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Intra-renal reflux in children demonstrated by micturating cystography
Clin. l~adioL(1974)25, 81-85 INTRA-RENAL REFLUX IN CHILDREN DEMONSTRATED BY M I C T U R A T I N G C Y S T O G R A P H Y T. M. J. MALING and G. L. ROLLESTON
From the Department of Radiology, Christchurch Hospital and Clinical School, Christchurch, New Zealand The techniques of micturating cystography employed in 386 patients with vesico-ureteric reflux, 16 of whom showed intra-renal reflux, are outlined. The radiographic appearances of intra-renal reflux (pyelotubular backflow) occurring during micturating cystography are described. It is stressed that for the demonstration of intra-renal reflux, it is essential to have good radiographic definition of the renal areas. This is helped by taking all radiographs at a film to focus distance of 100 cm and by having adequate bowel preparation of the patient. control. The contrast medium enters the bladder under low pressure due to the narrow internal diameter of the catheter. A radiograph which includes both the upper and lower urinary tracts is taken during the filling phase. Further radiographs are taken during spontaneous micturition with the male infant 15° oblique from the supine position. All radiographs include the renal areas, bladder and urethra and are taken with an overcouch tube and a film focal distance of 100 cm. Children. - Following catheterization with a Vygon plastic infant feeding tube, FGo8, the bladder is filled by gravity feed with 15 ~ Urografin using image intensification control. An overcouch radiograph is taken with the bladder full. The examination is carried out under general anaesthesia in those children, usually under the age of 5 years, where co-operation cannot be gained. Micturating films are obtained in anaesthetized children during 'expression' micturition, achieved by applying external pressure over the full bladder with a wooden spoon. These radiographs are taken with the overcouch tube, with the male patient slightly oblique from the supine position, and include both TECHNIQUE OF MICTURATING the upper and lower urinary tracts. CYSTOGRAPHY Older children and adults. - The same technique Apart from variations depending upon the age of catheterization and gravity feed as described group and ability of the patient to co-operate, above are employed, but the contrast medium used the techniques are the same in each instance and is 7.5 ~ freshly prepared sodium iodide. Filling is have changed little over the past 10 years. Our aim supervised by image intensification, and a supine has been at all times to obtain high-quality radio- radiograph which includes the bladder and upper graphs of the upper as well as the lower urinary urinary tract is taken with the overcouch tube at tract. the completion of the filling phase. To obtain Infants. - The infant is immobilized on a frame, micturating films, the technique varies between catheterized with a Vygon plastic feeding tube, the sexes. FGo5, and the bladder filled by gravity feed with Females. - The patient is seated on a commode 15~ Urografin under imagine intensification constructed so that it is portable with a wooden 81
THE phenomenon of contrast medium passing out into the renal parenchyma in association with vesico-ureteric reflux has been called intra-renal reflux - Rolleston et al. (1973). They demonstrated intrarenal reflux occurring in 16 children under the age of 5 years, and showed a very significant association between the areas of intra-renal reflux occurring with severe vesico-ureteric reflux and the subsequent development of scarring in the same anatomical sites. The 16 children with intra-renal reflux were from a series of 386 patients, of all ages, all with vesico-ureteric reflux and without evidence of obstruction. The techniques involved in the micturating cystograms of these 16 children with intra-renal reflux were those which are employed at the Christchurch Hospital. The purpose of this paper is to describe in detail these techniques, the appearances of the intra-renal reflux and to discuss the factors involved in the demonstration and detection of intra-renal reflux occurring with vesico-ureteric reflux.
82
CLINICAL
RADIOLOGY
frame to hold a 43 × 35.5 cm film with a stationary grid. In this way it is possible to obtain radiographs during micturition with the patient in a sitting position. Males. The patient remains supine and is placed 10 to 15° oblique to enable adequate visualization of the urethra, and he micturates into a plastic container. RADIOGRAPHIC APPEARANCES OF INTRA-RENAL REFLUX
Intra-renal reflux was most easily detected when the contrast medium radiated from the centre of the calyx and opacified a wedge of renal tissue with the base of the wedge being the subcapsular border of the kidney. In the most spectacular example, the intra-renal reflux was highlighted by sparing of the intervening septa of Bertin (Fig. 1). The remainder of the cases were not as florid as in this patient. The area of renal paranchyma involved by intra-renal reflux showed differing radiographic appearances. In some the involved area had a distinctly striated appearance (Fig. 2), whilst in others there was homogenous opacification of the area of renal parenchyma similar to the nephrogram phase of an excretion urogram (Fig. 3). The amount of renal tissue involved varied from the entire kidney, as seen in Fig. 1, to little more than a renal lobule.
