Skip to main content
Prof. Dr Joachim C. Mertens, FEBGH -  Specialist in Gastroenterology - Portrait

Prof. Dr Joachim C. Mertens, FEBGH

Specialist in Gastroenterology

+41 44 546 57 40

Gastroenterology Zurich: Prof. Dr Joachim C. Mertens

Treatment focus

  • Gastric, intestinal, liver, and pancreatic diseases, gastroscopy, colonoscopy (endoscopy), ultrasound (sonography)
  • Anal and rectal diseases, hemorrhoidal disease, anal fissures, continence disorders
  • Proctoscopy and anorectal functional diagnostics and transanal endoscopic 3D ultrasound
  • Liver and biliary tract diseases, alcoholic and non-alcoholic fatty liver, viral hepatitis, autoimmune liver diseases (PSC, PBC, AIH), elastography (fibroscan), liver biopsy
  • Liver tumors, hepatocellular carcinoma (HCC), cholangiocellular carcinoma (CCC)


GastroZentrum Hirslanden
Klinik Hirslanden
Witellikerstrasse 40, CH-8008 Zurich

P: +41 44 546 57 40 F: +41 44 387 39 66

Consultation Hours:

8:00 AM until 5:00 PM
and by arrangement
Saturday/Sunday by arrangement


GastroZentrum Hirslanden - TeamGastroZentrum Hirslanden - EntranceGastroZentrum Hirslanden - Patient roomGastroZentrum Hirslanden - Outside view

Medical Range

Range of Diagnostic Services

  • Gastroscopy
  • Colonoscopy
  • Rectosigmoidoscopy
  • Capsule endoscopy
  • Proctoscopy
  • Endosonography
  • Anal 3D sonography
  • Anorectal physiology
  • High-resolution anal manometry
  • Sonography
  • Contrast sonography
  • Bravo capsule
  • Smart Pill


Range of Therapeutic Services

  • Polypectomy
  • Dilatation
  • Bougienage
  • Hemorrhoid laser coagulation/argon plasma coagulation
  • Biofeedback
  • Injection treatment
  • Hemorrhoidal treatment, according to Rafaleo
  • SpeedBand ligation treatment
  • PelviPower therapy
  • Percutaneous tibial nerve stimulation therapy

Personal information


Prof. Dr Joachim C. Mertens, FEBGH, is a specialist (FMH) in gastroenterology, hepatology, and internal medicine and a partner at the GastroZentrum Hirslanden in Zurich.

Dr Mertens diagnoses and treats patients with digestive tract diseases with a high level of expertise and many years of international academic experience. He has access to the latest equipment and the professional infrastructure of one of Switzerland's most renowned private clinics at the GastroZentrum Hirslanden to make a significant contribution to a healthy or at least symptom-free life.

Highest Level of Expertise in the Treatment of Chronic and Acute Gastric and Intestinal Diseases

General practitioners often treat upper abdominal pain with typical symptoms without a profound diagnosis with medication that reduces stomach acid. This approach is often valuable and successful in healing inflammation and mucosal defects in the upper digestive tract. However, not all patients can be helped sustainably with this general therapy.

Dr Joachim C. Mertens has the most up-to-date equipment available at the GastroZentrum Hirslanden in Zurich to diagnose the upper and lower digestive tract thoroughly. This allows him to exclude other possible causes of abdominal pain, such as bacterial colonization, food intolerances, or chronic intestinal diseases.

State-of-the-Art Diagnostics: Proctoscopy and Transanal Endoscopic 3D Ultrasound

Proctoscopy is a medical procedure for examining the rectum and anal canal. A narrow, tubular instrument, the proctoscope, is used to identify changes such as hemorrhoids, inflammation, or polyps. Smaller therapeutic measures, such as hemorrhoid treatment, can also be carried out directly.

Dr Mertens also has the necessary equipment for transanal endoscopic 3D ultrasound examinations at the GastroZentrum Hirslanden. This is an advanced imaging procedure for the detailed diagnosis of complaints in the rectum and anus area and enables high-resolution, three-dimensional ultrasound images that make specific anatomy and pathologies such as tumors, fistulas, or sphincter defects visible. It is often used in the diagnosis and treatment of diseases of the rectum and anal canal, such as incontinence or tumors, to provide precise information about the affected areas.

Medical Expertise for Anal and Rectal Disorders such as Hemorrhoids and Anal Fissures

Hemorrhoids and anal fissures are two common problems in the anal area that often cause discomfort and pain. Hemorrhoids are swollen veins in the anal region that can cause discomfort, such as itching, pain, or bleeding. The discomfort results from increased pressure in the rectum, which can be caused by factors such as constipation, pregnancy, or prolonged sitting.

