Simon K. S. Choong

MBBS(Lon), FRCS(Eng), FRCSEd, MS(Lon), FRCS(Urol)

Consultant Urologist & Honorary Senior Lecturer

 

EDUCATION & QUALIFICATIONS

1989	Oundle School, Oundle, Peterborough, UK M.B.B.S. University College Hospital, London
1994	F.R.C.S.(Eng)
1994	F.R.C.S.Ed
1997	M.S. (University of London)
2000	Hunterian Professorship
2001	F.R.C.S.(Urol)

 

APPOINTMENTS

Aug.1989-Jan.1990                 House Physician to Dr. P. McIntyre and Dr. A.Young

Queen Elizabeth II Hospital , Welwyn Garden City.

Feb.1990-July1990                  House Surgeon to Mr.R.C.G.Russell and Mr. J.Scurr.

University College Hospital, London.

Aug.1990-Jan.1991                  SHO in Accident & EmergencyDepartment

Hammersmith Hospital, London.

Feb.1991-July1991                   SHO to Professor R.C.N.Williamson and Mr. N.Habib

Hammersmith Hospital, London.

Feb.1992-July1992                   SHO in Orthopaedics to ProfessorS.Hughes,

Ealing Hospital, London.

Feb.1993-July1993                   SHO in Urology to Mr.C.R.J.Woodhouse

St. George's Hospital, London.

Aug.1993-Jan.1994                  SHO in Vascular and General Surgeryto

Mr. R.S.Taylor and Mr. J.A.Dormandy

St. George's Hospital, London.

Feb.1994-Jan.1995                  SHO in Urology and GeneralSurgery

to Mr. P.Abel and Mr. D.Sellu.

Ealing Hospital, London.

Feb.1995-April1997                 Research Fellow to Mr. H.N.Whitfield

Institute of Urology and Nephrology, London.

May1997-Sept.1998                Specialist Registrar (SpR) in Urologyto

Mr. H.N. Whitfield & Mr. M. Gleeson

Central Middlesex Hospital NHS Trust, London.

Oct.1998-March1999               SpR in Urology to Mr. R. Miller and Mr. M.Emberton

Whittington Hospital, London.

April1999-Sept.1999                SpR to Mr. C.R.J. Woodhouse and Mr. P.M.Cuckow

Institute of Urology and Nephrology, London.

Oct.1999-Sept.2000                 SpR to Mr. Roger Kirby, Mr. Mike Bailey, Mr.Ken

Anson, Mr. John Boyd and Mr. Chris Anderson

St. George's Hospital, London.

Oct.2000-Oct. 2001                 SpR to Mr. R.C. Tiptaft, Mr. J. Glass & Mr. S.Khan

Guy’s Hospital, London.

Oct2001-June2002                   SpR to Mr. S. Carter, Mr. JWARamsay,

Charing Cross Hospital, London.

July2002-Present                       Consultant Urological Surgeon & HonorarySenior

Lecturer, Institute of Urology, University College London Hospitals

Sept2009-Present                      Honorary Consultant UrologicalSurgeon

Great Ormond Street Hospital for Children, London

 

RESEARCH ( MS THESIS and HUNTERIAN PROFESSORSHIP)

ENCRUSTATION OF UROLOGICAL DEVICES

Introduction: There is no objective encrustation result on urological devices in current use and mechanisms of encrustation are incompletely understood. Consequently, the use of urological devices in the urinary tract carries significant complications [1,2,3,4].

 

Methods: An in vitro encrustation model was developed and validated [5] to quantify encrustation on polymers, urinary catheters and ureteric stents using fresh human urine under standard conditions (pH 6.0 and 37 0C). The same materials tested in vitro were implanted into the bladders of rats to extend the study to an in vivo situation.

 

Ten different types of ureteric stents in current use were studied. The amount of encrustation was correlated with the surface roughness, the number and shape of side-holes, the different materials used in their construction and their hydrophobicity.

To identify novel biomaterial, 20 different polymers were screened by the in vitro encrustation model and those which encrusted least were implanted into the bladders of 48 male Wistar rats. Of the latter group those that encrusted least were made into ureteric stents.

 

In addition, variation in the chemical composition of urine influences encrustation, in particular, the relationship between urinary pH and [Ca2+]. This relationship was studied in fresh urine samples collected from urinary catheter ‘blockers’ and ‘non-blockers’. The pH at which crystals precipitated and its correlation with [Ca2+] was determined. Chemical analysis and bacteriological studies of the urine samples were performed using standard chemical pathological techniques.

 

Results: The amounts of encrustation on the ureteric stents in current use were measured using the in vitro model. Silicone stents encrusted least. Stents coated with hydrogel encrusted more than the same uncoated stents. Examination of the currently used devices by scanning electron microscopy revealed several features that enhanced encrustation. These included manufacturers’ surface markings, increased roughness and irregular side-holes.

