What is gastroparesis?

Most published literature describes gastroparesis as delayed gastric emptying without a mechanical obstruction.

At Children’s Hospital of Philadelphia (CHOP), our definition of gastroparesis is stricter. We consider gastroparesis to be a gastrointestinal (GI) motility disorder when there is objective delay in gastric emptying in the absence of any of the following:

• Mechanical obstruction
• Biochemical disorder (electrolyte imbalance, diabetes, hypothyroidism)
• Gastric infection (e.g. H. pylori gastritis, cytomegalovirus [CMV] gastritis, bacterial overgrowth)
• Medication side effect
• Significant non-infectious gastroduodenal inflammation (e.g. eosinophilic gastroenteritis, lymphocytic gastritis, celiac disease, Crohn’s disease, vasculitis) 

Causes of gastroparesis

The term gastroparesis is ambiguous because it implies a specific condition — paralysis of the stomach — without addressing causes or severity.

The exact cause of gastroparesis is unknown. The stomach is not paralyzed. Instead, gastroparesis seems to be both a muscle and sensory problem (neuromuscular disorder).

Factors that may contribute to gastrointestinal symptoms include: antral hypomotility, gastric dysrhythmia, impaired gastric fundic accommodation, antral distention, visceral hypersensitivity and psychological disturbance.

Diabetic gastroparesis occurs when delayed gastric emptying affects individuals with diabetes.

Diabetes is the disease most frequently identified as a link to gastroparesis.

Signs and symptoms of gastroparesis

Gastroparesis symptoms mirror some symptoms of delayed gastric emptying and include:

• Early satiety (feeling full after only a few bites of food, inability to finish meals)
• Abdominal bloating (upper abdomen feels or actually looks distended, tight after eating)
• Abdominal pain or “burning” between the lower part of the breastbone and the navel
• Nausea (urge to vomit, queasy, “sick to stomach” sensation)
• Indigestion (combination of “burning,” feeling bloated, queasy after eating)
• Episodic vomiting
• Fear of eating
• Feeding difficulty in infants and young children
• Weight loss

These symptoms, however, are non-specific and do not distinguish gastroparesis from a mechanical, infectious or non-infectious inflammatory or biochemical disorder that also causes delayed gastric emptying.

To make diagnosing GI disorders even more challenging, these same symptoms may also occur in patients with normal gastric emptying, the degree of delay in gastric emptying does not predict symptom severity, and correlation between symptom reductions and improved emptying cannot be always demonstrated.

Often a companion diagnosis

In children, gastroparesis may be an acute primary self-limiting disorder triggered by infection, surgery or excessive weight loss. More commonly, however, pediatric gastroparesis overlaps in an individual patient with other chronic GI motility disorders including:

• Gastroesophageal reflux disease
• Functional dyspepsia
• Irritable bowel syndrome
• Cyclical vomiting
• Enteric dysmotility
• Pseudo-obstruction  

Testing and diagnosis of gastroparesis

At Children's Hospital of Philadelphia, we offer expert clinicians and a full spectrum of diagnostic tests for gastrointestinal motility disorders at the Suzi and Scott Lustgarten Center for GI Motility. The Lustgarten Center provides diagnostic resources and integrated patient-centered services that are not available at most children's hospitals.

First, exclude what’s not gastroparesis

Before a definitive diagnosis of gastroparesis can be reached, physicians must rule out the possibility that other mechanical, infectious or non-infectious inflammatory and biochemical reasons are causing the delayed gastric emptying.

At the Lustgarten Center, our clinicians gather a comprehensive family history, perform a physical exam and schedule diagnostic tests for each pediatric patient with a suspected gastroparesis diagnosis. Diagnostic tests include: a barium contrast upper GI series, upper endoscopy, biochemical testing and a gastric emptying study.

Barium contrast upper GI series

In a barium contrast upper GI series, your child drinks a barium liquid that coats the upper GI tract, illuminating the flow of the liquid through the esophagus, stomach and duodenum. Completed under the careful supervision of a radiologist, this test rules out mechanical causes of delayed gastric emptying including gastric outlet obstruction, malrotation and partial small bowel obstruction.

