"The upper limits of normal for the presacral space width is 15 mm in patients younger than 45 years old 2. However, some patients have measurements over 15 mm with no apparent reason (fewer still have 'normal' measurements above 20 mm), which increases with older age. Factors such as sex and weight of the patient should also be taken into consideration 2."
Expected headings
"Contents"
"Radiographic appearance"