Transabdominal ultrasound colon diagnostics with the purpose of assessment of the endoscopic activity of ulcerative colitis in children

Transabdominal ultrasound examination of the colon is an informative research method that does not require special training, which is vital in pediatric practice. The purpose of the study was to compare the informativeness of transabdominal ultrasound of the colon vs the colonoscopy using the clinical and laboratory data of pediatric patients with ulcerative colitis (UC). Materials and methods used: a single-center retrospective cohort study was conducted at the Gastroenterology Department of the National Medical Research Center for Children’s Health (Moscow, Russia) in 2021-2023, which included 119 children 7 to 17 years and 11 months old with an established UC diagnosis. All children have undergone clinical and laboratory tests, ultrasound and ileocolonoscopy. The UCEIS scale and the PMI index of clinical activity were used to assess the endoscopic activity. The study of fecal calprotectin was carried out with immunochromatographic method. During transabdominal ultrasound, the thickness of the intestinal wall and blood flow were assessed using the Color Doppler imaging mode. Results: statistically significant increase in the thickness of the intestinal wall against the background of the growth of UCEIS (Rs=0.654; p<0.001), PUCAI (Rs=0.642; p<0.001) and the level of fecal calprotectin (Rs=0.463; p<0.001) was detected. Statistically significant differences in increased blood flow in the intestinal wall of the sigmoid colon were found with the UCEIS, PUCAI index (p<0.001, for both indices) and the level of fecal calprotectin (p=0.014). The area under the ROC curve corresponding to the relationship between the prognosis of the development of ulcerative colitis and the thickness of the sigmoid colon was 0.850±0.054 with 95% CI: 0.745-0.955. The resulting model was statistically significant (p<0.001). The threshold value of the sigmoid colon thickness was 2.05 mm, in case of an increase in this value, a high risk of exacerbation of ulcerative colitis was predicted. The sensitivity and specificity of the method were 84.3% and 72.7%, respectively. When comparing the PUCAI index, the UCEIS index and the level of fecal calprotectin based on the blood flow in the sigmoid colon wall, the statistically significant differences were found (p<0.001, for both indices, and p=0.014 for fecal calprotectin, respectively). Conclusion: transabdominal ultrasound diagnostics showed good correlation with colonoscopy, clinical activity of the disease and the level of fecal calprotectin, as a result of which ultrasound of the colon should be considered as a useful imaging method for assessing inflammatory activity in the colon and follow-up of patients with UC.