British Journal of Urology (1976), 41, 781-787 0
A Simple Classification of Wide Ureters ROBERT H. WHITAKER
and
J. H. JOHNSTON
Departments of Urology, Addenbrooke's Hospital, Cambridge and Alder Hey Children's Hospital, Liverpool
There can be few topics in urology which are more confused or confusing than that of the abnormal ureter. As a result, rational discussion on the management of such lesions is almost impossible unless it is made quite clear which abnormality is present. Efforts have been made to classify abnormal ureters but generally they have failed to clarify the situation because they have been either too simple or unnecessarily complex. Also, the basic distinction between the refluxing and the non-refluxing ureter has often been ignored. We wish to discuss the problems of classifying ureters in the light of the numerous efforts reported in the literature and to set out an alternative classification which hopefully incorporates the best features of some of them and at the same time excludes the confusing aspects. We feel it is time for a classification which is internationally acceptable. The Problem 3 factors make a new classification desirable. Firstly, there are now too many terms which convey different pathological entities to different observers (Fig. 1). Secondly, the need to distinguish between a refluxing and a non-refluxing ureter has been highlighted by the increasing and now well established awareness of the problems of reflux. Thirdly, a newer concept, but of paramount importance in terms of management, is the need to diagnose accurately the presence or absence of obstruction in the wide non-refluxing ureter. It is not our intention to criticise all previous attempts at classification but it is necessary to analyse some aspects of them to rationalise a new approach.
megau ret er ?
megaloureter?
aperistaltic?
Fig. 1. The problem.
781
782
BRITISH JOURNAL OF UROLOGY
For instance, in his text book, Campbell (1970) discusses the Primary Megaloureter as an example of congenital dilatation of the upper tract and lists possible aetiological factors. He accepts, rightly in our opinion, that not all such ureters are obstructed but suggests that reflux is usually present. Hence, he is using this term for too large a group of abnormal ureters which includes both the refluxing and non-refluxing types. Hinman (1 970) prefers the term Hydroureter for the wide non-refluxing ureter and argues that all dilatation of the ureter is due to obstruction. We would beg to differ with this view. Many early classifications are much less specific and give two broad categories of congenital and acquired aetiologies. Others (Culp, 1967) make a distinction on anatomical or embryological lines. Williams (1 970) provides a realistic approach. He distinguishes clearly between refluxing and non-refluxing ureters and then categorises the wide non-refluxing ureter into groups according to the following pathogenic factors: Polyuria ; Bacterial toxins ; Obstruction (stricture, atresia, associated saccule); Obstructive megaureter; Dilated ureter with bladder outflow obstruction; Dysplasia with or without renal impairment. Although this classification has much to recommend it, it fails in the light of present knowledge to clarify the group of what Williams calls (Primary) Obstructive Megaureters (Williams and Hulme-Moir, 1970; Williams, 1974). The word obstructive suggests that it is the ureter, perhaps because of its width, which causes the obstruction and indeed this may sometimes be the case (Whitaker, 1975) but many feel that the dilatation is due to an abnormal lower ureteral segment in which case the term should be obstructed ureter. However, more important is the fact that the concept of obstruction is used too loosely in connection with this type of ureter. This is not just a quibble with the nomenclature but has a major clinical implication now that obstruction can be accurately assessed (Whitaker, 1973). Having used the expression Primary Obstructive Megaureter Williams begs the question of its usage by quoting his own findings of occasional spontaneous improvement in the appearances of such ureters with conservative treatment only (Williams and Hulme-Moir, 1970). He also accepts the findings of Backlund and Reuterskiold (1969) that low ureteric pressures may sometimes be demonstrable on perfusing such ureters. Both these findings are incompatible with a significant degree of obstruction. Furthermore, Heal (1973), using the same unfortunate termPrimary Obstructive Megaureter-showed that in 10 of 15 adults the pyelographic appearances remained unchanged, a feature again incompatible with a significant degree of obstruction. This suggests that Wide non-refluxing ureters come in varying degrees of obstruction. Those presenting early in life are naturally more likely to be obstructed. Johnston (1967), who termed these ureters Functionally Obstructed Megaureters found considerable improvement following re-implantation in children whilst Heal (1973) was seeing adults at the other end of the range with very mild or absent obstruction. Belman’s classification (1 974) fails to distinguish adequately between the obstructed and nonobstructed “primary megaureter” and some authors (Hodgson and Thompson, 1975) are still erroneously stating that “megaureters” are either refluxing or functionally obstructed and ignore the concept of a non-obstructed, non-refluxing wide ureter. Finally, there is the problem of confusing terms. This is often because attempts are made to indicate the aetiology of the defect as well as an anatomical description. The word dilated, for instance, implies that the ureter was once of normal calibre, which is clearly not always so as in the prune belly or megaureter-megacystis syndromes. The term Hydroureter has little to recommend it and to some it implies a high pressure within it. Megaureter has been used for so many
783
A SIMPLE CLASSIFICATION OF WIDE URETERS
STASIS + OBSTRUCTIO?I
STASIS
STASIS REFLUX
WIDE
-
PRIMARY
SECONDARY
Fig. 2. The 3 possible complicating factors in wide ureters.
