Effective September 1, 2007, documentation requirements for fetal fibronectin testing (CPT-4 code 82731) will change. You no longer need to document in the Reserved for Local Use field (Box 19) of the claim that the patient is symptomatic for pre-term labor. Entering ICD-9-CM diagnosis code 644.03 (premature labor after 22 weeks but before 37 weeks of completed gestation without delivery) in the diagnosis field on the claim is sufficient documentation to justify billing code 82731.