Fecal hemoglobin stability in FOB testing
At ADLM 2026, Sentinel is presenting abstract n. 6460 on the impact of storage conditions on qualitative fecal hemoglobin (Hb) results, comparing raw stool samples with buffered collection devices. Fecal occult blood (FOB) testing is widely used for colorectal cancer screening, detection of lower gastrointestinal bleeding, post‑polypectomy surveillance, and triage of symptomatic patients, but Hb in native stool is unstable and can degrade during storage and transport. This degradation may cause false‑negative results and misclassification, especially when Hb concentrations are close to the clinical decision threshold.
Study design and storage conditions
The study evaluated five individual stool specimens classified as negative, positive near the 100 ng/mL cut‑off, or highly positive, tested both as raw stool and in SENTiFIT® pierceTube devices containing a preservation buffer. Samples were stored at multiple temperatures (from −70 °C to +38 °C) for up to 60 days depending on the condition, and qualitative FOB classifications at each timepoint were compared with baseline results.
Key findings on raw and buffered sampless
Raw stool showed progressive Hb degradation over time, with faster loss of positivity at higher temperatures and considerable inter‑sample variability, while frozen storage improved but did not fully preserve stability. In contrast, buffered samples maintained complete qualitative concordance for positive specimens across most storage conditions, with stability up to 60 days at refrigerated and frozen temperatures and up to 14 days at 25–28 °C; at 38 °C, positivity was preserved for 2 days before declining. Negative specimens remained negative in both raw and buffered formats throughout the study.
Clinical impact of buffered collection devices
The use of buffered collection devices such as SENTiFIT® pierceTube helps stabilize fecal Hb immediately after collection, reducing the risk of false‑negative FOB results and preserving result integrity during transportation and storage. This improved stability supports at‑home sample collection, flexible logistics, and reliable CRC screening and triage workflows, including in remote areas where environmental temperatures and transport times are difficult to control.