Gastroparesis

Gastroparesis is delayed gastric emptying in the absence of mechanical obstruction, causing nausea, vomiting, early satiety and postprandial fullness.

• Prevalence about 10 per 100,000 (probably higher), more in women (4:1).
• Causes: idiopathic (most common, often post viral), diabetes mellitus (25 to 30%, long standing with autonomic neuropathy), postsurgical (vagotomy, fundoplication, bariatric surgery), medications (opioids, GLP 1 agonists, anticholinergics, calcium channel blockers, tricyclics), Parkinson disease, scleroderma, amyloidosis, paraneoplastic, hypothyroidism, hypothyroidism, connective tissue disease.
• Pathophysiology: loss of interstitial cells of Cajal, enteric neuropathy, impaired antral contractions, pylorospasm.
• Complications: malnutrition, dehydration, electrolyte disturbance, bezoar formation, erratic glucose control, poor quality of life.

• Nausea (90%), vomiting of undigested food hours after meals (70 to 80%), early satiety, postprandial fullness, bloating, upper abdominal pain, weight loss.
• Variable severity; episodes of cyclical exacerbation.
• Succussion splash, signs of weight loss.
• Differential diagnosis: gastric outlet obstruction, functional dyspepsia, cyclic vomiting syndrome, rumination syndrome, cannabinoid hyperemesis, superior mesenteric artery syndrome, pregnancy.

• Exclude obstruction with upper endoscopy (retained food after fasting suggests gastroparesis) or CT/MR enterography.
• Gastric emptying scintigraphy with a standardised low fat egg white meal, imaging at 0, 1, 2 and 4 hours: retention over 60% at 2 hours or over 10% at 4 hours is delayed. Stop prokinetics for 2 days and opioids, and control glucose (below 275 mg/dL).
• Alternatives: gastric emptying breath test (13C octanoic acid), wireless motility capsule.
• Laboratory: glucose, HbA1c, TSH, electrolytes, magnesium, albumin, ANA, paraneoplastic antibodies where indicated.
• Antroduodenal manometry in selected cases. Assess nutrition (weight, BMI, albumin, micronutrients).

• Medication review: stop opioids, GLP 1 agonists, anticholinergics where possible. Optimise glycaemic control in diabetes.
• Dietary: small frequent low fat, low fibre meals (4 to 6 daily), liquid or pureed calories, avoid carbonated drinks and alcohol.
• Prokinetics:
  • Metoclopramide 5 to 10 mg 30 minutes before meals and at bedtime (maximum 40 mg daily, avoid beyond 12 weeks because of tardive dyskinesia risk).
  • Domperidone 10 mg three times daily before meals (monitor QTc, where available).
  • Erythromycin 125 to 250 mg three times daily (tachyphylaxis within weeks).
  • Prucalopride 2 mg daily (off label).
• Antiemetics: ondansetron 4 to 8 mg, prochlorperazine 5 to 10 mg, promethazine; mirtazapine 15 mg at night; low dose nortriptyline 10 to 25 mg for refractory nausea.
• Nutritional support: oral supplements, jejunostomy feeding, parenteral nutrition for severe malnutrition.
• Refractory: gastric peroral endoscopic myotomy (G-POEM, response in 50 to 70%), pyloric botulinum toxin 100 to 200 units (limited benefit), gastric electrical stimulation (for diabetic or idiopathic), venting gastrostomy, surgical pyloroplasty.
• Bezoar: endoscopic fragmentation, enzymatic dissolution.