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Bondarenko Sergey Georgievich, Head of department of pediatric urology Municipal hospital № 7.
Volgograd. Russian Federation, Agzamkhodjaev Saidanvar Talatovich, Head of department of pediatric urology Tashkent pediatrical medical institute, Tashkent, Uzbekistan E-mail: evovision@bk.ru
EVALUATION OF URETERO-PELVIC JUNCTION URODYNAMICS IN CHILDREN WITH CONGENITAL HYDRONEPHROSIS
Abstract: Parameters of diuretic ultrasonography (DUS) were analyzed in 44 normal and 27 hydronephrotic renal units. Pelvis area, diameter of pyelo-ureteral segment (D) before and after (Dd) increase of diuresis, velocity of pelvis area normalization (V) after increase of diuresis, incrementations of pelvis area as a tone of pelvis (AS) and diameter of pyelo-ureteral segment (AD) after increase of diuresis was measured. To find out whether parameters of DUS reflect urodynamics at pelvis-ureter level we compared intercoupling in parameters of DUS with regularity hydrodynamic parameters of mathematic model of fluid outflow. Reliable correlation between theoretical model and empirical data was observed.
Our study suggests that diuretic ultrasonography is an appropriate method for evaluation of urodynamics of pyelo-ureteral segment.
Keywords: Uereteropelvic junction, diuretic ultrasonography, hydronephrosis, obstruction.
Introduction Methods. Parameters of DUS were analyzed in 44
Assessing of uretero-pelvic junction (UPJ) condition children: 18 boys and 26 girls aged 1 to 5 years. 17 of
has important significance in establishing treatment plan them had suspecting obstructive uropathy and 27 with
of urodynamic disturbances in this zone of urinary tract UPJ obstruction. In one sided hydronephrosis group
[1]. If that is the case, widely performed method - di- contralateral kidney values were examined with intrave-
uretic ultrasonography (DUS) is considered as the least nous pyelography, all patients did not have infection of
invasive diagnostic tool [2]. As a matter of practice, in urinary tract and compensatory enlargement and hyper-
urodynamic condition assessment of UPJ obstruction le- function of normal kidney. sions, such parameters as characterizing dilatation of pel- Following DUS parameters were studied: vis and time of pelvic area reduction after forced diuresis - Pelvic area initially on cross sectional scan,
are used [6] Additionally, evaluation ofpathologic values S (mm2);
is based on comparing with empirical and observational - Pelvic area after 5 mins of diuretic injection,
data, retrieved during assessment of normal kidney with- S (mm2);
' O / maxv '1
out taking into consideration of natural hydrodynamic - Pelvic area after 20-40 mins of diuretic injection
regularity and variable UPJ physiology. Latter is linked to on cross sectional scan, St (mm2); impossibility of non-invasive hydrodynamic parameters Percentage of increased area when diuresis reached
estimation in upper urinary tract [5]. its maximum, Percentage ofincreased area when diuresis
Aim of research. To study urodynamic normal and reached its maximum, AS hydronephrotic values, their interpretation with urody- Velocity of pelvic area normalization after increase
namic mathematic modeling. of diuresis, V, calculated by (Smax-St)/1, (mm2/min);
- Diameter of UPJ area before (D) and after (Dd) increase of diuresis;
- UPJ diameter increase when max diuresis is reached, AD (mm);
Following statistical analysis methods were used: rank correlation and regressive; since values variation have not normal distribution, non-parameteric Craskel-Wallis analysis and K-values cluster method was also used. Chosen parameters included in next table are: M-mean, s-standard deviation, n- size of analyzed subTable 1. - Diuretic ultrasonography in
group, p reached significance value. Critical values of significance level are taken as 5%. Statistical data analysis performed using SPSS 11.5 package.
