Aetna considers electrogastrography or colonic motility studies experimental and investigational because these approaches have not yet been standardized for routine clinical use.

Aetna considers a wireless capsule for measuring gastric emptying parameters (SmartPill GI Monitoring System) experimental and investigational because of inadequate published evidence of its diagnostic performance and clinical utility over conventional means of measuring gastric emptying.

Aetna considers radionuclide gastric emptying study medically necessary for the evaluation of gastroparesis.

See also CPB 616 - Antroduodenal Manometry.

Cutaneous electrogastrography (EGG) is a noninvasive test that detects gastric arrhythmias by recording the frequency and regularity of gastric myoelectrical activity.  It has been used to investigate the mechanisms of gastric motility and sensation in patients with gastric motility disorders or motion sickness.  By means of surface electrodes, EGG records gastric myoelectrical activity from the surface of the body.  The cutaneous signals are low in amplitude, and thus must be markedly amplified.  The resultant signals are heavily contaminated with noise, and visual analysis alone of EGG signals is inadequate.  Consequently, EGG recordings require special methodology for acquisition, processing and analysis.

There appears to be a close relationship between gastric myoelectrical activity and gastric motility.  Although it has been reported that EGG satisfactorily reflects frequency of internal gastric myoelectrical activity, there is not acceptable correlation with gastric contractions or gastric emptying.  Many attempts have been made to relate EGG “abnormalities” with clinical syndromes and diseases.  Although abnormalities of the electrogastrogram have been described in a variety of disorders, their specificity and their prevalence in patients with functional gastrointestinal disorders have not been determined.  Electrogastrography cannot determine the etiology of detected abnormalities because there are no specific EGG patterns to differentiate one epigastric condition from another.  The clinical role of EGG remains to be established, and its proponents need to demonstrate that EGG results can affect therapeutic decisions.

Krusiec-Swidergol and Jonderko (2008) checked on reproducibility of parameters of a multi-channel electrogastrogram in adults after intake of typical, applied in EGG, test meals.  Recordings of multi-channel electrogastrograms were accomplished in 4 blocks comprising 18 subjects (9 healthy volunteers and 9 patients with functional gastrointestinal disorders) each.  Every subject had two examinations taken 1 to 2 days apart, and a third one was accomplished at least 2 weeks before or after the two other sessions.  The registration involved a 30-min fasted and a 2-hr post-prandial period after one of the meal stimuli tested within a given block: 400 ml water, 400 g yoghurt (378 kcal), a scrambled eggs sandwich (370 kcal), a pancake (355 kcal).  From among the parameters reflecting the propagation of the gastric slow waves, the average percentage of slow wave coupling (APSWC) exhibited a good (coefficient of variation for paired examinations CV(p) less than or equal to 10 %) to moderate (10 less than CV(p) less than or equal to 30 %) reproducibility.  On the other hand, the reproducibility of the maximum dominant frequency difference and the spatial dominant power difference was found to be unsatisfactory.  The reproducibility of the multi-channel EGG parameters did not differ between healthy volunteers and patients with functional gastrointestinal disorders.  Gender or the kind of a test meal did not affect the reproducibility of the EGG parameters either.  The medium-term reproducibility was not any worse than the short-term one.  From among the parameters of a multi-channel EGG intended to quantify the propagation of slow waves, only the APSWC offers a reproducibility potentially good enough for clinical applications.

Colonic motility studies are used to assess the flow of intraluminal contents, the motions of the colonic wall that induce flow, and the control systems that integrate and regulate these processes.  The approaches employed have consisted of manometric techniques to record colonic contractions, barostatic methods to measure colonic tone, and recordings of myoelectric signals from the colon that initiate and control muscular contractions.  However, the study of colonic motility in a clinical setting proves to be difficult.  Accurate positioning of the probes via colonoscopy requires pre-procedure cleansing of the colon, which raises the possibility of altered physiology. Recording of intraluminal pressure, by means of manometric catheters inserted per rectum, requires prior bowel cleansing, which may modify colonic motility. In contrast to other segments of the gastrointestinal tract, contents move through the colon in hours or days, instead of seconds to minutes; thus, prolonged observations are needed.  Moreover, in contrast to the upper gastrointestinal tract, in which reliable manometric recordings can be obtained, the larger diameter of the colon hinders the accurate detection of manometric events. Furthermore, interpretation of intraluminal pressure measurements is complicated, because many contractions of the colonic wall do not occlude the lumen and therefore are detectable by manometry only if they cause significant pressure changes. And finally, all of these techniques, which continue to be used extensively in a research context, have not yet been standardized for routine clinical use.

