Gastroparesis

Etiology and Risk Factors

Etiology or contributor	Interpretive point
Diabetes mellitus	Long-standing dysglycemia and neuropathy can affect gastric sensorimotor function, but symptoms alone cannot determine the extent of emptying delay.
Postsurgical or vagal injury	Altered neural control or anatomy can impair coordination; some surgical states cause rapid rather than delayed emptying.
Idiopathic or postinfectious	Patients may have persistent symptoms without a single established trigger.
Medication-related delayed emptying	Opioids, anticholinergic medications, and some glucose-lowering agents can retard emptying. Reassess medication exposure before labeling symptoms as irreversible disease.
Other systemic/neurologic disease	Consider endocrine, connective tissue, or neurologic contributors where history supports them.

Epidemiology and Clinical Context

Population context: Gastroparesis may arise in longstanding diabetes, after upper-GI surgery, or without an identified cause; delayed emptying can also be medication-associated. In diabetes, gastric emptying abnormalities and glucose excursions can reinforce one another, so symptoms and nutritional risk should be interpreted with glycemic patterns and drug exposure (Mills & Ciorba, 2019).

Pathophysiology

Normal gastric emptying and what fails

Effective emptying depends on fundic accommodation, coordinated antral grinding, pyloric opening, and duodenal feedback. Vagal and enteric pathways integrate smooth-muscle contraction with neural and hormonal signaling. Diabetes-associated autonomic and enteric dysfunction, postsurgical disruption, and certain medications can interfere with these processes, slowing delivery of nutrient-containing chyme to the small bowel (Mills & Ciorba, 2019).

• Failure of coordinated gastric propulsion or impaired pyloric opening leaves solids in the stomach longer than expected.
• Retained contents increase distension, producing early fullness, nausea, or vomiting and occasionally bezoar formation.
• Unpredictable nutrient delivery to the intestine disrupts the timing of carbohydrate absorption and insulin effect.
• Acute hyperglycemia can itself worsen delayed emptying, creating a bidirectional cycle of dysglycemia and impaired motility (Mills & Ciorba, 2019).

Clinical Manifestations

Symptoms include early satiety, nausea, fullness after small meals, bloating, and sometimes vomiting of food eaten hours earlier. Severe disease can cause inadequate intake, dehydration, weight loss, and bezoars. Bacterial overgrowth or disrupted intestinal delivery may contribute to diarrhea. Importantly, symptom severity often correlates poorly with measured gastric emptying, and some patients have substantial metabolic effects with relatively few gastrointestinal symptoms (Mills & Ciorba, 2019).

Diagnostic Evaluation

• Exclude mechanical gastric outlet obstruction using upper endoscopy or appropriate imaging when clinically indicated. Retained food on endoscopy is suggestive but cannot independently establish gastroparesis.
• Confirm delayed emptying with standardized gastric emptying scintigraphy, commonly using a solid meal protocol followed through four hours; validated alternatives may be used depending on availability.
• Interpret the result alongside glucose levels, meal completion, smoking, and medications that change motility. Review diabetes control, nutritional status, medication effects, and alternate diagnoses.

Protocol quality is part of diagnosis

Interpreting four-hour solid-meal scintigraphy requires documentation of how much of the standardized meal was consumed, that glucose was reasonably controlled, and that drugs altering motility were managed in accordance with the test protocol and clinical safety needs. Opioids, anticholinergics and GLP-1 receptor agonists may slow emptying; prokinetics may obscure delay. Endoscopy showing retained food is not equivalent to a validated gastric-emptying test. Severity of nausea does not reliably predict the extent of delayed emptying, so exclude functional dyspepsia, rumination and mechanical obstruction before escalating therapy (Abell et al., 2008; Camilleri et al., 2022; Jameson et al., 2020; Mills & Ciorba, 2019; Staller et al., 2025).

Differential Diagnosis

Distinguishing common alternatives

Condition	Key discriminator
Mechanical gastric outlet obstruction	Structural or luminal narrowing on endoscopy/imaging. Symptom overlap is substantial.
Functional dyspepsia	Postprandial fullness and early satiety may occur without objectively delayed emptying.
Cyclic vomiting syndrome	Stereotyped discrete vomiting episodes with relatively well intervals; not necessarily sustained emptying delay.
Medication effect	Temporal relationship to a drug that impairs gastric transit; reassessment after adjustment can clarify causation.
Rapid gastric emptying/dumping	Meal-associated vasomotor or diarrheal symptoms caused by excessive nutrient delivery rather than retained contents.