Hydrophobicity did not confer resistance to encrustation.

Novel biomaterials that encrusted less than silicone in vitro and in vivo were identified and manufactured into urological devices. These included hyaluronidase-coated materials [6] and Chronoflex, a polyurethane.

The relationship between urinary pH and [Ca2+] and the pH at and above which crystallisation occurred (crystallisation pH) were also measured. The voided urine was alkaline in catheter ‘blockers’ with (7.86±0.55) and without (7.36±0.67) urine infection and crystallised at a more acidic pH (7.79±0.80 and 6.45±0.65 respectively). The voided urine of catheter ‘non-blockers’ was acidic (5.97±0.80) and crystallised at an alkaline value (7.46±0.73), p=0.005.

 

Conclusions: The in vitro encrustation model has provided objective data on existing urological devices and it has been adopted by several device manufacturers to test new polymers. The model will enable alternative designs and new biomaterials to be examined quantitatively to produce improved urological devices for clinicians and fewer complications for patients.

Catheter ‘non-blockers’ have a large safety margin between the acidic voided pH and alkaline crystallisation pH. In contrast, catheter ‘blockers’ who have acidic crystallisation pH and alkaline voided pH have a significantly reduced safety margin. The identification of crystallisation pH has opened a ‘therapeutic window’ for chemical manipulation to reduce encrustation.

References:

1.      Kohler-Ockmore J and Feneley RCL 1996 Long-term catheterisation of thebladder: prevalence and morbidity. Br J Urol 77:347-351

2.      Kunin CM, Chin QF, Chambers S 1987 Indwelling urinary catheters in the elderly. Am J Med 82:405-411

3.      Sassoon E, Abercrombie F, Goodrum P 1991 The permanent indwelling catheter:a domiciliary survey. Health Trends 23(3):109-111

4.      Keane PF, Bonner MC, Johnston SR et al 1994 Characterization of biofilm and encrustation on ureteric stents in vivo. Br J Urol 73:687-691

5.      Choong SKS, Whitfield HN 1997 The validation of a novel in vitro encrustation modeland corroboration with in vivo animal studies. J Endourol 11: S1:p2

6.      ChoongSKS,WhitfieldHN,AmbrosioL,ParvesioA1998Encrustation-resistantcoating for urological devices. J Urol 159: (5):324

 

Results achieved in brief:

1.        Developed and validated an in vitro encrustation model as there was no objective encrustation data on the encrustation potential of urological devices in currentuse.

2.        Quantified encrustation on urological devices in currentuse.

3.        Identified a novel surface coating and a polyurethane, which encrusted significantlyless than silicone, the current ‘gold standard’biomaterial.

4.        The in vitro encrustation model is being used by several device manufacturers intesting new biomaterials to identify encrustation-resistantbiomaterials.

5.        Identified the urinary pH values at which crystals precipitated out of urine in catheter ‘blockers’ and ‘non-blockers’, which explained the association of alkaline voidedurine with encrustation. The identification of crystallisation pH has opened a ‘therapeutic window’ for chemical manipulation to reduceencrustation.

6.        These studies have advanced our understanding of the multifactorial mechanisms of encrustation and they have identified new encrustation-resistant biomaterials toproduce improved urological devices for clinicians and fewer complications forpatients.

 

ACHIEVEMENTS

·         Hunterian Professorship2000

The Royal College of Surgeons of England

 

      ·         BAUS / BJU International Travelling Fellowship2001

·         Organized and run annual national live surgery and hands-onendourology masterclasses for the last 10 yearson:

1.      Percutaneousnephrolithotomy

2.      Flexibleureterorenoscopy

3.      Rigid ureterolithotomy and holmium lasering ofstones

4.      Nephro-Uro-Radiologicalsymposium

5.      Live surgery and hands-on courses for theatre nurses, 16th to date, Feb2017

6.      Innovations in Percutaneous Surgery, UCL, London, June,2016

7.      Second International Innovations in Percutaneous Surgery, UCL, London, March 2017

·         Hosted British Annual Endourology Meeting at UCLH, May2008

Annual Dinner at House of Lords

·         Pump-priming award, Royal College of Surgeons of England2003

·         Grants - St. Peter’s Research Trust -£26,029

The effect of urinary infection on encrustation of urological devices

·         Funding - Biocompatibles Ltd. -£100,000

Encrustation studies on urological devices based on patented encrustation model

·         Funding - Cook Urological Ltd. -£15,000

Studies on the effect of infection on encrustation

·         Best Presenting Team (St. George’s Hospital) - Coliseum London Teaching Hospital Challenge. Institute of Urology and Nephrology, November1999

·         Best podium presentation - 4th Asian Congress in Urology, Singapore. Sept 1998. Objective encrustation analysis of currently used uretericstents. Choong SKS, Wood S, WhitfieldHN.

