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Radiographic and endoscopic evaluation of the upper GI tract.

Disorders of the upper gastrointestinal tract -- the pharynx, esophagus, stomach, duodenum and proximal small intestine -- are relatively common. However, gastrointestinal symptoms may occur not only as a manifestation of primary gastrointestinal tract disease, but may be indicative of other systemic diseases as well. Although symptoms such as anorexia, nausea and vomiting can be the result of a variety of gastrointestinal disorders such as congenital artresias or blockage from adhesions from prior surgery, they also may be a manifestation of systemic diseases like congestive heart failure and uremia. Diarrhea and constipation, for example, may be the result of metabolic disorders such as electrolyte imbalance or thyroid dysfunction. Needless to say, proper diagnostic evaluation is critical in determining the underlying disorder so that proper treatment can be initiated.[1]

Radiologic examination of the alimentary tract is indicated for a variety of gastrointestinal conditions, including dyspepsia, changes in bowel habits, abdominal pain and gastrointestinal bleeding. Radiography of the GI tract often requires the administration of a radiopaque contrast medium to permit adequate visualization of the lumen and mucosal surface of the GI tract. Typically, barium or an iodinated contrast medium is administered orally during an esophagram to evaluate abnormalities of the pharynx and esophagus and during an upper GI series to evaluate the stomach, duodenum and proximal small intestine. These contrast agents also may be administered rectally for a retrograde examination of the colon and distal small intestine.[1]

Since the advent of endoscopy and its increasing use in the evaluation of gastrointestinal complaints, controversy has arisen regarding the appropriate use of endoscopy vs the traditional upper GI series. Although endoscopy is considered by many to be the "gold standard" for the evaluation of myriad disorders of the upper GI tract, critics argue that radiographic evaluation of gastrointestinal symptoms with barium or another radiopaque contrast agent provides a definitive diagnosis in the majority of cases. Furthermore, when compared with endoscopy, an upper GI series is a less expensive, less invasive procedure that requires less preparation and no anesthesia to sedate the patient. On the other hand, should a disorder be found under endoscopy, a biopsy can easily be performed during the procedure, thus avoiding the need for subsequent biopsy or possible surgery.

Numerous studies investigating the cost/benefit ratios of both procedures in the diagnosis of disorders of the upper GI tract have been undertaken and, not surprisingly, report conflicting results.

This article outlines the advantages and disadvantages of endoscopy and traditional radiography in the evaluation and diagnosis of gastrointestinal symptoms. In addition, the article reviews the pathology and etiology of a variety of GI disorders in both adult and pediatric patients.

Preliminary Evaluation Of Gastrointestinal Symptoms

A thorough patient history is key to determining the underlying factors involved in the manifestation of gastrointestinal symptoms. Although pain and indigestion are by far the most common gastrointestinal complaints, the source of the complaint can vary. Therefore, the health care professional should inquire about the specifics of the complaint, including its location, frequency and severity.

For example, it is important to determine whether the patient's pain is diffuse or concentrated in a particular area and whether the pain is constant or aggravated by certain activities, such as eating. If the pain is related to eating, it is important to ask whether the pain arises during or after eating. Chest pain that occurs during eating is commonly reported in esophageal disorders; pain that occurs immediately after eating can indicate biliary tract disease; and pain that occurs 30 to 90 minutes after a meal is typical of a peptic ulcer. In other cases, eating may alleviate the pain.

Other important information for the patient history includes asking whether pain is associated with bowel movements. For example, the cramps associated with ulcerative colitis often are relieved after defecation.[2]

Symptoms such as anorexia and weight loss often are related to disorders of malabsorption. In cases of diarrhea, the number of stools and their consistency should be determined. The number, frequency and consistency of stools can vary from patient to patient. For example, some patients with diarrhea may have stools of relatively normal consistency, while others may have very watery stools. Stools also should be assessed for the presence of occult blood or mucus, changes in color and changes in odor, because foul-smelling stools can be indicative of pancreatic disorders. The presence of blood in stools is common in ulcerative colitis, whereas blood rarely is a component of functional bowel disease. Bleeding also can be related to diverticula and tumors, including polyps and cancer.

