Annals of the Royal College of Surgeons of England (1979) vol 6i
Duplication of the upper urinary tract Patrick Smith chM FRCS Michael Dunn chM FRCS Department of Urology, Royal Hospital for Sick Children, Bristol
Summary as a result of complete duplication a normal or The possibility of ureteric duplication should orthotopic ureter opens into the usual position always be considered in children presenting on the trigone and drains the middle and with urinary infection. A high degree of suspicion should be present during X-ray investigation. Surgery is nearly always required to cure the problem, vesicoureteric reflux requiring reimplantation and a ureterocoele involving both uncapping and reimplantation techniques. Heminephroureterectomy is rarely required except in cases of bizarre ectopic opening in which incontinence is the presenting feature and the associated renal segment is dysplastic. Ureteropyelostomy is required for the rare situation of saddle reflux in the bifid ureter of incomplete duplication. It is occasionally employed for complete duplication, but it must be stressed that the primary defect is always at the lower end of the ureter and such bypass surgery must be combined with a ureterectomy and, when necessary, reimplantation of the remaining ureters.
lower calyces, while the upper pole calyx drains into an abnormal or ectopic ureter which is inserted lower down on the trigone. Sometimes this insertion is even more ectopic, and in the male may be into the bladder neck, prostatic urethra, or even the vas deferens. In the female the ectopic opening may occur at the bladder neck, vagina, introitus, or even the perineum. In all cases of complete duplication, as a result of alterations in the positioning of the developing trigone, the ectopic ureter crosses behind the orthotopic ureter so as to open below the ureteric orifice of the orthotopic ureter. This is a constant feature of the surgical anatomy of this condition.
Developmental anatomy The caudal part of the Wolffian duct forms the common excretory duct which connects via a ureteric bud with the adjacent nephrogenic cord or primitive kidney. This common duct is divided into cranial, middle, and caudal sections corresponding to the developing bladder base, trigone, and posterior urethra respectively. A ureteric bud arising from the middle section meets the corresponding central section of the nephrogenic cord, which contains the main area of developing nephrons. The migration of these tissues results in a single ureter draining the kidney and opening on to the trigone, the usual anatomical arrange-
Introduction Approximately i o 7o of children are born with congenital anomalies of the urinary tract, of which duplication of the upper urinary tract is the commonest. In autopsy studies an incidence of i in I6o has been reported, but in a more accurate radiological review an incidence of i in 55 was detected'. There is an inheritance factor which is related to incomplete penetrance of a dominant gene, but genealogical studies are of no practical clinical importance and routine screening of families is an unjustifiable exer- ment.
When complete duplication occurs an extra ureteric bud develops. This may arise from the Anatomy middle section and eventually drain normal Duplication of the upper urinary tract may be kidney tissue into the trigone (Fig. 3). When complete or incomplete. Incomplete dupli- this extra ureteric bud arises from the cranial cation finds its simplest form in a bifid pelvis. or caudal segment, however, it connects with In the commonest anatomical situation arising relatively poorly functioning tissue and eventu-
Patrick Smith and Michael Dunn
ally opens at an ectopic site in the vesico- Investigations urethral canal (Fig. 2)3. In incomplete dupli- Routine urine culture, examination for haemocation a bifid pelvis arises by too early branch- globin, and renal function studies are essential ing of a single ureteric bud. in the initial investigation of each case. The next step is excretion urography. High-quality films are essential, and in addition nephroClinical presentation tomography with delayed views of drainage Duplication in adults is often a chance finding may be required to demonstrate the lesion. It on excretion urography. It is usually of no is important to remember that the renal segclinical significance. ment associated with duplication may be Recurrent urinary infection is the main poorly functioning and not immediately appresenting feature of problems associated with parent on the early films. The radiologist duplication in childhood, when the presence of should be advised of the possibility of dupliduplication greatly increases the risk of in- cation so that the urogram can be tailored fection. The underlying causes for this sepsis accordingly. As well as defining the nature of are the dual problems of reflux and obstruction. the duplication, urography will reveal evidence A
HIG. I (A) Wolffian duct zones shown in relation to nephrogenic area. Note direction of migration of kidney cranially and Wolffian duct into developing bladder. (B) Migration of Wolffian duct zones into bladder is completed. (C) Double ureteric buds arising from normal zone strike nephrogenic area and migration occurs in direction of arrows. (D) Duplex kidney with both orifices arising from normal zone in bladder. Kidney is normal. (Reproduced by permission from the Journal of Urology3.)