i
URElER
PRIMARY
SECONDARY
A
NON OBSTRUCTED
-3
OBSTRUCTED
I Fig. 3. The proposed classification. The numerals indicate an empirical range of degrees of obstruction.
conditions with and without reflux and bladder outflow obstruction that it cannot now be usefully salvaged for a new classification. Primary and secondary are important terms and need careful definition. It is with this background of confusion that the following classification is proposed. A New Classification The term we believe to be the most acceptable for an abnormally wide ureter is simply wide. The purely descriptive term suggested by Backlund and Reuterskiold (1969) is anatomically and radiographically accurate and makes no effort to indicate the aetiology. The clinical implications of such a wide ureter are threefold (Fig. 2). First to be considered is the problem of stasis alone. In the absence of reflux or obstruction the mere presence of a large volume of urine in the upper tract may lead to repeated or continuous infection. Ureteritis appears to be an important factor in causing the ureteric widening often seen when there are infected stones in the renal pelvis; following removal of the stones and elimination of the infection the ureter promptly returns to normal. Secondly, there is the problem of obstruction which will lead not only to stasis with its risks of infection but also to back pressure on the kidney and deterioration in renal function. Thirdly, reflux may be present and the consequences of this are well known. It is on these 3 factors that the classification is based (Fig. 3). Firstly, wide ureters either show or do not show vesico-ureteric reflux and from the point of view of management we consider this distinction to be of paramount importance, although Hendren (1975) believes otherwise. It is often implied and indeed has been repeated recently (Hodgson and Thompson, 1975), that if a wide ureter is not showing reflux then it must be obstructed; this is a misconception which is hard to dispel.
784
BRITISH JOURNAL OF UROLOGY
Fig. 4. Primary refluxing ureters. (a) Massive neonatal reflux. (b) the more usual type of reflux (cystograms).
Secondly, the 2 groups of refluxing and non-refluxing ureters can be subdivided into primary and secondary. The term primary is used if the bladder functions effectively at normal pressures. If reflux is present such ureters can be conveniently subdivided into the massively refluxing type seen usually in the neonatal period (Fig. 4a) or the more conventional and less dramatic type of reflux seen in children of a much wider age group (Fig. 4b). A third category of primary reflux would include ureters in patients with a general dysplasia of the urinary tract such as the prune belly or megacystis-megaureter syndromes. Secondury means that there is, or has been a temporary or permanent high pressure in the bladder which has either caused or exacerbated the abnormality of the ureter. The most obvious example of this is the wide ureter which is seen with prostatic obstruction in men or with urethral obstruction in young boys with posterior urethral valves. In either situation reflux may be present and is probably caused by a “blowing-out’’ of the uretero-vesical junction by the high pressure within the bladder. Ureteric dilatation then occurs by the transmitted intravesical pressure. Alternatively, the uretero-vesical junction may retain its competence but the high pressure within the bladder may make it difficult for the ureter to empty and the result again is an increase in the width of the ureter. The final distinction in the classification is whether or not obstruction is present at the ureterovesical junction. It is this factor and the difficulty until recently in making a definite diagnosis of obstruction in a wide upper tract which has led to most of the confusion. We have already suggested that not all wide, non-refluxing ureters are obstructed and from a clinical management point of view it is all important to make this basic distinction. It cannot be overemphasised that unnecessary operations undertaken on the mistaken assumption that an obstruction exists are fraught with danger and disappointment.
