BACKGROUND: Endorectal ultrasound (ERUS) is a well established imaging technique in the evaluation of anorectal diseases, most notably in the preoperative staging of rectal cancer. Owing to its high resolution, ERUS is also useful in the assessment of perirectal pathology if the lesions are within the reach of the ultrasound probe, which - depending on the frequency - is generally in the range of 6 to 8 cm. The aim of our study was to evaluate the feasibility, safety and diagnostic accuracy of ERUS guided biopsies in patients with extrarectal, pelvic lesions.
METHODS: During a study period of seven years we prospectively collected data of all patients undergoing ERUS. All patients with suspicious or unclear extrarectal pelvic pathology who underwent ERUS guided biopsies were included in the present study. Patients were prepared for the procedure with an orthograde bowel lavage and local (i.e. intrarectal) application of an antiseptic solution immediately prior to the examination. Patients received i.v. antibiotic prophylaxis with Metronidazole and Cefotiam. The procedure was carried out in the lithotomy position using a rotating scanner with a special biopsy aid which allows the precise positioning of the biopsy needle under constant ultrasound control. Using the TRU-CUT principle a high speed biopsy needle is fired once the target has been precisely visualized both, transversely and longitudinally. The specimens were sent for histological examination. To evaluate the accuracy of the diagnosis all patients with benign histology but primary suspicion of a malignant lesion were followed up for a minimum of 12 months.
RESULTS: A total of 48 patients with a median age of 66 years underwent ERUS guided transrectal ultrasound. Apart from one post-biopsy hemorrhage which was treated conservatively, no other complication was encountered. Enough tissue was removed to allow a histological examination in all cases. A large variety of diagnoses including primary and secondary malignancies (n=25) as well as benign pathology (n=23) could be established. There were no false positive but 3 false negative histologies in patients with proven local recurrence of a malignant tumor during the follow up period. This results in a sensitivity of 89%, specificity of 100%, positive predictive value of 100% and negative predictive value of 81%.
CONCLUSION: ERUS guided transrectal biopsy is a safe method with a high diagnostic accuracy in the assessment of pelvic tumors.