Key clinical point: A substantial proportion of women have bone marrow edema on MRI of the sacroiliac joints postpartum. When suspecting axial spondyloarthritis, clinicians may need to wait at least 6 months after delivery to perform an MRI of the sacroiliac joints.

Major finding: Within 10 days after delivery, 77% of patients had sacroiliac bone marrow edema on MRI, and 60% fulfilled the Assessment of SpondyloArthritis International Society (ASAS) definition of a positive MRI for sacroiliitis. After 6 months, 46% had bone marrow edema on MRI, and 15% had a positive MRI according to the ASAS definition.

Study details: A prospective observational study of 35 women aged 18-45 years who had an uncomplicated, vaginal childbirth.

Disclosures: The study was supported by an ASAS research grant. The authors declared having no competing interests.