A SIMPLE CLASSIFICATIONOF WIDE URETERS
785
Fig. 5. Primary obstructed non-reflexing wide ureter. Intravenous urograms showing wide right ureter. (a) Before operation, and (b) 1 year after tapering and re-implanting.
Obstruction in the wide non-refluxing ureter, if present, can be due to primary or secondary causes as defined above. For instance, a defect in the uretero-vesical junction which prevents adequate emptying in the presence of a normal bladder is termed primary (Fig. 5a and b). This ureter has been termed primary (idiopathic), obstructed(ive) megaureter. More accurately, if rather more cumbersomely, it should be termed a primary obstructed, non-refluxing wide ureter. Although long-winded there is no doubt what is meant by this term. If the outflow from the bladder is obstructed either functionally, as in a neurogenic bladder, or anatomically, as in prostatism or posterior urethral valves, there is usually no actual obstruction at the uretero-vesical junction and relief of the bladder outflow obstruction will lead to resolution of the upper tract dilatation (Fig. 6a and b). This is a secondary non-obstructed, non-refuxing wide ureter. However, sometimes there can be such hypertrophy of the detrusor around the intramural ureter that even after relief of the raised bladder pressure the ureter still cannot drain satisfactorily. This is termed secondary obstruction and the ureter is a secondary obstructed, nonrefuxing wide ureter. If after resection of posterior urethral valves there is a deterioration in urographic appearances or renal function this type of ureter is suspected but it is a simple matter to prove it with a perfusion test. The term secondary must be kept strictly for the ureter associated with an “obstructed” bladder and not used for compression of the ureter by vessels, tumour or stone. Obstruction is, of course, relative and we suggest that there is a whole range of non-refluxing ureters which are variously obstructed from almost not at all to grossly and it is in this grey area of equivocal obstruction that the perfusion (pressure/flow) studies are so helpful (Whitaker, 1973). This classification can be extended to include any type of abnormal ureter although this can easily become an academic exercise and of limited clinical applicability.
786
BRITISH JOURNAL OF UROLOGY
Fig. 6. Secondary non-obstructed non-refluxing wide ureters. Boy with posterior urethral valves treated by endoscopic resection of valves only. Intravenous urograms. (a) A t age 4 months, before operation. Cystogram showed no reflux. (b) At a e 9 years. There has been considerablespontaneous improvement in the dilatation and tortuosity op the ureters incompatible with a significant degree of uretero-vesical obstruction.
The main usefulness of this classification is in distinguishing between the various types of congenital anomalies which are seen so commonly in children and its adoption should see an end to many of the confusing terms such as megaureter, megaloureter, hydroureter and at least 10 other obsolete terms listed by Belman (1974).
Summary
A simple classification of abnormal ureters is presented which categorises the ureters according to the presence or absence of 3 factors, namely reflux, bladder outlet obstruction and ureteric obstruction. It has been devised to try to rid the literature of many confusing and obsolete terms and it is hoped that this new classification may become internationally accepted. References BACKLUND, L. and REUTERSKI~LD, A. G. (1969). The abnormal ureter in children. 1. Perfusion studies on the wide non-refluxing ureter. Scandinavian Journal of Urology and Nephrology, 3, 2 19-228. BELMAN,A. B. (1974). Megaureter. Classification, etiology and management. Urological Clinics ofNorth America, 1, 497-5 13. CAMPBELL, M. F. (1970). In Urology, 3rd ed., vol 2, ed. by M. F. Campbell and J. H. Harrison. Philadelphia: Saunders, p. 1534. CULP,D. A. (1967). Congenital anomalies of the ureter. Proceedings of the Third International Congress of Nephrology, Washington, 1966. Basel: Karger, 2, 65-82. HEAL,M.R. (1973). Primary obstructive megaureter in adults. Brifish Journal of Urology, 45,490-496. HENDREN, W.H. (1975). Complications of megaureter repair in children. Journal of Urology, 113, 238-254. HINMAN, F . (1970). In Urology, 3rd ed., vol 1, ed. by M. F. Campbell and J. H. Harrison. Philadelphia: Saunders, p. 341.
