What Your Huisarts Cannot Order For You
A guide to diagnostic tests, procedures and treatments that require specialist referral in the Dutch healthcare system
⚠ MEDICAL DISCLAIMER This article is for educational and informational purposes only. It does not constitute medical advice. Protocols may vary by region, health insurer and hospital. Always consult your own huisarts or healthcare provider for advice specific to your situation.
In the Netherlands, your huisarts is far more than a first port of call. They are the cornerstone of the entire healthcare system, handling the vast majority of medical questions, prescriptions and basic diagnostics without any need for hospital involvement. But the system has clear boundaries, and understanding them can save you time, confusion and unnecessary frustration when navigating your care.
Not every test, scan or procedure is within the huisarts's remit. Some investigations require specialist equipment, clinical expertise, or hospital-grade infrastructure that simply isn't available in a GP practice. Others fall outside the protocols for which insurers reimburse primary care. This guide maps out exactly where those boundaries lie — and what happens on the other side of them.
96% of GP consultations are handled entirely in primary care, including lab tests and basic imaging.
How the System Works: First vs. Second Line
Dutch healthcare is organised into clearly defined tiers. The eerste lijn (primary care) encompasses your huisarts, physiotherapist, dietitian and similar practitioners. The tweede lijn (secondary care) is the world of hospital specialists — cardiologists, neurologists, gastroenterologists and so on.
Remember that the huisarts acts as a gatekeeper between these two worlds. You cannot simply book an appointment with a specialist. You need a verwijsbrief (referral letter) from your GP, which is then valid for one year. Without one, you pay out of pocket, and insurers will not reimburse the costs.
The distinction this guide focuses on is subtler than simply "do I need a referral to see a specialist?" It concerns which diagnostic tests the huisarts is permitted to order directly, and which can only be initiated once a specialist is involved.
What the Huisarts Can Order Directly
To understand the limits, it helps to know what falls within the GP's direct reach. The following are all available in primary care without specialist involvement:
Full blood count (CBC)
ESR, CRP (inflammation markers)
Glucose & HbA1c (diabetes)
Cholesterol & lipid panel
Thyroid function (TSH, fT4)
Liver & kidney function
Urine analysis & culture
Standard resting ECG
X-rays (chest, extremities)
MRI of knee, SI joint or lower back (within limits — see note below)
FOBT (bowel cancer screening)
MMSE (dementia screening)
Basic abdominal ultrasound (region and insurer dependent)
Note: MRI and ultrasound access varies by insurer and region. For MRI, only the knee, SI joint and acute lower back are covered under standard GP ordering rights by most insurers.
What Requires a Specialist Referral
The following sections cover each major specialization, detailing the specific tests and procedures that are only available through secondary care — meaning that your huisarts needs to refer you to a specialist first before the test or procedure can be done.
1. Cardiology
Echocardiography (Cardiac Ultrasound) While the huisarts can perform and interpret a resting ECG, an echocardiogram — the ultrasound examination of the heart — is exclusively a secondary care procedure. It is the gold standard for diagnosing heart failure, valve abnormalities, cardiomyopathy and structural heart disease, and requires both specialist equipment and a trained cardiologist to interpret the results.
Transoesophageal Echocardiography (TEE) An advanced variant of the cardiac echo in which the ultrasound probe is passed through the esophagus to obtain closer, clearer images of heart structures. This invasive procedure is performed only in a hospital setting by a cardiologist.
Cardiac Catheterisation & Coronary Angiography In this procedure, a thin catheter is guided through a blood vessel — usually in the wrist or groin — into the heart. Contrast dye is injected to visualise the coronary arteries and identify blockages. Additional procedures such as balloon angioplasty and stent placement can be performed during the same session. This is exclusively ordered and performed by cardiologists.
Exercise Stress Testing (Ergometry / Bicycle Test) The exercise stress test assesses how the heart performs under physical exertion, revealing ischemia or arrhythmias that may not appear at rest. It is performed under cardiac monitoring in a hospital or specialist clinic. Holter monitoring (a 24-hour continuous ECG recording) is similarly arranged via the cardiologist.
Cardioversion & Catheter Ablation For arrhythmias such as atrial fibrillation that do not respond to medication, electrical cardioversion (resetting the heart rhythm with a controlled shock) or catheter ablation (targeted destruction of abnormal electrical pathways) are hospital-only treatments requiring a cardiologist.
When your GP should refer you to cardiology: unexplained breathlessness or leg swelling (suspected heart failure); recurrent palpitations or irregular heartbeat; abnormal resting ECG requiring further evaluation; chest pain that is non-acute but requires imaging; suspected valve disease.
2. Neurology
EEG (Electroencephalogram) An EEG records the electrical activity of the brain through electrodes placed on the scalp. It is the primary investigation for epilepsy and is also used in the evaluation of encephalopathy, sleep disorders and altered consciousness. This test is exclusively available via the neurologist or paediatric neurologist.
