Hematuria is a common clinical symptom and the main complaint of patients visiting the clinic, with complex etiology. Common causes include urinary stones, infection, tumors (including renal cell carcinoma and urothelial tumors), urinary tract trauma and renal parenchymal lesions. Imaging is a common method to find the cause of hematuria in clinical practice, including abdominal plain film, intravenous pyelogram (IVP), retrograde pyelogram, ultrasonography, multilayer spiral CT and MRI. Because of the various causes of hematuria, each examination method has its own advantages and disadvantages, and it is worthwhile for clinicians to choose the most suitable examination method for different patients. In this regard, we have summarized the relevant literature at home and abroad in order to help the clinical rational examination. 1, abdominal plain film: It is the easiest way to detect positive urinary stones, but the detection rate of stones is limited (about 60%) due to more overlapping structures and the influence of intestinal gas, etc. In recent years, with the application of low-dose MDCT, the application of abdominal plain film has been affected, and some studies have reported that the dose of ultra-low-dose CT (0.5 mSv for men and 0.7 mSv for women) is equal to that of abdominal plain film, and the sensitivity and specificity of detecting urinary stones is about 1.5 mSv for men and 0.7 mSv for women. The sensitivity and specificity were 97% and 95%, respectively. For the detection of kidney and urinary tract tumors, abdominal plain films are of little value. Ultrasonography: Ultrasonography is noninvasive, simple, easy to perform, and economical, and is commonly used for the examination of urological lesions, and has a better diagnostic effect on kidney and bladder lesions. Recent findings suggest that ultrasonography is an important test in children and patients with low tumor risk hematuria for the evaluation of bladder lesions and renal cystic lesions. Ultrasound can be the first choice for patients with microscopic hematuria. 3. Intravenous pyelogram (IVP): Useful for evaluating indeterminate ureteral and bladder filling defects, but the low resolution of the images makes IVP limited for the demonstration of renal parenchymal lesions and for lesions of the ureteral wall of the renal pelvis and its surrounding structures, and does not provide much valuable information in patients with poor renal function. The combined application of ultrasound and IVP has certain advantages for the examination of malignant lesions of the kidney and urinary tract. 4.CT urological imaging (CTU): It can be used as a one-stop imaging technique to comprehensively evaluate urinary tract stones, kidney tumors and urinary tract tumors. It has been widely accepted that CTU is superior to ultrasound, IVP and general radiology in the evaluation of renal tumors and urinary stones, and the increasing use of multilayer spiral CT urological imaging (MDCTU) in recent years has contributed to its becoming a one-stop-shop imaging technique for patients with hematuria. Many studies have suggested that CTU can replace IVP as the imaging method for patients with hematuria. CTU has a positive predictive value of 90% for obstruction of urinary tract stones, and CT scan is superior to IVP in detecting stones, with a reported sensitivity of 98%-100% and specificity of 92%-100%. It can accurately identify urinary stones and calcified nodules in the abdominal and pelvic cavities, and helps to differentiate ureteropelvic stones from venous stones. CTU can also predict the possibility of natural expulsion based on stone size. 76% of ureteral stones with a diameter of 2-4 mm, 60% of stones with a diameter of 5-7 mm, and 48% of stones with a diameter of 7-9 mm have been reported to be expelled, and the rate of natural expulsion is less than 25% for stones larger than 9 mm. In addition, in patients with hematuria, the enhancement part of MDCTU examination is still necessary even if stones have been seen because some important pathological changes can be diagnosed only after contrast enhancement after CT plain scan has detected stones. CTU can accurately describe the location of renal tumors. Renal cell carcinoma originates in the renal cortex, whereas intrarenal migratory cell carcinoma presents as a fixed filling defect in the excretory phase, with the fat of the renal sinus displaced by compression. Although progressive migratory cell carcinoma can infiltrate into the renal parenchyma leading to destruction of adjacent tissues, the renal shape remains unchanged, thus concluding that it is not renal cell carcinoma. CTU has excellent sensitivity and specificity in detecting migratory cell carcinoma of the renal pelvis and ureter, more sensitive and specific than IVP, so it has been suggested that CTU should be used as a first-line test when the risk of lesions exceeds the risk of radiation dose, such as in patients with high-risk hematuria who are suspected of having urologic cancer. The results of an evidence-based medical study in 2010 demonstrated that CTU is a very sensitive and specific method for detecting upper urinary tract malignancies in patients with hematuria, with a sensitivity between 88% and 100%, a specificity between 93% and 100%, a meta-sensitivity of 95% (95% confidence interval is 88-100%), a specificity of 99% (95% confidence interval is 98- For patients with sarcoid hematuria, CTU has a higher possibility of detecting upper urinary tract lesions and is justified as the first-line screening tool. 5.Magnetic resonance urography (MRU): Like CTU, MRU can be used as a one-stop imaging technique to comprehensively evaluate urinary tract stones, renal tumors and urothelial tumors. Its advantages are that it is noninvasive, radiation-free, does not require contrast injection, and can show the site of urinary tract obstruction and the degree of obstruction. However, its density resolution is low and it is not sensitive to the display of urinary tract stones and calcifications. In addition, due to the long duration of MRU examination, patients with acute renal colic have difficulty in cooperating to complete the examination, and patients with pacemakers or other metal objects in their bodies cannot undergo MRU examination. In conclusion, a large body of literature shows that MDCTU is the most sensitive and specific method for diagnosing urinary tract tumors and stones and for detecting and displaying features of renal tumors. Many radiologists believe that the increased radiation dose of CTU has been replaced by a concern for the sensitivity of CTU to detect urothelial tumors, and the American College of Radiology also believes that CTU should be highly recommended for hematuria screening.