It also is important to inquire whether the patient is taking any medications. For example, patients taking NSAIDs on a daily basis, including aspirin, may have occult blood in their stools, while patients using laxatives on a regular basis may develop chronic diarrhea.[2] By completing a thorough patient history, the health care professional is in a better position to begin a physical examination and to refer the patient for the appropriate diagnostic evaluation.

Unfortunately, routine physical examination in the evaluation of gastrointestinal disease often is negative or inconclusive, necessitating the use of more thorough diagnostic techniques such as plain film radiography, endoscopy, computed tomography, endoscopic ultrasound or a routine upper GI series using orally ingested barium sulfate. Water soluble agents are used to evaluate perforations from trauma or leaks following surgical procedures.

Radiologic Evaluation of the Upper GI Tract

Although the use of endoscopy in the evaluation of gastrointestinal symptoms has become more common, radiographic examination of the upper gastrointestinal tract continues to play an important role in the evaluation of the structure and function of the pharynx, esophagus, stomach and duodenum. Recent improvements in radiologic technology combined with a more thorough understanding of the disorders that can affect these organs has resulted in the improved imaging of these structures.[1] As newer and more detailed imaging techniques continue to be introduced, it is important to understand the advantages and disadvantages of available procedures in an effort to ensure an accurate and cost-effective diagnosis.[1]

The routine use of barium sulfate suspensions for the radiographic evaluation of the gastrointestinal tract was first proposed in 1910.[3] Barium continues to be the preferred agent in radiographic examination of the gastrointestinal tract and may be administered during either a single-contrast or double-contrast study. During a single-contrast examination, 10 to 12 oz. of medium-density barium sulfate preparation (approximately 60% w/v) is administered to produce full-column opacification and distention of the segmental lumen under investigation. (See Fig. 1.) A double-contrast study involves the administration of 4 to 6 oz. of high-density barium sulfate (200% to 250% w/v) with low viscosity to coat the mucosal surface of the area in question. Distension of the lumen is accomplished by adding gas, most commonly by having the patient ingest a powder that, when combined with water, produces carbon dioxide. This combination results in specific mucosal opacification and delineation of fine surface detail.[4,5] (See Fig. 2.)

[Figures 1-2 ILLUSTRATION OMITTED]

Modern barium formulations can withstand variations in intestinal pH values without flocculation (breaking up of suspension). Low-density barium (less than 60% w/v) can be used by itself or in conjunction with high-density barium to examine the upper GI tract. However, high-density barium cannot be used if a small bowel series is to follow the upper GI exam, as the barium will obscure mucosal detail.

Single-contrast Evaluation

Until recently, single-contrast evaluation of the gastrointestinal tract was the most commonly used technique for radiographic evaluation of gastrointestinal symptoms. The desired objective of this examination is to fill the lumen of the gut with a relatively low-density barium preparation to reveal abnormalities. Radiographic films are taken at a relatively high kilovoltage (110 kVp to 120 kVp). Because the lumen is filled with barium, lesions not located on the contours of the bowel could be missed. The use of compression may help to reveal these lesions.[6]

Single-contrast examinations of the stomach can be difficult to perform for two reasons. First, compression must be applied meticulously for a successful examination. Second, sufficient attention to technique is essential, and its absence can result in numerous diagnostic errors. Criticism by endoscopists has lead to the reevaluation of the double-contrast technique, which provides a more sensitive look at the GI tract.[1,7]

However, the single-contrast examination is still very common and is in no way obsolete. When performed with attention to patient preparation and technique, its results can be thorough. (See Fig. 3.) The patient can take nothing by mouth for several hours prior to the exam. The primary disadvantage of the single-contrast study is that not all parts of the GI tract can undergo compression when mucosal folds can be seen. Certain areas such as the esophagus and portions of the stomach under the rib cage are not suitable for compression.[1]

[Figure 3 ILLUSTRATION OMITTED]

Situations in which a single-contrast upper GI exam may be preferred to a double-contrast exam include.[8]

* When there is a suspicion of a small bowel obstructing process.

* When patients are not able to cooperate with the extensive on-table positioning required for a double-contrast procedure.

* To rule out bowel obstruction in patients who are examined in an emergency situation.

Double-contrast Evaluation

Double-contrast examination of the upper GI tract involves gaseous distension of the lumen combined with uniform coating of the mucosal surface with barium. This requires the introduction of carbon dioxide into the lumen after the administration of a high-density, low-viscosity barium sulfate solution so that the barium can coat the mucosal surface.[1,8] (See Figs. 4 and 5.)