DEMONSTRATION AND DETECTION OF INTRA-RENAL REFLUX
The detection of intra-renal reflux depended upon good radiographic definition of the renal areas. This was achieved by the use of the overcouch x-ray tube with a film focal distance of 100 cm to obtain high quality radiographs. In our experience the definition obtained with cine fluorography has not been adequate for the demonstration ofintra-renal reflux, except in the most severe cases. All radiographs include the renal areas. This is particularly important in those taken during micturition, as vesico-ureteric reflux is usually maximal and this is the most likely time for intrarenal reflux to occur. The presence or absence of faecal material in the colon is a factor which affects the renal definition and is important in determining whether or not intra-renal reflux is present. This applies particularly to those cases where opacification of the renal parenchyma is the only evidence of intra-renal reflux.
FIG. 1 Extensive intra-renal reflux occurring into almost the entire right kidney of a 10-month-old girl in association with severe vesico-ureteric reflux. The intra-renal reflux has been highlighted in some areas by sparing of the intervening Septa of Bertin.
DISCUSSION It should be stressed that in all the micturating cystograms performed in this series of 386 patients, the bladder was filled by gravity feed from a low height and always through a catheter with a small internal diameter. The height of the reservoir was adjusted so as not to exceed the expected normal range of bladder pressures, and the narrow bore of the catheter ensured that the rate of filling was slow. Adherence to these criteria may prolong the time taken for the examination, but it does ensure that it is more physiological than in the frequently employed practice of filling the bladder by means of a syringe. The degree of bladder filling is important.
I N T R A , R E N A L R E F L U X IN C H I L D R E N
83
reflux is shown.
FIo. 3 Cystogram on a 4-week-old boy with bilateral vesico-m°eteric reflux and intra-renal reflux into the middle portion of the right kidney. In this ease the intra-renal reflux has resulted in diffuse opacifieation of the area of parenchyma involved.
Inadequate filling can lead to false negatives with regard to vesico-ureteric reflux (Shopfner, 1965). We continue bladder filling until the patient has a very strong urge to micturate. We have found that spontaneous dorsiflexion of the toes in children is usually a reliable indicator that the bladder is filled to capacity. In infants and anaesthetized children, bladder filling is continued until either spontaneous micturition occurs or there is no further filling by gravity with the reservoir held at a height of not greater than 50 cm. If the examination is carried out in this manner, intra-vesical pressure should not exceed the normal physiological range. Too little is known about the mechanics of intrarenal reflux to determine whether excessive bladder filling, in the presence of vesico-ureteric reflux,
might sometimes produce intra-renal reflux not necessarily present in the natural state. If intrarenal reflux has a purely mechanical basis, it is conceivable that excessive bladder filling might lead to an increase in intra-vesical pressure which will be transmitted upwards along the refluxing column of urine in the ureter. In some instances this increased pressure might be just sufficient to cause intra-renal reflux. The use of general anaesthesia in uncooperative young children does not appear to influence the production of intra-renal reflux, as we have seen equal numbers of patients with intra-renal reflux in cystograms performed with or without general anaesthesia. The different patterns of intra-renal reflux described, with either a striated appearance or
FIG. 2 Cystogram on a 7.month-old girl with moderate vesieoureteric reflux and intra-renal reflux into the upper pole of the left kidney. The striated pattern of tbe intra-renal
84
CLINICAL
RADIOLOGY
FIG. 4n Fig. 4A--Excretion urogram on a 14-month-old girl shows a duplex left kidney. Damage is present throughout the lower moiety.