Results and discussion. During the study obtained results showed quite considerable deviations of mean values from initial pelvic area size S, pelvic area normalization velocity after increased diuresis and its increased area when diuresis reached its max (table 1). he rate of drainage of the pelvis V and the area.
the general group of children under test
Parameters n min max M s
S 44 7.85 507.11 149.67 136.47
V 44 0.25 11.74 3.46 3.08
D 44 35.29 880.00 188.39 185.46
D 44 0 4.0 0.67 1.1
DA 44 1.5 4.0 2.34 0.64
D 44 0 4.0 1.62 1.11
Additionally, there was observed positive correlation between S and AS (Spirman correlation coef. R =-0.62,
between initial pelvic area and pelvic area normalization p = 0.0003). These data witness requirement subgroup
velocity after peak diuresis V(Spirman correlation coeffi- division, depending on initial pelvic area size S (Table 2). cient r = 0.77; p < 0.0001) and negative correlation stated
Table 2. - The rate of drainage of the pelvis V and the area increments AS in clusters
Cluster
Parameters I Cluster II Cluster III Cluster
n=19 n = 15 n = 10
S 96.7 ± 36.6 237.9 ± 66.0 579.2 ± 124.6
V 1.4 ± 0.75; x2 = 18.9; p < 0.0001 3.7 ± 1.7; x2 = 8.7; p = 0.003 9.2 ± 3.9
D 191.6 ± 84.5; x2 = 8.48; p = 0.004 60.8 ± 18.1; x2 = 0.42; p = 0.52 58.4 ± 9.1
While studying velocity parameters V, in clusters were found essential differences depending on cluster relation, but less deviation grade was observed compared to mean group values
Analysis of percentage increase of initial pelvis size AS, depending cluster relation, it was found that these values had practically close numbers in II and III clusters, which were significantly less than cluster I.
Further, there was not established direct relation between AS grade and V (regression coef. F = 0.006, p = = 0.94), additionally, since those parameters depend on initial pelvic size S, established positive relation between stated before values (r = 7, p = 0.005, when S = const).
UPJ examination in 11 cases (25%) had successful identification before furosemide injection, it's mean diameter was 2.04 ± -0.76 mm. during max postfurose-mide diuresis this segment visualized in all children and its size was 2.6 ± -0.7 mm.
UPJ diameter during diuresis stimulation significantly differed in 2 age groups. Thus, in group were children were less than age 1 pelvis diameter D was quite smaller in comparison with group were kids were older, between 1 and 5 years and as in elder group. Segment diameter practically did not differ in 1-5 year age group from group elder than 5 year old children (Table 3).
Table 3. - The rate of drainage of the pelvis V and the area increments AS in clusters
Parameters Under 1 year From 1 to 5 years Older than 5 years
Dd 1.9 ± 0.09 2.3 ± 0.4 2.6 ± 0.8
x2 6.85 (p < 0.001) 1.76 (p > 0.05 = 0.19) 3.2 (P < 0.001)
Performed regressive analysis revealed absent relationship as between velocity pelvic drainage, V and max diameter UPJ -Dd (regressive coef = 0.07, F = 0.08; p = 0.93), as between Dd and pelvic area increase value AS (regressive coef = 0.16; F = 0.49; p = 0.49). Also, has been found positive connection between post-furose-mide pelvic area increase AS and PUJ diameter increase AD (Spearman correlation coef. rs = 0.75; p = 0.0001), as in contrast negative connection between diameter increase AD and initial pelvic area size S (rs =-0.70; p = =0.0001). Significant AD difference was found in cluster I as well as in II and III clusters (2.6 ± 0.6 and 1.7 ± 0.09 relatively, x2 = 7.7; p = 0.005).
Before going over to interpretation of obtained results it is essential to elaborate some aspects of UPJ physiology and urine passage thru the junction. During normal diuresis and pelvis filling, UPJ and proximal end of ureter is in a collapsed state. Electrical activity at UPJ is absent [4]. When intra pelvic pressure and wall tangential tension is increased, pacemaker is activated that leads to pelvic contraction and UPJ opening. After urine volume passed to proximal segment of ureter pressure in pelvis is decreased, pacemaker activity disappears and UPJ collapses. Thus, there is 2 main hydrodynamic factors determine urine passage efficiency- intra-pelvic pressure and UPJ diameter. Theoretically, interaction of those two factors may be expressed using math model offluid outflow thru hole underlying a level, which may be used in pelvic-ureteral system:
D = ^4Q / pnfe (Pp ± Pu) / p
So, this equation concludes that larger Radius is, hence size and volume of pelvis, the lower hyperbolic pressure is. Except various factors (wall elasticity) pelvis tone or tangential tension grade defines basic pressure-the higher this is, the higher wall tension grade is, therefore, lower ability to expand and to increase volume is.
