Are we being prudent or profligate? Overblocking in colorectal adenocarcinoma resections

There are two main margins in histopathological assessment of colorectal resections for primary adenocarcinoma: non-peritonealised and longitudinal margins (proximal and distal). The Royal College of Pathologists of Australasia (RCPA) recommends microscopic examination of longitudinal margins only if tumour extends within 30 mm macroscopically, unless aggressive features are present. We evaluated the utility of microscopic longitudinal margin assessment by auditing colorectal resections presented at the Royal Prince Alfred Hospital (RPAH) multidisciplinary meetings (between July 2023 and June 2025) and surveying Australasian Gastrointestinal Pathology Society (AGPS) members on sampling practices. A total of 308 specimens were identified, of which all underwent routine longitudinal margin sampling. Findings were present in 2.27% (n=7) of margin sections, including five neoplastic and two non-neoplastic abnormalities. Neoplastic findings included adenocarcinoma (n=2), sessile serrated lesion (n=1), low-grade dysplasia (n=1), and Paget disease (n=1). Both adenocarcinomas were macroscopically identified and margin status was not altered by microscopy. Regarding the survey, there were 82 participants; 89% reported routine universal longitudinal margin sampling and 91% donut sampling. Most participants believed routine microscopic examination of margins rarely yields diagnostic information (91% for longitudinal margins; 68% for donuts). A targeted approach to selective sampling could reduce costs, workload, and environmental impact without compromising patient care.