A retrospective data analysis of WMC test data was performed. In total, data of nine adolescent patients with functional GI disorders (i.e. chronic abdominal pain, nausea, functional dyspepsia, constipation) and possibly affected gastrointestinal motility from the Paediatric Gastroenterology outpatient clinic at the University Hospital of Cologne, Germany, who underwent the WMC test between July 2017 and February 2019 were included for further analysis (Table 1). The diagnosis of each functional GI disorder was made according to Rome IV criteria and detailed clinical evaluation and examination, laboratory investigations and ultrasound were performed in all patients prior to the WMC test. After exclusion of contraindications for the WMC test such as swallowing difficulties, inflammatory bowel disease or history of bowel surgery with possible GI obstruction, written informed consent was obtained from all patients and caregivers. Medications possibly affecting GI motility were discontinued at least three days before the WMC test and no bowel management was carried out before capsule ingestion.
Table 1
Summary of WMC test results including regional gut transit times and contractility parameters calculated for the gastric and the small bowel region
No | Sex | Age | Dx | Transit times | | Contractility parameter |
| | | | | | | | | | Gastric window | | Small bowel window |
| | | | GET | SBTT | CTT | SLBTT | WGTT | | Ct | MI | AUC | | Ct | MI | AUC |
| | | | < 5h | < 6h | < 59h | < 64h | < 73h | | > 0.48 min− 1 | > 9.82 | > 1358 mmHg s− 1 | | > 0.6 min− 1 | > 10.57 | > 1456 mmHg s− 1 |
Patients with normal transit | | | | | | | | | |
1 | f | 16y | IBS | 3.44 | 4.11 | 14.52 | 19.04 | 22.48 | | 0.46 | 44.94 | 2636 | | 0.55 | 17.98 | 1072 |
2 | m | 12y | AM | 4.08 | 3.4 | 15.47 | 19.27 | 23.36 | | 0.89 | 37.25 | 2185 | | 0.9 | 28.61 | 1678 |
6 | f | 16y | IBS | 2.35 | 4.27 | 23.37 | 28.05 | 30.4 | | 0.14 | 7.25 | 246 | | 0.46 | 14.03 | 800 |
4 | m | 14y | FC | 2.14 | 6.0 | 12.05 | 18.07 | 20.22 | | 4.11 | 97.28 | 5773 | | 3.09 | 82.27 | 3867 |
7 | m | 12y | N/V | 2.27 | 5.1 | 41.19 | 46.3 | 48.57 | | 1.98 | 42.88 | 2015 | | 1.83 | 41.89 | 2220 |
Patients with abnormal transit (GET; SBTT; CTT) |
3 | f | 15y | FD | 5.04 | 6.29 | 23.22 | 29.51 | 34.56 | | 0.13 | 15.43 | 802 | | 1.16 | 26.44 | 1578 |
9 | f | 17y | N/V | 13.44 | 12.21 | 18.33 | 30.55 | 44.4 | | 0.58 | 61.43 | 3522 | | 0.2 | 5.28 | 313 |
5 | m | 12y | IBS, FC | 0.43 | 7.02 | 50.05 | 57.07 | 57.5 | | 1.71* | 32.5* | 673* | | 5.33 | 124.5 | 5727 |
8 | m | 15y | FD, FC | 3.5 | 8.56 | 102.37 | 111.34 | 115.24 | | 0.7 | 111.8 | 3987 | | 1.06 | 41.35 | 2026 |
* 30 min before gastric emptying | |
| | | Median | 3.4 | 6.0 | 23.2 | 29.5 | 34.6 | | 0.6 | 43.9 | 2411 | | 1.1 | 28.6 | 1678 |
| | | IQR 25 | 2.3 | 4.3 | 15.5 | 19.3 | 23.4 | | 0.4 | 31.8 | 1712 | | 0.6 | 18.0 | 1072 |
| | | IQR 75 | 4.1 | 7.0 | 41.2 | 46.3 | 48.6 | | 1.2 | 70.4 | 3638 | | 1.8 | 41.9 | 2220 |
Dx, diagnosis; GET, gastric emptying time; SBTT, small bowel transit time; CTT, colonic transit time; SLBTT, small and large bowel transit time; WGTT, whole gut transit time; Ct, number of contractions per minute; MI, motility index; AUC, area under the pressure curve; IBS, irritable bowel syndrome; AM, abdominal migraine; GP, gastroparesis; FC, functional constipation; N/V, nausea and vomiting; FD, functional dyspepsia; IQR, interquartile range. |
The WMC test was performed according to the manufacturer’s recommendations (SmartPill®; SmartPill Corporation, Buffalo, New York, USA). After an overnight fast, the patient ingested a standardised meal (260 kcal nutrient bar, SmartBar) just before swallowing the capsule with a glass of water. After starting the measurement, a six-hour fasting period followed. The patient wore the recording data receiver for five days and documented any symptoms or activities. After excretion of the capsule (accompanied by loss of connection to the receiver) or after approximately 120 hours when the battery was flat, the recorded data were uploaded from the receiver via the corresponding manufacturer`s test software (Supplemental Fig. 1a).
The WMC test continuously measured temperature, pH and pressure to calculate gastric emptying time (GET), small bowel transit time (SBTT), small and large bowel transit time (SLBTT), colonic transit time (CTT) and whole gut transit time (WGTT). GET was defined as time from ingestion, indicated by an increase of temperature and a pH decrease (norm < 4) when the capsule reaches the stomach until pyloric passage into the duodenum. This was determined by an abrupt pH increase (norm 2–4 pH units) from the lowest postprandial value. SBTT was defined as the time interval between capsule entry into the small bowel and the passing of the ileocecal valve indicated by a pH decrease of 0.5-1 units. CTT was defined as the time between the end of SBTT and excretion of the capsule, indicated by an abrupt temperature and pressure drop. SLBTT and WGTT can be calculated, respectively (Fig. 1) [8, 13–14]. The reference ranges of transit times and contractility parameters have not been established in the paediatric population so far, therefore, adult reference ranges were used. A GET > 5 hours and an SBTT > 6 hours were considered prolonged. Colonic transit time was defined as normal < 59 hours and the capsule should be excreted within 72 hours (WGTT) [8]. Moreover, for the gastric and small bowel region additional contractility parameters such as motility index, contraction frequency (contractions per minute; Ct/min), area under the curve (AUC) and motility index (MI) were calculated using the Software GIMS Data Viewer, version 3.0.0.
In the context of this publication the WMC test results were pseudonymised for further retrospective data analysis. To summarize measures of the WMC test, descriptive statistics was used. WMC test data were described using median and interquartile ranges (IQR) (Table 1).