What finding would you expect when investigating a patient with low back pain?

When assessing a patient with low back pain, an exacerbation of symptoms with straight-leg raising is a classic finding indicative of underlying issues such as herniated disc or nerve root irritation. The straight leg raise test is used to evaluate for nerve root irritation, specifically in the L4, L5, and S1 nerve roots, which may be affected by conditions like sciatica. When the leg is raised, if the patient experiences pain that radiates down the leg, it suggests that a nerve root may be under tension or compression, typically leading to increased pain.

The other options represent findings that could indicate more severe complications. Loss of bowel and bladder function could suggest cauda equina syndrome, which is a medical emergency. Increased ankle jerk is not a common finding with low back pain and typically indicates normal or hyperactive reflexes rather than the specific pain condition in question. Increased lumbar lordosis may occur in some patients with back pain due to muscle imbalances, but it is not a definitive finding and not as directly indicative of low back pain as the straight-leg raise test results are.