Interpretation patterns for mixing study results include the following scenarios:
- If the results of the mixing study show correction for both the immediate and incubated PT/aPTT tests, the patient most likely has a factor deficiency (or multiple factor deficiencies).
- If the results of the mixing study show no correction in either the immediate or incubated PT/aPTT, the patient may have a coagulation inhibitor, most likely a lupus anticoagulant.
- If the results of the mixing study show correction for the immediate PT/aPTT results, but no correction in the incubated PT/aPTT, the patient may have a slow-acting inhibitor such as anti-factor VIII.
Note: if the control tubes also show prolongation after incubation, there may have been a problem with the heat-labile factors in the sample losing their activity. If this is the case, the mixing study should be repeated.