Lumbar Puncture (Spinal Tap) A lumbar puncture involves inserting a needle into the spinal canal to collect a sample of cerebrospinal fluid (CSF). Analysis of this fluid is essential for diagnosing bacterial or viral meningitis, multiple sclerosis, subarachnoid haemorrhage and certain cancers. In non-emergency cases, the huisarts refers to the neurologist. In cases of suspected acute meningitis, the patient is sent directly to the emergency room.
Electromyography (EMG) & Nerve Conduction Studies EMG and nerve conduction studies assess the health of muscles and the nerves controlling them. They are used to diagnose carpal tunnel syndrome, peripheral neuropathy, polyneuropathy, ALS and various muscle diseases. These are specialist-only investigations ordered and performed by neurologists.
Brain & Cervical Spine MRI (Beyond Basic Indications) While the GP can order an MRI of the lower back, MRI of the brain, the cervical spine when neurological pathology is suspected, or MRI angiography of the cerebral vessels all require a neurology referral.
When your GP should refer you to neurology: first-ever seizure or suspected epilepsy; suspected multiple sclerosis; progressive weakness, numbness or coordination problems; severe or sudden-onset headache; suspected TIA or stroke (emergency referral / SEH).
3. Gastroenterology (MDL)
Colonoscopy A colonoscopy involves passing a flexible camera through the entire large intestine to visualise the colon and rectum, detect polyps, take biopsies and diagnose conditions such as colorectal cancer and inflammatory bowel disease. This procedure is performed by a gastroenterologist or surgeon.
Important note: for the national bowel cancer screening programme (bevolkingsonderzoek darmkanker), no GP referral is needed — the RIVM initiates the process directly. However, when clinical symptoms are present (rectal bleeding, unexplained weight loss, altered bowel habit), a GP referral for colonoscopy is required.
Gastroscopy (Upper Endoscopy / OGD) Gastroscopy examines the esophagus, stomach and duodenum using a flexible camera. It is indicated for persistent dyspepsia, suspected Barrett's oesophagus, gastric or duodenal ulcers, upper GI bleeding and swallowing difficulties. Referral to the gastroenterologist is required.
ERCP (Endoscopic Retrograde Cholangiopancreatography) ERCP combines endoscopy with X-ray fluoroscopy to examine and treat conditions of the bile ducts, gallbladder and pancreas. It can remove gallstones from the bile duct, place stents and take biopsies. This is an advanced hospital procedure exclusively available via the gastroenterologist or surgeon.
Capsule Endoscopy The patient swallows a small wireless camera capsule that photographs the lining of the small intestine as it passes through. It is used to investigate obscure GI bleeding, Crohn's disease and small bowel tumours. Available only via specialist referral.
Oesophageal Manometry & 24-Hour pH Monitoring These tests measure pressure and acid levels within the oesophagus over time. They are used to diagnose GERD, achalasia and non-cardiac chest pain. Both require specialist hospital equipment.
When your GP should refer you to gastroenterology: rectal blood loss or unexplained anaemia; unintentional weight loss with GI symptoms; persistent dysphagia (difficulty swallowing); positive FOBT result; suspected inflammatory bowel disease.
4. Sleep Medicine
Polysomnography (PSG / Full Sleep Study) Polysomnography is the most comprehensive investigation for sleep disorders. It simultaneously records brainwave activity (EEG), eye movement, heart rhythm (ECG), muscle movement (EMG), breathing effort, airflow and blood oxygen levels throughout the night. In the Netherlands, this can be performed either in a specialist sleep clinic or increasingly at home (through providers such as the Nederlands Slaap Instituut), but always requires a referral letter from the huisarts or a medical specialist.
The huisarts may suspect a sleep disorder and prepare the referral, but the ordering, performance and interpretation of the PSG is handled in secondary care.
CPAP Initiation & Titration If obstructive sleep apnoea (OSA) is confirmed, CPAP therapy is initiated and titrated in secondary care, under the supervision of a pulmonologist, neurologist or ENT specialist.
When your GP should refer you to sleep medicine: loud snoring combined with excessive daytime sleepiness; witnessed breathing pauses during sleep; suspected narcolepsy; restless legs syndrome not responding to primary care management; suspected REM sleep behaviour disorder.
5. Pulmonology (Respiratory Medicine)
Comprehensive Lung Function Testing Basic spirometry can be performed by the GP (per NHG guidelines for asthma and COPD). However, comprehensive lung function testing including diffusion capacity (DLCO) and body plethysmography — used for diagnosing interstitial lung disease, pulmonary fibrosis and complex COPD — requires referral to the pulmonologist.
Bronchoscopy Bronchoscopy passes a flexible camera through the nose or mouth into the airways and lungs. It is used to investigate suspected lung cancer, take tissue biopsies, remove foreign bodies and evaluate serious infections. This is an invasive hospital procedure performed exclusively by a pulmonologist or thoracic surgeon.
