Diagnostic advantages of transrectal ultrasound with gastrointestinal agent instillation for rectal adenoma and early-stage rectal cancer: comparison of conventional transrectal ultrasound techniques.

Background: Despite being a major focus of medical research for decades, rectal cancer remains a major threat to human health. This study aimed to compare and analyze the diagnostic value of transrectal ultrasonography (TRUS) for rectal adenoma and early-stage rectal cancer before and after gastrointestinal agent instillation. Methods: In this prospective study, patients diagnosed with rectal adenomas and early-stage rectal cancer by ultrasound were randomly selected for inclusion. All patients underwent ultrasound examination at the Outpatient Department of the First Affiliated Hospital of China Medical University and underwent surgical treatment at the First Affiliated Hospital of China Medical University. Patients with a lesion located 13 cm or more from the edge of the anus, or history of surgery, and a history of radiation and chemotherapy were excluded. A gastrointestinal agent was directly instilled into the rectal cavity during conventional TRUS to compare and analyze the display of rectal lesions before and after such instillation and to evaluate the infiltration depth of rectal lesions. These findings were compared to the pathological findings to determine the diagnostic efficacy. Results: Both the conventional TRUS and TRUS with gastrointestinal agent instillation were able to show the rectal wall structure and rectal lesions; the detection rate of rectal lesions of the former was 75.0%, and that of the latter was 97.1% (P<0.001). Of the 27 rectal adenomas, conventional TRUS detected 10, and TRUS with gastrointestinal agent instillation detected 25 lesions. The accuracy [90.54%; 95% confidence interval (CI): 81.48-96.11%; P=1.05E-08], specificity (87.88%; 95% CI: 71.80-96.60%; P=1.09E-05), and sensitivity (92.68%; 95% CI: 80.08-98.47%; P=1.05E-08) of TRUS in diagnosing early-stage rectal cancer were consistent with the pathological findings (P<0.001). The accuracy (95.95%, 95% CI: 88.61-99.16%; P=3.82E-11), specificity (93.94%, 95% CI: 79.77-99.26%; P=1.31E-07), and sensitivity (97.56%, 95% CI: 87.15-99.94%; P=3.82E-11) of TRUS after gastrointestinal agent infusion in diagnosing early-stage rectal cancer were consistent with the pathological findings (P<0.001). The specificity (87.88%; 95% CI: 71.80-96.60%; P=1.09E-05) of TRUS in diagnosing rectal adenomas was consistent with the pathological finding (P<0.001), but the accuracy (65%; 95% CI: 51.60-76.87%; P=0.25) and sensitivity (37.04%, 95% CI: 19.40-57.63%; P=0.25) were not (P>0.05). Meanwhile, the accuracy (93.33%; 95% CI: 83.80-98.15%; P=5.65E-06), specificity (93.94; 95% CI: 79.77-99.26%; P=1.31E-07), and sensitivity (92.59%; 95% CI: 75.71-99.09%; P=5.65E-06) of TRUS after gastrointestinal agent infusion in diagnosing rectal adenomas were consistent with the pathological findings (P<0.001). Conclusions: TRUS with gastrointestinal agent instillation had significantly improved accuracy in diagnosing early-stage rectal cancer and detecting intrarectal adenomatoid lesions.