Megacalices—How Broad a Spectrum?

British Journal of Urology (1981), 53, 1-6 0 1981 British Association of Urological Surgeons

0007-1331/81/06230001$02.00

Megacalices - How Broad a Spectrum?

R. H. WHITAKER and C. D. R. FLOWER Department of Urology, Addenbrooke’s Hospital, Cambridge

Summary-Ten patients with a suspected diagnosis of rnegacalices have had pressure-flow studies to confirm or exclude obstruction. Eight had no evidence of obstruction and amongst these there were 2 patients with a non-obstructed megaureter. Two patients showed evidence of obstruction and remain a dilemma from a management viewpoint. If “megacalices” is used simply as a descriptive term, then the spectrum of disease is wider than previously suspected.

The condition of megacalices has been described as an underdevelopment of the renal pyramids in association with oversized calices (Talner and Gittes, 1972). It may affect one or both kidneys. One of the prime requisites for the diagnosis has been the absence of obstruction. This was stressed in the early description of this condition by Puig- vert (1 963) and in subsequent discussions (Talner and Gittes, 1972, 1974).

In the early studies the exclusion of obstruction was by urography, ureterography and standard isotope renography. Although in some cases the renograms suggested some delayed emptying, it was assumed to be due to gradual mixing of the isotope within the larger volume of the kidney and not due to obstruction.

During the last 5 years the need to diagnose even minor degrees of obstruction accurately has been emphasised. Doubt has been cast on the ability of the above methods to do this and newer methods have been developed such as sophisticated radioisotope studies measuring parenchymal transit times, or by using diuresis renography and by direct measurement of the dynamics within the kidney by means of percutaneous pressure-flow studies. Each method has its own advantages and we have concentrated on direct dynamic assess- ment. Although such studies are invasive, they are generally accepted as giving an accurate appraisal of the degree of obstruction. In the light of these developments we have studied a few patients with suspected megacalices to determine the absence or presence of obstruction and to see to what extent this group of patients is homogeneous.

Read at the 36th Annual Meeting of the British Association of Urological Surgeons in Liverpool, June 1980.

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Patients We studied only those patients who had kidneys with the urographic appearance of megacalices. In 8 of the 10 patients the ureter was entirely normal, but in 2 the ureter was wide with what proved, on pressure-flow studies, to be a primary non-obstructed megaureter. We have included these 2 patients in this series because previous authors have commented upon the association of megacalices and non-obstructed wide ureters (Von Niederhausern and Tuchschmid, 1971 ; Talner and Gittes, 1974). We have excluded all patients in whom there was a strong suspicion of a pelvi- ureteric junction obstruction.

The essential urographic features in all 10 cases were “dilated” calices, but with no infundibular narrowing and a symmetrical loss of renal paren- chyma suggestive of medullary loss (Figs. 1 and 2). There was no obvious site of obstruction within the upper urinary system as judged by the ready filling of the ureter and transit to the bladder. Four of the 10 patients had renography with hydration and all 10 underwent percutaneous pressure-flow studies (Whitaker, 1973, 1979).

Results The pressure-flow studies showed that with per- fusion at 10 ml per min, 8 of the kidneys showed normal pressures as defined by a pressure drop from kidney to bladder of 15 cm of water or less. Figures 1 and 2 illustrate 2 patients with typical megacalices. In the 2 patients in this group who had renograms the study confirmed the absence of obstruction. Two patients had raised pressures indicative of obstruction.

2 BRITISH JOURNAL OF UROLOGY

Fig. 1 A 33-year-old male (K.K.) found to have transient mild hypertension on a routine medical examination. No urinary symptoms. (a) IVU-left megacalices, normal ureteric filling. (b) Early tomogram showing medullary loss. (c) Antegrade pyelogram. (d) Pressure tracing showing a relative pressure of 4 cm water at 10 ml per min.

K = Pressure in kidney. B = Pressure in bladder. C = Resistance of cannula.

MEGACALICES-HOW BROAD A SPECTRUM? 3

a C

‘“1 K

B IRC u 2ol d

Fig. 2 A 30-year-old female (S.M.) with a questionable urinary tract infection during pregnancy. (a) IVU-left megacalices, normal ureteric filling. (b) Early tomogram showing medullary loss. (c) Antegrade pyelogram. (d) Pressure tracing showing a relative pressure of 5 cm water at 10 ml per min.



K

Fig. 3 A 28-year-old obese patient (S .S. ) . (a) IVU suggestive of bilateral megacalices but with narrow ureters. (b) Antegrade pyelogram: ureters show good peristalsis but remain thin. (c) Pressure tracing showing a relative pressure of 36 cm water at 10 ml per min.


