The Two Types of Pyelosinus Extravasation PETER DAVIES, HAZEL M. PRICE and DONALD R. KNAPP
The Department o f Radiology, City Hospital, Nottingham
There are two types of extravasation into the renal sinus from the fornices of the calyces; one due to transu- dat ion through an intact mucosa and the other due to an actual defect in the calyx. It is suggested that extra- vasation from the fornices into the renal sinus can occur spontaneously in the absence of obstruction and without a rise in pressure. Truly spontaneous extravasation can occur whether ureteric compression is used or not.
During a recent study of urography in acute renal colic several examples of extravasation o f contrast medium were seen. Extravasation occurred in asso- ciation with other conditions and it appears that it is not a single ent i ty nor is it due to a single mecha- nism.
M E T H O D S
The films of 12 patients were studied; nine are presented in this paper (Table 1) and three are described elsewhere (Davies et al., 1981).
RADIOLOGICAL FEATURES
Two patients showed dense nephrograms persisting in the presence of extravasation from the fornices (cases 1 and 2). In three, dense nephrograms faded when extravasation appeared (3, 4 and 5). In one p a t i e n t extravasation was present at an early exami- nat ion but not some days later, al though the obstruc-
ting agent persisted unchanged (4). One patient showed extravasation from the pelvis which relieved the higher intrapelvic pressure, indicated by loss of the dense nephrogram (5). The extravasation resolved within a few hours although the obstructing ureteric stone remained for at least 24 h.
Three patients revealed the onset of extravasation before the examination, evidence being present on the first f'tim to show contrast medium in the calyces (6, 8 and 9).
In a pat ient with carcinoma of the prostate, renal colic supervened upon a chronic obstruction (7). Pain had resolved by the time of the examination and extravasation proceeded from calyces in the early stages of chronic dilatation. One patient had colic and showed extravasation in association with an ovarian cyst (8).
In one patient, t ruly spontaneous extravasation appeared on the urogram after acute retention had been relieved (9). Ureteric compression was not used in this examination.
Table 1 - Summary of the cases discussed in this paper
Case Age Sex S ide Colic No. of hours number elapsing between
onset of colic and urography
Calculus present
D e n s e Extravasation No. of week nephrogram after which repeat lasted for Started Ended urography showed
normal appearances
1(Fig. l) 63 M L + 8 + 2(Fig. 2) 36 M L + 12 0 3 55 M L + 46 0 4 63 M L + 12 + 5(Fig. 5) 40 M L + 6 + 6(Fig. 3) 55 F L + 10 + 7(Fig. 4) 59 M R + 5days 0 8 47 F L + 7 0 9 68 M L 0 0 0
30 min 20 min NK* 3 90 rain 40 min 90 rain 4
t 10 min 10 min NK 6 ~15 min 15 rain NK 4
20 min 31A h 5% h 6 0 5 "rain NK 2 0 20 min NK 0 0 5 min NK 4 0 5 min NK 0
*NK = Not known + = Yes 0 = No t = Dense nephrogram lost when extravasation occurred.
4 i4 CLINICAL RADIOLOGY
DISCUSSION
There are two sites of extravasation from the pelvi. calyceal system; one from the fornices of the calyces and the other from the renal pelvis. Three such examples of extravasation from the renal pelvis are discussed elsewhere (Davies et al., 1981).
Pelvic and Ureteric Pressures
Kiil (1957) showed that pressures in the ureter and renal pelvis are not usually dependent on one another. The pressure in the ureter during contraction is between 25 and 80mmHg, but pressure in the renal pelvis equals the resting pressure of the ureter, i.e. a few mm of mercury (effectively zero). The response to abdominal compression is to increase the number and rapidity of ureteric contraction waves, but resting ureteric pressure and ureteric pressure during a contraction wave do not increase (Kill, 1957). If the ureter is obstructed, its resting pressure rises until it attains the pressure achieved during a contrac-
tion, after which no more pressure waves are seen in the ureter which is distended as far as the obstruction (Kiil, 1957; Rose and Gillenwater, 1973). Following this a dense nephrogram develops when the pressure is 3 0 - 4 0 mmHg (Bretland, 1972).
Animal studies showed that the bursting pressure of the pig's renal pelvis, determined with a particulate contrast medium (Barium Sulphate), was 60mmHg (Cuttino et aL, 1978) which is rather more than the pressures quoted above. A pressure of 150 mmHg has been recorded in the humaff renal pelvis with a dense nephrogram but no visible pyelogram or extravasation (Johnson, 1969). After obstruction for a few weeks in dogs the pressure in the ureter drops to normal levels and the pressure during contractions is less than in normal unobstructed ureters (Rose and Gillenwater, 1973). After obstruction for 10 weeks, the pressure does not rise above 15 mmHg even during an osmotic diuresis (Schweitzer, 1973). Schweitzer (1973) thought that permanent renal damage occurred after complete obstruction lasting one week.
(a) (b) Fig. 1 - Case 1. (a) Ten minute film showing no filling of the upper ureter with a dense nephrogram. (b) Twenty minute film showing the nephrogram is denser with extravasation medial to the pelvis (arrow).
PYELOSINUS EXTRAVASATION 415
In man, a dense nephrogram can no longer be Obtained after several days obstruction (Elkin, 1963) and this is confirmed by animal studies (Elkin et al., 1964). In animals, the duration of obstruction is accurately known. The nephrogram in the post-acute phase of obstruction is no longer increasingly dense eight days after the onset of the obstruction.