·         Best poster awards -14th World Congress of Endourology, Melbourne, Nov96.

1.  Current design faults in uretericstents.

Choong SKS, Whitfield HN, Petrik A, Nicholas C.

2.  The scientific basis of catheterencrustation.

Choong SKS, Fry C, Whitfield HN.

   ·        Highlighted presentationsat

BAUS Annual Meeting, Birmingham 2000

9th International Symposium on Urolithiasis, Cape Town, Feb 2000.

17th World Congress on Endourology and SWL, Rhodes Island, Greece, Sept 99. BAUS Annual Meeting, Glasgow, June 1999

AUA, San Diego, 1998

13th Congress of European Association of Urology, Barcelona 1998. 15th World Congress of Endourology, Edinburgh 1997

·        Established an encrustation database on existing ureteric stents and urethral catheters and identified novel biomaterials and surface coating whichresisted encrustation better than silicone, the current                  goldstandard.

·        Patented the design of a model to quantifyencrustation.

 

·        Determined the optimum period lignocaine gel should be left in the urethra for maximal effect prior to intraurethral manipulation - a prospective,randomised, double-blindstudy

 

RESPONSIBILITIES

·         BAUS representative and committee member of the British Standards Institution on CH/1 ‘Catheters’

·         Specialty Training Committee Member in Urology for North & South Thames,London

·         College Tutor, Institute of Urology, University College London

·         Director of Teaching Programme in Urology for North & South Thames,London

·         Referee for British Journal of Urology International 1999 tocurrent

·         Referee for Journal ofUrology

·         Committee Member and referee for UrologicalResearch

·         Examiner for MB,BS examinations in Surgery, University College London.

·         MD Supervisor to Ms Sian Allen on mechanism of crystallisation and stoneformation, 2008

·         MD Supervisor to Mr Senthy Sellatury on measurement of urinary salts using ion selective electrodes,2008

·         Junior Doctor Representative in Urology, St. George’s Hospital, London,2000.

·         Trainee representative, Brainstorming Meeting, Section of Urology, Royal Society of Medicine, October2000

·         Chairman, podium session on BPH, The 4th Asian Congress in Urology, Sept 1998, Singapore.

·         Chairman of Stones Poster Session, SIU, Honolulu,2004

·         Teacher in Anatomy for Urologists course 2004 &2005

·         Course organiser for MSc inUrology

·         Course organiser for North & South Thames SpRs teachingprogramme

·         Chairman & Course Organiser, Flexible ureterorenoscopy BAUS2005

·         Participating in live surgery teaching at St Peter’s Course, UCLH, 2007 &2008

·         Examiner for Master of Surgery / MDThesis

·         Chaired Urolithiasis session during 1st World Congress of Urology, Beijing, China,2015

·         Urology Module Lead for Royal College of Surgeons of England,2016

 

PUBLICATIONS

AUA 2017

Ureteric Rendezvous to treat complex discontinuities

Arumuham V, Mazzon G, Bolgeri G, Allen C, Allen S, Smith D, Choong S

 

AUA 2016

Rendezvous procedure to treat complex ureteric discontinuities

Mazzon G, Bolgeri M, Arumuhan V, Allen S, Smith D, Philp T, Allen C, Walkden M, Ramachandran N, Choong S

 

Peri-operative outcomes of percutaneous stone surgery in patients with urinary diversions.

Bolgeri M, Mazzon G, Dale R, Arumuhan V, Allen S, Smith D, Allen C, Choong S

 

EAU 2016

Can post-operative white cell count, C-reactive protein or stone culture help predict length of stay after percutaneous nephrolithotomy?

Dale R., Mazzon G., Bolgeri M., Pal P., Longhorn S., Choong S., Philp T., Smith R., Allen S

 

Functional outcomes of rendezvous procedure to treat complex ureteric discontinuities Mazzon G, Choong S, Smith D, Allen S, Pallavi P, Bolgeri M, Dale R, Allen C, Ramachandran N, Philp T

Papers submitted to 13th International Symposium on Urolithiasis, July 2016

Do multiple access tracts increase peri-operative complications in percutaneous management of complex renal stones?

Giorgio Mazzon, Marco Bolgeri, Vimoshan Arumuham, Rebecca Dale, Clare Allen, Sian Allen, Daron Smith, Simon Choong

 

Comparison of stone culture using two different sampling methods (wet and dry) Marco Bolgeri, Paula Pal, Rebecca Dale, Vimoshan Arumuham, Giorgio Mazzon, Bruce Macrae, Daron Smith, Simon Choong, Sian Allen

Can we identify predictors for the risk of embolization following percutaneous nephrolithotomy?

