A comparison of two techniques of detecting vesico-ureteric reflux

[Evidence-based medicine and vesicoureteral reflux]

Vesicoureteral reflux (VUR) remains one of the most controversial subjects in paediatric urology. Much literature has been published on VUR, making the understanding of this anomaly and its treatments quite opaque. Evidence-Based Medicine (EBM) should be helpful to clarify the various VUR approaches contained in the 6224 titles found on Medline using the keywords "vesicoureteral reflux" and "vesicoureteric reflux". These articles were critically reviewed and graded according to EBM scorings, with regard to their methodological designs. This review of VUR literature suggests that most of our knowledge is based on publications with a low level of evidence, and that EBM lacks arguments to support recommendations for VUR diagnostic and treatment. It appears yet that antenatal dilatation of the urinary tract and symptomatic urinary tract infections (UTI) justify VUR screening. Surgery should be discussed in recurrent UTIs or deterioration of renal function. There is no consensus in case of persistent asymptomatic VUR regarding indication and duration of antibio-prophylaxis, and selection of radical treatment.

Pediatric applications of renal nuclear medicine

This review should be regarded as an opinion based on personal experience, clinical and experimental studies, and many discussions with colleagues. It covers the main radionuclide procedures for nephro-urological diseases in children. Glomerular filtration rate can be accurately determined using simplified 2- or 1-blood sample plasma clearance methods. Minor controversies related to the technical aspects of these methods concern principally some correction factors, the quality control, and the normal values in children. However, the main problem is the reluctance of the clinician to apply these methods, despite the accuracy and precision that are higher than with the traditional chemical methods. Interesting indications are early detection of renal impairment, hyperfiltration status, and monitoring of nephrotoxic drugs. Cortical scintigraphy is accepted as a highly sensitive technique for the detection of regional lesions. It accurately reflects the histological changes, and the interobserver reproducibility in reporting is high. Potential technical pitfalls should be recognized, such as the normal variants and the difficulty in differentiating acute lesions from permanent ones or acquired lesions from congenital ones. Although dimercaptosuccinic acid scintigraphy seems to play a minor role in the traditional approach to urinary tract infection, recent studies suggest that this examination might influence the treatment of the acute phase, the indication for chemoprophylaxis and micturating cystography, and the duration of follow-up. New technical developments have been applied recently to the renogram: tracers more appropriate to the young child, early injection of furosemide, late postmicturition and gravity-assisted images and, finally, more objective parameters of renal drainage. Pitfalls mainly are related to the interpretation of drainage on images and curves. Dilated uropathies represent the main indication of the renogram, but the impact of this technique on the management of the child is, in a great number of cases, still a matter of intense controversy. Direct and indirect radionuclide cystography are interesting alternatives to the radiograph technique and should be integrated into the process of diagnosis and follow-up of vesicoureteral reflux.

How good is technetium-99m mercaptoacetyltriglycine indirect cystography?

The aim of the present study was to estimate the sensitivity of indirect radionuclide cystography (IRC) performed with technetium-99m mercaptoacetyl-triglycine (MAG3), in comparison with the micturition cystourethrography (MCUG) and direct radionuclide cystography (DRC), for the diagnosis of vesicoureteric reflux. Two groups of patients were selected: group I comprised 40 children who underwent IRC during the acute phase of urinary tract infection and an MCUG 6 weeks later; group II comprised 42 (other) children with known reflux, who underwent IRC and DRC during follow-up. Taking as the reference the total number of refluxing kidneys detected by means of any cystographic technique, 99mTc-MAG3 ICR missed two-thirds of the refluxing kidneys. Most of the small refluxes were missed, but so too were 50% of the major refluxes. Taking as the reference 99mTc dimercaptosuccinic acid (DMSA) scintigraphy, MCUG detected 91% of the patients with DMSA abnormalities on at least one kidney, DRC detected 95%, and IRC detected 46% and 43% respectively, in groups I and II. The use of 99mTc-MAG3 IRC as the sole technique for the detection of vesicoureteric reflux gives rise to an unacceptable number of false-negative results.

Indirect radionuclide cystography: a sensitive technique for the detection of vesico-ureteral reflux

The detection or exclusion of vesico-ureteral reflux (VUR) has classically been by micturating cystourethrography (MCUG). Radionuclide cystography will detect VUR but fails to provide the same detailed anatomical informations as MCUG. This study allowed a comparison of indirect radionuclide cystography (IRC) and MCUG in 65 children. Renal reflux was detected by IRC in 32% of renal units, while VUR was seen in 36% by MCUG. When a comparison was made with MCUG, IRC had a sensitivity of 74.1% and a specificity of 90.5%. The markedly reduced radiation dose, avoidance of a bladder catheter plus the ability to monitor the urinary tract constantly during the entire procedure should ensure that IRC is the examination of choice in follow-up studies for VUR in all toilet-trained children.

Indirect radionuclide cystography demonstrates reflux under physiological conditions

Indirect radionuclide cystography (IRC) is a useful technique for the detection and quantification of vesico-ureteric reflux (VUR). Its principal advantage over micturating contrast cysto-urethrography (MCU) is its ability to demonstrate VUR under physiological conditions. Three children (age range 6-9 years) reported here illustrate some physiological features of micturition readily seen only on IRC. The most important of these was uretero-ureteric reflux which, because of bladder activity, is not usually identifiable on IRC or MCU but is probably more common than previously thought and misinterpreted as VUR.

