Indications for MCP and IP Joint Arthrocentesis Diagnosis of the cause of a synovial effusion (eg, infection, crystal-induced arthritis) Removal of a synovial effusion and / or injection of medications as part of treatment and for pain relief Contraindications to MCP and IP Joint Arthrocentesis Absolute contraindications Infection of skin or deeper tissues at the anticipated site of needle insertion If possible, an alternate, uninfected puncture site should be used.