgical intervention. Megaureters are an infrequent ureteral abnormality, and optimal imaging can diagnose it antenatally as well. However, undiagnosed megaureters may progress to occupy the whole abdomen, and impose diagnostic difficulties. The following case represents an uncommon form of megaureter that created a diagnostic challenge.
| Case Report | | |
A four-month-old child presented with a massively distended abdomen for further characterization and extent of the mass. Previous investigations included ultrasound (US) and computerized tomography (CT) scan, which revealed a large multicystic mass that was reported as cystic lymphangioma.
The child had a history of slowly progressive enlargement of the abdomen since birth. There was no history of any antenatal sonography.
The contrast enhanced CT scan of the whole abdomen revealed a large, multicystic, multiseptate mass occupying almost the complete mid and lower abdomen. The septae were in complete and no evidence of any soft tissue density was noted within the mass. The mass appeared to be in close relation with the bladder in the pelvis, [Figure - 1],[Figure - 2],[Figure - 3]. Close examination of the coronal and sagittal multiplanar reconstructed images of the scanned region illustrated bifid collecting system in the kidney bilaterally with normally functioning lower moiety and poorly functioning upper moieties. These images also revealed some sort of communication between the abdominal mass and the upper moieties of the kidney on either side.
Bladder was well distended with contrast on delayed images but was deformed with superior displacement of its base by the pelvic component of the abdominal mass [Figure - 3],[Figure - 4]. No evidence of free contrast was noted in the mass even on delayed images. Cine display of the images in the region of the mass revealed its tortuous nature. The rest of the organs in the scanned region appeared normal.
Detailed examination of the contrast enhanced CT images of the abdomen suggested the diagnosis of bilateral duplication of the collecting system and ureters with dysplastic changes in the upper moiety bilaterally and megaureter bilaterally.
The patient was then referred for the renal scan and MR imaging, but the patient's inadequate resources postponed them.
The patient was finally underwent surgical exploration that confirmed the radiologically suggested diagnosis.
| Discussion | | |
Megaureter is defined as an enlarged or a dilated ureter with or without dilatation of the renal pelvis and calyces. Megaureter is a sporadic or familial disease, [1],[2],[3] where males are more commonly affected than females, [4],[5] and the commonest cause is bladder outlet obstruction. [6]
Megaureters are classified as obstructed, refluxing, obstructed and refluxing, and nonobstructed and non-refluxing. Each category is further divided into primary or secondary. The term "primary" refers to a ureteral defect, whereas "secondary" refers to a pathologic process in another organ leading to dilatation of the ureter. Distinction among these different conditions is important, since treatment varies accordingly. Obstructive or refluxing hydroureter requires surgical correction, whereas nonrefluxing, non-obstructive megaureters can be managed expectantly.
In primary obstructive megaureter, the obstruction is at or just above the ureterovesical junction (UVJ) and is most commonly the result of an adynamic juxtavesical segment of the ureter that fails to effectively propagate urine flow. [7],[8],[9] Bilateral involvement is present in 20% of the cases with a male-to-female ratio of 4:1. The left side is more commonly affected. On the other hand, secondary obstructive megaureter results from a functional ureteral obstruction associated with elevated bladder pressures as with posterior urethral valve (PUV) or neurogenic bladder (NGB), that impede ureteral emptying.
Primary refluxing megaureter is due to a failure of the anti-reflux mechanism at the UVJ. Megaureter-megacystis syndrome is an extreme form of this type. Secondary refluxing megaureter occurs secondary to PUV and NGB when elevated bladder pressure causes incompetence of the UVJ.
Primary refluxing obstructed megaureter occurs in the presence of an incompetent VUJ that allows reflux through an adynamic distal segment.
Primary nonrefluxing non-obstructive megaureter, a diagnosis of exclusion, is an idiopathic dilatation above VUJ, while secondary non-refluxing non-obstructive megaureter is characterized by high rates of urine formation as in diabetes insipidus or infection, and ureters that remain wide open after spontaneous cessation of VUR.
Megaureter may be associated with unilateral renal agenesis, complete or incomplete duplex system, ectopic kidney, contralateral cystic and dysplastic kidney, horseshoe kidney, or Hirschsprung's disease. [5],[10],[11]
Progressive megaureter ultimately results in increasing hydroureteronephrosis, decrease in renal function of the involved kidney and development of urinary tract infection (UTI) or recurrent pain.
