Referred pain
Pain felt in one part of the body that actually originates from another.
Referred pain is pain perceived at a site away from its true source. Because nerves from different structures converge on shared pathways into the spinal cord, the brain can misattribute where a signal began, which is why a problem in one region can be felt somewhere else entirely.
It matters for diagnosis: treating the place where pain is felt can miss the structure that is generating it. Regions such as the lower back, buttock and pelvis are particularly prone to this, with pain around the sacroiliac joint often linked to referral patterns originating in the thoracolumbar spine.
Clinicians deal with this by screening: systematically examining the regions that could be referring pain into the symptomatic area before settling on a diagnosis. When that step is skipped, both individual diagnoses and research studies built on them become less reliable.