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Biomedical subjects

K K Choong

Publications and source records attributed to K K Choong.

13 recordsLinked to original sources
PubMed1999

Mercaptoacetyltriglycine diuretic renography and output efficiency measurement in renal transplant patients.

Suspected urinary tract obstruction following renal transplantation presents a diagnostic dilemma. The purposes of this study were: (1) to establish a normal range of measurement of output efficiency (OE) in the renal transplant population, and (2) to assess prospectively the usefulness of OE in the setting of allograft obstruction. Twenty-two renal transplant patients with stable renal function and no evidence of hydronephrosis on serial ultrasound examination had a diuretic mercaptoacetyltriglycine scan with calculation of OE. Three renal transplant patients with confirmed graft obstruction were also studied. Standard qualitative and quantitative parameters as well as OE were calculated. The mean OE for the 22 normal renal transplant patients was 86.3%+/-3.7% (range: 77%-91%). OE values in the three obstructed patients were 59%, 68% and 75% respectively. It is concluded that OE should normally exceed 77% in renal graft recipients. OE is a promising means of diagnosing functional obstruction in these patients.

Adult↗
PubMed1999

Acute renal failure in critically ill patients: evaluation of an ultrasound contrast agent.

The purpose of the present paper was to evaluate an ultrasound contrast agent (Levovist) in patients with oliguric acute renal failure (ARF) in order to assess renal vascularity, differentiate acute tubular from cortical necrosis and predict prognosis. Ten intensive care unit (ICU) patients with oliguric ARF were prospectively investigated by ultrasound including colour, power and pulsed Doppler before and after injection of Levovist. Doppler signals were graded as absent, equivocal or present from the inner and outer portions of the renal parenchyma, and these findings were correlated with clinical parameters and outcome. Only one patient had findings in keeping with acute cortical necrosis. All patients who survived had parenchymal vascularity while only three of six (50%) who died had parenchymal vascularity after Levovist. The ultrasound contrast caused no side effects and additional information was provided which improved diagnostic confidence, enabled appropriate classification of patients as having tubular or cortical necrosis and therefore added prognostic information.

APACHE↗
PubMed1997

Assessment of pediatric hydronephrosis using output efficiency.

UNLABELLED: Diagnosing obstruction in pediatric patients with hydronephrosis, and renal impairment is often difficult. Renal output efficiency (OE) is a parameter that may improve diagnostic accuracy by allowing normalization of washout according to renal function. The aims of this study were to define a normal range for OE in infants and children and to evaluate its diagnostic accuracy in cases with hydronephrosis. METHODS: Seventy-four children (91 hydronephrotic kidneys; median age, 4 mo; 22 girls and 52 boys) underwent 99mTc-labeled mercaptoacetyl-triglycine scintigraphy using intravenous volume expansion (15 ml/kg normal saline), furosemide diuresis and urethral catheterization, if vesicoureteric reflux was present. Images were interpreted by consensus of two or more experienced observers using visual assessment of the images, differential function and clearance half-time after furosemide (T(1/2)), as well as OE. The final diagnosis was based on surgical findings (n = 23 kidneys) or follow-up for >12 mo (n = 68). RESULTS: Final diagnosis in 22 of the 91 hydronephrotic kidneys was obstruction at the pelviureteric (n = 21) or vesicoureteric (n = 1) junction and no obstruction in the remaining 69. The overall diagnostic accuracy of OE was 89%. Using exhaustive search multivariate logistic regression analysis, only reduced OE (p < 0.001) and decreased renal uptake by visual assessment (p = 0.058) were independently predictive of obstruction (R2 = 0.726). In dilated but unobstructed kidneys, mean OE was 93% +/- 7.1%. In the normal kidneys, mean OE was 96% +/- 3.1%. CONCLUSION: OE improves the diagnostic accuracy of diuretic renography in children and neonates with hydronephrosis and suspected obstruction. Output efficiency should exceed 89% in normal kidneys and 79% in unobstructed, hydronephrotic kidneys.

Adolescent↗
PubMed1994

Postnatal diagnosis and outcome of urinary tract abnormalities detected by antenatal ultrasound.

OBJECTIVES: To determine the incidence of urinary tract abnormalities detected by antenatal ultrasound; the value of fetal renal measurements in predicting significant uropathy; and the nature and clinical outcome of fetal uropathy. DESIGN AND SETTING: A retrospective analysis of babies with urinary tract abnormalities detected before birth who were born at or referred to a teaching hospital. PATIENTS: One hundred and twenty-five babies born between June 1989 and November 1992. Sixty-nine babies were born at Westmead hospital and 56 were born elsewhere and referred to Westmead Hospital for investigation. RESULTS: The incidence of uropathy detected before birth among babies born at the teaching hospital was 5.1 per 1000 births. In 60% of these babies, significant abnormalities were confirmed after birth (3.1 per 1000 births). We found a significance of 71% and a specificity of 89% for fetal measurements in predicting significant uropathy. Among all 125 babies the most common abnormalities were pelviureteric junction (PUJ) anomalies (34%), minimal hydronephrosis (26%), ureteric reflux (18%) and multicystic kidney (7%). Pyeloplasty has been performed in 23 (46%) of the 52 kidneys with PUJ anomalies. Renal parenchymal abnormality was detected in four of 22 kidneys with ureteric reflux (18%). Of these four, all were exposed to Grade IV or V ureteric reflux but none had been infected. CONCLUSIONS: Antenatal ultrasound is a sensitive, though nonspecific, tool for the non-invasive identification of congenital abnormalities of the urinary tract, which are common and frequently asymptomatic after birth. Although ureteric reflux may not be predicted from renal measurements, the degree of fetal hydronephrosis indicates the likelihood of obstructive abnormality and, thus, the extent of postnatal investigation required.

Female↗
PubMed1992

Fetal laryngeal obstruction: sonographic detection.

A patient was referred at 21 weeks' gestation for unexplained fetal lung hyperechogenicity and ascites. Amniocentesis was normal. Fetal lung biopsy was consistent with the clinical diagnosis of cystic adenomatoid malformation of the lungs. However, autopsy of the stillborn infant demonstrated a cartilaginous bar, causing total laryngeal obstruction. The distinctive ultrasonographic appearance is presented.

Journal Article↗
PubMed1992

Volume expanded diuretic renography in the postnatal assessment of suspected uretero-pelvic junction obstruction.

Controversy surrounds the role of 99mTc-diethylenetriamine pentaacetic acid renography in suspected uretero-pelvic junction obstruction in early life. Accordingly, we retrospectively reviewed 18 patients (28 hydronephrotic kidneys) with a mean age of 2 mo (range: 1 wk-6 mo) who underwent a total of 36 scans using intravenous volume expansion (10 ml/kg) and furosemide diuresis (1 mg/kg). Initial scans were classified as obstructed, not obstructed or indeterminate using differential renal function, furosemide washout T 1/2 and visual assessment of tracer clearance. Those initially classified as obstructed (n = 8) have been surgically confirmed. In the indeterminate (n = 6) and nonobstructed (n = 14) groups, three and two kidneys, respectively, developed obstruction on progress scans. Mean follow-up in the nonsurgical patients was approximately 9 mo (range: 4-17 mo). A total of 13 kidneys had developed obstruction by renographic criteria, and to date 12 have surgical confirmation. Our data indicate that: (1) scans classified as obstructed correlate well with surgery; (2) an initial classification of indeterminate or nonobstructed does not exclude later development of obstruction; and (3) serial scans correctly stratify children with possible uretero-pelvic junction obstruction.

Female↗