[Figures 4-5 ILLUSTRATION OMITTED]

Unlike the single-contrast study, the double-contrast study relies not only on detection of contour abnormalities, but on evaluation of the mucosal surface as well. Initially, double-contrast studies may be more time consuming to perform and can be associated with greater radiation exposure to the patient. However, experience and familiarity with the procedure should result in an examination that takes only slightly longer to perform than a single-contrast examination.

During a biphasic examination of the upper GI tract, the single- and double-contrast techniques are combined, with the single-contrast part performed first. Current opinion is that properly performed double-contrast or biphasic studies can increase the detection of polyps, early cancer, inflammation and infection. (See Fig. 6.)

[Figure 6 ILLUSTRATION OMITTED]

The viscosity of the contrast agent used in double-contrast studies must be sufficient to provide uniform coating of the GI lumen for the entire time required to complete the exam. Since the viscosity and, therefore, the thickness of the barium preparation is limited, the density of the double-contrast barium preparation must be sufficiently high to yield adequate x-ray examination.[1,8]

Upper GI procedures routinely use commercially available sodium bicarbonate powder or granules that are specially designed for this purpose. After oral administration with a small amount of water, these agents produce a sufficient volume of carbon dioxide for adequate distention. The high-density barium sulfate preparation is administered immediately after the effervescent agent.[9] A series of fluoroscopic images then are obtained according to a protocol of the radiologist's choice.

Endoscopy

Because of their low cost and noninvasive nature, it is likely that millions of radiographic studies of the gastrointestinal system will continue to be performed each year. However, the use of endoscopy to evaluate the upper GI tract increases annually in the United States. For example, until the early 1980s, the treatment of choice in patients with upper GI bleeding was angiography and surgery. Today, endoscopic treatment has become the first-line therapy for these patients. Endoscopy is appealing for cases of upper GI bleeding because it not only offers a definitive diagnosis, but also adds a treatment option. Most causes of upper GI bleeding and some causes of lower GI bleeding are treatable with endoscopy. (See Table 1.) Recommendations regarding the appropriate use of diagnostic endoscopy in cases of uncomplicated dyspepsia vary widely and are based on the patient's age, his or her age at onset of symptoms and on the response of symptoms to appropriate pharmacologic therapy.[11-13]
Table 1
Diagnosis in Patients
With Upper GI Hemorrhage[10](*)

Peptic ulcers        47%     Esophagitis         6%
   Duodenal          24%     Erosive
   Gastric           21%        duodenitis       6%
   Stomal             2%     Tumors              3%
Gastric erosions     23%     Esophageal
Varices              10%        ulcers           2%
Mallory-Weiss                Angiodysplasia    0.5%
   tears              7%     Other lesions       6%


(*) The sum is greater than 100% because some patients had more than one lesion.

Endoscopy also has been used Successfully to evaluate gastric ulcers and gastric cancer. (See Figs. 7 and 8.) Some researchers, however, question the need for endoscopy to evaluate patients gastric ulcers. According to Eisenberg,[14] double-contrast upper GI studies are virtually 100% accurate if the radiographic appearance of a gastric ulcer is benign. Endoscopy is indicated only when the radiographic findings are not typical of a benign ulcer, when healing of the ulcer does not progress at the expected rate or when any feature of the ulcer is suggestive of an underlying gastric cancer. Otherwise, Eisenberg recommends that benign ulcers be followed radiographically until healed without any need for endoscopic intervention.[14]

[Figures 7-8 ILLUSTRATION OMITTED]

Endoscopy usually is performed under anesthesia. Typically, a liquid anesthetic is sprayed on the back of the patient's throat to reduce discomfort during insertion of the endoscope, and Demerol and Versed are administered intravenously to ease pain.[15] During endoscopy, the patient's stomach is filled with air to permit better visualization of the lining of the upper digestive tract. Then, a long, thin fiberoptic tube is passed into the stomach via the esophagus. Attached to the end of the tube is a light and a miniaturized color camera with a wide angle lens. The camera can send live images to a video monitor and also can produce photographs or video footage of the area of interest.

