Sudden pain in the left side of the lower back in women, in general, the common causes are mainly the following conditions. A. Acute renal colic caused by left-sided urinary stones and impaction. Most commonly seen in left ureteral stones, embedded in the upper and middle ureter, which can cause obstruction of urinary excretion, dilatation of the upper ureter and left pelvic effusion. Patients may experience swelling and pain in the left side of the lower back with radiating pain in the groin area. At this time, the patient can clarify the condition through urological ultrasound and CT examination, and perform extracorporeal impact lithotripsy as soon as possible to break up the stones and discharge them in urine, which can release ureteral obstruction and relieve pain symptoms. In female patients, acute severe pancreatitis can be induced after overeating, causing peripancreatic tissue necrosis due to large amount of pancreatic fluid infiltration into the abdominal cavity, and causing severe pain in the left side of the waist. Patients can clarify the condition of the pancreas through enhanced CT of the pancreas and blood test for amylase. The symptoms of pancreatitis can be reduced and the pain relieved by active rehydration, strengthening anti-infection treatment and inhibiting pancreatic enzyme secretion.