Objectives Bone marrow oedema (BMO) on MRI of sacroiliac joints (SIJs) represents a hallmark of axial spondyloarthritis (SpA), yet such lesions may also occur under augmented mechanical stress in healthy subjects. We therefore sought to delineate the relationship between pregnancy/delivery and pelvic stress through a prospective study with repeated MRI. Results were matched with maternal, child and birth characteristics.
Methods Thirty-five women underwent a baseline MRI-SIJ within the first 10 days after giving birth. MRI was repeated after 6 months and, if positive for sacroiliitis according to the Assessment of SpondyloArthritis International Society (ASAS) definition, after 12 months. BMO and structural lesions were scored by three trained readers using the Spondyloarthritis Research Consortium of Canada (SPARCC) method.
Results Seventy-seven per cent of the subjects (27/35) displayed sacroiliac BMO immediately postpartum, 60% fulfilled the ASAS definition of a positive MRI. After 6 months, 46% of the subjects (15/33) still showed BMO, representing 15% (5/33) with a positive MRI. After 12 months, MRI was still positive in 12% of the subjects (4/33). Few structural lesions were detected. Intriguingly, in this study, the presence of BMO was related to a shorter duration of labour and lack of epidural anaesthesia.
Conclusion A surprisingly high prevalence of sacroiliac BMO occurs in women immediately postpartum. Our data reveal a need for a waiting period of at least 6 months to perform an MRI-SIJ in postpartum women with back pain. This study also underscores the importance of interpreting MRI-SIJ findings in the appropriate clinical context.
- magnetic resonance imaging
- low back pain
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FEVdB and DE are joint senior authors.
Handling editor Josef S Smolen
TR and AD contributed equally.
Contributors TR and AD contributed equally to this manuscript and share first authorship. FEVdB and DE both supervised the manuscript and act as senior author. TR, AD, GV, FEVdB and DE conceived of the presented idea. ID, GV and KR helped in recruiting the subjects. TR, AD, A-SDC, LD, GV and PC recruited the subjects and collected the study data. LJ, MdH and NH evaluated and scored the magnetic resonance images. A-SDC did the statistical analyses. TR and AD wrote the manuscript. FVdB and DE reviewed the manuscript.
Funding This observational prospective study has been supported by an Assessment of SpondyloArthritis International Society (ASAS) research grant. DE is supported by grants of the Fund for Scientific Research-Flanders (FWO), an Excellence of Science Grant (EOS), Fund for Scientific Rheumatology Research (FWRO) and the Research Council of Ghent University.
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting or dissemination plans of this research.
Patient consent for publication Not required.
Ethics approval This study was approved by the Ethics Committee of the Ghent University Hospital. All study subjects provided written informed consent.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available on reasonable request.
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