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S Choong

Publications and source records attributed to S Choong.

At least 19 recordsLinked to original sources
PubMed2006

The effect of image size on screen-positive rates for nuchal translucency screening.

It has been shown previously that the absolute measurement of nuchal translucency (NT) thickness, one of the most effective screening tests for fetal Down syndrome, significantly decreases with increasing image size. We undertook a prospective study to assess whether this effect materially alters the NT-derived risk estimation for fetal Down syndrome. In 350 women, NT was measured at both 100 and 200% image sizes. The median NT measurement at 200% was 8% smaller than at 100%. The screen-positive rates at 100 and 200% image sizes were 5.1% (18/350) and 2.3% (8/350), respectively (P= 0.048). Altering the image magnification settings is likely to decrease the sensitivity of NT-derived Down syndrome risk estimation. Further study is required to test the effect of our finding on the sensitivity of NT screening and to assess whether adjustments in gain settings mitigate the effect.

Adult↗
PubMed2005

Pelvi-calyceal height, a predictor of success when treating lower pole stones with extracorporeal shockwave lithotripsy.

Extra corporeal shockwave lithotripsy (ESWL) is the treatment of choice for the majority of renal stones, however, it has the lowest success rate in complete clearance of stones located in the lower pole. We assess whether pelvi-calyceal height is a useful measurement in predicting successful stone clearance from the lower pole. A total of 105 patients with a solitary lower pole calculus of less than 20 mm treated with ESWL were reviewed. Stone size, location and pelvi-calyceal height were measured by intravenous urogram. Success was defined as complete stone clearance. Fifty-four patients (51.4%) had successful treatments, with the remaining 51 (48.6%) having incomplete stone clearance (including two patients in whom treatment had no effect). There was a statistically significant difference (P<0.0001) in pelvi-calyceal height between the two groups. Mean pelvi-calyceal height in patients with complete stone clearance was 15.1 mm (SD=3.9) compared with 22.9 mm (SD=5.2) for those with incomplete clearance. Pelvi-calyceal height is a useful predictor of success when treating lower pole renal stones with ESWL.

Adult↗
PubMed2004

Dystrophic ureteral calcification associated with Churg-Strauss vasculitis.

Churg-Strauss syndrome is an uncommon systemic vasculitis affecting small blood vessels. Renal involvement is typical; however, calcinosis of the urinary tract has not previously been described. Dystrophic calcification in the urinary tract is rare, although it is occasionally associated with schistosomiasis, tuberculosis, and polyarteritis nodosa. We report the case of a 19-year-old man with newly diagnosed Churg-Strauss syndrome who presented to us with dystrophic calcification in both ureters causing bilateral obstruction.

Adult↗
PubMed2003

Ultrasound prediction of risk of spontaneous miscarriage in live embryos from assisted conceptions.

OBJECTIVE: An accurate method to predict subsequent miscarriage in live embryos has not yet been established. This pilot study aimed to determine the most discriminatory ultrasound-based model for predicting spontaneous miscarriage after embryonic life was first detected in assisted conceptions. A method for estimating individual risk of miscarriage was developed. METHODS: This was a prospective cross-sectional survey of 322 live singleton embryos in women from an assisted reproductive technology program. Mean sac diameter (MSD), crown-rump length (CRL), embryonic heart rate (EHR), maternal age and gestational age at the first transvaginal scan detecting embryonic life (between 42 and 62 days) were observed. These variables were included in a multivariate model for predicting spontaneous miscarriage occurring prior to 20 weeks. MSD, CRL and MSD minus CRL were assessed in univariate logistic regression analyses. The global diagnostic accuracy of each model was compared directly using receiver-operating characteristics (ROC) curves. RESULTS: The multivariate model demonstrated the best ROC curve for predicting miscarriage (ROC area 0.87; 95% CI, 0.80-0.95). The separate univariate analyses had less diagnostic accuracy. In particular, MSD - CRL had a significantly smaller ROC area (0.65) than did the multivariate model (P < 0.01). CONCLUSIONS: The most discriminatory test for predicting spontaneous miscarriage in live embryos was a multivariate model, which allows estimation of individual risk levels.

Abortion, Spontaneous↗
PubMed2003

Epidemiology of paediatric renal stone disease in the UK.

BACKGROUND: The previous epidemiological study of paediatric nephrolithiasis in Britain was conducted more than 30 years ago. AIMS: To examine the presenting features, predisposing factors, and treatment strategies used in paediatric stones presenting to a British centre over the past five years. METHODS: A total of 121 children presented with a urinary tract renal stone, to one adult and one paediatric centre, over a five year period (1997-2001). All children were reviewed in a dedicated stone clinic and had a full infective and metabolic stone investigative work up. Treatment was assessed by retrospective hospital note review. RESULTS: A metabolic abnormality was found in 44% of children, 30% were classified as infective, and 26% idiopathic. Bilateral stones on presentation occurred in 26% of the metabolic group compared to 12% in the infective/idiopathic group (odds ratio 2.7, 95% CI 1.03 to 7.02). Coexisting urinary tract infection was common (49%) in the metabolic group. Surgically, minimally invasive techniques (lithotripsy, percutaneous nephrolithotomy, and endoscopy) were used in 68% of patients. CONCLUSIONS: There has been a shift in the epidemiology of paediatric renal stone disease in the UK over the past 30 years. Underlying metabolic causes are now the most common but can be masked by coexisting urinary tract infection. Treatment has progressed, especially surgically, with sophisticated minimally invasive techniques now employed. All children with renal stones should have a metabolic screen.

