Brilish Jorirnal of Urology (1916). 41, 771-779 0

Equivocal Pelvi-ureteric Obstruction ROBERT H. WHITAKER

Deparrrnenr of Urology, Addenbrooke’s Hospital, Cambridge

From time to time urologists are faced with difficult problems of upper urinary tract obstruction. Neither pyeloplasties nor ureteric re-implants are free from morbidity or even mortality, so it behoves the surgeon to be absolutely sure that the operation is necessary. This may be difficult as in the truly equivocal case radiographic and radio-isotope techniques have severe limitations. However, with the better understanding of urodynamics and the advent of a clinically applicable perfusion (pressure/flow) study (Whitaker, 1973a and c) it is now not only possible, but practical, to assess accurately the degree of obstruction and hence make a logical decision as to management. The pelvi-ureteric junction presents a particularly difficult problem because of its tendency to an intermittent obstruction, often with a sudden onset. Although the classical type of idiopathic pelvi-ureteric obstruction usually presents no diagnostic difficulty there are many variations on the theme. For instance, the findings of a narrowed junction with a little calyceal clubbing and full pelvis makes one suspicious of obstruction (Fig. 1) but are perhaps insufficient evidence by themselves to demand a pyeloplasty. The result is a period of uncertainty for both the patient and the surgeon during which time further X-rays are taken and much time is spent in both the clinic and radiographic departments, often only to find that the subsequent appearances are the same and one remains haunted by the prospect of slow and surreptitious deterioration in renal function. In children this prospect is even more daunting. The pressure/flow findings and their clinical usefulness in the typical and atypical pelviureteric anomalies will be presented.

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Fig. 1. 1I-year-old boy with equivocal obstruction at the right pelvi-ureteric junction. 771

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Fig. 3. The problem of equivocal obstruction after pyeloplasty. (a) Urogram of an 18-year-old girl who had had a right pyeloplasty 13 years before. (b) Antegrade pyelogram and tracing showing free flow through the pelviuretericjunction at a relative pressure of only 2 cm H 2 0 at 10 ml/min. This excluded obstruction.

Patients Studied There are 3 categories of patients. Those investigated at the time of a pyeloplasty for a pelviureteric junction obstruction sufficiently obvious that it would have been performed whether

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simulated diuresis - a perfusion of IOml/minute.

Fig. 4. Technique of perfusion study. During perfusion of therenal pelvis the pressure is measured i n the pelvis and in the bladder to give a relative pressure.

or not the test had been available (19 studies in 10 patients). Those who had previously had a pyeloplasty performed but in whom it was suspected from the clinical and radiographic appearances that all was not entirely satisfactory (5 studies in 5 patients) and, finally, a group of I 1 patients (16 studies) who presented with equivocal findings and in whom it was very much in doubt as to whether or not a degree of obstruction was present.

Method The perfusion study and its application in a variety of obstructive problems has been discussed in detail elsewhere (Whitaker, 1973a, 6 and c ; 1975a; Marshall and Whitaker, 1975). Essentially, a single cannula is introduced into the renal pelvis and a fast perfusion of 10 or 5 ml/min is commenced. The back pressure to perfusion and the bladder pressure are measured. The latter subtracted from the former produces a “relative pressure” or pressure drop across the pelviureteric junction at the fixed and steady perfusion rate (Fig. 4). As judged by the results in over 120 such studies in a variety of conditions both with and without obstruction it seems clear that this relative pressure at 10 ml/min should not exceed 10 to 12 cm HzO. The apparatus needed for this test is listed in the appendix. If the decision has been made on clinical and radiographic grounds to perform a pyeloplasty in the certainty that an obstruction is present, clearly such a test is superfluous, but nevertheless a perfusion study with the kidney exposed just before the pyeloplasty produces documented evidence of obstruction and a baseline against which to compare the pressure on perfusing the kidney via a nephrostomy on the 10th postoperative day. Such studies also provide a standard against which the difficult cases can be compared. The cannula or needle is inserted into the renal pelvis away from the pelvi-ureteric junction and before this region is dissected. The kidney is allowed to lie in its natural position. In the equivocal case the study is performed before, and to help with the decision as to whether or not an operation is necessary. The technique is the same but the cannula is introduced percutaneously under fluoroscopic control after an intravenous injection of contrast medium. It is usually possible to enter the pelvis via a dilated calyx. In the majority of patients, including older children, the procedure is tolerated well under local anaesthesia. If a low perfusion pressure is found the patient can be discharged from hospital after 24 hours reassured that no pyeloplasty is necessary. If a higher than normal pressure is encountered it is best to drain back the contrast medium via the cannula before withdrawing it and probably wise to advise operation on that admission.

