Accurate staging of rectal cancer is essential for selecting patients who can undergo sphincter-preserving surgery and identifying those who could benefit from neoadjuvant therapy. (See "Neoadjuvant chemoradiotherapy and radiotherapy for rectal cancer".)
Clinical staging is usually accomplished using a combination of physical examination and CT scanning. Other imaging modalities such as magnetic resonance imaging, transrectal and transvaginal ultrasound using rigid instruments, and transrectal endoscopic ultrasound are also frequently used, although their roles are still being determined. (See "Pretreatment local staging evaluation for rectal cancer", section on 'Imaging evaluation'.)
This topic review will summarize experience with endoscopic ultrasound. Discussions on the diagnosis and management of rectal cancer (including other staging methods) are presented separately. (See "Clinical presentation, diagnosis, and staging of colorectal cancer" and "Neoadjuvant chemoradiotherapy and radiotherapy for rectal cancer" and "Pretreatment local staging evaluation for rectal cancer".)
Transrectal endoscopic ultrasound (EUS) is performed with the patient in the left lateral decubitus position. However, optimal tumor visualization may require repositioning the patient to place the region of interest in the dependent portion of the rectum. This is particularly important when assessing the primary tumor (T) stage of early superficial lesions because the rectum is filled with water, and minimal compression by the balloon is desired to achieve acoustic coupling.
A radial scanning echoendoscope is inserted approximately 30 cm to assess for iliac adenopathy. The wall and periluminal structures are carefully inspected while slowly withdrawing the echoendoscope. If necessary, the linear scanning echoendoscope is also inserted for fine needle aspiration (FNA) sampling of suspicious extramural lesions (mass/adenopathy) (image 1). The American Society for Gastrointestinal Endoscopy guidelines regarding endoscopic prophylaxis for gastrointestinal procedures do not make a recommendation with regard to antibiotic prophylaxis for EUS-FNA of solid lesions in the lower gastrointestinal tract. Our practice is to give prophylactic ciprofloxacin prior to the FNA (500 mg orally 30 to 60 minutes prior to the procedure or 400 mg IV 30 minutes prior). Oral ciprofloxacin (250 to 500 mg twice daily) is then given for 48 hours after the procedure. However, not all endoscopists routinely use antibiotics in this setting. Conscious sedation is not mandatory but may be helpful when EUS-guided FNA is performed. (See "Antibiotic prophylaxis for gastrointestinal endoscopic procedures" and "Overview of procedural sedation for gastrointestinal endoscopy".)