The treatment spectrum at Hirslanden GastroZentrum ranges from medication to relieve pain and inflammation to minimally invasive procedures such as rubber band ligation or sclerotherapy.

Anal fissures are small tears or wounds in the anal canal that hard stools, diarrhea, or strain during defecation can cause. They often cause severe pain during or after defecation and can also lead to bleeding.

Treatment usually involves a diet rich in fiber and ointments to relieve discomfort. Prof. Mertens offers an innovative treatment method for anal fissures at the Gastrozentrum Hirslanden, which is based on a targeted injection in the area of the anal canal. In some cases, anal fissures may require surgical intervention to support healing.

It is advisable to consult a specialist in both cases, not only because of the bleeding but to exclude malignant diseases of the intestines, which can also accompany a discharge of blood. Dr Mertens offers comprehensive diagnostics and treatment for proctological complaints.

Many Years of Experience in the Treatment of Liver and Biliary Tract Diseases

Gallstones, which develop in the gallbladder due to excess cholesterol or calcium, lead to obstruction of the large bile ducts outside the liver. As a result, the bile duct tissue becomes inflamed and causes colicky upper abdominal pain.

Liver cirrhosis, a progressive loss of the microscopic liver architecture, including the destruction of the minor bile ducts in the liver tissue, which can result from chronic alcohol consumption, viral hepatitis, and an unhealthy diet, for example, also leads to obstruction of the bile ducts.

The obstruction of the large bile ducts outside the liver and the intrahepatic transformation lead to congestion so that degradation substances can no longer be excreted. These yellow pigments are deposited in the eyes and later color the skin yellow.

Gallstones or preliminary stages of liver cirrhosis occur frequently in the population and usually do not cause any symptoms. It is, therefore, a doctor's skill to recognize acute bile duct obstruction, inflammation of the organs, or chronic autoimmune diseases as complications at an early stage and to treat them appropriately. Dr Joachim C. Mertens at GastroZentrum Hirslanden in Zurich has many years of clinical experience in treating patients with liver and bile duct diseases.

Liver Cancer Specialist in Zurich: Treatment of Benign and Malignant Tumors of the Liver

In most cases, benign tumors such as hemangiomas, adenomas, focal nodular hyperplasia (FNH), and liver cysts do not require immediate treatment once imaging procedures have confirmed the diagnosis.

In some cases, however, the rapid growth of these benign tumors causes overexpansion of the liver capsule and consequently causes pain or a feeling of pressure in the upper abdomen, so surgical removal should be considered to restore quality of life.

Malignant liver tumors, including primary liver cancer (hepatocellular carcinoma) or metastases from other types of cancer, which often settle in the liver, require more comprehensive therapy, which is based on chemotherapeutic treatment of the primary tumor. In addition to this systemic component, metastases and malignant tumor foci can also be attacked locally, for example, with surgical removal or targeted radiation of the tumor volume.

Early diagnosis and regular monitoring are crucial. Prof. Dr Joachim C. Mertens cooperates with an interdisciplinary team of radiologists and surgeons in Zurich to develop the best individual treatment strategy.

You can find more information on Prof Dr Joachim C. Mertens, FEBGH, on the Hirslanden GastroZentrum Zurich website.