Upper endoscopy

An upper endoscopy allows your child's doctor to use an endoscope (a long, thin tube) to look at the lining of your child's stomach and proximal small bowel to confirm the absence of mechanical obstruction, and exclude infectious and inflammatory causes of delayed gastric emptying. This test can rule out H. Pylori gastritis, peptic ulcer, reactive gastritis, eosinophilic gastroenteritis, celiac disease and upper GI Crohn’s disease.

Biochemical testing

At CHOP, clinicians use a variety of biochemical tests to rule out correctable electrolyte and balance status, renal function and endocrine status.

Gastric emptying study

The “gold standard” for diagnosing gastroparesis is a gastric emptying study, a diagnostic test that measures the rate your child empties a standard radio-labeled solid meal over a defined period of time. In infants and small children, milk is used as the test meal. 

At the Lustgarten Center, expert radiologists perform gastric emptying to evaluate patients. After radio-labeling the solid or liquid component of a meal, the gastric counts measured correlate directly with the volume of test meal remaining in the stomach.

Unfortunately, at this time, there is lack of national standardization of test protocol for pediatric patients. Techniques vary in hospitals regarding size or volume of the test meal used, patient positioning, frequency and duration of monitoring.

Additionally, there are differences between hospitals about how the quantitative data is reported. Hospitals may measure any of the following:

• Time to half-empty gastric contents
• Rate of gastric emptying (percentage per minute)
• Percent of gastric emptying at different time intervals (e.g. 30 minutes, 1 hour)
• Percent of gastric retention at different time intervals (e.g. 30 minutes, 1 hour)

In pediatrics, normal values have not been established for the protocols used. A standard practice at many hospitals has been to use adult normal values or to develop institutional norms developed from sub-populations of the patients studied.

At CHOP, our Nuclear Medicine Department works in conjunction with gastroenterologists and other specialists to use best practices in testing pediatric patients.

A child undergoing a study will eat a radio-labeled egg (equivalent to two large eggs), bread or toast, and water as the solid test meal. Then, clinicians will measure the child’s percentage of gastric emptying at 30, 60, 90, and 120 minutes after the meal. Measurement is done with a gamma camera placed on the child's chest and abdomen to picture the perfused organs.

Patients are categorized as having delayed gastric emptying if emptying of the meal is less than 10 percent at 60 minutes or less than 50 percent at two hours post meal. These criteria are less strict than adult consensus guidelines established by the American Motility and Nuclear Medicine Society where two-hour emptying is considered delayed if less than 40 percent of the meal empties at 120 minutes.

Although adult studies have shown that extending measurements out to four hours increases the detection rate of delayed emptying in patients who appear normal at two hours, we feel our less stringent criteria at two hours will pick up this subgroup, and thus, reserve four-hour studies for patients with late postprandial symptoms.

Factors that must be considered in interpretation of test results include:

• Time to ingest the test meal.
• Presence of vomiting during the test, which can lead to values suggesting more rapid emptying.
• Medications the patient may be taking. (When medically possible, we ask patients to stop taking opiates, anti-cholinergic agents and prokinetic agents 48-72 hours before testing. Ondansetron [Zofran®] may be given before testing as it does not affect emptying and may help reduce nausea and chance for vomiting during the study.)
• The presence of significant hyperglycemia. (Ideally, the child’s blood glucose level should be lower than 275 mg/dl on the morning of the test if the patient has diabetes).

Since population studies have shown a poor correlation between a rate of solid gastric emptying and the severity of gastric symptoms, we use the scintigraphy test to classify patients as having objective evidence of delayed gastric emptying.

Antroduodenal manometry

An antroduodenal manometry provides information about the muscle and nerve activity of the stomach and small bowel. The test can measure how strong and how well your child’s muscle contractions coordinate between the two organs. This test uses a catheter that has pressure sensors to record the contractions of the GI tract. The catheter contains pressure sensors that will measure stomach and intestinal contractions over approximately six hours during a fasting state and during a fed meal state.

A diagnosis of gastroparesis is established if upper GI series and endoscopy of the stomach and duodenum are normal, and biochemical testing rules out correctable electrolyte or metabolic disorder.