Most Specific Test to Diagnose Gastroparesis

Gastric emptying scintigraphy (GES) of a radiolabeled solid meal is the most specific and gold standard test for diagnosing gastroparesis. 1, 2

Proper Gastric Emptying Scintigraphy Technique

GES should be performed for at least 2 hours after ingestion of a radiolabeled meal, with 4-hour testing providing higher diagnostic yield and accuracy 2
The radioisotope must be cooked into the solid portion of the meal for accurate results 1
A standardized low-fat, egg white meal labeled with 99mTc sulfur colloid consumed with jam and toast as a sandwich is typically used 2, 3
Shorter test durations (<2 hours) are inaccurate for determining gastroparesis and should be avoided 1
Extension of the gastric emptying test to 4 hours significantly improves diagnostic accuracy - studies show 23% of patients with normal values at 2 hours had abnormal GES at 4 hours 4

Medications that influence gastric emptying should be withdrawn for 48-72 hours prior to testing 2
Smoking should be avoided on the test day 2
Blood glucose should be monitored and maintained within normal range during the test, as hyperglycemia itself can slow gastric emptying 2
Patients are diagnosed with gastroparesis using adult criteria if gastric retention of meal is >90%, >60%, and >10% at 1,2, and 4 hours, respectively 4

Breath testing using non-radioactive 13C isotope to label octanoate or Spirulina can be used as an alternative when scintigraphy is unavailable 1, 2
The wireless motility capsule (WMC) can evaluate gastric emptying and also investigate lower gut transit, which may provide additional diagnostic information in patients with suspected gastroparesis 5
Antroduodenal manometry provides information about coordination of gastric and duodenal motor function and may help differentiate between neuropathic or myopathic motility disorders 1

First-line test: 4-hour gastric emptying scintigraphy with standardized meal 2, 4
If scintigraphy unavailable: Consider breath testing with 13C-labeled octanoate or Spirulina 1, 2
If additional information on gut transit needed: Consider wireless motility capsule testing 5
For further characterization of motility disorder: Consider antroduodenal manometry 1

Relying solely on symptoms for diagnosis is inadequate as symptoms correlate poorly with the degree of gastric emptying delay 2
Failure to control blood glucose during testing can lead to false positive results 2
Not accounting for medications that can affect gastric emptying (prokinetics, opioids, anticholinergics) can lead to inaccurate results 2
Using only 1-2 hour scintigraphy protocols significantly reduces diagnostic sensitivity 4
Failing to rule out mechanical obstruction with upper endoscopy before diagnosing gastroparesis 6, 7

Studies show that WMC transit results promote more medication changes and eliminate additional diagnostic testing more often than GES alone due to greater detection of delayed gastric emptying and profiling the entire GI tract 5
Proper diagnosis with appropriate testing is essential for guiding treatment, which may include dietary modifications, prokinetic medications, antiemetics, and in refractory cases, more invasive interventions 3