The RBC’s here have stacked together in long chains. This is known as “rouleaux formation” and it happens with increased serum proteins, particularly fibrinogen and globulins. Such long chains of RBC’s sediment more readily.
This is the mechanism for the sedimentation rate, which increases non-specifically with inflammation and increased “acute phase” serum proteins.
Differential Diagnoses:
- Plasma cell Neoplasms (e.g. plasma cell myeloma)
- Chronic liver disease with hypergammaglobulinemia
- Chronic infections
- Chronic inflammation
- Evaluating the wrong area of a slide (e.g. thick area of a blood smear with pseudo-rouleaux)
Source: http://library.med.utah.edu