If an abnormality is revealed during endoscopy, in some cases a biopsy may be obtained immediately. If a suspicious lesion is found, a miniature forceps can be passed through a hollow channel inside the endoscope and used to collect a sample of tissue for laboratory analysis. If a polyp is found, it can be removed with a wire-loop snare that cuts off the polyp and then cauterizes the base.[15] In addition, certain disorders can be treated during the endoscopic procedure. For example, if a narrowed area is found in the esophagus, a small balloon may be inserted to dilate the stricture.

Risks associated with endoscopy include bleeding or a perforation of the stomach or esophagus lining. Bleeding may occur at the site of a biopsy or polyp removal and often can be controlled with cauterization. In other cases, surgery may be necessary to control the bleeding.[15]

Endoscopic Yield in the Adult Patient: Results From A Large Prospective Study

As the number of upper GI endoscopies has increased, concerns have arisen regarding the appropriate indications for the use of endoscopy as a first-line diagnostic tool in the evaluation of patients with gastrointestinal complaints. In an attempt to answer this question, researchers in the Netherlands organized a large prospective study involving more than 2900 patients who had been referred for diagnostic evaluation of the upper gastrointestinal tract.[16] Investigators wanted to determine the appropriateness of clinical indications for diagnostic endoscopy.

A primary goal of the Dutch study was to determine whether "alarm" symptoms such as upper GI bleeding are associated with the endoscopic demonstration of serious disease; to compare the outcomes of endoscopy in dyspeptic patients younger than 45 with those older than 45; and to compare the yield of initial endoscopy to that of endoscopy after a trial of medical treatment.[16]

In the study, all 2900 patients referred for diagnostic evaluation of the upper gastrointestinal tract were included. Data were prospectively collected using a standardized study form that included the reasons why the patient had been referred for endoscopy. This portion was completed by hospital personnel as well as by the referring physician. The completed survey form then was reviewed by the endoscopist and the data transferred to a study form with a list of indications.[16]

For the purposes of this study, investigators defined dyspepsia as episodic or persistent pain and/or discomfort related to the proximal alimentary tract.[17-19] A history of peptic ulcer was recorded separately. Signs of upper GI bleeding, anorexia, weight loss and dysphagia were considered "alarm" symptoms.

Cases of upper GI bleeding were divided into two categories: active hemorrhage manifested as hematemesis, melena or both; and chronic bleeding occurring for weeks or months with stools positive for occult blood and/or iron-deficiency anemia. Some of the patients in the study were referred for follow-up after abnormal findings on upper GI series.[16] (See Table 2 for a list of referral indications.)
"Table 2
Referral Indications in Study Population[14]

                                No. of         % of
Indication                      patients       Patients

Dyspepsia                       1562           53.9%
Retrosternal pain                263            9.1%
Previous peptic ulcer            168            5.8%
Hematemesis                      226            7.8%
Melena                           164            5.7%
Fecal occult blood                23            0.8%
Iron-deficiency anemia           155            5.3%
Anorexia and weight loss         143            4.9%
Dysphagia                        183            6.3%
Abnormal upper GI radiograph      30            1.0%
Other referral indications       368           12.7%


Prior to endoscopic examination, patients were asked to describe their pain and to indicate whether it was retrosternal or abdominal in nature. Retrosternal pain was reported as the primary symptom in 9% of patients.[16] Patients also were queried about their use of nonsteroidal anti-inflammatory drugs (NSAIDs) or steroids and whether they were taking antacids or other drugs. Dyspepsia was the most commonly reported symptom in 54% of patients and the only symptom in 46% of the patients. Signs of GI bleeding were present in 18% of the patients, and 6% had a history of peptic ulcer disease. It is interesting to note that only 1% of the endoscopic evaluations were performed as the result of abnormal findings after an upper GI series.[16]

Endoscopic examination was performed using a forward-viewing fiberoptic endoscope. For the purpose of this study, only endoscopic diagnoses were considered; additional histopathologic findings were not taken into account. Upon endoscopy, normal findings were reported in 29.7% of patients who underwent a complete upper GI endoscopy. Relevant endoscopic disease was reported in nearly 30% of patients. Esophagitis was the most frequent acid-related disorder, followed by duodenal and gastric ulcers. Gastric cancer was diagnosed in 2% of the patients and esophageal cancer was diagnosed in 1%.[15]

