Gastroparesis

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Gastric emptying depends on fundal accommodation, coordinated antral grinding, pyloric opening and duodenal feedback. Neuropathy, smooth-muscle dysfunction or postsurgical vagal injury can disrupt this sequence. In diabetes, acute hyperglycaemia itself slows emptying, while delayed nutrient absorption makes insulin timing unpredictable, producing a cycle of early hypoglycaemia and later hyperglycaemia. The diagnostic label therefore requires both appropriate chronic symptoms and objective delay after a structural blockage has been excluded.

Several mimics are common: functional dyspepsia, rumination, cyclic vomiting, cannabinoid hyperemesis, eating disorder, medication effect, gastric outlet obstruction and small-bowel dysmotility. Visible food despite fasting raises suspicion but can reflect inadequate fasting, opioids or obstruction and should not be treated as a motility study. Scintigraphy uses a standardised radiolabelled solid meal with protocolled imaging; non-standard meal duration or major hyperglycaemia can undermine interpretation.

Treatment is layered. Correct dehydration and glucose derangement, remove reversible contributors, then use specialist dietetic modification. A short therapeutic trial should have a predefined symptom and nutrition outcome. UK regulators restrict metoclopramide to short-term use because of neurological harm and domperidone to short-term nausea and vomiting because of cardiac risk; erythromycin for gastroparesis is off-label and loses effect through tachyphylaxis. Refractory nutritional failure is managed beyond the stomach where feasible rather than allowing repeated admissions for rescue fluid.

Key points

Gastroparesis is a symptom-compatible delay in gastric emptying without a mechanical blockage; symptoms alone and retained food at one endoscopy are insufficient for diagnosis.
Typical features are postprandial fullness, early satiety, nausea, vomiting, bloating and upper abdominal pain, but their severity correlates imperfectly with measured emptying delay.
Diabetes, vagal injury after upper-GI surgery, neurological or connective-tissue disease and medicines that slow motility are recognised causes; many cases remain idiopathic.
Review opioids, antimuscarinics and GLP-1 receptor agonists among other medicines, while avoiding abrupt withdrawal when the original indication or metabolic benefit is important.
Upper-GI endoscopy or anatomical imaging excludes obstruction; standardised solid-meal gastric-emptying scintigraphy is the conventional objective test for delayed emptying.
Dietetic treatment uses smaller, more frequent and easier-to-empty meals with texture, fat and fibre adapted to symptoms while protecting energy, protein and micronutrient intake.
Metoclopramide, domperidone and erythromycin all have major duration, licensing, neurological, cardiac or interaction limitations, so chronic repeat prescribing without specialist review is unsafe.
Severe refractory disease may require jejunal feeding, venting, pylorus-directed therapy or gastric electrical stimulation through a specialist motility and nutrition MDT.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Diabetic autonomic injury

Longstanding diabetes and acute hyperglycaemia can impair vagal, enteric and smooth-muscle function, causing variable delayed emptying.

Postsurgical or neurological injury

Vagal damage after upper-GI surgery and neurological or connective-tissue disorders can disrupt coordinated gastric propulsion after otherwise successful procedures.

Idiopathic and medicine-related

Many cases remain idiopathic, sometimes post-infective; opioids, antimuscarinics and other motility-slowing medicines can cause or compound the phenotype.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Neuromuscular discoordination
Vagal, enteric neuronal, interstitial-cell or smooth-muscle dysfunction weakens antral grinding and pyloric coordination during meal processing.
2
Delayed solid emptying
Food remains in the stomach despite no mechanical obstruction, producing early satiation, fullness, nausea and delayed vomiting.
3
Nutritional and glycaemic feedback
Unpredictable nutrient delivery destabilises glucose, while hyperglycaemia further slows emptying and reduced intake worsens malnutrition in diabetes.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Meal-linked retention

Early satiety, prolonged post-meal fullness and vomiting of recognisable food hours after eating suggest gastric retention. Ask about frequency, timing, portion tolerance and whether vomiting relieves distension.

Diabetic instabilityRed flag

Longstanding diabetes with autonomic neuropathy, unpredictable post-meal glucose and recurrent early hypoglycaemia may reflect a mismatch between insulin action and delayed carbohydrate delivery. Check ketones during acute illness.

Postsurgical onset

Symptoms after fundoplication, oesophagectomy, gastric surgery or vagal injury can indicate postsurgical delayed emptying, although an anastomotic stricture or altered anatomy must be assessed first.

Nutrition failure

Progressive weight loss, reduced fluid intake, micronutrient deficiency or inability to take essential medicines indicates clinically severe disease and warrants specialist dietetic and enteral-access assessment.

