Nuclear medicine · Gastroenterology
Gastric emptying scan, 4-hour scintigraphic test for gastroparesis and rapid gastric emptying.
A 4-hour scintigraphic gastric emptying scan measures the percentage of a Tc-99m-labelled standard meal remaining in the stomach at 1, 2, 3 and 4 hours. The gold-standard test for gastroparesis (delayed emptying) and dumping syndrome (rapid emptying).
Why patients choose us
- 01
The right hands
We route you to a consultant nuclear medicine physician — with a gastroenterologist to interpret the result and set the plan.
- 02
Standard 4-hour protocol
Serial imaging at 1, 2, 3 and 4 hours using the standardised low-fat Tc-99m egg-white meal — the internationally accepted method.
- 03
Independent, and free
We are paid by no clinic, so the recommendation is impartial and costs you nothing.
Key facts
What a gastric emptying scan is, in six lines.
The essentials — what the test measures, what the meal is, what the threshold means, and who reads it.
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4-hour scintigraphic gastric emptying study
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Standard low-fat egg-white meal with Tc-99m label
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Emptying at 4 hours < 90% = gastroparesis
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Very rapid emptying suggests dumping syndrome
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Reported by a nuclear medicine consultant
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Complements gastroscopy and manometry
Preparation and pathway
From referral to plan — what happens, in order.
The seven steps of a standard 4-hour scintigraphic gastric emptying study.
Phase 1 · Before your scan
Referral, fasting, medications held
Phase 2 · On the day
~4 hours at the department
Phase 3 · After
Report and plan
- 01
Before
Gastroenterology referral
A gastroenterology referral confirms the scan is the right next step, with prokinetics and diabetic control noted.
- 02
Before
Fast for 6 hours
Nothing to eat for 6 hours before the appointment. Sips of water are fine.
- 03
Before
Withhold prokinetics for 48 hours
Metoclopramide, domperidone, prucalopride and erythromycin are held for 48 hours unless your gastroenterologist advises otherwise.
- 04
On the day
Consume the Tc-99m egg-white meal
A standardised low-fat egg-white meal is labelled with Tc-99m and eaten within 10 minutes under supervision.
- 05
On the day
Serial gamma-camera images
Images are acquired immediately after the meal and at 1, 2, 3 and 4 hours — you sit or lie under the gamma camera for a few minutes each time.
- 06
After
Nuclear medicine reporting
A consultant nuclear medicine physician calculates the percentage retention at each time point and issues a written report.
- 07
After
Structured plan with your gastro
Your gastroenterologist reviews the report and sets the treatment plan — dietary, prokinetic, endoscopic or surgical.
Typical appointment: ~4 hours. Report: within a few working days.
What it shows
When a gastric emptying scan is the right test.
The scan answers a specific question — how fast the stomach empties, and whether that fits with symptoms. These are the presentations we see most.
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Delayed gastric emptying (gastroparesis)
The gold-standard diagnostic finding — retention above published thresholds at 2 and 4 hours.
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Very rapid emptying (dumping)
Excessive early emptying suggests dumping syndrome, often after gastric surgery.
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Reflux during scanning
The gamma camera can pick up reflux of the labelled meal into the oesophagus.
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Post-surgical anatomy alteration
Changes after fundoplication, sleeve gastrectomy or bypass are visible on the study.
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Response to prokinetic therapy
Repeat studies quantify how much a prokinetic drug has changed emptying.
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Baseline before bariatric surgery
Baseline emptying informs surgical planning and post-op comparison.
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Post-fundoplication assessment
Assesses emptying after anti-reflux surgery when symptoms persist.
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Red flag: severe gastroparesis with malnutrition — nutritional support and MDT
Severe delay with weight loss and dehydration needs urgent nutritional support and MDT input.
Treatment options / next steps
What happens after an abnormal scan.
A stepped ladder — dietary first, then prokinetics, then endoscopic and surgical options for refractory cases.
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Dietary modification
Small, low-fat, low-fibre meals eaten frequently — the first-line intervention for most patients.
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Prokinetics
Metoclopramide, domperidone or prucalopride to accelerate emptying, with cardiac and neurological monitoring.
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Erythromycin as prokinetic
Motilin agonist used short-term for symptomatic control when other prokinetics fail.
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Gastric pacing (specialist)
Implanted gastric electrical stimulator for refractory diabetic or idiopathic gastroparesis.
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Endoscopic pyloromyotomy (G-POEM)
Endoscopic division of the pylorus — an increasingly used option for outlet-obstruction gastroparesis.
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Pyloric botulinum injection
Temporary chemical relaxation of the pylorus, sometimes used to predict G-POEM response.
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Bariatric surgery consideration
In selected patients with severe gastroparesis, gastrectomy or bypass may be considered by an MDT.
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MDT gastroenterology follow-up
Long-term follow-up in a specialist motility clinic with dietitian and endocrine input where relevant.
Our vetted London network
A small panel of departments, we picked them.
Nuclear medicine departments across central and greater London that run the full 4-hour protocol and report to consensus criteria.
Selection criteria
How we choose every clinic in our network.