Adolescent↗
PubMed2002

Mid-trimester fetal subdural hemorrhage: prenatal diagnosis.

A routine antenatal ultrasound examination at 20 weeks' gestation revealed a space-occupying lesion in the fetal right cerebral hemisphere. The borders of the mass were indistinct and there was no midline shift. A small collection of echogenic bowel was identified at the right iliac fossa. In an attempt to explain both findings a provisional diagnosis of a fetal blood dyscrasia was made. Fetal cranial magnetic resonance imaging 24 h later confirmed the diagnosis of a subdural hemorrhage. Subsequent fetal blood sampling confirmed severe fetal thrombocytopenia. To our knowledge this is the first report of the antenatal diagnosis of spontaneous mid-trimester fetal subdural hemorrhage.

Adult↗
PubMed2001

Couch or crouch? Examining the prostate: a randomized study comparing the knee-elbow and the left-lateral position.

OBJECTIVE: To compare two methods of examining the prostate, the knee-elbow (KE) and left-lateral (LL) positions, to establish which allows a more complete examination, and to determine if there is any difference in patients' perception of pain or embarrassment for either method. PATIENTS AND METHODS: All men attending two urology clinics who required a prostate examination were eligible for the study. Both the KE and LL methods were used for each participant, by the same clinician. The order in which the examinations were conducted was randomized using the last digit of the patient's hospital number. RESULTS: Five clinicians examined 117 men; three patients refused to participate and the examination data were incomplete for two. Irrespective of the order in which the examinations were conducted (P = 0.6), the KE position permitted a greater proportion of the prostate to be palpated (Wilcoxon signed-ranks test, z = -4.7, P < 0.001) in 35% of patients, but there was no difference in 60%. Most patients found the examinations equally painful and embarrassing. However, for those who expressed a difference, the KE was 1.9 times more comfortable than the LL position and twice as embarrassing. CONCLUSION: The two methods of prostate examination were equal for completeness of examination, pain and embarrassment in most patients. However, the KE offers an alternative to the LL position for those patients in whom the prostate is difficult to palpate or who find the examination painful.

Adult↗
PubMed2000

Reperfusion injury pathophysiology in sickle transgenic mice.

Reperfusion of tissues after interruption of their vascular supply causes free-radical generation that leads to tissue damage, a scenario referred to as "reperfusion injury." Because sickle disease involves repeated transient ischemic episodes, we sought evidence for excessive free-radical generation in sickle transgenic mice. Compared with normal mice, sickle mice at ambient air had a higher ethane excretion (marker of lipid peroxidation) and greater conversion of salicylic acid to 2,3-dihydroxybenzoic acid (marker of hydroxyl radical generation). During hypoxia (11% O(2)), only sickle mice converted tissue xanthine dehydrogenase to oxidase. Only the sickle mice exhibited a further increase in ethane excretion during restitution of normal oxygen tension after 2 hours of hypoxia. Only the sickle mice showed abnormal activation of nuclear factor-kappaB after exposure to hypoxia-reoxygenation. Allopurinol, a potential therapeutic agent, decreased ethane excretion in the sickle mice. Thus, sickle transgenic mice exhibit biochemical footprints consistent with excessive free-radical generation even at ambient air and following a transient induction of enhanced sickling. We suggest that reperfusion injury physiology may contribute to the evolution of the chronic organ damage characteristic of sickle cell disease. If so, novel therapeutic approaches might be of value.

Allopurinol↗
PubMed2000

The management of paediatric urolithiasis.

