Transabdominal and Transperineal Ultrasound in Proctitis Assessment

Objective: To evaluate the accuracy and reliability of transabdominal and trans-perineal ultrasound in assessing the rectum, using colonoscopy or flexible sigmoidoscopy as the reference standard, and to explore the impact of subcutaneous adipose tissue(SAT) and bladder fullness on image quality and accuracy. Design: Cross-sectional study Recruitment: Participants: Adults with known or suspected IBD involving the rectum undergoing colonoscopy or flexible sigmoidoscopy for any clinical indication and intestinal ultrasound (IUS) within 30 days. Methods: Undergo colonoscopy or flexible sigmoidoscopy, with endoscopists blinded to ultrasound findings. Ultrasound: Preparation – 2 hours not emptying ones bladder First part - Transabdominal ultrasound (TAUS) - 10 minutes Standard of care intestinal ultrasound, including assessing the rectum transabdominally in both the transverse and sagittal views. Assessment of bladder fullness Measurement of Subcutaneous Adipose Tissue (SAT): a. Above the Umbilicus (for comparison): Identify a point 1 cm above the umbilicus in the midline. Using a high-frequency linear probe, obtain an image initially on transverse view and later in the longitudinal (or sagittal) axis. Freeze the photo at the end of the expiration. Measure the distance from the inner surface of the skin to the outer surface of the linea alba. This distance represents the thickness of the SAT in the upper abdomen. SAT will appear as a hypoechoic (darker) layer between the hyperechoic (brighter) skin and the hyperechoic linea alba Take 2 sagittal and 2 transverse multiple and average them for added accuracy. b. Suprapubic Area: Applying a similar strategy but now placing the probe perpendicular to the skin in the midline, approximately 5-10 cm below the umbilicus. Measure the thickness of the SAT from the inner surface of the skin to the outer surface of the linea alba. Take 2 sagittal and 2 transverse multiple and average them for added accuracy. Second part Transperineal ultrasound(TPUS) - 5 minutes Use the micro-convex prob. Measure first in coronal and later in sagittal. Consider having two sonographers measure the SAT and VAT independently in a subset of patients to determine inter-rater reliability Both will be done on the same day, starting with transabdominal approach followed by the transperineal approach.