Most acute renal colic is caused by stones, and most of them occur in ureteral stones, so the so-called “renal colic” is in fact mostly ureteral colic. Renal colic has specific pathophysiological changes and clinical manifestations, and it can be regarded as an independent disease (identity) in clinical practice. Nowadays, with the development of clinical medical technology, the pathophysiology of renal colic and the concept of diagnosis and treatment are also changing accordingly. 1, pathophysiology Acute renal colic is due to the reactive muscle contraction caused by upper urinary tract stones, the mechanism of occurrence of two: 1, stones in the renal pelvis, ureter, rapid movement or sudden impaction, resulting in acute obstruction of the upper urinary tract, due to increased tension in the lumen wall, pain receptors in these areas are stretched to cause severe pain; 2, ureteral or calyx wall edema and smooth muscle ischemia to increase the inflammatory transmitters. activates more pain receptors, further aggravating the pain. Meng Xiangjun, Department of Urology, Dongguan People’s Hospital When upper urinary tract obstruction persists without relief, a series of pathophysiological changes will occur. In a model of acute upper urinary tract obstruction, both renal pelvic pressure and renal blood flow are increased during the first 15 h. In the following 4 h, renal pelvic pressure remains high but renal blood flow begins to decay. After this period, both pelvic pressure and renal blood flow began to decay. The initial increase in renal blood flow is mediated by prostaglandins, which also lead to diuresis, increased intrapelvic pressure, and redistribution of renal plasma flow in the cortex and medulla. With a further decrease in blood flow, it also affects glomerular filtration rate, renal blood flow, and renal oxidative metabolism, and these physiological and biochemical parameters decrease over several hours and reach their lowest values 2 h after unilateral ureteral occlusion. Therefore, when obstruction caused by stones affects renal function, the best treatment is to decompress the kidney and reduce the risk of renal injury by removing the stones, placing a ureteral stent or percutaneous puncture nephrostomy. 2. Diagnosis The qualitative and localized diagnosis of stones complicated by renal colic depends mainly on imaging. Stones causing renal colic are usually small, and in the past, a single plain imaging test (e.g., KUB) was used, which could easily lead to a missed diagnosis or a mistaken belief that the stone had been expelled. Nowadays, with the application of non-enhanced spiral CT (UHCT) technology, the detection rate of stones is greatly improved. 2.1. Ultrasound In China, ultrasound has become the preferred screening method for the diagnosis of renal colic. Its main advantage is that it is independent of the nature of the stone, either X-ray translucent or radiopaque stones, and it can also be used to identify some other acute abdominal conditions. A mild dilatation of the renal collecting system usually begins 6 h after the onset of acute renal colic, which is indirect evidence that a stone has triggered the colic. However, ultrasonography has its limitations: 1) it is a highly subjective test, and the operator’s experience and interest have a greater impact on the detection rate; 2) a homogeneous body (e.g., kidney tissue or urine in the bladder) is needed as a background for the stone image, the so-called “sound window”, but ureteral stones are more difficult to detect because of the lack of such a background. However, ureteral stones are more difficult to detect due to the lack of such background, unless the obstruction of the stone causes the ureter to dilate and form a “waterway” as a localization guide, otherwise the diagnostic error is large or even impossible, especially in the middle ureteral stones. Therefore, B-ultrasound results alone should not be used as the only basis for confirming the diagnosis by imaging. In recent years, Doppler ultrasound has been used abroad to diagnose acute renal colic by determining the impedance index (RI). It is believed that this technique has high sensitivity and specificity for the assessment of acute unilateral upper urinary tract obstruction, and is particularly suitable for patients in pregnancy who are not suitable for X-ray examination. 2.2. Abdominal plain film KUB is a routine test for the diagnosis of renal colic. Although 90% of urinary stones are theoretically X-ray blocked stones, the detection rate of stones in emergency KUB is actually much lower than this value due to the presence of intestinal distension in most patients with renal colic and the generally small size of stones causing renal colic, as well as the possibility of being blocked by bone. Two investigations in the United States and Japan found that the stone detection rate for routine KUB in acute renal colic was less than 50%. It was previously thought that the remaining undetected stones were probably due to their small size and had expelled themselves before the KUB examination, but in fact the majority of stones remained in the urinary tract. The sensitivity and specificity of KUB plus ultrasound for the qualitative diagnosis of stones is equal to or even higher than that of IVU. 2.3. Intravenous urography IVU was once the gold standard for the diagnosis of renal colic. IVU was once the gold standard for the diagnosis of renal colic, but its sensitivity is only 64% and is no longer the preferred diagnostic method. When IVU is performed during or within two weeks after the onset of colic, the urinary tract is often unremarkable. This phenomenon of “non-functioning kidney”, also known as “silent kidney”, is caused by transient functional oliguria due to acute upper urinary tract obstruction. This is a reversible renal impairment, and the kidneys usually start to show after two weeks, and most of them can return to the previous level after four weeks. During this period, IVU may present with parenchymal renal imaging, which is due to the reabsorption of contrast from the small intrarenal veins caused by intraurethral hypertension. Because of the poor visualization of IVU in acute renal colic, it can only indicate acute renal impairment without clarifying the pathological pattern of the urinary tract. In terms of localization and diagnosis, it is not superior to other methods, and because contrast agents can aggravate renal function damage, emergency IVU has been replaced by KUB plus ultrasonography in recent years abroad. However, IVU examination is still needed in certain cases: 1. percutaneous nephrological, ureteroscopic or open surgical treatment is required; 2. suspected urological tumor; 3. diabetes mellitus with stone renal colic and suspected to be renal papillary necrosis; 4. abdominal plain film and ultrasound fail to meet the diagnostic requirements. 