Results of the Dutch study showed endoscopic yield was highest in patients referred with upper GI bleeding, with a more than 40% rate of relevant endoscopic findings in this group of patients. (See Fig. 9.) Researchers found that generally recognized "alarm" symptoms indeed were associated with the demonstration of significant endoscopic disease, such as active upper GI bleeding with acid-related disorders.[16]

[Figure 9 ILLUSTRATION OMITTED]

The findings of the study performed in the Netherlands were in accordance with the results of a 1986 RAND/UCLA Health Services Utilization Study.[18] The RAND/UCLA study was the first of its kind to assess the appropriateness of indications for diagnostic endoscopy. A subsequent study reported in 1988 by the Standards of Training and Practice Committee of the American Society for Gastrointestinal Endoscopy (ASGE) evaluated the appropriateness of 38 indications for upper GI endoscopy.[21] Another more recent report published by the Upper Gastrointestinal Endoscopy Audit Committee,[11] a panel consisting of seven gastroenterologists, reviewed the appropriateness of indications in a consecutive series of 390 patients who were referred for upper GI endoscopy. In these studies,[23-26] the prevalence of clinically relevant disease was approximately 30%, with esophagitis most common (14%), followed by duodenal ulcer (8%) and gastric ulcer (8%).

Some interesting differences surfaced between studies. For example, in the RAND study, only 15% of patients had been referred because of dyspepsia, whereas dyspepsia was the most common indication in the more recent Netherlands study. This difference was attributed to the fact that in the Dutch study, more than 40% of patients in the study were referred directly by general practitioners. Research suggests that general practitioners tend to refer patients with dyspetic symptoms more often than hospital specialists do.[27] In addition, the RAND study included endoscopies performed only on patients older than 65.

Age also was a determining factor in the diagnostic yield of endoscopy. In the Dutch study, patients with esophageal or gastric cancers had the highest mean ages,[23-26] whereas no malignancies were found in patients younger than 45. Gastric cancers are rarely found in patients younger than 45, and it is reasonable to assume that patients with gastric cancer will continue to be symptomatic or to have recurrent symptoms when treatment for dyspepsia is ended.[28] Limiting the duration of treatment to 6 weeks will prevent chronic usage of unnecessary medication and allows quick diagnostic pursuit in the relatively small group of patients whose symptoms have persisted despite such treatment.[16,29]

A previous history or concurrent signs of hematemesis and melena were significantly associated with the detection of peptic ulcers, and researchers in the Dutch study recommended that these patients undergo endoscopy. In more than 10% of patients with anorexia and weight loss, gastric cancer was diagnosed, whereas gastric cancer was rarely diagnosed in patients with isolated dyspepsia, with or without gastric pain. As such, the presence of weight loss or anorexia is sufficient cause to perform an endoscopy, even without dyspepsia.[16,29]

The rate of relevant disease in patients with uncomplicated dyspepsia was less than 20% in those who did not report any epigastric or retrosternal pain. However, one-third of the dyspeptic patients who had retrosternal pain appeared to have relevant disease, mostly esophagitis. Researchers in the Dutch study concluded that dyspepsia as an isolated symptom and without prior medical treatment is insufficient cause to warrant endoscopy.[16] However, the yield of endoscopy in patients with uncomplicated complaints that persisted or recurred during or after long-term empiric treatment was considerable: 36% of those 45 or younger and 30% of those older than 45 had one or more relevant endoscopic findings. Obviously, it is important for patients with persistent or recurrent symptoms despite antipeptic therapy to undergo endoscopic examination even if they are younger than 45.[16,29]

The authors of the Dutch study noted that had endoscopy not been performed in patients with dyspepsia as an isolated symptom, in patients who had no previous empiric treatment, or in patients 45 or younger, 259 endoscopies could have been prevented and disease would have failed to have been discovered in 46 patients (approximately 18%). According to a recent study by Sonnenberg and Townsend,[30] any diagnostic test with a probability of less than 20% to discover treatable disease is not cost-effective. As such, the authors of the Dutch study advise against the use of diagnostic endoscopy in patients with uncomplicated dyspepsia who have not undergone previous medical treatment or in patients younger than 45 years of age.