A SIMPLE CLASSIFICATION OF WIDE
787
URETERS
HODGSON, N. B. and THOMPSON, L.W. (1975). Technique of reductive ureteroplasty in the management of megaureter. Journal of Urology, 113, 1 18-120. JOHNSTON, J. H. (1967). Reconstructive surgery of megaureter in childhood. Brirish Journal of Urology, 39, 17-21. REUTERSKI~LD, A. G. (1969). The wide ureter: functional studies in children and dogs. Acta Universitatis Upsaliensis. Abstracts of Uppsala Dissertations in Medicine. Stockholm: Almquist and Wiksell, 76, 1-18. WHITAKER, R. H. (1973). Methods of assessing obstruction in dilated ureters. British Journal of Urology, 45, 15-22. WHITAKER, R. H. (1975). Some observations and theories on the wide ureter and hydronephrosis. British Journal of Urology, 47, 377-385. WILLIAMS, D. I. (1970). The ureter, the urologist and the paediatrician. Proceedings of the Royal Sociefy of Medicine, 63, 595-602. WILLIAMS, D. I. (1974). Urology in childhood. Encyclopedia of Urology, XV, supplement. Berlin: Springer. WILLIAMS, D. I. and HULME-MOIR, I. (1970). Primary obstructive megaureter. Brifish Journal of Uro/ogy, 42, 140149.
The Authors Robert H. Whitaker, MChir, FRCS, Consultant Urological Surgeon, Addenbrooke’s Hospital, Cambridge. J. H. Johnston, FRCS, Consultant Urological Surgeon, Alder Hey Children’s Hospital, Liverpool. Requests for reprints to Mr R. H. Whitaker, Department of Urology, Addenbrooke’s Hospital, Cambridge.
A Simple Classification of Wide Ureters ROBERT H. WHITAKER
and
J. H. JOHNSTON
Departments of Urology, Addenbrooke's Hospital, Cambridge and Alder Hey Children's Hospital, Liverpool
There can be few topics in urology which are more confused or confusing than that of the abnormal ureter. As a result, rational discussion on the management of such lesions is almost impossible unless it is made quite clear which abnormality is present. Efforts have been made to classify abnormal ureters but generally they have failed to clarify the situation because they have been either too simple or unnecessarily complex. Also, the basic distinction between the refluxing and the non-refluxing ureter has often been ignored. We wish to discuss the problems of classifying ureters in the light of the numerous efforts reported in the literature and to set out an alternative classification which hopefully incorporates the best features of some of them and at the same time excludes the confusing aspects. We feel it is time for a classification which is internationally acceptable. The Problem 3 factors make a new classification desirable. Firstly, there are now too many terms which convey different pathological entities to different observers (Fig. 1). Secondly, the need to distinguish between a refluxing and a non-refluxing ureter has been highlighted by the increasing and now well established awareness of the problems of reflux. Thirdly, a newer concept, but of paramount importance in terms of management, is the need to diagnose accurately the presence or absence of obstruction in the wide non-refluxing ureter. It is not our intention to criticise all previous attempts at classification but it is necessary to analyse some aspects of them to rationalise a new approach.
megau ret er ?
megaloureter?
aperistaltic?
Fig. 1. The problem.