CT-Guided Lung Biopsy When a suspicious lesion is identified on CT imaging, a biopsy under CT guidance is performed by an interventional radiologist in secondary care, following referral.
6. Rheumatology
Synovial Fluid Analysis (Joint Aspiration) While a GP can in principle aspirate a joint, laboratory analysis of synovial fluid — including microscopy for crystals (gout, pseudogout) and culture for infection — requires specialist laboratory infrastructure. Diagnosis and management of inflammatory joint disease falls within rheumatology.
Temporal Artery Biopsy & PET-CT for Vasculitis When giant cell arteritis (reuscelarteriitis) is suspected — a serious inflammatory condition that can cause blindness — the NHG guideline recommends the GP refers within 24 hours. The definitive investigations, a temporal artery biopsy or FDG PET/CT scan, are exclusively secondary care procedures performed under specialist supervision.
Advanced Autoimmune Blood Panels While a GP can order basic autoimmune markers (ANA, RF), specialist panels such as anti-dsDNA, anti-CCP, ANCA and complement levels are typically ordered by rheumatologists and immunologists who have the clinical context to interpret them correctly.
7. Oncology & Suspected Malignancy
When a GP suspects cancer, they follow the urgente verwijsroute (urgent referral pathway), submitted digitally via ZorgDomein. The following investigations are exclusively available in secondary care:
Tissue biopsy (needle biopsy, excision biopsy, punch biopsy) — performed by surgeon, dermatologist or radiologist
PET-CT scan — ordered by the oncologist for cancer staging and treatment planning
MRI prostate & MRI rectum — specialist-ordered imaging for staging and surgical planning
Sentinel node procedure & nuclear medicine investigations — exclusively arranged via the oncologist or nuclear medicine specialist
8. Other Specializations
Ophthalmology: A GP referral is required for all ophthalmologist consultations. Secondary care procedures include fluorescein angiography, formal visual field testing, retinal OCT and treatment of intraocular pressure (glaucoma).
Urology: Cystoscopy (camera examination of the bladder), urodynamic studies, proctoscopy and anal manometry.
Gynaecology: Hysteroscopy (examination of the uterus), laparoscopy (keyhole abdominal surgery) and colposcopy (examination of the cervix following an abnormal smear).
Dermatology: A GP referral is required for all dermatology consultations. Secondary care procedures include skin biopsy, epicutaneous patch testing for contact allergies and advanced phototherapy.
Nuclear Medicine: Bone scan, thyroid scintigraphy and myocardial perfusion scan — all ordered by the relevant specialist.
Vascular Surgery: Duplex ultrasound of the extracranial neck vessels and duplex of blood vessels in the extremities are specialist-led vascular investigations.
Psychiatry / GGZ: Formal neuropsychological testing, structured diagnostic interviews for complex mental illness and specialised psychotherapy are accessed via GGZ referral.
Costs, Insurance & the Eigen Risico
All secondary care investigations covered in this article fall under the basispakket (basic health insurance package) of the Zorgverzekeringswet (Zvw), meaning they are reimbursed by your insurer — provided you have a valid verwijsbrief.
However, secondary care costs count towards your eigen risico (mandatory deductible), which is set at €385 per person per year in 2026. GP consultations and most primary care services do not attract the eigen risico, but the moment you step into secondary care, this deductible applies.
Referral letters are valid for one year from the date of issue. If waiting times exceed 365 days — which does occur in some specialisms — your referral remains valid.
Without a valid referral letter, you will be treated as an uninsured patient and may be required to pay a deposit before being seen. Always ensure your referral is in place before attending a specialist appointment.
Why These Boundaries Exist
The division between what the huisarts can and cannot order is not arbitrary. It reflects four distinct realities of modern medicine:
Equipment: Cardiac cath labs, sleep labs, endoscopy suites and specialist MRI protocols require hospital infrastructure that is simply not available in primary care.
Expertise: EEGs, cerebrospinal fluid analysis and polysomnograms require specialist clinical training to perform and interpret safely.
Risk: Invasive procedures carry procedural risks that demand specialist training and immediate access to emergency backup.
Regulation: The NHG guidelines, the Zorgverzekeringswet and regional agreements via ZorgDomein together define the legal and clinical scope of what is reimbursable and appropriate in primary care.
Understanding these boundaries empowers you as a patient. If you have symptoms that concern you and believe further investigation is warranted, raise this with your huisarts. You have the right to discuss a referral, and if one is refused, you have the right to seek a second opinion from another GP.
Information sourced from the Nederlands Huisartsen Genootschap (NHG), Zorginstituut Nederland, Rijksoverheid.nl, and leading Dutch health insurers. This article is for informational purposes only and does not constitute medical advice. Always consult your huisarts for personal health decisions.