FI~. 4B Fig. 4B--Cystogram on the same child a few days later shows vesico-ureteric reflux and intra-renal reflux into the lower renal moiety. Notice how this has resulted in diffuse opacification of the parenchyma of the lower segment but the upper moiety cannot be seen.
diffuse homogeneous opacification of an area of renal parenchyma, correspond very closely to the different appearances of pyelotubutar backflow seen on retrograde pyelography and described by Kohler (1953). Experimental work, to be published shortly, has shown that intra-renal reflux is due to pyelotubular backflow. It is easy to overlook intra-renal reflux when the only evidence is opacification of the renal parenchyma and it will be missed frequently unless first-class radiographic detail of the kidneys is obtained in all radiographs, especially those taken during voiding. At the commencement of a micturating cystogram we take a radiograph of the abdomen before any contrast medium has entered the bladder. We have found that comparison of radiographs showing vesico-ureteric reflux with the initial plain radiograph has been of great value in detecting
intra-renal reflux. The renal outline in infancy and early childhood is often difficult to define on a plain radiograph. If during voiding cystography, when vesico-ureteric reflux is present, the renal outline, in part or in full, becomes clearly visible, it is highly possible that this is due to intra-renal reflux. This is well demonstrated in Fig. 4, where intra-renal reflux has occurred into the lower half of a duplex kidney. The subsequent increase in density of the parenehyma is confined to the lower renal moiety which is clearly visible in contrast to the obscurity of the upper moiety. The important association of intra-renal reflux and renal damage has already been referred to (Rolleston et al.,) and in view of this we believe that the demonstration of intra-renal reflux is a major objective in the performance of micturating cystography. The majority of patients with intra-renal reflux
INTRA-RENAL
R E F L U X IN CHILDREN
85
will only be detected when the examination follows good bowel preparation and high definition radiographs are obtained of the renal areas, especially during micturition.
pyelography. A roentgenological and clinical study. Acta Radiologica SuppL 99. ROLLESTON, G.L., MALING,T. M. J., HODSON,C. J. Accepted~ifor publication. Archives of Disease in ChiM-
REFERENCES KOHLER,R. (1953). Investigation of backflow in retrograde
SHOPFNER,C. E. (1965). Cystom'ethrography: an evaluation of method. American Journal of Roentgenology, 95, 468-474.
hood, 1973.
From the Department of Radiology, Christchurch Hospital and Clinical School, Christchurch, New Zealand The techniques of micturating cystography employed in 386 patients with vesico-ureteric reflux, 16 of whom showed intra-renal reflux, are outlined. The radiographic appearances of intra-renal reflux (pyelotubular backflow) occurring during micturating cystography are described. It is stressed that for the demonstration of intra-renal reflux, it is essential to have good radiographic definition of the renal areas. This is helped by taking all radiographs at a film to focus distance of 100 cm and by having adequate bowel preparation of the patient. control. The contrast medium enters the bladder under low pressure due to the narrow internal diameter of the catheter. A radiograph which includes both the upper and lower urinary tracts is taken during the filling phase. Further radiographs are taken during spontaneous micturition with the male infant 15° oblique from the supine position. All radiographs include the renal areas, bladder and urethra and are taken with an overcouch tube and a film focal distance of 100 cm. Children. - Following catheterization with a Vygon plastic infant feeding tube, FGo8, the bladder is filled by gravity feed with 15 ~ Urografin using image intensification control. An overcouch radiograph is taken with the bladder full. The examination is carried out under general anaesthesia in those children, usually under the age of 5 years, where co-operation cannot be gained. Micturating films are obtained in anaesthetized children during 'expression' micturition, achieved by applying external pressure over the full bladder with a wooden spoon. These radiographs are taken with the overcouch tube, with the male patient slightly oblique from the supine position, and include both TECHNIQUE OF MICTURATING the upper and lower urinary tracts. CYSTOGRAPHY Older children and adults. - The same technique Apart from variations depending upon the age of catheterization and gravity feed as described group and ability of the patient to co-operate, above are employed, but the contrast medium used the techniques are the same in each instance and is 7.5 ~ freshly prepared sodium iodide. Filling is have changed little over the past 10 years. Our aim supervised by image intensification, and a supine has been at all times to obtain high-quality radio- radiograph which includes the bladder and upper graphs of the upper as well as the lower urinary urinary tract is taken with the overcouch tube at tract. the completion of the filling phase. To obtain Infants. - The infant is immobilized on a frame, micturating films, the technique varies between catheterized with a Vygon plastic feeding tube, the sexes. FGo5, and the bladder filled by gravity feed with Females. - The patient is seated on a commode 15~ Urografin under imagine intensification constructed so that it is portable with a wooden 81