Bezoar or obstruction clueRed flag

A palpable succussion splash, focal transition on imaging, severe distension, faeculent vomiting or inability to tolerate liquids argues for mechanical obstruction or bezoar and prohibits reflex prokinetic treatment.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Upper-GI endoscopyFirst step
Why
Exclude a mucosal, pyloric or duodenal mechanical cause and inspect retained contents.
Interpretation and limitations
A normal patent outlet supports but does not prove gastroparesis. Retained food raises aspiration risk and may necessitate a repeat with enhanced preparation; biopsy a suspicious narrowing rather than dilating blindly.
02
Cross-sectional anatomical imaging
Why
Look for extrinsic compression, tumour, pancreatobiliary disease or distal obstruction.
Interpretation and limitations
Contrast CT is selected when vomiting, weight loss, pain or endoscopic limitation raises structural concern. A dilated stomach with a transition point is obstruction until explained, not functional delay.
03
Solid-meal gastric-emptying scintigraphy
Why
Objectively measure delayed emptying using a validated physiological meal.
Interpretation and limitations
Use the local standardised meal, imaging schedule and reference range. Record glucose and motility-altering medicines; an abbreviated or non-standard study may miss late retention and should not be compared uncritically.
04
Blood glucose and HbA1c
Why
Identify acute and chronic glycaemic contributors and treatment risk.
Interpretation and limitations
Marked hyperglycaemia can delay emptying and confound testing. HbA1c gives a longer view but does not show the meal–insulin mismatch; continuous glucose data may help the diabetes team adjust timing.
05
U&E, magnesium, phosphate and nutrition profile
Why
Measure vomiting-related loss and the consequences of restricted intake.
Interpretation and limitations
Hypokalaemia and hypomagnesaemia increase arrhythmia risk from prokinetics. Low phosphate or major weight loss identifies refeeding risk when nutrition is restored; albumin is not a stand-alone nutrition marker.
06
Cause-directed assessment
Why
Find reversible endocrine, neurological, autoimmune or medicine contributors.
Interpretation and limitations
Review thyroid function, connective-tissue and neurological features and the complete prescription. A temporal drug association supports causality but cessation decisions should reflect the drug's original benefit.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Gastric outlet obstruction

Endoscopy and cross-sectional imaging identify a fixed antral or duodenal narrowing; gastroparesis requires its exclusion before emptying tests are interpreted.

Functional dyspepsia or rumination

Meal-related fullness with normal emptying supports functional dyspepsia, while effortless immediate return of food suggests rumination rather than delayed retention.

Cyclical or cannabinoid-related vomiting

Stereotyped symptom-free intervals or sustained cannabis exposure with characteristic relief patterns suggests an episodic vomiting syndrome rather than continuous gastric delay.

Additional chapter-specific clues

Alternative vomiting behaviour

Effortless regurgitation soon after eating, stereotyped symptom-free intervals, hot-bath behaviour or self-induced vomiting may suggest rumination, cyclic vomiting, cannabinoid hyperemesis or an eating disorder requiring a different pathway.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01ConfirmSeparate delay from blockageFirst stepChronic meal-related fullness, nausea or food vomiting raises suspicion of impaired gastric emptying.

1Take a detailed symptom, surgical, diabetes, eating-behaviour and medicine history, measure weight trajectory, hydration, glucose and electrolytes, and identify cancer or obstruction features.
2Exclude structural disease through endoscopy and appropriate imaging before arranging a standardised solid-meal gastric-emptying study under valid glucose and medicine conditions.
3Only apply the gastroparesis label when compatible symptoms, objective delay and absence of mechanical obstruction converge; reconsider functional dyspepsia or another vomiting disorder when they do not.

02NourishRestore intake and metabolic stabilityDelayed emptying causes impaired oral intake, weight loss, dehydration or unstable diabetes.

1Use a specialist dietitian to trial smaller frequent meals and softer or liquid texture with individually adjusted fat and insoluble fibre, while maintaining adequate energy and protein.
2Coordinate diabetes technology, insulin timing and sick-day rules with the diabetes team; avoid chasing delayed post-meal hyperglycaemia in a way that causes early hypoglycaemia.
3When oral intake remains inadequate, trial post-pyloric feeding and consider venting or parenteral support only through a nutrition MDT with explicit goals and complication monitoring.

03EscalateTreat refractory symptoms safelyEscalationDiet, reversible-cause treatment and a carefully monitored medicine trial have not restored acceptable symptoms or nutrition.

1Review whether the diagnosis and emptying test remain valid, stop ineffective or harmful prokinetics, and distinguish nausea control from a true improvement in nutrition and emptying.
2Refer to a regional motility service for pyloric physiology and intervention, gastric electrical stimulation or other advanced options under current NICE governance and local availability.
3Use shared decision-making about uncertain benefit, device or procedural complications and realistic endpoints, continuing nutritional rescue while intervention is assessed.