781
782
BRITISH JOURNAL OF UROLOGY
For instance, in his text book, Campbell (1970) discusses the Primary Megaloureter as an example of congenital dilatation of the upper tract and lists possible aetiological factors. He accepts, rightly in our opinion, that not all such ureters are obstructed but suggests that reflux is usually present. Hence, he is using this term for too large a group of abnormal ureters which includes both the refluxing and non-refluxing types. Hinman (1 970) prefers the term Hydroureter for the wide non-refluxing ureter and argues that all dilatation of the ureter is due to obstruction. We would beg to differ with this view. Many early classifications are much less specific and give two broad categories of congenital and acquired aetiologies. Others (Culp, 1967) make a distinction on anatomical or embryological lines. Williams (1 970) provides a realistic approach. He distinguishes clearly between refluxing and non-refluxing ureters and then categorises the wide non-refluxing ureter into groups according to the following pathogenic factors: Polyuria ; Bacterial toxins ; Obstruction (stricture, atresia, associated saccule); Obstructive megaureter; Dilated ureter with bladder outflow obstruction; Dysplasia with or without renal impairment. Although this classification has much to recommend it, it fails in the light of present knowledge to clarify the group of what Williams calls (Primary) Obstructive Megaureters (Williams and Hulme-Moir, 1970; Williams, 1974). The word obstructive suggests that it is the ureter, perhaps because of its width, which causes the obstruction and indeed this may sometimes be the case (Whitaker, 1975) but many feel that the dilatation is due to an abnormal lower ureteral segment in which case the term should be obstructed ureter. However, more important is the fact that the concept of obstruction is used too loosely in connection with this type of ureter. This is not just a quibble with the nomenclature but has a major clinical implication now that obstruction can be accurately assessed (Whitaker, 1973). Having used the expression Primary Obstructive Megaureter Williams begs the question of its usage by quoting his own findings of occasional spontaneous improvement in the appearances of such ureters with conservative treatment only (Williams and Hulme-Moir, 1970). He also accepts the findings of Backlund and Reuterskiold (1969) that low ureteric pressures may sometimes be demonstrable on perfusing such ureters. Both these findings are incompatible with a significant degree of obstruction. Furthermore, Heal (1973), using the same unfortunate termPrimary Obstructive Megaureter-showed that in 10 of 15 adults the pyelographic appearances remained unchanged, a feature again incompatible with a significant degree of obstruction. This suggests that Wide non-refluxing ureters come in varying degrees of obstruction. Those presenting early in life are naturally more likely to be obstructed. Johnston (1967), who termed these ureters Functionally Obstructed Megaureters found considerable improvement following re-implantation in children whilst Heal (1973) was seeing adults at the other end of the range with very mild or absent obstruction. Belman’s classification (1 974) fails to distinguish adequately between the obstructed and nonobstructed “primary megaureter” and some authors (Hodgson and Thompson, 1975) are still erroneously stating that “megaureters” are either refluxing or functionally obstructed and ignore the concept of a non-obstructed, non-refluxing wide ureter. Finally, there is the problem of confusing terms. This is often because attempts are made to indicate the aetiology of the defect as well as an anatomical description. The word dilated, for instance, implies that the ureter was once of normal calibre, which is clearly not always so as in the prune belly or megaureter-megacystis syndromes. The term Hydroureter has little to recommend it and to some it implies a high pressure within it. Megaureter has been used for so many
783
A SIMPLE CLASSIFICATION OF WIDE URETERS
STASIS + OBSTRUCTIO?I
STASIS
STASIS REFLUX
WIDE
-
PRIMARY
SECONDARY
Fig. 2. The 3 possible complicating factors in wide ureters.
i
URElER
PRIMARY
SECONDARY
A
NON OBSTRUCTED
-3
OBSTRUCTED
I Fig. 3. The proposed classification. The numerals indicate an empirical range of degrees of obstruction.
conditions with and without reflux and bladder outflow obstruction that it cannot now be usefully salvaged for a new classification. Primary and secondary are important terms and need careful definition. It is with this background of confusion that the following classification is proposed. A New Classification The term we believe to be the most acceptable for an abnormally wide ureter is simply wide. The purely descriptive term suggested by Backlund and Reuterskiold (1969) is anatomically and radiographically accurate and makes no effort to indicate the aetiology. The clinical implications of such a wide ureter are threefold (Fig. 2). First to be considered is the problem of stasis alone. In the absence of reflux or obstruction the mere presence of a large volume of urine in the upper tract may lead to repeated or continuous infection. Ureteritis appears to be an important factor in causing the ureteric widening often seen when there are infected stones in the renal pelvis; following removal of the stones and elimination of the infection the ureter promptly returns to normal. Secondly, there is the problem of obstruction which will lead not only to stasis with its risks of infection but also to back pressure on the kidney and deterioration in renal function. Thirdly, reflux may be present and the consequences of this are well known. It is on these 3 factors that the classification is based (Fig. 3). Firstly, wide ureters either show or do not show vesico-ureteric reflux and from the point of view of management we consider this distinction to be of paramount importance, although Hendren (1975) believes otherwise. It is often implied and indeed has been repeated recently (Hodgson and Thompson, 1975), that if a wide ureter is not showing reflux then it must be obstructed; this is a misconception which is hard to dispel.