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Results

1. Patients with Typical Zdiopathic Pelvi-ureteric Junction Obstruction Perfusion studies were performed on 1 1 kidneys in 10 patients at the time of pyeloplasty o r nephrectomy for this condition. The diagnosis was based on the clinical findings of pain and the typical radiographic appearances of delayed excretion and abnormal accumulation of contrast medium. In the majority of patients a further study was performed via the nephrostomy tube on the 10th postoperative day, 2 days after removal of the ureteric splint. In all but one of these kidneys there was clear urodynamic evidence of obstruction. The typical finding was the inability of the renal pelvis to tolerate a flow of 10 ml/min without a marked rise in pressure. In 3 kidneys there was an equilibration of pressure at 10 ml/min of between 23 to 36 cm H 2 0 whilst in 7 others the pressure continued to rise suggesting the pelvi-ureteric junction was completely intolerant of this flow rate (Fig. 2a). There were lower polar vessels across the ureter in 5 cases and no such vessels in the other 6. 1 patient with a normal pressure had previously had the opposite kidney operated upon after obstruction had been proven by this method. This patient will be discussed, together with details of the other results in this section and the implications of lower pole vessels, in a subsequent report. On the 10th day after operation perfusion pressures were measured via the nephrostomy tube and they varied between 4 to 16 cm H 2 0 (mean 10 cm H20) in these patients (Fig. 2b). 2. Patients Who had Previously had a Pyeloplasty Because of the residual dilatation of the pelvis and calyces after a pyeloplasty for chronic pelviureteric obstruction it is often extremely difficult to evaluate the significance of pain and urinary infection occurring sometimes many years afterwards. 5 such patients have been studied. In 1 patient the kidney was explored, found to be thin with a high perfusion pressure (equilibrating at 80 cm HzO) and was removed. In a second patient a percutaneous study showed a perfusion pressure of 32 cm HzO, 10 years after a pyeloplasty. During this time she had undergone 6 intravenous urograms and considerable loin pain. The kidney which was thin was removed and she is now pain free. A third patient, an 18 year-old girl, had had some discomfort in her right side and a urinary tract infection 13 years after a right pyeloplasty. A plain film showed 3 minute stones in the right kidney and a urogram (Fig. 3a) showed considerable residual dilatation but with good ureteric filling and the stones were in the calyces. A percutaneous antegrade study into this still dilated kidney showed a perfusion pressure of only 2 cm H20 at 10 ml/min which clearly indicated the absence of any new or residual obstruction (Fig. 3b). She has remained well since without any action being taken. In a fourth patient it was not possible to locate successfully the renal pelvis by the percutaneous method and in a fifth patient, a 9-month-old boy with posterior urethral valves, the study was used to evaluate the upper tract after extensive tapering of the upper ureter together with a pyeloplasty. 3. Patients with Equivocal Pelvi-ureteric Junction Obstruction These 11 patients presented difficult diagnostic problems and without this test it would have been impossible to be sure that the correct line of management was being taken. All 1 1 patients were suspected of having some degree of pelvi-ureteric obstruction. This was confirmed in 5 patients who subsequently underwent operation, whilst in 6 patients normal pressures were found and no action was taken. The subsequent clinical and investigative results in these patients provide no evidence to refute the findings of the tests. All these patients cannot be described here but 2 examples illustrate the way the results can influence management. 41/7-~

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b

Fig. 5. Equivocal pelvi-ureteric obstruction. (a) Urogram of a 27-year male with left loin pain. Late opacification of the large, middle calyx and full pelvis. (b) Antegrade and tracing via this calyx showing no hold-up of the medium at the low relative pressure of 7 cm H20, excluding obstruction. Case 1

R. P..a 27-year-old teacher had 2 episodes of left loin pain and microscopic haematuria ovcr a period of I year before investigation. Plain X-ray showed a few small calculi in both kidneys. No metabolic defect was found. An intravenous urogram (Fig. 5a) showed dilated calyces in the left kidney with a full pelvis. The middle calyx was large and opacified poorly in the early films. A percutaneous antegrade pyelogram was performed (Fig. Sb) which showed good flow through the pelvi-ureteric junction and satisfactory emptying of the distended calyx into which the cannula was inserted at a low pressure of 7 cm HlO. The patient has had no further pain but as a result of this test we were able to reassure him that, although the stones may give more trouble, if they eventually needed to be removed it would not be necessary to pay any surgical attention to the hydrocalicosis or pelvi-ureteric junction in terms of obstruction. As he spent much of his time travelling we felt this was important information for him to pass on if he was admitted. Case I1

G . B., an 1 I year old boy had a left pyeloplasty performed 3 years previously for a definite pelvi-ureteric obstruction. I t was noted at that time that the right calyces and renal pelvis were full and that this right side would need watching carefully in case it, too, developed an acute hydronephrosis (Fig. I ) . A further urogram (Fig. 6a) showed a satisfactory result on the left side but persistent abnormality on the right although the ureter appeared to fill well. A percutaneous antegrade study (Fig. 6b) showed a narrow area at the pelvi-ureteric junction and the pressures confirmed that this represented a significant degree of obstruction. The relative pressure at both I0 and 5 ml/min was 25 cm HzO. This child has now had a right pyeloplasty. At operation the renal pelvis rapidly became tense with a perfusion of either 5 or 10 ml/min and the ureter showed poor attempts a t peristalsis. A further perfusion study at that time confirmed the obstruction. A Culp type of pyeloplasty was performed and a pressure controlled nephrostogram at 10 days showed good drainage at a pressure half the preoperative level.