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Consultant nuclear medicine physicians reporting to standardised protocols
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Standardised Tc-99m low-fat egg-white meal per international consensus
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Full 4-hour acquisition — not truncated 90-minute studies
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Onward gastroenterology and motility-clinic pathway if disease is found
Safety and eligibility
Safe, low-dose, well-tolerated.
A low-dose nuclear medicine study — the practical points are fasting, held medications and pregnancy.
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Very low radiation dose
The Tc-99m dose is small and comparable to a few months of natural background radiation.
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Pregnancy — relative contraindication
Not offered in pregnancy unless the clinical need is exceptional and consultant-approved.
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Breastfeeding
Short interruption of breastfeeding is usually advised — the team gives specific timings.
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Fast for 6 hours
Nothing to eat for 6 hours beforehand. Sips of water are fine.
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Withhold prokinetics 48 hours
Metoclopramide, domperidone, prucalopride and erythromycin are stopped for 48 hours before the scan.
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Diabetic patients
Blood glucose above 15 mmol/L can slow emptying artefactually — the team may reschedule if levels are high.
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Egg allergy
Tell the team in advance — an alternative meal preparation is used.
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Opiates and cannabinoids
Both delay emptying and should be paused, where safe, in the days before the scan.
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Bring your medication list
A full list of current medications and doses helps interpretation and the onward plan.
Red flags and higher-risk groups
When the scan and the plan matter most.
Groups in which findings materially change management, and where an MDT view is often needed.
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Severe gastroparesis with dehydration
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Malnutrition secondary to gastroparesis
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Post-vagotomy gastroparesis
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Diabetic gastroparesis
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Neurodegenerative disease (Parkinson’s)
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Amyloidosis
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Post-radiotherapy gastroparesis
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Dumping syndrome with hypoglycaemia
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Pregnancy (relative contraindication)
Reading your report
A gastric emptying report can look intimidating. It isn’t.
Whatever the finding, the report keeps to the same four parts.
A quiet reminder
The report is written for your doctor, not for you — and that’s normal.
If you would like us to talk you through it before your follow-up, just ask.
- 01 Header
Indication and medications
Your details, the reason for the scan and the medications that could influence emptying.
- 02 Technique
Meal, isotope dose and imaging schedule
The labelled meal used, the Tc-99m dose administered and the times images were acquired.
- 03 Findings
Percentage retention at 1, 2, 3 and 4 hours
The gastric retention percentages at each time point, compared against published normal ranges.
- 04 Impression
The conclusion: read this first
Normal, delayed (gastroparesis) or rapid (dumping) emptying, with the concrete next step.
Recognised by major UK insurers
Cover depends on your policy and clinic; we confirm with your insurer before booking.
Frequently asked
Everything we get asked about gastric emptying scans.
Quick answers on the meal, the radiation, held medications, and what an abnormal scan means for treatment.
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What does a gastric emptying scan show?
The percentage of a standardised low-fat Tc-99m-labelled egg-white meal remaining in the stomach at 1, 2, 3 and 4 hours. Retention above published thresholds means gastroparesis; very rapid emptying suggests dumping syndrome.
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How long does the test take?
The whole appointment runs for about 4 hours. You eat the labelled meal and then return under the gamma camera for a few minutes at 1, 2, 3 and 4 hours.
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Is it safe? What about the radiation?
The Tc-99m dose is small and roughly comparable to a few months of natural background radiation. It is not offered in pregnancy unless the clinical need is exceptional.
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Do I have to fast?
Yes — nothing to eat for 6 hours before the scan. Sips of water are fine.
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Which medications do I need to stop?
Prokinetics (metoclopramide, domperidone, prucalopride, erythromycin) are held for 48 hours unless your gastroenterologist tells you otherwise. Opiates and cannabinoids should also be paused where safe.
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What happens if my scan is abnormal?
A gastroenterologist reviews the report and sets a plan — dietary changes and prokinetics first, then G-POEM, gastric pacing or bariatric surgery in refractory cases.
Sources
- British Society of Gastroenterology.
- European Association of Nuclear Medicine.
- American Gastroenterological Association.
- International Motility Society.
Published 2026-07-30 · Reviewed by Pulse Atlas Editorial Board, · Next review 2027-07-30 · 5 min read
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In practice, in London
The London pathway for gastric emptying scan
With gastric emptying scan, the London question is usually about report turnaround and the radiologist reading it — not whether the scan is available. On the NHS, gastric emptying scan typically sits behind a triage step and a wait that can stretch from a few weeks into months. In London’s private sector, the same appointment often lands within days. That speed matters when symptoms are disrupting work, sleep, or a plan you’d already committed to — and it’s the single most common reason people call us in the first place.
The mechanics are straightforward: a consultant appointment, any tests done at a nearby CQC-registered site, and a written report back within a few days. London’s density of private diagnostics — Marylebone, the City, Chelsea, Canary Wharf — means most patients can find something that fits around work without a cross-town trek. For gastric emptying scan specifically, the difference between a routine report and a sub-speciality read is where private care earns its keep.
Honesty about expectations is part of the job. A private gastric emptying scan appointment in London won’t change the underlying medicine — the guidelines, the consultants, and the equipment are largely the same as on the NHS. What it changes is speed, continuity, and the amount of time you get to actually talk through the findings. Everyone we route to is GMC-registered and works within CQC-regulated facilities.