One Step Nucleic Acid Amplification (OSNA)

Histopathology

---

Description

Routine histological analysis of sentinel nodes to identify metastatic deposits is not possible within an intra-operative time frame and positive findings result in further surgery to clear the axilla and a delay in starting the most appropriate post-surgery treatment regimen for patients with metastatic disease. Conventional intra-operative analysis of the SLN can be performed via frozen section or touch imprint with a rapid H&E staining. Although this will produce an intra-operative result, the sensitivity of these methods is low because only a small proportion of the lymph node tissue can be investigated. As a result, there is a considerable risk of false-negative results. OSNA (One Step Nucleic Acid Amplification) is an alternative diagnostic approach which enables analysis of the whole lymph node in an intra-operative timeframe enabling an intra-operative clinical decision and removing the requirement for a second surgical procedure or treatment delay.

---

Sample Type

Intra-operative unfixed lymph node tissue

---

Reference Range

A calculated copy number of less than 250 copies/µl is considered a negative result (equivalent to no tumour or isolated tumour cells). A copy number between 250 and 5000 per µl correlates with a micrometastasis (equivalent to a tumour deposit between 0.2mm and 2mm across.) A copy number above 5000/µl is indicative of a macrometastasis (equivalent to a tumour deposit greater than 2mm across).

---

Turnaround Time

Within 1 - 2 hours

---

Testing Frequency

Daily

---

Please note: the above information is subject to change and we endeavour to keep this website up to date wherever necessary.