Postpartum patients may be at risk for false-positive axial spondyloarthritis diagnosis
Click Here to Manage Email Alerts
As many as 41% of patients who are 1 year postpartum meet the ASAS criteria for sacroiliitis, which could lead to false positive diagnoses of axial spondyloarthritis, according to data published in Arthritis & Rheumatology.
“Subchondral bone marrow edema (BME) at the sacroiliac joints (SIJs) identified by magnetic resonance imaging (MRI) is a key finding in axial spondyloarthritis (axSpA), a chronic inflammatory disease involving the axial skeleton,” Rosa Marie Kiil, PhD, of Aarhus University Hospital, in Denmark, and colleagues wrote. “The causes of pregnancy-related [lower back pain (LBP)] and/or buttock pain remain unclear, but strain at the SIJs may be a contributing factor.”
To investigate the prevalence and change in sacroiliac joint MRI lesions in pregnant and postpartum patients, the Kiil and colleagues conducted a prospective cohort study from February 2019 through September 2021 of 103 first-time mothers older than 18 years. For women enrolled during pregnancy, MRIs were scheduled at gestational weeks 20 and 32. Following delivery, MRIs were scheduled at 3, 6 and 12 months’ postpartum. Seventy-one women underwent the final MRI at 12 months’ postpartum.
A team of two radiologists and one rheumatologist found the greatest prevalence of BME at the 3-month postpartum timepoint, in 69% of participants, using the Spondyloarthritis Research Consortium of Canada (SPARCC) method of assessment. Using the same assessment, BME was still present at 12 months in 54% of participants.
Using the Assessment of Spondyloarthritis International Society (ASAS), the researchers found 41% of participants met the current definition of sacroiliitis at 12 months postpartum, while 21% met the proposed ASAS MRI criteria for active sacroiliac joint lesion. However, the researchers rarely found ligamentous BME and observed SPARCC erosion scores of 3 or greater in only 2.8% of women at 12 months.
“In addition to the common presence of SIJ BME postpartum, structural lesions increased in the postpartum period, contributing to a risk of false-positive diagnosis of axSpA in postpartum women presenting with back pain,” Kiil and colleague wrote.
“However, the topographical distribution of BME predominantly in the anterior middle cartilaginous joint portions and the virtual absence of the clinically relevant SPARCC erosion score of 3 at 12 months postpartum may help discriminate pregnancy-related conditions from sacroiliitis due to axSpA,” they added. “During a 12 months postpartum period, assessment of SIJ MRI remains a major challenge towards reliable interpretation in clinical settings where early axSpA is suspected.”
Collapse
Click Here to Manage Email Alerts