All physician specialties and non-physician practitioners are required to use ICD-10 CM diagnosis codes and must code to the highest level of specificity.
Reference 
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Section 4317(b) of the Balanced Budget Act of 1997.
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Medicare Carriers Manual 4020.3C.
If the physician has confirmed a diagnosis based on the results of the diagnostic test, the physician interpreting the test should code that diagnosis. The signs and/or symptoms that prompted ordering the test may be reported as additional diagnoses if they are not fully explained or related to the confirmed diagnosis. If the diagnostic test did not provide a diagnosis or was normal, the interpreting physician should code the sign(s) or symptom(s) that prompted the treating physician to order the study.
Diagnoses documented in the medical record as ‘probable’, ‘suspected’, ‘questionable’, or ‘rule out’ should not be coded with ICD-10 CM codes. Instead, code the condition(s) to the highest degree of certainty for that visit such as the symptoms, signs, abnormal test results or other reason for the visit or request for services.
Source:
CMS, Transmittal B-01-61
Date: SEPTEMBER 26, 2001
SUBJECT: ICD-9-CM Coding for Diagnostic Tests