Use of a convex probe-endobronchial US endoscope in EUS of the rectum and FNA

A 52-year-old white man was referred to the gastroenterology clinic for evaluation of a rectal mass felt on physical examination and confirmed on colonoscopic examination as an external compression. He had a history of locally invasive bladder cancer; bladder resection and ileal conduit were performed a year ago. Magnetic resonance imaging of the pelvis revealed a 1.8 × 2.1 × 2.9-cm mass posterolateral to the rectum on the right side, causing an indentation along the lateral wall of the rectum (Fig. 1). EUS with FNA was planned, but on the day of the procedure, the EUS processor had malfunctioned. An Olympus BF-UC-UC160F-OL8 EBUS endoscope (Olympus America Inc, Center Valley, PA) was used for rectal EUS. The US processor used was the EU-ME1. This revealed a 1.8-cm hypoechoic mass beside the posterior wall of the rectum (Fig. 2). FNA was performed with a 22-gauge needle. Pathology showed malignant cells, urothelial primary (Figure 3, Figure 4). The convex probe-endobronchial US (CP-EBUS) endoscope is used mainly for mediastinal lymph node staging for lung cancer. It has also been used for diagnosis of intrapulmonary tumors, unknown hilar and mediastinal lymphadenopathy, and mediastinal tumors. We believe that this is the first case in which a CP-EBUS endoscope has been used in the rectum. The main differences between the CP-EBUS endoscope and the linear echoendoscope are listed in Table 1. There is no channel for air insufflation or water irrigation. Water or air could be delivered through the 2-mm instrument channel. There is 1 wheel for control of up and down deflection of the tip of the endoscope. There is no control for right to left deflection as is available with the EUS endoscope. However, right and left movement can be achieved by clockwise and anticlockwise torque on the endoscope. A possible limitation is a narrow scanning range of 50 degrees versus 180 degrees with the linear echoendoscope. EUS in the rectum is used for local staging of rectal cancer, restaging after chemoradiation,^{,  ,}  detection of recurrent rectal cancer, subepithelial lesions of the rectum, rectosigmoid endometriosis, and anal sphincter defects.^{,  ,}  The CP-EBUS endoscope could be used effectively for all the indications described. Because the distal end outer diameter of the CP-EBUS endoscope is much smaller than the curvilinear EUS endoscope, this endoscope makes the procedure less uncomfortable and may require less sedation.