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MEGA-URETERBy D. INNES WILLIAMS, M.D., M.CHIR., F.R.C.S.

Surgeon, St. Peter's and St. Paul's Hospitals; Genito- Urinary Surgeon, The Hospital for Sick Children,Great Ormond Street and Whipps Cross Hospital

The term mega-ureter is used to describe statesof chronic dilatation of the ureter for which noorganic obstructive cause can be found; it impliesan ignorance of the fundamental pathology and itis hoped that it will be replaced in time by amore enlightened nomenclature; at present it iseasier to say what mega-ureter is not than what itis and certainly more than one disease is includedunder the heading. The chronic dilatations whichaccompany congenital malformations such asureterocele, ureteric ectopia and congenital stric-ture are not, by definition, included in the categoryof mega-ureter, though it may well prove thatsimilar causes of dilatation are operative in theseconditions. Dilatations secondary to congenitalurethral obstructions and vesical retention, on theother hand, are also excluded but show a markeddifference in behaviour from the mega-ureter.The degree of ureteric dilatation is estimated in

ordinary practice from X-rays and it is importantto recognize the limits of normal variation as wellas different appearances which are presented bydifferent methods of filling. The intravenouspyelogram seems to involve least disturbance ofnormal conditions and is probably the most satis-factory method of delineation, though it is ofteninvalidated by the deterioration of renal function.Nevertheless, the ureter becomes wider as theurine flow increases and since the opaque mediumitself produces an osmotic diuresis, the ureter willappear more dilated in the later films of the seriesthan the earlier. In conditions of extreme poly-uria, as in diabetes insipidus, the normal ureterwill reach proportions comparable with the mega-ureter and yet still be capable of efficient function.In retrograde pyelography, the distending force isto some extent under the control of the operator,yet the presence of the foreign body and thestimulus of the injection result in a forceful con-traction and, in most cases, a ureter will appearless dilated in the retrograde than in the intra-venous series. Finally, when uretero-vesical refluxis present and ureteric filling occurs during amicturating cystogram, the distending force is

very considerable; under such circumstances aureter which is normal on intravenous pyelogramsmay appear grossly dilated. In assessing progressof an individual case, it is therefore vital to ensurethat the films at various periods are strictlycomparable.The effects of acquired disease are not always

easy to distinguish from the congenital mega-ureter; it is recognized that infection can beresponsible for some ureteric dilatation, but con-fusion arises from the fact that mega-ureter isfrequently complicated by infection. When alarge calculus is present in the renal pelvis, it iscommon to find some dilatation of the lumbarureter beneath it; this may be due to infection orto a disorder of ureteric activity consequent uponthe pelvi-ureteric obstruction, but it is in anacquired lesion and not a form of mega-ureter.Slight dilatation of the whole length of the ureteris also a feature of many cases of congenital hypo-plasia of the kidney with chronic urinary infection.Infection and cystitis with oedema of the uretericorifice interfere with the normal valvular actionof the uretero-vesical junction and reflux maytherefore occur; it sometimes happens in a case ofchronic urinary infection in which the intravenouspyelogram shows only minimal dilatation, that acystogram demonstrates reflux into grossly dilatedureters. In these cases it is possible that somecongenital abnormality is present, yet the prog-nosis appears to be good if the urine is keptsterile and no permanent dilatation is seen despite-the ready distensibility during micturition.

The Mega-Ureter-Megacystis SyndromeIn one of the syndromes associated with mega-

ureter, the bladder shows a characteristic disturb-ance of function, distinct from, though sometimesconfused with, the results of urethral obstruction.,The pathology of this syndrome is still unex-plained and the term mega-ureter-megacystis istherefore only a convenient description. Thedisorder usually presents early in childhood andaffects both sexes equally.

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,6o0 POST'GRAD)UA'T'E M1EMI)ICAL JOUItNAI, Aarch 1958Pathology

Bilateral ureteric dilatation is present, often atbirth, and may reach extreme proportions;vesico-ureteric reflux is usually free though insome it occurs only during micturition and activeretrograde peristalsis has been observed in theseureters by cine-radiology. The bladder is oflarge capacity, but there is little evidence ofdetrusor hypertrophy and never more than aslight trabeculation; the bladder neck and urethraare normal. It has been claimed by Swensonet al. that the number of ganglion cells in thebladder wall is diminished in this condition andthat it is analogous to, indeed sometimes asso-ciated with, Hirschsprung's disease. This asso-ciation has not been observed in any case at theHospital for Sick Children and in two post-mortem examples of megacystis a careful count byDr. Leibovitz has shown a normal ganglion cellpopulation.