Treatment and Management

• Reduce meal size and favor easily tolerated, low-fat, low-fiber or small-particle meals when symptoms are substantial. Protect oral hydration and escalate nutritional support when intake is inadequate.
• Optimize glucose management while anticipating altered timing of nutrient absorption. Medication reconciliation should identify potentially reversible motility inhibition.
• Following exclusion of mechanical obstruction and confirmation of delayed gastric emptying with standardized four-hour solid-meal gastric emptying scintigraphy (or an appropriate validated alternative), consider metoclopramide or erythromycin in selected patients. The 2025 AGA guidance conditionally favors these agents and suggests against domperidone or prucalopride as first-line treatment. Domperidone is not FDA-approved in the United States; an expanded-access investigational-new-drug application may be considered only if a suitable supplier is found. The former supplier stopped distribution after September 2025, so access must not be assumed. Metoclopramide has a boxed warning for potentially irreversible tardive dyskinesia; the February 2026 Reglan tablet label directs the shortest effective treatment and generally avoidance of treatment beyond 12 weeks for diabetic gastroparesis, with prompt discontinuation for dyskinetic symptoms. The same label specifies dose adjustment for creatinine clearance of 60 mL/minute or less, moderate or severe hepatic impairment (Child-Pugh B or C), CYP2D6 poor metabolizers, or concurrent strong CYP2D6 inhibitors; older adults may need a lower starting dose. Avoid metoclopramide in mechanical obstruction, GI bleeding or perforation, and review interacting dopamine-blocking drugs and other contraindications before prescribing. Erythromycin may lose efficacy with repeated use and requires assessment of interactions and cardiac risk (ANI Pharmaceuticals, Inc., 2026; Staller et al., 2025; U.S. Food and Drug Administration, 2025).
• Antiemetics may relieve nausea without normalizing gastric emptying. Refractory disease, recurrent hospitalization, or nutritional compromise merits gastroenterology referral and individualized advanced interventions.

Escalate according to nutritional and functional consequences

Escalation is warranted when poor hydration or nutrition, repeated admissions, impaired function, or persistent symptoms continue despite a verified diagnosis and optimized reversible factors. Support may include liquid or small-particle nutrition, dietitian assessment, specialist review of prokinetic risks, and enteral feeding delivered beyond the stomach when oral intake fails. The 2025 AGA guideline conditionally suggests against routinely using pyloric botulinum toxin injection, gastric peroral endoscopic pyloromyotomy (G-POEM), or gastric electrical stimulation in medically refractory gastroparesis; this is not a categorical prohibition for carefully selected patients after shared decision-making. The guideline makes no recommendation regarding surgical pyloromyotomy or pyloroplasty because the evidence is insufficient. Multidisciplinary specialist assessment should distinguish these procedures, nutritional rescue needs, and individual risks rather than treating all interventions as equivalent (Camilleri et al., 2022; Staller et al., 2025).

Complications and Red Flags

• First assess warning signs: hematemesis, severe dehydration, progressive weight loss, persistent bilious vomiting, focal peritoneal findings, and suspicion of bowel obstruction warrant a different level of evaluation.

Clinical Reasoning Priorities

A patient with long-standing diabetes reports vomiting several hours after meals and erratic postprandial glucose readings. The pattern suggests delayed gastric emptying but could also reflect mechanical obstruction or a medication effect. Before naming gastroparesis, evaluate the medication list and glucose state, exclude obstruction, and document an emptying defect. A confirmed diagnosis should lead to parallel nutrition, glycemic, and symptom plans rather than treating nausea alone.

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References

Abell, T. L., Camilleri, M., Donohoe, K., Hasler, W. L., Lin, H. C., Maurer, A. H., McCallum, R. W., Nowak, T., Nusynowitz, M. L., Parkman, H. P., Shreve, P., Szarka, L. A., Snape, W. J., Jr., & Ziessman, H. A. (2008). Consensus recommendations for gastric emptying scintigraphy: A joint report of the American Neurogastroenterology and Motility Society and the Society of Nuclear Medicine. Journal of Nuclear Medicine Technology, 36(1), 44–54. https://doi.org/10.2967/jnmt.107.048116

ANI Pharmaceuticals, Inc. (2026). Reglan (metoclopramide hydrochloride) tablets [Prescribing information; revised February 2026]. DailyMed. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=de55c133-eb08-4a35-91a2-5dc093027397

Camilleri, M., Kuo, B., Nguyen, L., Vaughn, V. M., Petrey, J., Greer, K., Yadlapati, R., & Abell, T. L. (2022). ACG clinical guideline: Gastroparesis. American Journal of Gastroenterology, 117(8), 1197–1220. https://doi.org/10.14309/ajg.0000000000001874

Jameson, J. L., Fauci, A. S., Kasper, D. L., Hauser, S. L., Longo, D. L., & Loscalzo, J. (Eds.). (2020). Harrison’s manual of medicine (20th ed.). McGraw-Hill Education.

Mills, J. C., & Ciorba, M. A. (2019). Gastrointestinal disease. In G. D. Hammer & S. J. McPhee (Eds.), Pathophysiology of disease: An introduction to clinical medicine (8th ed., Chapter 13). McGraw-Hill Education.

Staller, K., Parkman, H. P., Greer, K. B., Leiman, D. A., Zhou, M. J., Singh, S., Camilleri, M., Altayar, O., & AGA Clinical Guidelines Committee. (2025). AGA clinical practice guideline on management of gastroparesis. Gastroenterology, 169(5), 828–861. https://doi.org/10.1053/j.gastro.2025.08.004

U.S. Food and Drug Administration. (2025, August 4). How to request domperidone for expanded access use. https://www.fda.gov/drugs/investigational-new-drug-application-ind/how-request-domperidone-expanded-access-use