Scintigraphic assessment of lower urinary tract function in children with and without outflow tract obstruction

Analysis of lower urinary tract function with an extension of standard renography with 123I-hippurate was carried out in 199 children. Maximum bladder capacity, voiding and residual bladder volumes, average and maximum urine flow rates and urine flow patterns were estimated. The index of urine transport (IUT), representing the relationship between urine flow rate and bladder volume, was introduced as a measure of outflow capability. Of 129 children without evidence of outflow obstruction, 90% had a normal urine flow pattern; in 96% the average IUT was 0.8 or higher and in 87% the maximum IUT was 1.2 or higher. A sawtooth-shaped pattern with both normal and abnormal IUT values was observed in 10% of these children. In 63% of the children with outflow tract obstruction there was a low, flat urine flow pattern together with decreased IUT values. A sawtooth-shaped pattern with varying IUT values was observed in 15%, whereas in 20% the urine flow pattern and IUT values were normal. This extension of standard radionuclide renography as a method of screening lower urinary tract function is recommended. It is at least as good as conventional direct urine flow rate recording, it has the advantage of being non-invasive and it is also part of an established urological investigation.

The many faces of vesico-ureteric reflux: factors contributing to renal damage

Current controversies in the pathogenesis and management of vesico-ureteric reflux (VUR) and reflux-associated nephropathy (RAN) are critically reviewed, together with the advantages and limitations of surgical correction of reflux. Special emphasis is given to pitfalls in diagnosis and ongoing reassessment, to the importance of associated urinary tract abnormalities, and to the need for continuing long term chemoprophylaxis in the presence of persisting VUR.

Improving the technique of nuclear cystography: the manometric approach

A simple technique of manometric scintigraphic retrograde cystography was applied prospectively to 125 patients (85 per cent children) with 142 studies. 99mTechnetium sulfur colloid (0.5 to 1 mCi.) was instilled in the bladder followed by increments of normal saline under manometric control. The sensitivity of the test was increased when the filling phase was concluded at 25 cm. water pressure rather than when the patient complained of fullness (usually at 15 cm.). The studies had a voiding phase that was essential for patients in whom pressures greater than 15 cm. could not be achieved. Reflux was not detected on the voiding phase alone in 5 patients and the voiding phase could not be performed in 5 of 34 positive studies. It was not possible to predict volumes of fluid instilled to achieve satisfactory pressures. Monitoring during the entire study was necessary to diagnose reflux, which may occur at low or high pressure, or while voiding only.

Renal scintigraphy: quantitative assessment of upper urinary tract dilatation in children

A standard method of Tc-DTPA renal scintigraphy has been used to examine 426 dilated upper urinary tracts in children aged 2 days-16 yr. The method provides an accurate estimate of individual kidney function and defines the extent of dilatation. Renogram analysis and frusemide-induced diuresis have been applied in an attempt to distinguish between the obstructed upper tract and the dilated upper tract without obstruction. In 304 upper tracts, obstruction was predicted with an overall sensitivity of 0.87. The sensitivity for diagnosis of pelviureteric junction obstruction was 0.93. The value of scintigraphy in excluding significant obstruction and in follow-up studies is emphasized. This is a noninvasive, low-radiation investigation which plays an important role in the assessment of obstructive uropathy in childhood and represents a major advance in diagnostic facilities.

Intravenous radionuclide cystography for the detection of vesicorenal reflux

Intravenous radionuclide cystography using a single intravenous injection of 99mtechnetium diethylenetriaminepentaacetic acid, provides information on individual kidney function, coarse anatomy and vesicorenal reflux. This study investigates the effectiveness of intravenous radionuclide cystography in detecting reflux. In 58 children intravenous radionuclide cystography detected 53 ureters with reflux compared to 32 detected by voiding cystography. This difference was investigated further with patients in whom other test suggested reflux. While there was no statistically significant difference for patients having pyelonephritis or hydronephrosis, intravenous radionuclide cystography detected significantly more ureters with reflux in patients with abnormal ureteral orifices or infected urine and, therefore, predisposed to reflux. Intravenous radionuclide cystography is a more comprehensive and sensitive test for vesicorenal reflux than voiding cystography.

"Stasis"--a test for vesico-ureteric orifice competence in children with reflux

Intravenous radionuclide cystography (IVRNC) with one injection on 99m-Tc-DTPA measures renal function and detects vesico-renal reflux [1, 2, 3]. This paper describes a possible means of detecting incompetent ureteric orifices during IVRNC examinations. In some patients a hold-up of material in the renal areas (stasis) was observed which suddenly cleared at micturition. A prospective study of 58 patients who had IVRNC and cystoscopy within 28 days of each other revealed that 76.3% had anatomically abnormal ureteric orifices on the same side as the stasis. This contrasted with only 12.8% of abnormal uretic orifices found in patients not showing stasis (p less than 0.005). As incompetent ureteric orifices are recognised as the major aetiological factor in vesico-renal reflux [4, 5, 6] this additional information gained at IVRNC could be of clinical use and perhaps avoid some cystoscopies.