BAL: to exclude infection. Infection is considered in the differential of PGD, acute rejection (ACR, AMR), and BO/BOS.
ACR: histopathological findings are the gold standard diagnostic test.
AMR: histopathological findings and positive C4d stain are suggestive diagnostic features.
BO: pathological findings are characteristic; disease is patchy and biopsy may be negative; not required for diagnosis.
Recurrence of the primary lung disease such as sarcoidosis.
Malignancy such as post-transplant lymphoproliferative disorder.
Dehiscence in early post-operative period.
Stenosis and malacia can cause abnormal spirometry; differential diagnosis of BOS.
Sensitive in detecting graft dysfunction;
BOS: irreversible obstructive pattern; > > 20% decline in FEV1 of baseline
RAS: irreversible restrictive pattern; > 20% decline in FEV1 of baseline.
Cardiac dysfunction: cardiogenic edema or volume overload may cause diffuse lung opacities and should be considered in the differential of PGD in particular.
Pulmonary venous thrombosis: in the differential diagnosis of PGD.
Aspiration: in the differential of PGD and acute rejection; may co-exist with either one; it is a potential risk factor of BO/BOS