Ghoshal et al (2007) stated that constipation is a common problem, which may be due to slow transit or fecal evacuation disorders.  Though the screening test of colonic transit study using radio-opaque markers given at 0, 24 and 48 hours followed by abdominal X-ray at 72 hours is a good protocol in the West, it is not suitable for Indians who have a rapid gut transit.  Nine patients with adult Hirschsprung disease, 11 with chronic intestinal pseudo-obstruction diagnosed using standard investigations and 11 healthy subjects were evaluated by colonic transit study using radio-opaque markers (SGmark), 20 each at O, 12 and 24 hours followed by an abdominal X-ray at 36 and 60 hours.  The cut-off was determined by using receiver operating characteristic (ROC) curves, and sensitivity, specificity, positive and negative predictive values and diagnostic accuracy were determined.  The total number of markers retained in the abdomen and those in the right segment at 36 hours in patients with Hirschsprung disease and chronic intestinal pseudo-obstruction was higher than that in healthy subjects though the number in the left and rectosigmoid segments were comparable.  The abdominal X-ray at 60 hours, total number of markers and number in all segments were higher in patients with Hirschsprung disease and chronic intestinal pseudo-obstruction than in healthy subjects.  The best cut-off by ROC curves at 36 and 60 hours was 30 and 14 markers, respectively.  The sensitivity, specificity, positive and negative predictive values, diagnostic accuracy and area under the ROC curve at 36 hours were 90 %, 82 %, 90 %, 82 %, 87 % and 0.9, respectively; the corresponding values at 60 hours were 95 %, 100 %, 100 %, 92 %, 97 % and 0.99, respectively.  The authors concluded that using the proposed protocol, the colonic transit study is able to distinguish patients with specific motility disorders causing constipation such as Hirschsprung disease and chronic intestinal pseudo-obstruction from healthy subjects with reasonable sensitivity and specificity, and shows that an abdominal X-ray at 60 hours is better than one at 36 hours.  This was a small study reporting a moderate sensitivity and specificity of the colonic transit study; its findings need to be validated.

An American Gastroenterological Association guideline on nausea and vomiting (AGA, 2001) concluded that “the place of such tests of motor function as gastric emptying studies, electrogastrography, and manometry have not been defined, and the yield of such diagnostic studies has not been adequately compared with a therapeutic trial of an antiemetic and/or prokinetic agents."  An American Gastroenterological Association guideline on constipation (AGA, 2000) stated that colonic manometry “is not generally available and is not appropriate for most patients, except in research settings.” The consensus opinion of the American Motility Society Clinical GI Motility Testing Task Force on the performance and clinical utility of EGG (Parkman et al, 2003) stated that no therapies have convincingly demonstrated in controlled studies that correcting abnormalities detected by EGG improves upper gastrointestinal symptoms.  Proposed clinical indications for performance of EGG in patients with unexplained nausea, vomiting and dyspeptic symptoms must be validated by prospective controlled investigations.

In an editorial on EGG, Verhagen (2005) stated that because of its low sensitivity and specificity, EGG can not be used as a diagnostic clinical tool.  In certain diseases, EGG may be useful in defining a subgroup of patients.  However, at present there is no evidence to support a role for EGG in the diagnostic work-up of patients or in directing therapy.