They do state, however, that patients with "alarm" symptoms warrant early endoscopic investigation. They also recommend that diagnostic endoscopy be performed on patients older than 45 with newly occurring dyspepsia that continues despite adequate pharmacologic treatment, since relevant disease can be demonstrated in a considerable percentage of patients with these symptoms.[24,31-36]

Some authors have suggested the possibility of a positive "psychological aftereffect" of a normal endoscopy. It is postulated that the reassurance provided by normal findings may have a sort of placebo effect, resulting in fewer symptoms, discouraging unnecessary treatment, and resulting in a decreased consultation rate.[25,37,38] Data from a separate study suggest that in more than two-thirds of cases in which patients had a normal endoscopic result, the results were likely to influence patient management, either as a basis for terminating treatment with antipeptic agents or as a means of providing direction to further investigation.[39]

Assessment of Upper GI Bleeding

Endoscopic treatment is considered the treatment of choice for severe, persistent upper G1 bleeding. Although many cases of upper GI bleeding resolve spontaneously, persistent episodes of upper GI bleeding do not respond well to medical treatment and often require surgery. The mortality rate for patents with persistent upper GI bleeding is 10%.[16,40-43]

Obviously, the location of the lesion must be determined prior to beginning endoscopy, because the procedure can vary depending on whether the bleeding is coming from the upper or lower GI tract. As stated previously, a thorough patient history is essential. A history of cirrhosis, esophageal varices, duodenal or gastric ulcers, retching before bleeding or recent ingestion of aspirin is suggestive of an upper GI hemorrhage. A history of bleeding after straining upon defecation or colitis or diverticular disease is suggestive of lower GI bleeding. Blood return on a nasogastric tube is almost always indicative of an upper GI bleed.[16,40-43]

The color of the blood also is suggestive of the origin of the hemorrhage. Bright red blood per rectum generally is indicative of a lower GI bleed, whereas black stools generally indicate an upper GI bleed. Information like this helps to determine where the endoscopy will begin. A screening endoscopy often is performed in cases where there is a possibility of an upper GI bleed.

In patients with an obvious upper GI bleed, several factors are important in determining the course of action. If the bleeding is persistent and ongoing, urgent endoscopy may be indicated as soon as the patient is medically stable. In cases in which the bleeding is intermittent, the trend is to perform endoscopy when appropriate medical personnel are available in an effort to achieve the best possible outcome. In general, endoscopy should be performed in an endoscopy suite or intensive care unit where space, monitoring, resuscitation equipment and support personnel are available.[40-43]

An initial assessment of any patient with suspected upper G1 bleeding is essential prior to endoscopic evaluation. The following precautions are recommended:

* Assessment of the patient's hemodynamic stability.

* Determination of the rate and activity of the bleeding.

* Collection of blood samples.

* Notification of appropriate medial personnel.

* Transportation of the patient to the designated endoscopy site once he or she has been stabilized.

Research indicates that the ideal opportunity for locating the source of upper GI bleeding occurs when endoscopy is performed within 24 hours of the bleed. Unfortunately, however, this time frame is not possible in some cases. For patients who have rare blood types, the time frame may be longer because a cross-match must be found. For patients who refuse blood transfusions for religious reasons, the time frame may be shorter because endoscopy should be initiated as quickly as possible so that appropriate therapy can begin.[40-43]

Evaluation of the Pediatric Upper GI Tract

Plain Film Radiography in Children

Conventional plain film radiography often is under-appreciated as a diagnostic technique in both children and adults. Plain films of the chest and abdomen are an important first step in the diagnosis of upper GI symptoms in children. Furthermore, plain film radiography is widely available and quickly and easily performed. These films often are diagnostic and specific, offering valuable insights regarding pathologies and suggestions for more detailed imaging procedures.[44]

Plain films are most useful in the evaluation of gastrointestinal obstruction in newborns and infants. Congenital high obstruction of the upper GI tract such as esophageal atresia with distal atresias of the duodenum and jejunum can be accurately diagnosed with plain films using air that is ingested or introduced through a nasogastric tube. Furthermore, findings on plain film may provide direction for subsequent imaging techniques.[44]

Conventional radiography is the imaging mode of choice in the evaluation of ingested foreign bodies. The complete foreign body survey includes a lateral view of the neck and an anteroposterior supine view of the chest and abdomen. Plain films often are able to reveal the presence of an opaque foreign object as well as its shape; the presence of sharp, smooth, round or elongated edges; its location in the upper GI tract; and related complications such as tracheal edema.[44] (See Fig. 10.)

