Characterization of the colon by endoscopic ultrasonography

Introduction: indications to EUS of the colon are emerging. Aims: (1) characterization by EUS of colonic/rectal walls and peri-colonic/rectal spaces; (2) compare 12 and 20MHz probes; (3) create an EUS data base of the colon/rectum in healthy to compare with patients. Material: Study of 60 healthy;30 females;20 between 18–39 years old;20, 40–59; 20, 60–80; in each of this age groups 50% female. EUS was performed with 12 and 20MHz; in each age groups half of the cases evaluated with 12MHz and half with 20MHz. We evaluated the right colon (RC), transverse (TC), descending (DC), sigmoide (SC) and rectum (RE). Parameters: (1) nº of layers; (2) thickness: mucosa, subm., m. propria, entire wall; (3) regularity of mucosal surface and interface between layers; (4) pattern of different layers; (5) vessels in submucosa; (6) peri-intestinal lymph nodes. Results: (1) (p<0.05) nº of layers identified in the submucosa and m. propria comparing 12 and 20MHz; the RE and DC presented the highest median; (2) thickness of the entire wall and of it's layers (p<0.05): entire wall and m. propria thicker in RE and SC; subm. thinner in TC; mucosa thinner in DC and SC; (3) larger m. propria thickness in DC and RE in the age 40–59 years; (4) high regularity of mucosal surface and interface between layers (>90%); (5) homogeneous pattern in >90% of the cases in wall layers; (6) presence of subm. vessels in 30% of cases in DC and RE and fewer in RC (11.7%); (7) presence of lymph nodes in 10% of cases. Conclusions:(1)20MHz identifies higher nº of layers than 12MHz; (2) nº of layers higher in DC and RE; (3) rectal wall is thicker than colon; (4) differences in thickness of the various layers between different colonic segments (5) there are differences in thickness of m. propria and of entire wall depending on age; (6) wall and it's different layers present a high regularity and homogeneity.