Suggested imaging studies to diagnose megaureters may include the following:
- Renal and bladder ultrasound is a first line imaging study to evaluate the upper and lower urinary tract.
- Voiding cystourethrogram (VCUG) is an essential evaluation of the lower urinary tract.
- Diuretic nuclear renography is an excellent study to objectively establish differential renal function and to evaluate the drainage efficiency of the dilated collecting system (i.e., washout times).
- Intravenous pyelogram (IVP) is a useful study as it delineates anatomy and provides subjective estimation of relative renal function. Contrast enhanced CT is definitely better than IVP in all respects.
- MRI is an excellent anatomical study to evaluate the rare cases when dysplastic non-functioning ectopic renal moieties or ectopic ureteral insertion are suspected.
Additional tests may include:
- Urodynamic studies (e.g., flow study, cystometrogram) assess voiding and bladder functional characteristics.
Diagnostic procedures that can be performed include:
- Cystoscopy, vaginoscopy and retrograde pyelogram allowing assessment of the genital and urinary tracts. Pressure perfusion studies (i.e., Whitaker test) measure differential pressures of the renal pelvis and the bladder.
Important differential diagnoses with megaureters include mesenteric and adnexal masses in females. These masses are usually round to oval in contrast to the tubular and tortuous shape of the megaureters. Furthermore, some of the septae in these masses are complete, which is not the case with megaureters. Dilated bowel loops are another important differential diagnosis but they can be differentiated from the megaureters by the fact that they may demonstrate peristalsis on sonography and have particulate matter (admixture of solid, liquid, and gas) in their lumen.
Surgical therapy is indicated for the megaureters that are secondary to severe VUR or obstruction, and it is usually managed with ureteral reimplantation. Occasionally, nephroureterectomy may be indicated, when, the function of the kidney is severely impaired by a megaureter.
| References | | |
| 1. | Mebust WK, Forest JD. Vesicoureteral reflux in identical twins. J Urol 1972;108(4):635-6.  |
| 2. | Mogg RA. Familial and adult reflux. Birth Defects 1977;8(5):365-6. |
| 3. | Stephens FD, Joske RA, Simmons RT. Megaureter with vesicoureteric reflux in twins. Aust NZJ Surg 1955;24:192. |
| 4. | Hanna MK, Jeffs RD. Primary obstructive megaureter in children. Urology 1975;6 (4):419-27. |
| 5. | Wood BP, Ben-Ami T, Teele RL, Rabinowitz R. Ureterovesical obstruction and megaloureter: Diagnosis by real-time ultrasound. Radiology 1985;156(1):79-81. |
| 6. | Hobbins JC, Romero R, Grannum P, Berkowitz RL, Cullen M, Mahoney M. Antenatal diagnosis of renal anomalies with ultrasound, I: Obstructive uropathy. Am J Obstet Gynecol 1984;148(7):868-77. |
| 7. | Gosling JA, Dixon JS. Functional obstruction of the ureter and renal pelvis: A histological and electron microscopic study. Br J Urol 1978;50:145. [PUBMED] |
| 8. | Tokunaka S, Koyanagi T. Morphologic study of primary nonreflux megaureters with particular emphasis on the role of ureteral sheath and ureteral dysplasia. J Urol 1982; 128(2):399-402. |
| 9. | Tokunaka S, Koyanagi T, Tsuji I. Two infantile cases of primary megaloureter with uncommon pathological findings: Ultrastructural study and its clinical implication. J Urol 1980;123(2):214-7. |
| 10. | Sant GR, Barbalias GA, Klauber GT. Congenital ureteral valves: An abnormality of ureteral embryogenesis. J Urol 1985;133 (3):427-31 |
| 11. | Swenson O, Macmahon E, Jaques WE, Campbell JS. A new concept of the etiology of of megaloureters. N Engl J Med 1952; 246 (2):41-6. |
Correspondence Address:
Rajul Rastogi
Consultant Radiologist, C-002, Upkari Apartments, Plot No.9, Sector 12, Dwarka, Delhi –110078
India
 Source of Support: None, Conflict of Interest: None  | Check |
PMID: 18445905 
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4] |
