Purpose: The aim of this study was to evaluate the use of rectal endosonography for preoperative staging of tumour extension and lymph node involvement in rectal tumours.
Material and methods: Over a 4-year period 100 patients with rectal tumours were studied with sonography using 7 MHz endoprobes. Tumour spread was assessed according to the TNM classification, and the number and maximum size of perirectal lymph nodes were registered. The sonographic findings were compared with the surgical and histological findings.
Results: The overall accuracy of endosonography in assessing local tumour extension was 85% (76-91%; 95 percent confidence limits). T4 tumours with a large contact surface to an adjacent organ tended to be nonresectable. Lymph node assessment could be made in 81 patients who underwent radical resection: sonography showed lymph nodes in 49 patients, 30 of whom had nodal metastases; the histological examination showed lymph nodes in the remaining 32 patients, 8 of whom had nodal metastases. The number of lymph nodes at the histological examination was markedly higher than the number depicted by preoperative ultrasound.
Conclusion: This study confirmed the use of endoluminal ultrasound in the preoperative evaluation of local tumour spread. However, endosonographic assessment of perirectal nodal involvement seems to be too unreliable to be used for the preoperative selection of patients.