Our Specialists

Mr Ralph Van Dalen

MB ChB (Otago 1985) FRACS (1995)

Trained in Dunedin and completed surgical training in Christchurch. Spent 3 years in England to further colorectal training. Worked in Waikato since 2001 as general and colorectal surgeon. Currently involved in implementation of bowel screening programme for the Waikato region.

Current Practice:

  • Laparoscopic Cholecystectomy, Laparoscopic Hernia repair
  • Laparoscopic colon and rectal surgery,
  • Pelvic floor surgery for incontinence and emptying difficulties
  • Haemorrhoids –  latest ligasure banding treatment,   excisions
  • Anal skin tag excisions,  pilonidal surgery, fistula and fissure surgeries
  • Endoscopy :   Colonoscopy, Gastroscopy and Flexible Sigmoidoscopy 

Dr Win Meyer-Rochow

MB ChB (Otago 1996) FRACS (2005) PhD (Sydney 2010)

Dr. Meyer-Rochow gained his MB ChB from Otago Medical School in 1996. After completion of General Surgery specialist training in 2005 he was selected for sub-specialty training in Endocrine Surgery with the University of Sydney’s Endocrine Surgery unit, recognised internationally as one of the world’s leading units for thyroid, parathyroid and adrenal gland surgery. Dr. Meyer-Rochow has a particular interest and expertise in minimally invasive thyroid and parathyroid surgery and laparoscopic surgical techniques. In addition to his specialist and subspecialist qualifications he has also completed a medical doctorate in his area of subspecialty. Having had a personal experience with thyroid surgery Dr. Meyer-Rochow also has a particular insight into surgery from a patient’s perspective which is reflected by the exceptional care and excellent outcomes he provides for his patients.

With a background in General Surgery he also provides a wide range of General Surgery procedures. As an academic surgeon and senior lecturer at the University of Auckland, Dr. Meyer-Rochow is actively engaged in research and training of new surgeons, published numerous peer reviewed journal articles and regularly presents at Australasian and International surgical meetings. As a result he is at the cutting edge of evidence based treatment and new advancements in surgery.

Dr. Meyer-Rochow has a close working relationship with local and regional Endocrinologists to ensure optimal outcomes for patients treated with an endocrine disorder.

 Areas of specialisation:

  • Endocrine procedures for thyroid, parathyroid and adrenal 
  • Laparoscopic surgery including abdominal, gallbladder,  hernia and colon
  • Fistula, fissure and pilonidal surgeries
  • Haemorrhoids – including ligasure banding and excisions
  • Skin lesions including lipoma

Visit endocrinesurgeon.co.nz for more information.


Mr Damien Ah Yen

MBChB (Otago, 2005) FRACS (General Surgery, 2015)

Growing up in a small village in Samoa, Damien received a New Zealand Scholarship Award to study Medicine in Otago. It was during his return for his internship at the Main Hospital in Samoa that he discovered his passion for General Surgery. He returned to New Zealand to undertake general surgical training becoming a Fellow of the Royal Australasian College of Surgeons. After completing his post fellowship training at the Waikato Public and Royal Melbourne Hospitals, Damien and his young family returned to Waikato as a Consultant General and Trauma Surgeon. Damien is the Deputy Director of New Zealand’s only Level 1 Trauma Centre. His elective practice comprises all general surgical cases with a special interest in minimally invasive general abdominal surgery, proctology and endoscopy. As well as his surgical expertise, Damien aims to establish a relationship of honesty and trust with each of his patients along their surgical journey.

Current Practice:

  • Laparoscopic colon, hernia and gallbladder surgery
  • Anorectal disease including haemorrhoids, fissures and fistula
  • Pilonidal disease surgery, skin tags
  • Gastroscopy, Flexible Sigmoidoscopy,  and Colonoscopy

Minor surgery including skin lesions, lumps and bumps

Dr Ryan Paul

MB ChB Medicine, Surgery (Auckland 2002) FRACP (2012) PhD (Auckland) 2016

Ryan is passionate about the best care for his patients with endocrinological disorders and diabetes. He is well respected within his field as reflected by being the current President of the New Zealand Society of Endocrinology (NZSE) and as an Executive Member of the New Zealand Society for the Study of Diabetes (NZSSD).

Ryan is active in research in his roles as a Senior Lecturer at the University of Waikato and as a Clinical Associate of the Maurice Wilkins Centre. He also has a key role in teaching as a member of the Royal Australasian College of Physicians (RACP) New Zealand Endocrinology Advanced Training Subcommittee and leading the Diabetes Nurse Prescribers in New Zealand. Ryan is also a clinical advisor for Diabetes and Exercise and Sports Association (DESA) and Diabetes and Eating Disorder Awareness. 


Dr Marianne Elston

MB ChB (Otago) FRACP PhD (Sydney)

Marianne Elston, MB ChB, FRACP, PhD, obtained her MBChB with distinction from the University of Otago and completed her Endocrinology training in Auckland and Waikato Hospitals. She then worked in Professor Bruce Robinson’s Cancer Genetics Laboratory at the Kolling Institute of Medical Research, Royal North Shore Hospital in Sydney where she undertook a PhD investigating the molecular basis of pituitary adenomas.  Her interests include familial endocrine conditions and thyroid disease. Dr Elston is currently a Consultant Endocrinologist at Waikato Hospital and Senior Lecturer with the University of Auckland.