FIG. 2 (A) Ectopic bud arises from normal zone and strikes normal nephrogenic area. Orthotopic bud strikes diminished tissue and migration occurs. (B) After migration ectopic bud is arising from normal zone and kidney is normal. Ureter of orthotopic segment is too far lateral and kidney is abnormal. (C) Orthotopic bud arises from normal zone and strikes normal nephrogenic area. Ectopic bud arises too far laterally on Wolffian duct and strikes abnormal nephrogenic area. (D) After migration abnormal ectopic segment has its orifice arising from caudal zone and normal orthotopic segment arises from normal zone. (Reproduced by permission from the Journal of Urology3.)
Duplication of the upper urinary tract of upper tract damage. It may also show the presence of a ureterocoele, which is often apparent as a negative shadow on the cystogram phase. Micturating cystourethrography will reveal the presence of reflux. Such reflux is usually confined to the orthotopic ureter, whereas obstruction due to a ureterocoele is almost invariably associated with the ectopic ureter. An ectopic ureter at or below the bladder neck normally shows as an obstruction, but there may also be reflux and cystography will sometimes reveal this poorly functioning segment when excretion urography has failed. Cystoscopy is of help in defining the precise anatomical situation of the ureteric orifices in the bladder and their relation to the vesicourethral canal. Occasionally cystoseopy combined with the use of methylene blue may help in defining the opening of an ectopic ureter, though often the concentrating power of the renal segment associated with such a ureter is poor and the dye is therefore not easily identified.
FIG. 3 Duplex ureters and associated urinary tract anomalies in ioo children. (Reproduced by permission from the Journal of Urology4.)
minal portion of both ectopic and orthotopic ureters bound together in a common fascial sheath. It may be difficult to dissect free the terminal segment of the refluxing ureter without endangering both its own blood supply and that of the non-refluxing ectopic ureter. Reimplantation techniques therefore require that both ureters are mobilised and reimplanted together in the same submucosal tunnel5.
Treatment It must again be stressed that the presence of When it is considered that the renal segduplication of the upper urinary tract is not ment involved is too diseased to be conserved in itself pathological and as such requires no a nephroureterectomy must be performed. It treatment. is insufficient to remove the kidney alone since Treatment of complications associated with the refluxing stump of the ureter will cause duplication of the urinary tract is directed towards control of infection and relief of ob- problems. The heminephrectomy stage of the struction or reflux so as to preserve renal func- operation is usually simple since the duplex tion. Occasionally relief of incontinence due kidney has an easily identifiable waist with to an ectopic opening may be the only reason separate vessels which can be divided without risk to the remaining functioning segment. for surgery. There are four main conditions which can Care is necessary in the ureterectomy part of arise in association with duplication and may the operation as damage can be caused to the require treatment. These are reflux, uretero- terminal portion of the non-refluxing ectopic coele, ectopic opening, and saddle reflux4. ureter. The refluxing orthotopic ureter should Figure 3 demonstrates a typical percentage be divided as close as possible to the bladder. The ectopic ureter and any remnant of orthodistribution of these complications. Antibiotic therapy is initially indicated in topic ureter are now mobilised and the orthothe presence of infection but this is seldom topic 'stump' divided along its lateral border, sufficient to cure the condition because of the laying it open in such a way that it can be wrapped around the ectopic ureter, which is severity of the anatomical abnormalities. then reimplanted. When the degree of ureteric dilatation associated with the reflux makes a REFLUX Primary vesicoureteric reflux usually occurs in- reimplantation technique difficult a ureteroto the orthotopic ureter owing to its short in- pyelostomy between the refluxing ureter and tramural and submucosal course (Fig. 4). The the pelvis of the ectopic segment can be perdevelopment of duplex ureters leaves the ter- formed. The remaining ureter is then excised
Patrick Smith and Michael Dunn
FIG. 4 (A) Intravenous pyelogram showing normal function and drainage from upper moieties but poor function on the right and non-function on the left in the lower moieties. (B) Cystogram on same patient showing bilateral vesicoureteric reflux, worse on left.
also relieve any obstructive effect on the ipsilateral orthotopic ureter or even, in the case of a large ureterocoele, the contralateral ureter (or ureters). Removal of a large ureterocoele will also relieve any concomitant obstruction at the bladder neck or, particularly in young girls, the urethra. However, uncapping of the ureterocoele produces reflux in the ectopic ureter and may predispose to reflux in the other ureters, especially the ipsilateral orthotopic ureter. Because of this problem simple uncappingfor example, by the transurethral route-is of little value other than as an emergency procedure to relieve obstruction6. The correct apECTOPIC URETEROCOELE proach is a transvesical uncapping of the This is an intravesical fusiform dilatation of ureterocoele combined with antireflux surthe lower end of a ureter almost always asso- gery. The ectopic ureter associated with the ciated with the ectopic ureter draining the ureterocoele will require reimplantation toupper moiety (Fig. 5). Uncapping of a uretero- gether with, for the anatomical reasons stated coele will immediately relieve the obstruction above, its partner, the orthotopic ureter. Either which is the pathological feature of this con- by preliminary cystoscopy or direct inspection dition. The collapse of the ureterocoele will at operation it should be possible to decide as described above with, if necessary, 'obliteration' of the terminal stump and reimplantation of the ectopic ureter. Rarely it may be difficult to decide whether the degree of function in the affected renal moiety is worth preserving. In these cases consideration can be given to a temporary ureterostomy. Any improvement in renal function can then be assessed and subsequently conservative or radical surgery performed. In practice, ureterostomy presents its own problems and it is best to make a firm decision on conservative or radical surgery early on and not to expose the child to excessive surgery.