Abid and Lindberg (2007) examined if there is a correlation between electrical activity measured by EGG and contractile activity of the stomach as measured by antro-duodenal manometry (ADM).  These researchers also studied if the underlying motility disorder could be predicted from EGG parameters.  They compared 21 parameters measured from EGG with 8 parameters measured from ADM.  The ability of EGG to identify the underlying diagnosis was tested by comparing EGG parameters for each diagnosis group against other patients.  The study comprised recordings from 148 patients (125 females).  Their median age was 45 years (range 17 to 76).  These investigators found few and weak correlations between EGG and ADM.  Specifically the correlation between parameters reflecting the response to meal was poor (r = -0.07, p = 0.39).  The discriminatory power of EGG for underlying motility disorder was also low.  Patients with slow transit constipation (STC) showed a lower post-prandial power in normogastric (3.7 +/- 0.5 versus 4.0 +/- 0.5) and tachygastric (3.5 +/- 0.4 versus 3.7 +/- 0.4) regions, a lower percentage of time with normogastria [87.2 % (56.5 to 100) versus 95.7 % (0 to 100)], and a higher percentage of time with tachygastria [9.3 % (0 to 33) versus 3.5 (0 to 100)] and bradygastria [1.8 % (0 to 20) versus 0 % (0 to 17.1)].  Patients with irritable bowel syndrome had a higher percentage of time with normogastria [96.5 % (62.5 to 100) versus 93.3 % (0 to 100)] and a less unstable dominant frequency as measured by the instability coefficient [15 (3 to 77) versus 24 (2 to 72)].  The authors concluded that EGG and ADM seem to measure different aspects of gastric motor activity but can not show a spatial correlation.  The diagnostic value of EGG is poor, but EGG may have some value for the identification of patients with STC.

It should also be noted that the American Gastroenterological Association's medical position statement on diagnosis and treatment of gastroparesis (Parkman et al, 2004) does not mention the use of electrogastrography.

A new approach for evaluating gastric motility function in patients with functional dyspepsia and other upper functional gastrointestinal disorders is the use of an ambulatory diagnostic test pill, the SmartPill (SmartPill Corporation; Buffalo, NY). On July 20, 2006, the Unites States Food and Drug Administration cleared the SmartPill GI Monitoring System through the 510(k) process for use as an aid in evaluating patients with suspected motility disorders such as gastroparesis. This wireless, ingestible, medical device assesses pH and pressure in the gastrointestinal lumen. When the capsule reaches the duodenum, the change in pH (from acidic to alkaline) indicates this transition, allowing an assessment of gastric emptying. The single-use, disposable, wireless capsule is slightly larger than a multi-vitamin (26 mm by 13 mm). As it passes through the gastrointestinal tract, miniaturized sensor technology measures pressure, temperature, and pH, as well as real and elapsed time. Acquired data are continuously transmitted over very low power radiofrequencies to a small receiver that can be worn on the patient's belt. Although the capsule normally has a transit time ranging from 24 to 48 hours, it is capable of transmitting data continuously for more than 72 hours in patients with reduced motility. Once the device has passed, the data set is downloaded from the receiver to a laptop computer, and special software provides tools for data analysis and a graphical user interface that indicates when gastric emptying, small bowel/large bowel transit, and total gastrointestinal tract transit time of the capsule has occurred. It should be noted that the SmartPill is intended to supplement, not replace, current gastrointestinal motility procedures such as endoscopy, duodenal manometry, and gastric emptying scintigraphy.

Kuo and associates (2006) reported their experience with the use of the SmartPill in 86 healthy subjects and 60 patients with documented gastroparesis by scintigraphy. The wireless capsule had a moderate sensitivity and specificity for half-time gastric emptying measurement (71 % and 74 %, respectively). These findings, originally reported in an abstract, were recently published in a full-length article. Kuo et al (2008) compared gastric emptying time (GET) and gastric emptying scintigraphy (GES) by assessing their correlation, and compared GET and GES for discriminating healthy subjects (n = 87) from gastroparetics (n = 61). Fasted subjects were ingested capsule and [(99m)Tc]-SC radio-labeled meal. Images were obtained every 30 minutes for 6 hours. Gastric emptying time and percentage of meal remaining at 2/4 hours were determined for each subject. The sensitivity/specificity and receiver operating characteristic analysis of each measure were determined for each subject. Correlation between GET and GES-4 hour was 0.73 and GES-2 hour was 0.63. The diagnostic accuracy from the receiver operating characteristic curve between gastroparetics and healthy subjects was GET = 0.83, GES-4 hour = 0.82 and GES-2 hour = 0.79. The 300-min cut-off time for GET gives sensitivity of 0.65 and specificity of 0.87 for diagnosis of gastroparesis. The corresponding sensitivity/specificity for 2- and 4-hour standard GES measures were 0.34/0.93 and 0.44/0.93, respectively. Although the SmartPill was able to distinguish normal state from disease, a case-control study is insufficient for evaluating test characteristics. Prospective, randomized, controlled trials are needed to ascertain the clinical value of the SmartPill. Furthermore, since the SmartPill itself does not empty like a meal from the stomach, the technology is likely to only provide an estimate of upper gastrointestinal transit.