OBJECTIVE: To evaluate the efficacy and safety of the management of paediatric urolithiasis by extracorporeal shock wave lithotripsy (ESWL), endoscopic ureterolithotomy, percutaneous nephrolithotomy (PCNL) and open nephrolithotomy. PATIENTS AND METHODS: In a 3-year period (1997-1999), 59 children were treated for urolithiasis and underwent a total of 79 procedures. Thirty-two ESWL sessions were performed in 23 children (mean age 7.4 years, median 6.0). PCNL was undertaken in 30 renal units in 25 children (mean age 6.4 years, median 4.0). Eight patients (mean age 7.8 years, median 5) underwent 17 ureteroscopic procedures, six of which involved the use of a holmium laser. Three children with staghorn calculi underwent open nephrolithotomy under conditions of renal ischaemia and hypothermia. RESULTS: Of the 23 children treated using ESWL, 21 (91%) became stone-free; 17 underwent one ESWL session (74%), three had two sessions and three (13%) had three sessions. All eight patients who underwent ureteroscopy became stone-free. Four patients in whom the stone could not be reached by ureteroscopy initially had a JJ stent inserted, and the stone and stent subsequently removed. Stones were cleared using PCNL in 27 of 30 renal units (90%); three patients who had residual stone fragments were rendered stone-free by ESWL. Two of three children undergoing open nephrolithotomy were stone-free after surgery and the remaining one rendered stone-free with ESWL. Metabolic evaluation showed that 25 of 45 children (55%) had a urinary infection, eight (18%) had hyperoxaluria, three (7%) had hypercalciuria, two (4%) had cystinuria, and no identifiable cause was found in seven (16%). Treatment by a single modality rendered 52 of the 59 children (88%) stone-free; when the different modalities were combined, 57 of 59 patients (97%) were cleared of their stones. CONCLUSIONS: Technological advances in ESWL, ureteroscopy and PCNL have had a significant effect on the management of urolithiasis in children, allowing a safe and successful outcome. The comprehensive care of children with urolithiasis should include a full metabolic evaluation. Anatomical anomalies contribute to the complexity of many cases, necessitating a close liaison between adult and paediatric urologists, nephrologists and radiologists to optimize stone management in children.

Adolescent↗
PubMed1997

Circulating activated endothelial cells in sickle cell anemia.

BACKGROUND: The vascular wall participates in the pathogenesis of sickle cell disease. To determine whether the endothelium is activated in this disease, we studied the number, origin, and surface phenotype of circulating endothelial cells in patients with sickle cell anemia. METHODS: We used immunohistochemical examination of buffy-coat smears to enumerate circulating endothelial cells, and we evaluated the surface phenotype by applying preparations of circulating endothelial cells. An immunofluorescence microscopy panel of antibodies was used, including a specific anti-endothelial-cell antibody, P1H12. RESULTS: Mean (+/-SD) numbers of circulating endothelial cells in normal blood donors, patients with sickle cell trait, and patients with hemolytic anemias not due to hemoglobin S were 2.6+/-1.6, 3.0+/-2.6, and 2.0+/-0.8 per milliliter of whole blood, respectively. Patients with sickle cell anemia who presented with acute painful episodes had 22.8+/-18.2 circulating endothelial cells per milliliter of blood (P<0.001 for the comparison with normal donors), and patients with no such events within one month before or after blood sampling had 13.2+/-11.8 circulating endothelial cells per milliliter of blood (P=0.002 for the comparison with normal donors and P=0.019 for the comparison with patients with acute events). Serial observations of three patients showed a tendency toward higher levels of circulating endothelial cells at the onset of acute painful crises. The average viability of circulating endothelial cells was 66+/-30 percent. In patients with sickle cell anemia, regardless of clinical status, the circulating endothelial cells were predominantly microvascular in origin (CD36-positive), and most of the cells expressed four markers of endothelial-cell activation: intercellular adhesion molecule 1, vascular-cell adhesion molecule 1, E-selectin, and P-selectin. CONCLUSIONS: Our studies suggest that the vascular endothelium is activated in patients with sickle cell anemia, regardless of the patients' clinical status. Adhesion proteins on activated endothelial cells may have a role in the vascular pathology of sickle cell disease.

Adolescent↗
PubMed1997

A prospective, randomized, double-blind study comparing lignocaine gel and plain lubricating gel in relieving pain during flexible cystoscopy.

OBJECTIVE: To determine the optimum duration for the retention of 2% lignocaine gel intraurethrally as an anaesthetic for flexible cystoscopy in men. PATIENTS AND METHODS: A prospective, randomized, double-blind, placebo-controlled trial was conducted in two parts. Initially, the importance of duration was determined, i.e. whether pain relief was significantly improved when lignocaine gel was instilled for longer than is currently practised. As pain relief was improved by retaining the lignocaine gel for longer, the optimum time was determined in a second trial. Initially, 90 patients were divided into four groups receiving 20 mL of 2% lignocaine gel or plain lubricating gel for 5 or 25 min. Subsequently, 60 men were divided into two groups receiving 20 ml of 2% lignocaine gel for 15 or 25 min. The patients' discomfort was recorded using a 4-point descriptive pain scale and a 100 mm non-graphical visual analogue scale. RESULTS: In the first study, those patients receiving lignocaine gel for 25 min experienced significantly less pain than the other three groups. In the second, lignocaine gel in the urethra for 15 min provided the same level of pain relief as lignocaine for 25 min. CONCLUSION: Pain during flexible cystoscopy can be significantly reduced when 20 mL of 2% lignocaine gel is left in the urethra for 15 min; lignocaine gel would be more effective when left for longer than is currently practised.

Analgesia↗