Key medicines and prescribing safety3 treatments · regimens, roles and cautions

Provides antiemetic and prokinetic effects during a short acute episode while hydration, nutrition and definitive assessment are addressed.

Metoclopramide for short-term nausea and vomiting

The adult licensed dose is 10 mg up to three times daily, maximum 30 mg or 0.5 mg/kg in 24 hours, for no longer than five days; gastroparesis use beyond the licence requires specialist governance.

Avoid in mechanical obstruction, bleeding or perforation. Monitor acute dystonia, akathisia, parkinsonism, sedation and tardive dyskinesia risk; reduce for renal or hepatic impairment and avoid unsafe dopamine-active combinations.

May reduce nausea and vomiting with less central dopamine exposure, but it is not licensed as indefinite gastroparesis therapy.

Domperidone for short-term nausea and vomiting

For licensed adults and adolescents at least 12 years and 35 kg, use 10 mg up to three times daily, maximum 30 mg daily, usually for no longer than one week.

Contraindicated when stimulation could harm, including obstruction, bleeding or perforation, and with QT prolongation, significant cardiac disease, severe hepatic impairment, potent CYP3A4 inhibitors, QT-prolonging drugs or confirmed or suspected phaeochromocytoma. Correct potassium and magnesium and review ECG need.

Motilin-receptor agonism can accelerate gastric emptying for a limited period, particularly as a bridge during nutritional rescue.

Oral erythromycin as an off-label prokinetic

If a motility specialist recommends it, use the locally agreed short-course dose and formulation with a documented response and stop point; NICE evidence includes heterogeneous regimens and does not establish one universal schedule.

Benefit commonly wanes through tachyphylaxis. Check QT interval risk, hypokalaemia, hypomagnesaemia, liver disease, hearing effects, antimicrobial stewardship and extensive CYP3A interactions.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Dehydration and electrolyte disturbance

Persistent vomiting causes volume depletion, kidney injury, hypokalaemia and metabolic alkalosis, sometimes requiring inpatient stabilisation and cardiac monitoring.

Malnutrition and micronutrient deficiency

Early satiety and avoidance of solid food reduce energy and protein intake, causing weight loss, sarcopenia and deficiencies.

Glycaemic instability and bezoar

Mismatched insulin and nutrient absorption causes hypo- or hyperglycaemia, while retained fibre can aggregate into a bezoar and worsen obstruction-like symptoms.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Record a symptom and nutrition baseline including vomiting days, meal completion, weight, hydration and healthcare use rather than relying on a global impression.
In diabetes, review capillary or continuous glucose patterns, ketone plans and hypoglycaemia around any diet, prokinetic or insulin-timing change.
Trend U&E, magnesium, phosphate and micronutrients according to vomiting and nutrition severity, with refeeding precautions for substantially depleted patients.
For each prokinetic, specify duration, target, adverse-effect review and discontinuation rule; repeat prescriptions should not silently convert a short licence into chronic use.
Monitor post-pyloric tubes and devices for displacement, blockage, infection and whether they deliver meaningful nutritional or symptom benefit.
Reinvestigate new weight loss, anaemia, progressive pain or changed vomiting because a prior motility diagnosis does not protect against later mechanical disease.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Food is not a stopwatch

Retained food seen at gastroscopy raises suspicion but depends on fasting, meal type, medicines and obstruction; standardised emptying measurement is still required.

Glucose works both ways

Hyperglycaemia slows gastric emptying, while delayed emptying destabilises insulin–nutrient matching, so both motility and diabetes teams must address the loop.

Liquids may pass better

Calorie-containing liquids and small-particle foods can empty more readily than coarse solids, allowing nutrition to improve even when fat restriction alone would reduce energy excessively.

Prokinetic is not generic

Each commonly used agent carries a different regulatory problem—neurological duration for metoclopramide, cardiac risk for domperidone and off-label tachyphylaxis for erythromycin.

Fasting may be inadequate

Delayed emptying increases residual gastric volume during procedures, so anaesthetic and endoscopy teams need explicit risk information and an individual aspiration plan.

11Common pitfallsFrequent interpretation and management errors.

01
Diagnosing gastroparesis from nausea alone without objective delayed emptying.
02
Starting a prokinetic before excluding gastric outlet or small-bowel obstruction.
03
Prescribing metoclopramide continuously despite the five-day UK neurological safety restriction.
04
Using domperidone with QT-prolonging treatment, electrolyte depletion or a potent CYP3A4 inhibitor.
05
Reducing fat and fibre so aggressively that an already underweight patient loses further energy and protein intake.
06
Assuming a normal resting endoscopy excludes extrinsic or intermittent mechanical obstruction.