Cassilly et al (2008) examined if the SmartPill wireless pH and pressure capsule given with a meal empties from the stomach with return of the fasting phase III migrating motor complex (MMC) or during the fed pattern with the solid meal. A total of 15 normal subjects underwent antro-duodenal manometry and ingestion of a radio-labeled meal and the SmartPill. In 5 subjects, emptying of the SmartPill was studied in the fasting period by ingesting the SmartPill with radio-labeled water. The SmartPill emptied from the stomach within 6 hours in 14 of 15 subjects. SmartPill pressure recordings showed high amplitude phasic contractions prior to emptying. SmartPill gastric residence time (261 +/- 22 mins) correlated strongly with time to the first phase III MMC (239 +/- 23 mins; r = 0.813; p < 0.01) and correlated moderately with solid-phase gastric emptying (r = 0.606 with T-50 % and r = 0.565 with T-90 %). Nine of 14 subjects emptied the capsule with a phase III MMC. In 5 subjects, the SmartPill emptied with isolated distal antral contractions. In 5 subjects ingesting only water, SmartPill gastric residence time (92 +/- 44 mins) correlated with the time to the first phase III MMC (87 +/- 30 mins; r = 0.979; p < 0.01). The SmartPill given with a meal primarily empties from the stomach with the return of phase III MMCs occurring after emptying the solid-phase meal. However, in some subjects, the SmartPill emptied with isolated antral contractions, an unappreciated mechanism for emptying of a non-digestible solid.

Rao, et al. (2009) assessed regional and colonic transit time with the SmartPill in constipated and healthy subjects and compared this with a radiopaque market. Seventy-eight constipated (Rome II) and 87 healthy subjects ingested a 260-kcal meal, a radiopaque marker capsule, and the SmartPill. Subjects wore a data receiver and kept daily stool diaries for 5 days. SmartPill recordings assessed colonic transit time, whole-gut transit time, small-bowel transit time, and gastric emptying time. Abdominal radiographs on days 2 and 5 assessed radiopaque marker transit. Sensitivity, specificity and receiver operating characteristics (ROCs) of each technique and utility were compared. Gastric emptying time, colonic transit time, and whole-gut transit time were slower (p < 0.01) in constipated subjects than controls. Colonic transit time was slower in women than men (p = 0.02). Day 2 and day 5 radiopaque marker transits were slower (p < 0.001) in constipated subjects. Correlation of the SmartPill colonic transit time with radiopaque markers expelled on day 2/day 5 was r = 0.74/r = 0.69 in constipation, and r = 0.70/r = 0.40 in controls, respectively. The diagnostic accuracy of the SmartPill colonic transit time to predict constipation from ROC was 0.73, with a specificity of 0.95. The authors reported that these were comparable with those of day 5 ROM (ROC, 0.71; specificity, 0.95).

It should be noted that a consensus statement from the Society of Nuclear Medicine as well as the American Neurogastroenterology and Motility Society (Abell et al, 2008) recommends scintigraphy as a standardized method for measuring gastric emptying.

In a review on radionuclide gastroesophageal motor studies, Mariani et al (2004) noted that radionuclide transit/emptying scintigraphy provides a means of characterizing exquisite functional abnormalities with a set of low-cost procedures that are easy to perform and widely available, entail a low radiation burden, closely reflect the physiology of the tract under evaluation, are well-tolerated and require minimum cooperation by patients, and provide quantitative data for better inter-subject comparison and for monitoring response to therapy. Despite the relatively low degree of standardization both in the scintigraphic technique per se and in image processing, these methods have shown excellent diagnostic performance in several function or motility disorders of the upper digestive tract. Dynamic scintigraphy with a radioactive liquid or semisolid bolus provides important information on both the oropharyngeal and the esophageal phases of swallowing, thus representing a useful complement or even a valid alternative to conventional invasive tests (e.g., stationary esophageal manometry) for evaluating abnormalities of oropharyngo-esophageal transit. Clinical applications of esophageal transit scintigraphy include disorders such as nutcracker esophagus, esophageal spasm, non-cardiac chest pain of presumed esophageal origin, achalasia, esophageal involvement of scleroderma, and gastro-esophageal reflux and monitoring of response to therapy. Scintigraphy with a radiolabeled test meal represents the gold standard for evaluating gastric emptying, whereas more recent radionuclide methods include dynamic antral scintigraphy and gastric SPECT for assessing gastric accommodation. Clinical applications of gastric-emptying scintigraphy include, among others, evaluation of patients with dyspepsia and evaluation of gastric function in various systemic diseases affecting gastric emptying.

