Integrative diagnostics of the gastro-intestinal tract – gastroesophageal reflux and constipation in practice

GER detection is possible using almost all imaging modalities, with varying sensitivity and specificity.

There are no published standards on how to perform an upper gastrointestinal seris (UGIs) and which/how GER provoking tests should be conducted, in fact over the past two decades, there have been almost no publications on the topic in general. A PUBMED search with keywords “Gastroesophageal Reflux[Mesh] AND Fluoroscopy[Mesh]” and applying an age filter (“birth-18 years”) retrieved no relevant studies; the one related paper (published in 2008) evaluated feeding strategies in neurologically impaired patients suffering from GER [8]. Carruci and Levine published guidelines for adult patients emphasizing the high sensitivity of double-contrast barium studies, especially for detection of esophagitis [9, 10]. Others reported GER detection with low sensitivity and specificity [11]. Aksglaede calculated a specificity of 100% and a sensitivity of 52% for UGI (compared to 24-h pH monitoring) [12]. For UGIs, DeBoer et al. published a sensitivity of 47.3%, specificity 74.2%, and positive predictive value of 50%, but there was no information given on either technique or provocative maneuver use (in particular, whether a water-siphon test was performed) [13]. Thompson et al. demonstrated in their study of 117 patients that UGIs detect unprovoked, spontaneous GER in only 26% of ph-monitoring–positive patients. Adding a water-siphon test to UGIs yielded a sensitivity of 70% at a specificity of 74% [14].

Since double-contrast barium studies are not feasible in most pediatric radiology units, the following UGIs technique has proven successful at the author’s institution:

A remote-operated fluoroscopy device is used. In order to keep radiation exposure as low as possible (ALARA principle), the device frame rate is set to 3 frames per second and most frequently, secondary capture images (Digital Imaging and Communications in Medicine screenshots) are used for documentation. Direct exposure (“a shot”) is only used for documentation of pathologies such as esophagitis.

Babies are positioned supine and older children are placed on a 45° tilted fluoroscopy table. Sometimes, young children do not want to swallow the contrast medium, and in these cases the following procedure can be helpful: a nasogastric tube is inserted and pushed forward to the gastric fundus. Under fluoroscopy control, the nasogastric tube is pulled back until its tip is located at the tracheal bifurcation level. A 50-ml contrast filled syringe is then connected and contrast medium injected using the bolus technique, where the first bolus is used to assess the esophageal motoric function, followed by anterior-posterior, lateral, and oblique (for gastroesophageal junction and HIS angle) projections of the contrast medium-filled esophagus. Care is taken to observe and document gastric emptying and correct position of the duodenal C, as well as of the duodenal–jejunal junction paramedian to the left, for exclusion of malrotation.

GER assessment is captured in three ways: (a) in the upright position—for air reflux (Fig. 4); (b) in the right lateral position—any occasion of spontaneous GER (Fig. 5), and (c) with the patient rotated to the left—for provocation using the water-siphon test, having pooled the contrast medium in the gastric fundus (by rotating the patient to the left). Patients swallow only a mouthful of water or tea (a maximum of three times) to provoke GER—any GER occurrence is of course documented. The UGIs ends with a secondary capture image of the upper abdomen, documenting gastric emptying and normal small bowel transit. If there is no gastric emptying by this time, the suspicion of a gastric motility disorder should be raised. GER is graded as shown in Table 2.

We have analyzed results of manometry, standard pH-metry, endoscopy, and histology in 284 of our patients and found that for UGIs, including the water-siphon test, sensitivity is 86–90% at a specificity of 28–42% when compared to esophageal manometry and standard pH-metry (unpublished work). In patients with high-grade GER demonstrated by an UGIs, there were statistically significant higher rates of esophagitis at endoscopy and histology. As such, the UGIs is not the preferred screening tool due to its low specificity and use of ionizing radiation. Another critical issue is the type of contrast medium used for UGIs. Barium can be used in patients without swallowing disorders, whereas a water-soluble contrast medium is used for others. However, water-soluble contrast media hamper the detection of esophagitis.