784
BRITISH JOURNAL OF UROLOGY
Fig. 4. Primary refluxing ureters. (a) Massive neonatal reflux. (b) the more usual type of reflux (cystograms).
Secondly, the 2 groups of refluxing and non-refluxing ureters can be subdivided into primary and secondary. The term primary is used if the bladder functions effectively at normal pressures. If reflux is present such ureters can be conveniently subdivided into the massively refluxing type seen usually in the neonatal period (Fig. 4a) or the more conventional and less dramatic type of reflux seen in children of a much wider age group (Fig. 4b). A third category of primary reflux would include ureters in patients with a general dysplasia of the urinary tract such as the prune belly or megacystis-megaureter syndromes. Secondury means that there is, or has been a temporary or permanent high pressure in the bladder which has either caused or exacerbated the abnormality of the ureter. The most obvious example of this is the wide ureter which is seen with prostatic obstruction in men or with urethral obstruction in young boys with posterior urethral valves. In either situation reflux may be present and is probably caused by a “blowing-out’’ of the uretero-vesical junction by the high pressure within the bladder. Ureteric dilatation then occurs by the transmitted intravesical pressure. Alternatively, the uretero-vesical junction may retain its competence but the high pressure within the bladder may make it difficult for the ureter to empty and the result again is an increase in the width of the ureter. The final distinction in the classification is whether or not obstruction is present at the ureterovesical junction. It is this factor and the difficulty until recently in making a definite diagnosis of obstruction in a wide upper tract which has led to most of the confusion. We have already suggested that not all wide, non-refluxing ureters are obstructed and from a clinical management point of view it is all important to make this basic distinction. It cannot be overemphasised that unnecessary operations undertaken on the mistaken assumption that an obstruction exists are fraught with danger and disappointment.
A SIMPLE CLASSIFICATIONOF WIDE URETERS
785
Fig. 5. Primary obstructed non-reflexing wide ureter. Intravenous urograms showing wide right ureter. (a) Before operation, and (b) 1 year after tapering and re-implanting.
Obstruction in the wide non-refluxing ureter, if present, can be due to primary or secondary causes as defined above. For instance, a defect in the uretero-vesical junction which prevents adequate emptying in the presence of a normal bladder is termed primary (Fig. 5a and b). This ureter has been termed primary (idiopathic), obstructed(ive) megaureter. More accurately, if rather more cumbersomely, it should be termed a primary obstructed, non-refluxing wide ureter. Although long-winded there is no doubt what is meant by this term. If the outflow from the bladder is obstructed either functionally, as in a neurogenic bladder, or anatomically, as in prostatism or posterior urethral valves, there is usually no actual obstruction at the uretero-vesical junction and relief of the bladder outflow obstruction will lead to resolution of the upper tract dilatation (Fig. 6a and b). This is a secondary non-obstructed, non-refuxing wide ureter. However, sometimes there can be such hypertrophy of the detrusor around the intramural ureter that even after relief of the raised bladder pressure the ureter still cannot drain satisfactorily. This is termed secondary obstruction and the ureter is a secondary obstructed, nonrefuxing wide ureter. If after resection of posterior urethral valves there is a deterioration in urographic appearances or renal function this type of ureter is suspected but it is a simple matter to prove it with a perfusion test. The term secondary must be kept strictly for the ureter associated with an “obstructed” bladder and not used for compression of the ureter by vessels, tumour or stone. Obstruction is, of course, relative and we suggest that there is a whole range of non-refluxing ureters which are variously obstructed from almost not at all to grossly and it is in this grey area of equivocal obstruction that the perfusion (pressure/flow) studies are so helpful (Whitaker, 1973). This classification can be extended to include any type of abnormal ureter although this can easily become an academic exercise and of limited clinical applicability.
