The sudden appearance of pain in the left rear waist of men mainly consider the following two aspects: 1, acute lumbar sprain on the left side of the back, usually with a clear history of trauma, at night only shows pain at the left rear waist injury, pain increases with activity, rest can be significantly improved, the local buckling pain is more obvious, magnetic resonance examination can see the local muscle or fascia injury signal. Treatment requires rest, wearing a lumbar girth, and those with significant pain can take oral meloxicam and other non-steroidal anti-inflammatory drugs for symptomatic treatment, which can be improved in about a week. 2. Left-sided urinary stones, most commonly left-sided ureteral stones, are mainly caused by the partial detachment of stable stones in the kidney, which are embedded in the left ureter, resulting in ureteral spasm and blockage, causing pain with paroxysmal colic, and some patients have The pain is paroxysmal colic and some patients have hematuria, which can be clarified by ultrasound or urological CT examination. Treatment requires temporary antispasmodic treatment with pain medication to promote the discharge of stones and unblock the ureter. If the effect is not obvious, extracorporeal lithotripsy can be considered.