Extravasation in Acute Obstruction
There are two theories of the aetiology of pyelo- sinus extravasation (Narath, 1940).
1. Extravasation occurs through minute tears in the fomix of the minor calyces (Cooke and Bartucz, 1974). If the kidney is acutely obstructed, leakage through these defects will result in loss of the dense nephrogram (Bonk e t al., 1966) (Cases 3, 4 and 5).
2. The phenomenon is due to transflow through an intact mucosa. Marshall and Castellino (1970) and Chisholm e t al. (1967) studied the permeability of the renal pelvis in acute obstruction and found that transport from the renal pelvis to the lym- phatics depended on both pressure and molecular
weight, supporting the theory of transflow through an intact mucosa. However, pyelosinus extravasation may occur at very low filling pressures (below 20mmHg) during retrograde pyelography (Ross, 1959).
Cases 1 and 2 (Figs 1, 2) in which dense nephro- grams persisted in the presence of extravasation indi- cate an intact mucosa which is necessary to maintain the pressure which results in a dense nephrogram. Conversely the situation (cases 3, 4 and 5) in which the nephrogram disappears as extravasation becomes apparent, suggests a defect in the pelvicalyceal system with a pressure drop. If it is accepted that disappearance of the dense nephrogram implies a defect in the pelvicalyceal system it is clear from the resolution of case 5 (Fig. 5) that such a defect can close even in the continuing presence of the obstruct- ing agent.
Spontaneous Extravasation
An obstructing agent is not a necessary antecedent to extravasation Caro and Waldbaum (1976) describe massive extravasation requiring operation where no
Fig. 2 - Case 2. A dense nephrogram, no filling of the pelvis and extravasation medial to the kidney (arrow) at 40 rain after injection. The appearances remained the same for I h.
Fig. 3 - Case 6. Medullary sponge kidney, showing extra- vasation from the pelvis around the ureter which is out- lined as a translucency and contains a stone (arrow).
416 C L I N I C A L R A D I O L O G Y
apparent obstruction or rupture of the collecting system existed and Harverson (1972) has described an instance in a patient with chronic pyelonephritis before compression was applied. According to Cooke and Bartucz (1974) no cause for extravasation could be found in 17 of 61 cases collected from the literature and in only six o f their 14 personal cases was an obstructing agent present. Thus, peri-pelvic extravasation can occur as a truly spontaneous phenomenon.
These observations suggest that peri-pelvic extra- vasation is an event that occurs from time to time in normal kidneys and no increase in pressure is needed to initiate it. The pressure in the pelvis is not raised when the ureters are subjected to external compression. Certainly, if ureteric spindles are seen, these indicate that the intra-ureteric pressure is the same as it is under normal conditions and it is not until the ureter is distended throughout its length that one can assume the pressure is raised (Rose and Gillenwater, 1973). External compression is a rela- tively ineffective obstructing agent since in many cases contrast medium can be seen to collect in the bladder while it is applied. We suggest, therefore, contrary to the opinion of Schwartz e t al. (1966), that extravasation may be truly spontaneous even if ureteric compression is used.
Fig. 4 - Case 7. (a) Five minu te film showing dilated calyces and a normal nephrogram indicating chronic obst ruct ion and a low pressure system. (b) Fifteen minute film showing extravasation alongside the pelvis (arrow). (c) At 30 rain extravasation outlines the ureter.
P Y E L O S I N U S E X T R A V A S A T I O N 417
(a) (b)
Fig. 5 - Case 5. (a) Twenty minute film showing a dense nephrogram with no extravasation. The ureter is not filled. (b) Three and a half hour film showing dense extravasation around the upper ureter. The ureter is filled as far as the bladder.
Extravasation in Chronic Obstruction
In chronic obstruction with hydronephrosis the pressure in the ureter and pelvis may not be raised (Schweitzer, 1973); thus in our cases 7, 8 and 9 there is reason to suppose that the intrapelvic pressure was not raised. Therefore extravasation can occur in the absence of a greatly raised pressure.
It may be that there are two types of extra- vasation, one from the fornices which is a normal phenomenon and one from the pelvis indicating a defect due to increased pressure. The extravasation from the fornices is, however, not always due to the
presence o f defects - the persistence o f extravasation while a dense nephrogram exists precludes this possibility.
CONCLUSIONS
1. Both mechanisms o f pyelosinus extravasation (Narath, 1940) i.e. through defects in the fornices o f the calyces or transflow through an intact mucosa have been demonstrated to occur during excretion urography.
2. A rise in intrapelvic pressure is not necessary for extravasation to occur.
418 CLINICAL R A D I O L O G Y
( c ) (d)
Fig. 5 - Case 5. (c) Five and a half hour film most of the extravasated contrast medium has disappeared. (d) Twenty-four hour film showing contrast medium retained in the ureter and pelvicalyceal system with no evidence of extravasation.
3. E x t r a v a s a t i o n can be t r u l y s p o n t a n e o u s even i f ex te rna l compres s ion is used.
Acknowledgements. We thank our clinical colleagues for allowing us to study their patients and Mr M. Dunn for helpful advice. Miss S. Chamberlain typed the manuscript and Mr G. Gilbert made the prints.
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PYELOSINUS E X T R A V A S A T I O N 419
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