Clinical, Cystoscopic and Radiological FeaturesThe majority of children present with persistent

or recurrent urinary infection, often with someimpairment of renal function. In the older casesit has often been noticed that the child passesurine rather infrequently but passes a largevolume at a time; moreover, on trial it will befound that a second and third micturition ispossible a few minutes after the first. Radio-logically it can be demonstrated that this is dueto the reflux of a large volume of urine into theureters with each bladder contraction: the bladderempties itself at each micturition, but as soon asit relaxes it is filled again from the distendedureters, leading to a ' false ' residual urine. Thisis in sharp contrast with the true residuum foundin the obstructed bladder, but unless doublemicturition is tried, the two are easily confusedand often at first examination children with themega-ureter-megacystis syndrome are suspectedof bladder-neck obstruction. A further difficultyarises from the fact that after instrumentation orduring a severe infection there may be a temporaryphase of true retention.

Intravenous pyelograms show the ureteric dila-tation provided renal function is adequate, cysto-grams show it more clearly (Fig. i). On cystoscopythe large bladder capacity will be noted, althoughtrabeculation is absent or slight. The uretericorifices usually gape widely, so widely in fact thatexcept for their obliquity they resemble theorifices of diverticula and the urethroscope caneasily be introduced into them. A characteristicmotility is also observed, the ureter is widelydilated at rest but exhibits from time to time apowerful contraction which, however, only obli-terates the lumen at the ureteric orifice. A cysto-

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FIG. i -Mega-ureter-megacystis syndrome. Cysto-gram with reflux in a girl aged 5 years, with a longhistory of general ill-health, vomiting, and nocturnalenuresis. Bladder usually palpable after micturi-tion, but cine radiology shows this to be falseresidual due to return of urine which had refluxedinto ureters. On cystoscopy, the bladder wall wassmooth, but the ureteric orifices were widelydilated. Ureteric contractions active but in-effective.

metrogram performed with slow filling willdemonstrate the large bladder capacity; often achild of 6 or 7 years will hold 900-I,000 ml. andthe intravesical pressure will rise only towardsthe end of this filling. In spite of this capacity,active contractions are still capable of emptyingthe bladder.

Differential DiagnosisThe differentiation from simple mega-ureter is

made without difficulty from the observation ofthe large bladder and the gaping ureteric orifices.Congenital bladder-neck or urethral obstruction,however, can also produce an increased capacityand ultimately reflux into dilated ureters, and thefollowing points must be noted in diagnosis: Firstof all, severe obstructions are common in boysbut rare in girls, the megacystis affects bothsexes equally and therefore a girl is more likelyto be suffering from the latter. Trial of doublemicturition will often distinguish the true from

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the false residual urine, and whereas overflowNincontinence is common in obstruction it is rarein megacystis. Cystoscopy in the obstructedb-ladder will show heavy trabeculation and saccu-lation, wvhile even if the ureteric orifices areincompetent they are usually surrounded byhypertrophied muscle and cannot become widelydilated; bladder-neck hypertrophy and sometirethral lesioni are also likely to be found. rhebladder capacity in cystometry is not so enormousin the obstructed case as in the megacystis anidpressure rises more rapidly. When an advanceddilatation of the ureter with reflux is due toobstruction, peristaltic activity is usually absentor minimal, whereas the mega-ureter retains theability to make forceful although ineffectivecontractions.

TreatmentIn mild cases, which are the majority, steriliza-

tion of the urine by chemotherapy and a regimeof double or triple micturition suffice to preventany further progress of the disease. The childshould be induced to empty the bladder at leastevery three hours by day and preferably once atnight, and the emptying process should always becompleted by a second and, if necessary, a thirdmicturition after each initial attempt. A singlecourse of chemotherapy may be enough or con-tinuous treatment with small doses may berequired. Deterioration can be due to pyelo-nephritis, a progressive renal scarring independentof the urinary stasis or to a gradual loss of efficientbladder emptying. In the latter circumstances abladder-neck resection or an anterior Y-V-plastyat the vesico-urethral junction may lead to animprovement and enable the double micturitionregime to be carried out more efficiently. Opera-tions designed to prevent reflux or narrow theureters by plastic reduction are still experimentalin this syndrome and not of proved value. Sym-pathectomy is unlikely to be helpful.

Simple Mega-UreterMega-ureter associated with a bladder of

normal capacity and function may be unilateralor bilateral, it occurs in both sexes and althoughit may be present in childhood, many are onlydiscovered in adolescence or adult life.