MEGACALICES-HOW BROAD A SPECTRUM? 5

C I

Fig. 4 A 15-year-old boy (P.L.) who had mild haematuria following a blow to the left side. (a) IVU suggestive of megacalices but with a wide ureter. (b) Antegrade pyelogram. The ureter empties readily into the bladder. (c) Pressure tracing showing a relative pressure of 15 cm water at 10 ml per min.


The first obstructed kidney remains a diagnostic problem in that the relative pressure was 26 cm of water, but there was no obvious site of obstruction to which we could direct surgical relief. His urographic appearances have not changed over 7 years. A hydrated renogram did not confirm our dynamic findings of obstruction.

The second patient showing obstruction was the more curious and perplexing of these 2 (Fig. 3). He was an overweight 28-year-old who was first seen at the age of 18 years with what was probably an attack of right renal colic. An intravenous urogram at that time showed “bilateral hydronephrosis”. Since then he has had

gesting a mild degree of obstruction on both sides. An antegrade pyelogram was performed on the right side and this showed a pressure differential between the kidney and bladder of 36 cm of water at 10 ml per min, indicative of obstruction. Both ureters were very narrow, but exhibited normal motility and did not resemble retroperitoneal fibrosis. Several experienced radiologists have independently stated that the urographic appearances are very suggestive of megacalices. It is evident that this patient has a degree of obstruction but the exact site is not apparent and it seems likely that the narrow ureters represent an overall increased resistance.

several further urograms showing no appreciable change.

mild right-sided pain and one episode of transient haematuria. A hydrated renogram in 1977 suggested good overall function, but with prolonged transit times sug-

Over the last 9 years he has had 2 further episodes of One of the 2 patients with a wide ureter is illus- trated in Figure 4. He exhibits the urographic appearances of megacalices in association with a non-obstructed megaureter.


Discussion Megacalices have been defined as a discrete entity with a typical pyelographic appearance and no evidence of obstruction. If this strict definition is adhered to, only 6 of our patients would meet the requirements for this diagnosis. The 2 patients with wide ureters could be described as non- obstructed megaureters with accompanying pelvi- caliceal changes. In the remaining 2 patients the urographic appearances are typical of megacalices, but in both there was evidence of obstruction. In one of these patients there remains some doubt as to the significance of the obstruction in view of the renographic evidence. In the other patient with bilateral thin ureters, there is unequivocal evidence of obstruction confirmed by both renography and dynamic studies. However, the exact level of the obstruction and whether operative relief is necessary remain uncertain.

If, however, megacalices is simply used as a descriptive term, then all 10 of these patients can be included whether or not they exhibit obstruction. This would suggest that perhaps there is a wider spectrum of this condition than previously suspected and maybe we should be forced to accept that lesser degrees of obstruction are compatible with the diagnosis of megacalices. If, indeed, the aetiology of this condition is a “burnt out obstruction”, as has been suggested, then it is perhaps not surprising that some cases may still show some evidence of this obstruction (Johnston,

1973). This theory, although convenient, is probably too simplistic.

Acknowledgement We are grateful to Dr L. B. Talner for allowing us to include 2 of his cases in this series.

References Johnston, d. H. (1973). Megacalicosis: a burnt-out obstruction?

Journal of Urology, 110, 344-346. Puigvert, A. (1963). Megacalicosis: diagnostic0 diferencial con

la hidrocaliectasia. Medicina Clinica, 41, 294-302. Talner, L. B. and Gittes, R. F. (1972). Megacalyces. Clinical

Radiology, 23, 355-361. Talner, L. B. and Gittes, R. F. (1974). Megacalyces: further

observations and differentiation from obstructive renal disease. American Journal of Roentgenology. 121,473486.

Von Niederhausern, W. and Tuehscbmid, D. (1971). Une association ma1 connue: le mkgauretere congenital primaire et le rein a mega-cakes. Annales d’Urologie, 5, 225-231.

Whitaker, R. H. (1973). Methods of assessing obstruction in dilated ureters. British Journal of Urology, 45, 15-22.

Whitaker, R. H. (1979). The Whitaker Test. Urologic Clinics of North America, 6, 529-539.

The Authors R. H. Whitaker, MChir, FRCS, Consultant Urologist,

Addenbrooke’s Hospital; Associate Lecturer, University of Cambridge.

C. D. R. Flower, FRCP(C), FRCR, Consultant Radiologist, Addenbrooke’s Hospital; Associate Lecturer, University of Cambridge.

Requests for reprints to: R. H. Whitaker, Department of Urology, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 2QQ.

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Megacalices—How Broad a Spectrum?