[Figure 10 ILLUSTRATION OMITTED]

The primary drawbacks of plain films are insufficient sensitivity and specificity in the primary diagnosis of many pediatric upper GI disorders and resultant exposure of the child to ionizing radiation. Plain films are inadequate in the imaging of mucosal diseases and nonopaque foreign bodies. Functional disorders like gastroesophageal reflux disease (GERD), esophageal motility disorders and delayed gastric emptying also are difficult to evaluate using plain films alone. Therefore, the lack of specificity with plain films may require additional evaluation with other imaging techniques. Health care professionals should be aware of the both the value and limitations of plain film radiography.[44]

Upper GI Series in Children

Examination of the entire pediatric upper GI tract from the oral cavity to the jejunum can be accomplished with a routine, single-contrast upper GI series. Examination of the child with positive contrast, usually barium or a low-osmolar nonionic agent,[45] is a safe and effective way to evaluate the child with upper GI symptoms. This simple test is widely available and easily performed and can distinguish between disease that can be treated medically and disease that must be treated surgically.[2]

Single-contrast Evaluation

The single-contrast upper GI series is considered the "gold standard" in the evaluation of common pediatric gastrointestinal abnormalities that require surgery, such as tracheoesophageal fistula, vascular rings, nonopaque esophageal foreign bodies, esophageal strictures, hiatal and paraesophageal hernias, gastric volvulus and midgut malrotation. Although many of these conditions are uncommon and infantile vomiting often is the result of GERD or hypertrophic pyloric stenosis (HPS), the potential morbidity and mortality of a missed diagnosis is hard to justify when a pediatric upper GI is readily available and easy to perform.[44]

Pediatric surgeons also use the upper GI series as a sort of preoperative and postoperative trail guide to evaluate their work. A preoperative upper GI series in a child with surgical GERD permits assessment of the gastroesophageal junction, stomach size and gastric emptying;[45] postoperative assessment can document the absence of GERD.[2,46]

However, the upper GI series is limited in the diagnosis of many medical diseases of the pediatric upper GI tract. In addition, a high false-positive rate is associated with the diagnosis of GERD, since it detects physiologic reflux. There also is a high false-negative rate due to its brief monitoring period.[46] Mucosal diseases are more accurately evaluated with endoscopy, and several studies have confirmed the efficacy of endoscopy over single-contrast barium studies in the evaluation of varices, peptic ulcer disease and gastritis.[2,47-49] However, the pediatric barium upper GI often is the first diagnostic test, and the rareness of pediatric peptic ulcer disease and the ease of performing a pediatric upper GI accounts for its continued popularity.

Double-contrast Evaluation

Although the results from double-contrast studies correlate well with endoscopic findings in mucosal disease of the pediatric upper GI tract,[2,48-50] the procedure is not practical in young children, who object to the use of an effervescent agent, high-density barium and intravenous glucagon. As such, the double-contrast upper GI series should be reserved for older children with suspected esophagitis, erosive gastritis or primary peptic ulcer disease.[2,51]

Barium radiography of the pharynx showing dynamic functionality of the uppermost pediatric GI tract, also known as the swallowing study or modified barium swallow, has become more popular. It effectively evaluates the swallowing mechanism and helps determine the types of food best tolerated and the overall effectiveness of oral alimentation.[2,52] It also is important as a noninvasive means of evaluating esophageal motility.

The disadvantages of the pediatric upper GI series are primarily technical. It is important to minimize radiation exposure to the patient during the examination, which can be achieved with conservative use of fluoroscopy and proper use of restraining devices that inhibit patient movement. Pulsed digital fluoroscopy currently is popular for pediatric GI radiography because of its low radiation dose and computer image-enhancing capability.

Another slight disadvantage of upper GI radiography for pediatric patients is that some children refuse to drink the barium. However, proper preparation prior to the examination will help. For instance, ensuring that the pediatric patient does not eat anything for a certain period of time before the test will help, since hungry or thirsty children often tend to drink the barium willingly. For children who dislike the taste of barium, adding flavoring such as chocolate or cherry can mask the taste, making the barium more palatable. Mixing the barium with milk also can make the taste more pleasing to young children.[2,53] Iced barium, however, inhibits the peristaltic wave and therefore is not desirable in studies of esophageal motility.