PathologyIn most the whole length of the ureter is dilated

down to the intramural portion which is of normalcalibre. Occasionally a sudden and unaccount-able narrowing occurs a short distance above thebladder, but the ' narrow' segment does notshow any evident abnormality and in bilateralcases the supravesical narrowing may be present

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FIG. 2.-Simple mega-ureter (solitary kidney). Intra-venous pyelogram on girl aged 7 years, wvho hadsuffered a single attack of urinarn infection. Milddilatation of the lower end of the left ureter. Nokidney found on the right side. The conditionwas entirely unchanged and the child symptom-free two years later.

on one side only. The muscle of the dilatedportion is always hypertrophied, and until thelatest stages remains actively contractile. It haslong been suspected that a ' functional' obstruc-tion must be present at the lower extremity andMurnaghan has recently suggested that there isan abnormality in the distribution of musclefibres which causes a contraction wave to beinitiated at the lower end, to travel upwards andto obstruct the normal downward flow of urine.

Clinical, Radiological and Cystoscopic FeaturesMost cases present with recurrent or persistent

urinary infection and have only slight loin painas a localizing symptom. In cases with sterileurine, there may be some lateral abdominal pain,but this seldom comes in such severe spasms asthe pain of hydronephrosis due to pelvi-ureteric

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obstruction. Haematuria has occurred as anisolated symptom in some, and although this maysuggest the presence of a stone it is not alwayspossible to find one. Nevertheless, secondarycalculi in the dilated segment are relativelycommon in both sterile and infected cases.The intravenous or retrograde pyelograms

demonstrate the ureteric dilatation for which noother causes can be found. The bladder isnormal on cystoscopy and cystometry, and theureteric orifice is either entirely normal or appearsto be raised on a small pyramidal eminence.Although this appearance may be confused withthat of a ureterocele, it is quite distinct and morein the nature of a slight prolapse which can infact be reduced at operation by pulling on theureter. A ureteric catheter passes easily into theorifice and carefully directed X-ray films willshow whether the dilatation reaches down to thebladder wall or ceases above (Fig. 2). Vesico-ureteric reflux is not usual in these cases and it isnever as free as in the mega-ureter-megacystissyndrome, but a little regurgitation may occurduring micturition.

Differential DiagnosisCongenital or acquired stricture is distinguished

by the obstruction to the passage of a uretericcatheter and most other congenital uretericanomalies produce distinctive radiological andcystoscopic appearances. In bilateral simplemega-ureter, the normality of the ureteric orificesand normal bladder capacity differentiate frommega-ureter-megacystis. When stones are present,it is important to judge whether they are primaryor secondary; in the mega-ureter a complicatingcalculus is usually rounded and freely mobile upand down the ureter.

TreatmentIn most cases, whether unilateral or bilateral,

the urine can be sterilized by chemotherapy andoften no further treatment is required. Suchcases have been carefully followed up for tenyears and over, and have neither suffered anysymptoms nor shown any increase of dilatation.

In advanced unilateral cases with renal damageand possibly calculi as well, nephro-ureterectomyis the treatment of choice.

In bilateral cases where there is persistent

NIPPLE

RE-IMPLANTATION

Ni

Fic. 3.-Diagram to show the method of 'nipple're-implantation of the ureter into the bladder.

infection, increasing dilatation or stone formation,and in a few unilateral cases with similar signs buta well-preserved kidney, the uretero-vesical junc-tion should be excised and the ureter re-implantedinto the bladder in such a manner as to preventuretero-vesical reflux. This is best accomplishedby turning the severed end back on itself forI-2 cm. and implanting it high into the bladderwith this projecting nipple (Fig. 3). Where thereis a supravesical narrow segment, the same tech-nique may be employed or the actual cone andsite of the narrowing may be excised and the twoends of the ureter rejoined by an end-to-sideanastomosis.

Plastic reduction and straightening of the kinksin a very dilated and tortuous ureter may beperformed at the same time as the re-implantationor an enormous organ may be better replaced bya loop of ileum.When there is any suggestion of a stricture at

the lower end of the ureter, instrumental dilatationis worth a trial.

BIBLIOGRAPHYWILLIAMS, D. I., BODIAN, M., EDWARDS, D., LEIBO-

VITZ, S., and MURNAGHAN, G. F. (I957), Brit. Y. Urol.29, 389.

SWENSON, 0. (1955), Arch. Dis. Childh., 30, 1.

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