Curriculum Vitae

2023Clinical Associate Professor for Gastroenterology (University of Nicosia Medical School, Zypern)
since 2022Hirslanden Gastrozentrum
2022Further Training Stay Augusta University Medical Center, USA (Prof. Dr S. Rao)
2019Visiting Professor Norwegian PSC Research Center, University of Oslo
2019 – 2022Coordinator Liver and Pancreatic Tumor Center, Comprehensive Cancer Center Zurich
2019 – 2022Head of the Interdisciplinary Liver Tumor Consultation Hours, University Hospital Zurich
2018Habilitation, Venia Legendi in Gastroenterology and Hepatology from the University of Zurich
2016 – 2022Senior Physician, Department of Gastroenterology and Hepatology, University Hospital Zurich (Prof. Dr M. Fried/ Prof. Dr G. Rogler)
2016 – 2018Head Physician Internal Medicine/Gastroenterology, Hospital Center Upper Valais
2016Acquisition of a Federal Diploma in Human Medicine for Gastroenterology (FMH)
2015 – 2019Ambizione SCORE Fellow of the Swiss National Science Foundation at the Department of Gastroenterology & Hepatology at the University Hospital Zurich
2013 – 2022Head of Hepatology Research Group, Department of Gastroenterology & Hepatology, University Hospital Zurich
2013 – 2015Assistant Physician, Clinic for Gastroenterology and Hepatology, University Hospital Zurich (Prof. Dr M. Fried)
2010 – 2013Fellow, Division of Gastroenterology and Hepatology, Mayo Clinic Rochester, USA (Prof. Dr Gregory J. Gores)
2010Senior Physician, Clinic, and Polyclinic for Internal Medicine, University Hospital Zurich (Prof. Dr E. Battegay)
2009 – 2010Assistant Physician, Department of Internal Medicine - Internal Intensive Care Medicine, University Hospital Zurich (Prof. Dr M. Maggiorini)
2009Acquisition of a Federal Diploma in Human Medicine for General Internal Medicine (FMH)
2006 – 2010Assistant Physician, Clinic and Polyclinic for Internal Medicine, University Hospital Zurich (Prof. Dr R. Speich)
2005 – 2006Assistant Physician, II. Medical Clinic at the University Hospital Rechts der Isar, Munich (Prof. Dr R. Schmid)
2008Dissertation Magna Cum Laude: "Influence of Stromal Fibroblasts on Epithelial Differentiation in Squamous Cell Carcinomas"
2004Practical Year at the Nuffield Department of Anesthetics, Oxford University, Great Britain
2001 – 2003Research Associate and PhD Student, German Cancer Research Center Heidelberg (DKFZ) (Prof. Dr N. Fusenig)
2001Research Stay Center for Molecular Biology Heidelberg (ZMBH) (Prof. Dr B. Dobberstein)
2001 – 2005Studies of Human Medicine at the Ruprecht-Karls University of Heidelberg
1999 / 2000Research Stays Yale Medical School – Yale Comprehensive Cancer Center (Prof. Dr Dr M. Reiss)
1998 – 2001Studies of Human Medicine at the Albert-Ludwigs University of Freiburg
1997 – 1998Studies of Law at the Albert-Ludwigs University of Freiburg


  • Dr Andreas Müller
  • PD Dr Jonas Zeitz
  • Prof. Dr Stefan Seewald

Research & Training



The Hirslanden GastroZentrum is one of Switzerland's most renowned private clinics at the highest level. The clinic has private rooms with a lake view, concierge service, award-winning cuisine, and limousine service.



Google Karte von Europa mit verschiedenen Standorten
Zurich Main Station5 km
Zürich Airport15 km

Information about Zurich

The capital of the canton of the same name is also the largest city in Switzerland. Geographically it is located north in eastern Switzerland. Zurich is situated on the Limmat River, directly at the outflow of Lake Zurich, and is thus also called the "Limmat City." Economically, socially and scientifically, Zurich is considered the center of Switzerland. Therefore, large banks, many media companies, and international companies are located there, and at the same time, the cultural offer is rich. The well-known Swiss Federal Institute of Technology Zurich (ETHZ) gives Zurich an international name in educational institutions.

Benefit Program for Patients and Relatives

Lufthansa Mobility Partner

PRIMO MEDICO is an accredited partner of Lufthansa Health & Medical. Benefit as a member or user of PRIMO MEDICO from special terms that provide you and your travelling companion with discounts on a variety of fares offered by Lufthansa, SWISS, Austrian and Brussels Airlines.

Professional Aviation Solutions

Professional Aviation Solutions is a young, motivated team of experienced aircraft charter experts, which collaborates with only the most reputable airlines.

Fischer Limousine AG

Fischer Limousine AG is an independent Swiss company. The company, based in Kloten near Zurich Airport, is a family-owned and run business. The services are aimed at patients, clinics, hospitals and private individuals for safe and comfortable care.

aja Resort Zurich

At the aja Zurich, you can choose from three different room categories: comfort, superior, and deluxe. The rooms are equipped with comfortable beds, modern bathrooms, flat-screen TVs, bathrobes, and slippers. Those seeking relaxation will find small oases of oases of peace and quiet at the aja…

Agent CS

Agent CS creates space so that you can concentrate on your most important tasks - an innovative service agency which uses existing networks in a wide variety of areas to provide you with a solution customised for you.

Prof. Dr Joachim C. Mertens, FEBGH

GastroZentrum Hirslanden

Klinik Hirslanden

Witellikerstrasse 40, CH-8008 Zurich

Contact data
Preferred Date
Confirm and send your request
PRIMO MEDICO only forwards the data made available by you to the medical specialists, no entitlement to medical treatment arises from our service. For acute diseases, please call a physician at your current location directly.
Loading... Ihre Anfrage wird versendet.