St. Louis Cardinals pitcher Kyle Lohse has been placed on the 15-day disabled list and will undergo surgery on his ailing right forearm Friday.

Lohse experienced discomfort in the forearm during his most recent start, last Saturday against the Angels, and a subsequent MRI scan showed inflammation but no evidence of structural damage.

Lohse underwent further examination and has been diagnosed with exertional compartment syndrome, which is an exercise-induced condition that causes pain and swelling, according to the Mayo Clinic’s website.

He is scheduled to have a fascial release surgery, performed by Dr. Steven Shin, Friday in Los Angeles. A return timetable has not been determined.

Lohse is 1-4 with a 5.89 earned run average in nine starts this season. In his start Saturday, Lohse allowed six runs in 3 1/3 innings.

The placement of Lohse on the disabled list is retroactive to May 23. To take his place, the Cardinals purchased the contract of pitcher Fernando Salas from Triple-A Memphis.