2.4 Spiral CT UHCT is the most reliable imaging method for the diagnosis of upper urinary tract stones because it can perform continuous scanning without missed layers and is very accurate. uHCT is very sensitive and can clearly show even uric acid stones with X-ray transillumination and tiny stones less than 05 mm. After an attack of colic, UHCT often shows subperitoneal fluid, which is a strong supporting evidence for the diagnosis of acute renal colic. The sensitivity of spiral CT is 94%~100%, the specificity is 92%~99%, and the diagnostic accuracy is 94%~100% in the qualitative and localization diagnosis of stones. Therefore, UHCT is currently advocated abroad as the first choice for acute renal colic patients, and the diagnosis can be confirmed in the majority of cases. It should be noted that because UHCT is too sensitive, it can sometimes reveal intrarenal calcified spots as Randall’s vesicles and be treated as renal microstones. Because of the high cost of this test, it is generally appropriate in China only for renal colic that cannot be confirmed by the aforementioned methods, especially for ureteral stones complicated by renal colic. MRU can show urinary tract fluid and also assess renal function, similar to standard IVU imaging, and it can still provide clear imaging evidence for those who do not show IVU. One study showed that gadolinium-enhanced MRU is more sensitive than T2-weighted series MRI for detecting ureteral stones and obstruction. In addition, MRU can identify physiologic versus pathologic dilatation of pregnancy. Because of its absence of radiation, it is particularly suitable for diagnosing acute renal colic in pregnant women and children. The management of acute renal colic complicated by stones is based on two main concepts: 1) analgesia and 2) stone removal. 3.1, analgesia For renal colic efficacy of the commonly used analgesics are currently recognized as non-steroidal anti-inflammatory drugs and narcotic analgesics. Currently, the clinical use of non-steroidal anti-inflammatory drugs (NSAIDs) is increasing. the analgesic mechanism of NSAIDs is to reduce the biosynthesis of pain transmitters such as prostaglandins in the kidney; reduce local edema and inflammation, and inhibit the increase in peristalsis caused by ureteral smooth muscle excitation and reduce ureteral internal pressure. In a randomized, controlled, prospective study of NSAIDs and morphine, the two drugs were found to have equal and significant relief of renal colic. The following three NSAIDs are commonly used for the treatment of renal colic: 1. Diclofenac sodium, the first analgesic recommended in the 2005 European Society of Urology guidelines for urolithiasis, is commonly used as a suppository or tablet of 50 mg twice daily for 3 to 10 days when stone self-exclusion is expected, not only to prevent the occurrence of colic, but also to reduce ureteral edema and facilitate stone exclusion. 2. (ketorolac), the international evidence-based medicine method has proved that ketorolac is an effective drug for the treatment of renal colic. Ketorolac is an isobutyric acid NSAIDs, commonly used in the amount of 30-60 mg / time, the maximum amount of 120 mg / d, continuous use of no more than 2 days. 3, anti-inflammatory pain, is a commonly used in the treatment of renal colic non-steroidal anti-inflammatory drugs, the use of anti-inflammatory pain anal suppository 100 mg, once a day. Although NSAIDs can reduce the degree of pain in renal colic, they can also potentially interfere with the kidney’s self-regulation of obstruction production by inhibiting prostaglandin synthesis. prostaglandins E-2 and I-2 are able to regulate renal blood flow, glomerular filtration rate, renin release, urine concentration and sodium and potassium secretion. The application of ketorolac to unilateral ureteral obstruction in dogs showed no effect on renal blood flow on the contralateral side, whereas on the obstructed side it could be decreased by 35%, and the decrease in renal blood flow could last up to 4 hours after a single dose. In normal subjects this effect is well tolerated, but in patients with underlying renal disease the use of NSAIDs may induce acute renal failure. Narcotic analgesics: For the management of renal colic, pethidine has long been used as standard analgesic therapy. Data on the effect of opioid analgesics on ureteral tone are controversial, but experimental effects have generally shown either increased or no effect on ureteral tone, and increasing ureteral tone can have the opposite effect. In addition, some drug users sometimes disguise symptoms of renal colic to deceive the use of narcotic analgesics. In this regard, narcotic analgesics are currently used mainly for those with poor analgesic effect of NSAIDs, and the commonly used drug is pethidine at a dose and usage of 1 mg/ kg body weight. The European Society of Urology believes that the use of strong opioids should be combined with atropine. Currently, there is a wide range of drugs available for the treatment of renal colic in China, and their use is not sufficiently standardized. Some drugs are not analgesics per se, such as calcium channel antagonists, progesterone, etc. Although they can theoretically reduce smooth muscle tone and thus act as antispasmodic and analgesic, their efficacy is not exact. In China, M-blockers such as atropine are widely used, but they are not effective and have large side effects, so they should not be used alone. Recently, some people abroad have pointed out after clinical studies that M-blockers such as scopolamine may be theoretically presumed to be effective with limited actual effects. In addition, another disadvantage of antispasmodics is that they slow down ureteral peristalsis, which is not conducive to stone removal, and this is one of the reasons for not advocating the use of antispasmodics alone. 3.2. Lithotripsy 3.2.1. Shock wave lithotripsy: SWL has been used to treat acute renal colic since its introduction, but it is controversial. Later, after a lot of clinical practice, it is now believed that there is a rationale for using SWL to treat stones complicated by renal colic. 3.2.2 Surgical procedures: ureteroscopic and percutaneous nephrolithotomy and conventional ureterotomy.