Thus, post-furosemide area increase AS, seems to be indicator, expressing pelvis tone condition (tangential tension grade), indirectly-basic pressure level.
As we can see on equation, pelvic drainage efficiency with increased urine passage either determined with
UPJ diameter D while pressure is constant Pp, or with increased intra-pelvis pressure Pp, whereas there is negative correlation between diameter and pressure of PUJ.
This regularity corresponds with obtained results -Pelvis drainage velocity V during forced diuresis have most essential value where pelvic area increase grade AS is low, i.e high pelvic wall tone (basic pressure) and positive correlation with UPJ opening grade AD. as performed diuretic US analysis suggests, first type urine passage in forced condition is more distinctive for kidneys with bigger pelvis area, where higher drainage velocity is conducted not only because of adequate UPJ diameter, but also in result of more higher pelvic wall tone. Accordingly, taking into count urine dynamic peculiarities stated above, there is obvious need to distinguish normative groups depending on initial pelvic size.
When assessing Diuretic US values in 27 children with hydronephrosis (14 cases with UPJ obstruction due to intrinsic factors and 13 crossed vessels) there found significant deviation in comparison with DUS values from 3rd cluster (kidneys with bigger pelvic area). Thus, in 23 (85%) cases UPJ was not visualized, and in 4 patients (15%) its diameter after forced diuresis Dd and its increase AD were 1.4 ± 0.3 mm and 0.7 ± -0.2 mm, respectively, which was considerably less than normative means. (x2 = 31.7; p < 0.0001 and x2 = 28.1; p < 0.0001, respectively). In 18 cases (66.7%) pelvic area after forced diuresis increased progressively and drainage velocity values were negative, mean -2.2 ± -0.6 mm2/ min. in 9 patients expressed slow pelvis drainage velocity occurred (v = 0.98 mm/min, x2 = 38.9, p,0.0001). analysis also showed that pelvis area increase AS values in 15 cases (55.6%) were considerably lower normal means (26.8 ± 14.6%, x2 = 17.0; p = 0.0001), i.e there was hypertonic state; in 7 (25.9%) - hypotonic state: AS values significantly higher (162.5 ± 51.4%, x2 = 9.8; p = 0.002), lastly in 5 (18.5%) AS was not practically different than normal and was equal to 71.8 ± 14.6%.
As performed research suggests, obtained DUS values appears to be in complex co-dependency. Established correspondence showed with mathematic model
shows that DUS values characterizes urine dynamics in pelvis-ureter level.
Standard DUS assumes assessing two main parameters: time of pelvis area normalization and its dilatation grade [3] where slow or absent normalization pelvis area and its excessive dilatation after forced diuresis, interpreted as urine passage lesion. Parameters of DUS introduced gives us measurable urodynamic estimation and UPJ condition, values relationship with initial pelvis area and age obtained during study suggest to divide normative groups for more precise comparison and DUS analysis in lesions is required. Moreover, mathematic model and data in patients with hydronephrosis points to incompetence of interpreting that area increase after forced
diuresis as obstruction sign. As research concludes, latter value only expresses pelvis tone grade, i.e its ability to dilate when diuresis is increased. Performed study in children with hydronephrosis suggest that:
- UPJ obstruction and urine passage impairment may have various grade;
- Functional state of UPJ is complicated: as it may appear to be in hyper-, hypo- and normotonic state. These data also confirmed by results of direct assess of pelvic and UPJ functional state in hydronephrosis.
Conclusion. To summarize, DUS is non-invasive functional method, which lets assess urine dynamics in UPJ and more precisely give quality and quantity characteristics in hydronephrosis.
References:
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2. Akgun V., Battal B., Kocaoglu M., Ozcan E., Akay S., Ilgan S. Sonographic measurement of diuretic-induced renal length changes: are they correlated with renal function? // J Ultrasound Med. - 2012.- Vol. 31(9).- P. 1351-1364.
3. Chow J. S., Koning J. L., Back S.J., Nguyen H. T., Phelps A., Darge K. Classification of pediatric urinary tract dilation: the new language // Pediatr Radiol.- 2017.- Vol.47(9).- P. 1109-1115.
4. Constantinou C. E., Djurhuus J. C. // Am J Physiol.- 1981.- Vol. 241.- P. 398-402.
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