Maurer and Parkman (2006) staetd that nuclear medicine offers a variety of studies for evaluating motility throughout the gastrointestinal tract. Gastric emptying remains the "gold standard" for studying gastric motor function, but its application in most centers remains limited to measuring only total gastric emptying in spite of data that show assessment of both fundal and antal function is of clinical value for evaluating patients with dyspepsia. Smith and Ferris (2003) noted that the diagnosis of diabetic gastroparesis may be confirmed by demonstrating gastric emptying delay during a 4-hr scintigraphic study. This is in agreement with the report by Stassen (2005) who noted that the diagnosis of diabetic gastroparesis may be confirmed by scintigraphy assessment of gastric emptying, preferably using a solid meal. Feigenbaum (2006) stated that the gold standard for the diagnosis of gastroparesis is a gastric emptying study. Furthermore, the American Gastroenterological Association's medical position statement on diagnosis and treatment of gastroparesis (Parkman et al, 2004) stated that gastric emptying scintigraphy of a radiolabeled solid meal is the best accepted method to test for delayed gastric emptying.

Ziessman and associates (2009) examined if a study of clear liquid gastric empting has added value for the diagnosis of gastroparesis over a study of solid emptying alone. A total of 101 patients underwent both solid and liquid gastric-emptying studies, acquired sequentially on the same day. A 30-min (1-min frames) liquid study (300 ml of water with 7.4 MBq [0.2 mCi] of (111)In-diethylenetriaminepentaacetic acid) was followed by a standardized 4-hr solid-meal study (a (99m)Tc-sulfur colloid-labeled egg-substitute sandwich meal). Emptying was quantified as a best-fit exponential emptying rate (T1/2) for liquids and percentage emptying at 4 hrs for solid empting. A total of 30 healthy volunteers underwent a study of clear liquid emptying to establish normal values. The results of the liquid and solid studies were compared. (111)In liquid downscatter into the subsequent (99m)Tc solid meal results was analyzed. The upper range of normal for clear liquid emptying (T1/2) for healthy volunteers was 22 mins (mean +/- 3 SDs) and 19 mins (mean +/- 2 SDs). Of 101 patients, delayed emptying was found in 36 % of liquid and 16 % of solid studies. Of all patients with normal solid emptying, 32 % had delayed liquid emptying. (111)In downscatter into the (99m)Tc window was not generally significant. The authors concluded that for the detection of gastroparesis, a 30-min study of clear liquid gastric-emptying has considerable added diagnostic value over a study of solid emptying alone.

Hyett et al (2009) evaluate the prognostic value of gastric emptying studies on the morbidity associated with diabetic gastroparesis. This was a parallel cohort study of 3 groups. Group A (n = 94) contained diabetics (type 1 and type 2) with classic symptoms of gastroparesis (including early satiety, post-prandial fullness, bloating, abdominal swelling, nausea, vomiting, and retching) and delay in radionucleotide gastric emptying study. Group B (n = 94) contained diabetic subjects with classic symptoms of gastroparesis but negative scintigraphy. Group C (n = 94) contained diabetic subjects without symptoms of gastroparesis. Data were gathered on the number of days hospitalized and hospitalizations, office visits, emergency department (ED) visits, death rate, glycosylated hemoglobin levels (HbA1c), medications and past medical history. Group A had significantly more hospital days per 1000 patient days (25.5) than both Group B (5.1; p < 0.01) and Group C (2.3; p < 0.01). Group A also had significantly more hospitalizations, office visits and ED visits than both Group B and Group C. Deaths and mean HbA1c level did not differ between the groups. Group A patients were more likely to have cardiovascular disease (19.2 % versus 6.4 % A versus C; p < 0.05), hypertension (63 % versus 43 % A versus C; p = 0.005) and retinopathy (33 % versus 11.7 % A versus C; p < 0.001). The authors concluded that a delayed radionucleotide gastric emptying study predicts negative health outcomes in diabetics with symptoms of gastroparesis. They identified a correlation between diabetic gastroparesis and cardiovascular disease, hypertension and retinopathy which may indicate an underlying vascular etiology.