786
BRITISH JOURNAL OF UROLOGY
Fig. 6. Secondary non-obstructed non-refluxing wide ureters. Boy with posterior urethral valves treated by endoscopic resection of valves only. Intravenous urograms. (a) A t age 4 months, before operation. Cystogram showed no reflux. (b) At a e 9 years. There has been considerablespontaneous improvement in the dilatation and tortuosity op the ureters incompatible with a significant degree of uretero-vesical obstruction.
The main usefulness of this classification is in distinguishing between the various types of congenital anomalies which are seen so commonly in children and its adoption should see an end to many of the confusing terms such as megaureter, megaloureter, hydroureter and at least 10 other obsolete terms listed by Belman (1974).
Summary
A simple classification of abnormal ureters is presented which categorises the ureters according to the presence or absence of 3 factors, namely reflux, bladder outlet obstruction and ureteric obstruction. It has been devised to try to rid the literature of many confusing and obsolete terms and it is hoped that this new classification may become internationally accepted. References BACKLUND, L. and REUTERSKI~LD, A. G. (1969). The abnormal ureter in children. 1. Perfusion studies on the wide non-refluxing ureter. Scandinavian Journal of Urology and Nephrology, 3, 2 19-228. BELMAN,A. B. (1974). Megaureter. Classification, etiology and management. Urological Clinics ofNorth America, 1, 497-5 13. CAMPBELL, M. F. (1970). In Urology, 3rd ed., vol 2, ed. by M. F. Campbell and J. H. Harrison. Philadelphia: Saunders, p. 1534. CULP,D. A. (1967). Congenital anomalies of the ureter. Proceedings of the Third International Congress of Nephrology, Washington, 1966. Basel: Karger, 2, 65-82. HEAL,M.R. (1973). Primary obstructive megaureter in adults. Brifish Journal of Urology, 45,490-496. HENDREN, W.H. (1975). Complications of megaureter repair in children. Journal of Urology, 113, 238-254. HINMAN, F . (1970). In Urology, 3rd ed., vol 1, ed. by M. F. Campbell and J. H. Harrison. Philadelphia: Saunders, p. 341.
A SIMPLE CLASSIFICATION OF WIDE
787
URETERS
HODGSON, N. B. and THOMPSON, L.W. (1975). Technique of reductive ureteroplasty in the management of megaureter. Journal of Urology, 113, 1 18-120. JOHNSTON, J. H. (1967). Reconstructive surgery of megaureter in childhood. Brirish Journal of Urology, 39, 17-21. REUTERSKI~LD, A. G. (1969). The wide ureter: functional studies in children and dogs. Acta Universitatis Upsaliensis. Abstracts of Uppsala Dissertations in Medicine. Stockholm: Almquist and Wiksell, 76, 1-18. WHITAKER, R. H. (1973). Methods of assessing obstruction in dilated ureters. British Journal of Urology, 45, 15-22. WHITAKER, R. H. (1975). Some observations and theories on the wide ureter and hydronephrosis. British Journal of Urology, 47, 377-385. WILLIAMS, D. I. (1970). The ureter, the urologist and the paediatrician. Proceedings of the Royal Sociefy of Medicine, 63, 595-602. WILLIAMS, D. I. (1974). Urology in childhood. Encyclopedia of Urology, XV, supplement. Berlin: Springer. WILLIAMS, D. I. and HULME-MOIR, I. (1970). Primary obstructive megaureter. Brifish Journal of Uro/ogy, 42, 140149.
The Authors Robert H. Whitaker, MChir, FRCS, Consultant Urological Surgeon, Addenbrooke’s Hospital, Cambridge. J. H. Johnston, FRCS, Consultant Urological Surgeon, Alder Hey Children’s Hospital, Liverpool. Requests for reprints to Mr R. H. Whitaker, Department of Urology, Addenbrooke’s Hospital, Cambridge.