The risk of aspiration during the barium GI study is rare and generally no greater than the risk of aspiration during a normal meal. Hypersensitivity to barium may be more common in children with food allergies.[2,54]

Endoscopy in Children

Clinical experience garnered during the past 20 years has proven that pediatric upper GI endoscopy is a safe and effective tool in the diagnosis and treatment of pediatric upper GI disease.[2,50,55,56] Pediatric gastroenterology recently has emerged as a subspecialty and, with it, the use of pediatric endoscopy has flourished. Endoscopy in the pediatric patient provides the advantage of simultaneous imaging, biopsy and treatment in cases of mucosal disease.[1]

Upper GI endoscopy is the imaging method of choice in the evaluation of unexplained upper GI bleeding in children, in whom bleeding often is related to inflammatory mucosal diseases such as esophagitis, gastritis, peptic ulcer disease and varices.[57] For these patients, endoscopy is useful not only in determining the cause and location of the bleeding, but it also can be used to determine the risk of rebleeding, for biopsy, and to stop the bleeding with coagulant techniques.[2]

Endoscopy, like plain radiography, also can be used to locate foreign bodies lodged in the esophagus,[2,58] Of course, with endoscopy, it does not matter whether the object is radiopaque.

The primary disadvantage of endoscopy in the pediatric patient is the need for preparation, sedation and monitoring of the child. The safe performance of pediatric endoscopy requires informed parental consent, intravenous access, intramuscular or intravenous sedation, monitoring by trained personnel and specialized equipment.[2]

The overall complication rate in pediatric endoscopy is less than 2%.[2,56] However, complications do occur and can be separated into three distinct categories: sedation-related, complications related to the procedure itself and complications related to therapeutic interventions. Sedation-related complications include transient respiratory arrest, bronchospasm and phlebitis. Complications secondary to the procedure include airway compression, bradycardia, bleeding, perforation and aspiration.[2,47]

In general, pediatric endoscopy is more invasive and more time-consuming than radiologic evaluation or adult endoscopy. As a result, its potential for overutilization has not materialized.

The respective roles of endoscopy vs radiologic examination of children with GERD, recurrent abdominal pain of childhood (RAP) and pediatric dyspepsia have yet to be determined.[2,59-62] Cases of mild GERD and RAP in an otherwise healthy child can be treated clinically, whereas more severe cases may require endoscopy and biopsy as part of the initial evaluation.[2,62] Pediatric endoscopy is a safe and effective diagnostic tool limited only by its mucosal scope, invasive nature and sedation requirements.

Conclusion

When evaluating possible disorders of the gastrointestinal tract in children or adults, it is important to use the safest, most appropriate technique available. Evaluation of the upper GI tract with a single-contrast radiographic exam is sufficient in many cases of dyspepsia, whereas double-contrast examination of the lumen of the bowel can accurately detect polyps, erosions, small ulcers and other mucosal diseases.

Endoscopy has an important and growing role in the diagnosis of disorders of the upper GI tract. Its safety and effectiveness have been proven in the diagnosis of conditions such as gastritis, esophagitis, duodenitis and peptic ulcer disease.[44] However, research suggests that diagnostic endoscopy should be reserved for use as a diagnostic tool in patients with "alarm" symptoms such as upper GI bleeding, anorexia, weight loss and dysphagia. For most other disorders of the upper GI tract, contrast radiography usually is effective.

In this era of managed care, there is an increased emphasis on improved patient outcomes while maintaining strict cost-containment guidelines. In many cases, choosing the appropriate diagnostic tool is the first step in the battle.

References

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Julliana Newman, B.A., ELS, is a certified editor of the life sciences. Her Radiologic Technology article titled "Early Detection Techniques in Breast Cancer Management" recently was awarded the 1997 Rose Kushner Award from the American Medical Writers Association for writing achievement in the field of breast cancer. The award was sponsored by the AMWA and Zeneca Pharmaceuticals. Ms. Newman resides in Albuquerque, N.M.

The author would like to thank Michael Davis, M.D., professor and chief of gastrointestinal radiology at the University of New Mexico School of Medicine, Albuquerque, N.M., for reviewing this article prior to its publication.

Reprint requests may be sent to the American Society of Radiologic Technologists, Publications Department, 15000 Central Ave. SE, Albuquerque, NM 87123-3917.
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Title Annotation:includes continuing education post-test
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Publication:Radiologic Technology
Date:Jan 1, 1998
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