Scoliosis can be diagnosed curing a physical examination performed by a school nurse, pediatrician or orthopedic surgeon. The principal sign is asymmetry of the back, as the spine bends sideways and twists. Most commonly, this is detected by noticing a hump on the ribs or flank, between the ribs and hip, after asking the child to bend forward. The tilt produced in the back can be measured in degrees by a level — 7 degrees or more is considered significant for scoliosis. Other signs of scoliosis include elevation of one shoulder compared with the other, tilting of the pelvis which may in turn make one leg appear shorter than the other, and a difference in the contours of the flanks.

The next step after the physical examination is an X-ray of the spine.

If a child with scoliosis is suspected of having an underlying disease, other tests may be necessary. Symptoms of possible underlying disease include significant pain, pigmented markings or a hairy patch on the skin or a deformity of the foot. Certain types of scoliosis also are associated with other diseases, such as kidney disease. Other tests include an ultrasound test to look for kidney disease, and a magnetic resonance imaging (MRI) study to look for an abnormality of the nervous system.