THE phenomenon of contrast medium passing out into the renal parenchyma in association with vesico-ureteric reflux has been called intra-renal reflux - Rolleston et al. (1973). They demonstrated intrarenal reflux occurring in 16 children under the age of 5 years, and showed a very significant association between the areas of intra-renal reflux occurring with severe vesico-ureteric reflux and the subsequent development of scarring in the same anatomical sites. The 16 children with intra-renal reflux were from a series of 386 patients, of all ages, all with vesico-ureteric reflux and without evidence of obstruction. The techniques involved in the micturating cystograms of these 16 children with intra-renal reflux were those which are employed at the Christchurch Hospital. The purpose of this paper is to describe in detail these techniques, the appearances of the intra-renal reflux and to discuss the factors involved in the demonstration and detection of intra-renal reflux occurring with vesico-ureteric reflux.
82
CLINICAL
RADIOLOGY
frame to hold a 43 × 35.5 cm film with a stationary grid. In this way it is possible to obtain radiographs during micturition with the patient in a sitting position. Males. The patient remains supine and is placed 10 to 15° oblique to enable adequate visualization of the urethra, and he micturates into a plastic container. RADIOGRAPHIC APPEARANCES OF INTRA-RENAL REFLUX
Intra-renal reflux was most easily detected when the contrast medium radiated from the centre of the calyx and opacified a wedge of renal tissue with the base of the wedge being the subcapsular border of the kidney. In the most spectacular example, the intra-renal reflux was highlighted by sparing of the intervening septa of Bertin (Fig. 1). The remainder of the cases were not as florid as in this patient. The area of renal paranchyma involved by intra-renal reflux showed differing radiographic appearances. In some the involved area had a distinctly striated appearance (Fig. 2), whilst in others there was homogenous opacification of the area of renal parenchyma similar to the nephrogram phase of an excretion urogram (Fig. 3). The amount of renal tissue involved varied from the entire kidney, as seen in Fig. 1, to little more than a renal lobule.
DEMONSTRATION AND DETECTION OF INTRA-RENAL REFLUX
The detection of intra-renal reflux depended upon good radiographic definition of the renal areas. This was achieved by the use of the overcouch x-ray tube with a film focal distance of 100 cm to obtain high quality radiographs. In our experience the definition obtained with cine fluorography has not been adequate for the demonstration ofintra-renal reflux, except in the most severe cases. All radiographs include the renal areas. This is particularly important in those taken during micturition, as vesico-ureteric reflux is usually maximal and this is the most likely time for intrarenal reflux to occur. The presence or absence of faecal material in the colon is a factor which affects the renal definition and is important in determining whether or not intra-renal reflux is present. This applies particularly to those cases where opacification of the renal parenchyma is the only evidence of intra-renal reflux.
FIG. 1 Extensive intra-renal reflux occurring into almost the entire right kidney of a 10-month-old girl in association with severe vesico-ureteric reflux. The intra-renal reflux has been highlighted in some areas by sparing of the intervening Septa of Bertin.
DISCUSSION It should be stressed that in all the micturating cystograms performed in this series of 386 patients, the bladder was filled by gravity feed from a low height and always through a catheter with a small internal diameter. The height of the reservoir was adjusted so as not to exceed the expected normal range of bladder pressures, and the narrow bore of the catheter ensured that the rate of filling was slow. Adherence to these criteria may prolong the time taken for the examination, but it does ensure that it is more physiological than in the frequently employed practice of filling the bladder by means of a syringe. The degree of bladder filling is important.
I N T R A , R E N A L R E F L U X IN C H I L D R E N
83
reflux is shown.
