Background: The use of complementary radiological studies for suspected pulmonary embolism (PE) during the same clinical episode is uncommon and is usually due to a suboptimal or indeterminate initial study. However, the prevalence and decision-making in this clinical scenario are uncertain. Aim: The objective of this study was to determine the appropriateness of complementary studies (computed tomography angiography [CTA] and perfusion single-photon emission computed tomography/low-dose computed tomography [SPECT/ldCT]) in patients with suspected acute PE in real-world clinical practice. Methods: We analyzed all patients who underwent both tests for suspected PE during the same clinical process over a 10-year period. Results: Pulmonary CTA and perfusion SPECT/ldCT were performed as complementary studies in 4.42% of patients with suspected PE. In 69.7% of these patients, CTA was the initial diagnostic test and was subsequently followed by perfusion SPECT/ldCT, of which 64.6% were considered to have been inappropriately indicated. In 30.3% of patients, an initial lung perfusion SPECT/ldCT was followed by CTA; of these, 26.4% of CTA and 33.9% of perfusion studies were considered inappropriate. The overall agreement between the results of both tests was 49.3%. Conclusion: At least one imaging test was considered inappropriately indicated in 67.6% of patients who underwent both tests. This may result in unjustified risk associated with these procedures, unnecessary increase in costs, and additional difficulty in interpreting the high proportion of studies with discrepant results. Diagnostic and treatment protocols should be implemented in patients with suspected PE to reduce differences in clinical outcomes and optimize resource use. Relevance for patients: Inappropriate indications for radiological studies may cause unnecessary harm to certain patients, especially with regard to contrast-induced nephropathy.