Marco Bolgeri, Rebecca Dale, Vimoshan Arunuham, Giorgio Mazzon, Miles Walkden, Sian Allen, Daron Smith, Simon Choong

 

Management of Spina Bifida patients with urinary tract stones

Vimoshan Arunuham, Marco Bolgeri, Rebecca Dale, Giorgio Mazzon, Sian Allen, Daron Smith, Simon Choong

 

Papers for Submission in 2016

Early multi centre experience of Ultra-Mini Percutaneous Nephrolithtomy in the UK

B Pullar, E Havranek, AJR Blacker, SN Datta, B Somani, S Sriprasad, H Ratan, S Scriven, S Choong, RD Smith, S Mackie, G Watson, OJ Wiseman

Bisphosphonates: novel inhibitors of calcium oxalate crystallisation

Allen S, Choong SKS, Fry C, Robertson W

Master of Surgery MS / MD Thesis Supervisor

Physicochemical basis for struvite stone formation

Thesis by Senthy Sellaturay

Postgraduate degree awarded by University of London, 2011

 

Physicochemical factors influencing the crystallisation of calcium oxalate in the urinary tract

Postgraduate degree awarded by University of London, 2011

Examiner for Master of Surgery MS / MD Thesis

Invited Speaker at Guangzhou Annual Meeting, China, Jan 2016

 

Faculty Member & Speaker, PERCON & IAU Meeting, Nov 2016, New Delhi, India

 

Published Papers

 

Using bisphosphonates to effectively inhibit calcium oxalate crystal aggregation

S.E. Allen, S. Choong, C.H. Fry, W.G. RobertsonMar 2013 European Urology Supplements

Computerised Tomography (CT) is not required for safe and effective Percutaneous Nephrolithotomy (PCNL) in children

A. Barnacle, S. Choong, W. Van't Hoff, N. SmeuldersOct 2011 European Urology Supplements

Portable extracorporeal shock wave lithotripsy in paediatric urolithiasis under general anaesthesia

M. Lalla, M. J. Cabrai, P. Duffy, S. Choong, A. Barnacle, W. Van't Hoff, N. SmeuldersOct 2011 European Urology Supplements

Is Routine Post-Operative Renal Tract Stone Culture Necessary?

D. Allen, J. Bycroft, T. Philp, S. Choong, D. SmithSep 2011 Urology

Renal stone disease

Nikhil Johri, Philippe Jaeger, William Robertson, Simon Choong, Robert Unwin Jul 2011 Medicine

Primary hyperoxaluria type 3 in children with renal calculi

E Williams, D Bockenhauer, N Smeulders, A Barnacle, S Choong, G Rumsby, W vant Hoff Apr 2011 Archives of Disease in Childhood

 

Percutaneous Urinary Drainage and Ureteric Stenting in Malignant Disease

D.J. Allen, S.E. Longhorn, T Philp, R.D. Smith, S ChoongNov 2010 Clinical Oncology

An Update and Practical Guide to Renal Stone Management

Nikhil Johri, Bruce Cooper, William Robertson, Simon Choong, David Rickards, Robert Unwin

 

Oct 2010 Nephron Clinical Practice

Flexible ureteroscopy for lower pole stones—Is it effective? One year's experience in a major stone unit

S. J. Graham, C. Nathaniel, S. Longhorn, T. Philp, R. D. Smith, S. C. S. ChoongMay 2010 British Journal of Medical and Surgical Urology

Is endourological management of upper tract TCC the way forward? Experience from a major endourological centre

S. J. Graham, P. Gurung, S. Longhorn, T. Philp, R. D. Smith, S. C. S. ChoongMay 2010 British Journal of Medical and Surgical Urology

Day case rigid and flexible ureterorenoscopy

O. Wiseman, S. Longhorn, T. Philp, S. ChoongMar 2007 European Urology Supplements

Recent technological developments in the management of urinary tract stones

Simon Choong

 

Mar 2007 Trends in Urology Gynaecology & Sexual Health

Heat-shock protein 25 ameliorates calcium oxalate crystal-mediated oxidative stress in renal epithelial cells

Amit B Patel, William G Robertson, Simon Choong, John S Hothersall Dec 2006 BJU International

Endoscopic management of impassable ureteric strictures: 8 year experience

G. Lee, S. Longhorn, M. Kellett, C. Allen, D. Rickards, S. Choong, T. PhilpApr 2006 European Urology Supplements

Calcium Oxalate Monohydrate crystals inhibit the expression of heat shock protein 25 in canine

renal distal tubule cells

A. Patel, S. Choong, W. Robertson, J. HothersallApr 2006 European Urology Supplements

Thermo-expandable ureteric stent in the management of complex refractory benign ureteric strictures: Longterm efficacy and risk factors associated with complications

G. Lee, S. Longhorn, M. Kellett, C. Allen, D. Rickards, S. Choong, T. PhilpApr 2006 European Urology Supplements