FIo. 3 Cystogram on a 4-week-old boy with bilateral vesico-m°eteric reflux and intra-renal reflux into the middle portion of the right kidney. In this ease the intra-renal reflux has resulted in diffuse opacifieation of the area of parenchyma involved.
Inadequate filling can lead to false negatives with regard to vesico-ureteric reflux (Shopfner, 1965). We continue bladder filling until the patient has a very strong urge to micturate. We have found that spontaneous dorsiflexion of the toes in children is usually a reliable indicator that the bladder is filled to capacity. In infants and anaesthetized children, bladder filling is continued until either spontaneous micturition occurs or there is no further filling by gravity with the reservoir held at a height of not greater than 50 cm. If the examination is carried out in this manner, intra-vesical pressure should not exceed the normal physiological range. Too little is known about the mechanics of intrarenal reflux to determine whether excessive bladder filling, in the presence of vesico-ureteric reflux,
might sometimes produce intra-renal reflux not necessarily present in the natural state. If intrarenal reflux has a purely mechanical basis, it is conceivable that excessive bladder filling might lead to an increase in intra-vesical pressure which will be transmitted upwards along the refluxing column of urine in the ureter. In some instances this increased pressure might be just sufficient to cause intra-renal reflux. The use of general anaesthesia in uncooperative young children does not appear to influence the production of intra-renal reflux, as we have seen equal numbers of patients with intra-renal reflux in cystograms performed with or without general anaesthesia. The different patterns of intra-renal reflux described, with either a striated appearance or
FIG. 2 Cystogram on a 7.month-old girl with moderate vesieoureteric reflux and intra-renal reflux into the upper pole of the left kidney. The striated pattern of tbe intra-renal
84
CLINICAL
RADIOLOGY
FIG. 4n Fig. 4A--Excretion urogram on a 14-month-old girl shows a duplex left kidney. Damage is present throughout the lower moiety.
FI~. 4B Fig. 4B--Cystogram on the same child a few days later shows vesico-ureteric reflux and intra-renal reflux into the lower renal moiety. Notice how this has resulted in diffuse opacification of the parenchyma of the lower segment but the upper moiety cannot be seen.
diffuse homogeneous opacification of an area of renal parenchyma, correspond very closely to the different appearances of pyelotubutar backflow seen on retrograde pyelography and described by Kohler (1953). Experimental work, to be published shortly, has shown that intra-renal reflux is due to pyelotubular backflow. It is easy to overlook intra-renal reflux when the only evidence is opacification of the renal parenchyma and it will be missed frequently unless first-class radiographic detail of the kidneys is obtained in all radiographs, especially those taken during voiding. At the commencement of a micturating cystogram we take a radiograph of the abdomen before any contrast medium has entered the bladder. We have found that comparison of radiographs showing vesico-ureteric reflux with the initial plain radiograph has been of great value in detecting
intra-renal reflux. The renal outline in infancy and early childhood is often difficult to define on a plain radiograph. If during voiding cystography, when vesico-ureteric reflux is present, the renal outline, in part or in full, becomes clearly visible, it is highly possible that this is due to intra-renal reflux. This is well demonstrated in Fig. 4, where intra-renal reflux has occurred into the lower half of a duplex kidney. The subsequent increase in density of the parenehyma is confined to the lower renal moiety which is clearly visible in contrast to the obscurity of the upper moiety. The important association of intra-renal reflux and renal damage has already been referred to (Rolleston et al.,) and in view of this we believe that the demonstration of intra-renal reflux is a major objective in the performance of micturating cystography. The majority of patients with intra-renal reflux
INTRA-RENAL
R E F L U X IN CHILDREN
85
will only be detected when the examination follows good bowel preparation and high definition radiographs are obtained of the renal areas, especially during micturition.
pyelography. A roentgenological and clinical study. Acta Radiologica SuppL 99. ROLLESTON, G.L., MALING,T. M. J., HODSON,C. J. Accepted~ifor publication. Archives of Disease in ChiM-
REFERENCES KOHLER,R. (1953). Investigation of backflow in retrograde
SHOPFNER,C. E. (1965). Cystom'ethrography: an evaluation of method. American Journal of Roentgenology, 95, 468-474.
hood, 1973.