Duplication of the upper urinary tract
to leave a small portion of the terminal segment of ectopic ureter which is opened out and wrapped around the orthotopic ureter before its reimplantation.
A high ureteropyelostomy may be used to bypass the obstruction, but again the collapse of the ureterocoele following this defunctioning procedure may result in reflux occurring into the orthotopic and possibly contralateral ureters. Any pyeloureterostomy should therefore be combined with excision of the ureterocoele and residual distal non-functioning ureter together with any necessary antireflux procedures. Temporary ureterostomy is occasionally used, but as with reflux it is best not to rely on this sometimes complicating procedure. ECTOPIC URETER
An ectopic ureter, particularly on, openinig at or below the bladder neck, is almost invariably associated with a poorly functioning renal segment. Indeed, in many cases this part of the urinary tract consists of a column of stagnant urine with a dysplastic kidney above. Excision of such an ectopic segment is the treatment of choice. The heminephrectomy is relatively straightforward, but care needs to be taken with excision of the ureter, particularly FIG. 5 Minor degree of ectopic ureterocoele associated when this is associated with the sphincter syswith ureteric duplication. tem, especially in the female. In certain cases it is sometimes better to leave a small stump whether the contralateral ureter also requires of terminal ureter rather than risk any subreimplantation. If in doubt it is best to assume sequent incontinence. that reflux will occur and to proceed to reimplantation. INCOMPLETE DUPLICATION In many cases the ureterocoele is associated In rare cases of incomplete duplication with a large defect in the muscle of the bladder. 'saddle' reflux may occur owing to difference in This defect must be repaired so as to provide the pressure between the two segments. Usually the higher pressure and hence the greater flow a good muscle backing to the reimplanted ureter7. The posterior layer of mucosa of the comes from the lower moiety and urine will ureterocoele is also preserved so as to provide therefore reflux back into the upper moiety. This may occasionally cause loin pain. Diagthe tunnel for reimplantation. difficult, but either screening Occasionally the renal segment associated nosis may be diuretic or isotope renography will pyelography with a ureterocoele may be too damaged to be In such cases a ureterothe condition. worth preserving. In this case a nephro- confirm the upper pole anastomosing pyelostomy ureterectomy should be performed. The hemiwill solve the lower pelvis the to pole ureter nephrectomy is usually straightforward, but reflux is likely to occur in the orthotopic seg- problem. ment following collapse of the ureterocoele, We would like to express our thanks to The Wiland antireflux surgery may be necessary. Since liams and Wilkins Co., Baltimore, Dr D Barrett and total excision of the ectopic ureter and its ure- his co-workers, and Drs G Mackie and F D Stephens terocoele can be difficult it may be necessary for permission to publish Figures I, 2, and 3.
Patrick Smith and Michael Dunn
References Privett, J T J, Jeans, W D, and Roylance, J (I976) Clinical Radiology, 27, 52I. 2 Atwell, J D, Cook, P L, Howell, C J, Hyde, I, and Parker, B C (I 974) Archives of Disease in Childhood, 49, 390. 3 Mackie, G C, and Stephens, F D (I975) Journal of Urology, II4, 274. I
4 Barrett, D M, Marek, R S, and Kelalis, P P (I975) Journal of Urology, I I4, I 26. 5 Johnston, J H, and Heal, M R (I97I) Journal of Urology, 105, 88i. 6 Johnston, J H, and Johnson, L M (I969) British Journal of Urology, 4I, 6i. 7 Williams, D I, and Woodward, J R (I964) Journal of Urology, 92, 635.
CORRECTIONS We regret that three errors occurred in Mr Selwyn Taylor's Sidney Weiner Lecture on 'The surgical treatment of thyroid disease in modern perspective' as published in the March issue of the Annals: Page 133, ist column, line 42: for 'those taking thyroxine' read 'those not taking thyroxine'. Page I35, Ist column, line 23: for 'MEA2' read 'MEA2b'. Page I35, 2nd column, lines 35 and 36: for 'some patients whose disease remits' read 'some patients whose disease never remits'.