At the author’s institution, the following workflow for GER evaluation was set up: Step 1: clinical examination, impedance-pH-metry, and an abdominal ultrasound in order to check gastrointestinal obstruction, e.g., pylorospasm in babies, or signs of malrotation in all age groups. Step 2: If impedance-pH-metry is pathologic, a patient is scheduled for an UGIs. Step 3: If the UGIs shows severe GER (6-8 points on our internal score), the patient has endoscopy with biopsy. Therefore, the reduced sensitivity of water-soluble contrast media for esophagitis is not an issue, because subsequent endoscopy and biopsy will detect it.

This simple approach allows smooth assessment of GER patients, is as non-invasive as possible, and enables initiation of appropriate therapy.

Sonography allows the entire bowel to be examined except loops hidden by gas, although the ascending and descending colon can be scanned even in these cases. Ultrasound can depict colon wall hypertrophy in stercoral colitis, as well inflammatory changes and coprolites (Fig. 8) [20].

Conventional radiographs can help to determine which parts of the gastrointestinal tract are dilated, demonstrate the amount of stool impaction (Fig. 9), show bezoars, and assess rectal diameter, which should normally be more than one-third and less than one-half of the pelvic diameter. An elongated sigmoid colon can be detected in all constipated children except neonates. Barr et al. published a scoring system for semi-quantitative assessment of fecal retention [21].

Colon transit time is a method whereby patients swallow radiopaque markers and their GI transit is monitored on abdominal radiographs. Markers can be given all at once or on several days, sequentially [22]. Vande Velde reported a modification of the technique for children [23]. Polythene radiopaque markers are swallowed on six consecutive days, followed by an abdominal radiograph on day 7. Based on marker number and distribution, the colon transit time can then be calculated (Fig. 10). Depending on the technique used, normal colon transit time values for children and adolescents are reported to be a median of 38.8 h, with an upper limit of 80.0 h [23]. Colon transit times may also be assessed using scintigraphy [24].

Defecography represents the gold standard for further evaluation in cases of pathologic high-resolution anorectal manometry. Fotter et al. have described the procedure in detail [25]. Patient preparation consists of rectal cleaning, with a small enema the evening before, and another 2 h before the examination. By placing a rectal catheter, the rectum, sigmoid, and descending colon are filled with barium suspension from the anus to the left colonic flexure. Documentation is by intermittent fluoroscopy.

RAIR can also be detected on defecography (Fig. 11), and an absent RAIR points to Hirschsprung’s disease—where the transition zone can be defined as the interface between the aganglionic segment and the dilated more proximal normal colon (Fig. 12).

The catheter is subsequently removed and the patient is asked to actively defecate. At this point in time, pelvic floor relaxation with flattening and opening of the anorectal channel can be observed and pathologies such as rectoceles and intussusceptions can be detected. The procedure ends after requesting the patient to close their sphincter (for continence assessment, demonstrated by an anorectal angle of 90 degrees or less).

Since it is a functional investigation and dynamics are slow, a frame rate of 1-2 frames/s can be used and dose settings reduced, as well as an exposure curve for high contrast, selected on the fluoroscope device.

Within the diagnostic odyssey, defecography represents the final examination before biopsy in patients with therapy-refractory constipation. High-resolution anorectal manometry yields pathologic results and therefore the suspicion of Hirschsprung’s disease is raised.

In conclusion, GER and constipation are frequent reasons to seek medical support. Using a staged approach of available diagnostic procedures helps to be as non-invasive as possible, adheres to the ALARA principle and represents “patient-tailored medicine.” Finally, it must be considered that up-to-date diagnostic equipment is not available everywhere, whereas fluoroscopy units are widespread. Using appropriate technique, fluoroscopy can contribute to the diagnostic pathway.