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Fig. 6. Equivocal pelvi-ureteric obstruction. An 1 I-year-old boy who 3 years previously had a left pyeloplasty for marked hydronephrosis. The right pelvi-ureteric junction had always been under suspicion (Fig. 1 shows a previous urogram). (a) Urograrn 3 years after left pyeloplasty. (b) Antegrade and tracing. Definite and constant narrowing at the pelvi-ureteric junction and study shows a relative pressure of 25 crn HzO at both 5 and 10 ml/min. This is a moderate obstruction.

Discussion These cases and others which have not been fully described illustrate the usefulness of this perfusion test in diagnosing obstruction in difficult situations. The obvious advantage of showing an obstruction is that an operation can be advised early before there is further deterioration in renal function. If the system can be shown to be unobstructed

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the patient can avoid multiple clinic attendances and unnecessary X-rays with the inevitable time off work and loss of earnings. Morbidity has consisted of I instance of haematuria with clot colic and 2 instances of pain for 24 hours from extravasation of contrast medium. With improved technique we feel that these problems can be minimised. The test requires the minimum of equipment (see appendix) and understanding of urodynamics, but for the percutaneous studies good radiological help and a suitable cannula are essential. In the light of these results the radiographic appearances of pelvi-ureteric obstruction need some reconsideration and the technique provides a control for the estimation of obstruction by radio-isotopic methods which to date have been disappointing in the equivocal cases. The findings have also helped the author to understand the mechanisms of obstruction in the pelviureteric region (Whitaker, 19756).

Summary A series of 40 studies have been used to assess whether or not there is obstruction in the pelviureteric region in 27 kidneys. The perfusion test which is discussed has provided an answer in all cases where the technique was possible and allowed a logical decision to be taken concerning management. 4 of the equivocal cases were patients under the care of Mr J. F. R . Withycombe and I am grateful to him for allowing me to study them.

Appendix For those who wish to perform a perfusion the following list of equipment may be helpful. It is appreciated that most of the equipment is probably available from several manufacturers but those listed have been used by the author and found satisfactory. Basic Equipment 1. Perfusion Pump (Braun (acc 71 104) with autoclavable 50 ml luerlocking syringe (acc 72465)). 2. Pen Recorder (Smiths Servoscribe 1 channel (RE 501.20)). 3. Physiological Pressure Transducer (Statham P23 Db.). Disposable Sterile Equipment The following items are needed for each test: 1 4-way stopcock. (Baxter BR 62s). 2 3-way stopcocks. (Pharmaseal K75a). 1 wide-bore extension set (Avon-A60). 1 200 cm manometer line (Portex 200/490/200). 2 60 cm manometer lines (Protex 200/490/060). 1 male-to-male connector for connection between the urethral catheter and the apparatus (This can be made using a small length of silastic tubing and two male connectors.) 1 bottle of glycerine or liquid paraffin to lubricate syringe. 1 bottle of saline or contrast medium (30 % Urograffin) for perfusion. I cannula-hondwel Catheter (Teflon) (Becton, Dickinson & Co. 18.G. 6" or 4").

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References MARSHALL, V. and WHITAKER, R. H. (1975). Ureteric pressure-flow studies in difficult diagnostic problems. Journal of Urology, 114, 204-207. WHITAKER, R. H. (1973~).Methods of assessing obstruction in dilated ureters. British Journal of Urology, 45,15-22. -(19736). The ureter in posterior urethral valves. Brirish Journal of Urology, 45, 395-403. -(1973~).Diagnosis of obstruction in dilated ureters. Annals of the Royal College of Surgeons of England, 53, 153-166. __ (1975~).Urodynamic assessment of ureteral obstruction in retroperitoneal fibrosis. Journal of Urology, 113, 26-29. __ (19756) Some observations and theories on the wide ureter and hydronephrosis. British Journal of Urology, 47, 377-385.

The Author Robert H. Whitaker, MChir, FRCS, Consultant Urologist. Requests for reprints to the author at the Department of Urology, Addenbrooke’s Hospital, Cambridge.

Equivocal pelvi-ureteric obstruction.

A series of 40 studies have been used to assess whether or not there is obstruction in the pelvi-ureteric region in 27 kidneys. The perfusion test whi...
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