Renal Doppler ultrasonography in infants with hydronephrosis

Renal Arterial Doppler Resistive Index in Differentiating Obstructive and Non-Obstructive Hydronephrosis in Children at Tikur Anbessa Specialized Hospital, Ethiopia, October, 2018

BACKGROUND

Most congenital anomalies of the urinary tract present with hydronephrosis. Some are physiological while others pathological. Ultrasound, micturating cyst urethrography, dynamic renal scintigraphy, intravenous urography, dynamic and static magnetic resonance urography are used for examination. Currently, renal arterial Doppler resistance index is used as complimentary mechanism. This study assesses our experience in resistive index measurement in differentiating obstructive from non-obstructive hydronephrosis in children.

METHODS

A cross-sectional study of forty-two infants and children (<14 years) with hydronephrosis were enrolled using consecutive sampling. Ultrasonography to assess the degree of hydronephrosis and avoiding cystourethrogram were used for the diagnosis of vesicoureteral reflux and posterior urethral valve. Intravenous urogram and surgery were used to confirm causes for obstructive hydronephrosis. Doppler ultrasonography assessed both kidneys to determine mean resistive index for both obstructive and non-obstructive hydronephrosis as well as nonobstructive kidneys. Independent t test was used for analysis at p< 0.005.

RESULTS

The major cause for obstructive hydronephrosis was pelviuretheric junction obstruction (47.6%) followed by posterior urethral valve (16.7%). For non-obstructive hydronephrosis, vesicoureteral reflux was the main cause followed by prune belly syndrome. The mean resistive index for non-hydronephrotic kidneys was 0.6654 ±0.053, for nonobstructive hydronephrotic ones was 0.6825 ± 0.06668 and obstructive ones was 0.7791 ± 0.11977. The mean resistive index difference between the obstructive and non-obstructive hydronephrosis was 0.09661 with standard error of difference 0.02443. The difference was statistically significant (P-<0.001). A mean RI ROC curve showed sensitivity, specificity and accuracy of 71.1%, 81.2%, 75.4% respectively (p=0.003).

CONCLUSION

This study has shown that the mean renal arterial resistive index was significantly higher in obstructive hydronephrotic kidneys than non-obstructive hydronephrotic kidneys. This can be a valuable tool for diagnosis and follow-up after intervention.

Functional evaluation of the urinary tract by color-Doppler ultrasonography (CDU) in 100 patients with renal colic

INTRODUCTION AND OBJECTIVE

To evaluate if the addition of a renal color-Doppler ultrasonography (CDU) in the setting of acute renal colic improves the sensitivity of conventional sonography.

MATERIALS AND METHODS

Between July 2002 and June 2003, 100 patients (median 49 years) with renal colic have been evaluated. Within 24 h of the admission, a CDU study of the urinary tract was performed using a sonograph GE Logiq 500 PRO with a multifrequency (3-5 MHz) convex probe. The following parameters were evaluated: ultrasonography (US) of both kidneys, ureters and bladder; resistive index (RI) of the arciform arteries of both kidneys in three different parenchymal areas; ureteric jets in response to hydration. A renal RI>0.70 and/or a 10% difference between the kidneys were considered as diagnostic of obstructive uropathy; an asymmetric and/or reduced ureteric jet from the ureteric orifices was an additional indicator of obstruction. All patients underwent a CT scan both with and without the administration of contrast medium.

RESULTS

Enhanced helical CT demonstrated an urinary stone in 90 out of the 100 patients (90%): 29 pyelic, 28 at the pyelo-ureteral junction, 23 lumbo-iliac and 10 juxtavesical stones. Among 90 patients with urolithiasis, the stone was undetectable with US in 11 cases (12.2%); in 8 cases (8.9%) pyelocalicectasis was absent, and in 6 patients (6.6%) a non-obstructive hydronephrosis was present. Median RI in obstructed and non-obstructed kidney was 0.73 (range 0.71-0.87) versus 0.62 (0.50-0.68), respectively; in two, obstructed kidneys RI was <0.70 but greater than 10% compared with normal side. Sensitivity and specificity of US, CDU (RI+ureteric jet), unenhanced helical CT and CDU in association with unenhanced helical CT were 94.8 and 55.5, 98.9 and 90.9, 100 and 100%, respectively.

DISCUSSION AND CONCLUSIONS

CDU in patients with renal colic and/or pelvicalicectasis improves the diagnostic accuracy of US in distinguishing between obstructive and non-obstructive dilatation. Combined with unenhanced CT, CDU has a 100% sensitivity and specificity. Moreover, due to the absence of contraindications and side-effects, CDU is indicated for the follow-up of patients after ESWL, pregnant women and children.