Kidney stones Why do kidney stones cause hydronephrosis? Hydronephrosis refers to the obstruction of the urinary tract, the urine secreted by the kidneys is blocked, or the passage is not smooth, urine accumulates in the kidneys, and the pressure in the renal pelvis gradually rises, after a certain period of time, resulting in dilatation of the renal pelvis and/or calyces, called hydronephrosis. Patients with kidney stones often have a combination of hydronephrosis. The cause of hydronephrosis is urinary tract obstruction. The cause of urinary tract obstruction can be congenital (e.g., pelvic-ureteral junction stenosis) or acquired (e.g., stones). Obstruction and stones are causal, as obstruction can cause stone formation; in turn, stones can cause or worsen urinary tract obstruction. When a kidney stone lodges at the exit site, such as the pelvic-ureteral junction or the calyx neck, it can cause dilatation and fluid accumulation in the renal pelvis or corresponding calyces. If the stone stalls when it drains into the ureter, it is more likely to cause hydronephrosis due to the narrow lumen of the ureter. What are the symptoms of patients after hydronephrosis caused by kidney stones? After the formation of hydronephrosis, patients will have symptoms such as pain in the affected side of the back due to the rising pressure in the renal pelvis and calyces. In case of acute obstruction, patients may experience colic, which is manifested as severe pain in the lumbar region, unbearable, even restlessness, profuse sweating, also accompanied by nausea and vomiting, and obvious percussion pain on the affected side of the lumbar region during physical examination. In chronic obstruction, the symptoms are mostly discomfort and distension in the lumbar region. If secondary urinary tract infection occurs, systemic symptoms such as increased pain, chills and fever may appear. As the function of urine secretion by the glomerulus decreases after hydronephrosis, toxins cannot be discharged from the body. Patients with bilateral hydronephrosis or congenital isolated kidney with only one kidney may show symptoms of renal insufficiency such as anorexia, depression, anemia and swelling. A small number of patients with bilateral kidney stones or isolated kidney stones present with acute urinary tract obstruction and clinical manifestations of acute anuria. What tests are needed for suspected kidney stones combined with hydronephrosis? Ultrasound is a simple, safe and non-invasive test that can not only understand the location, size and number of kidney stones, but also determine the extent of hydronephrosis and the condition of the kidney parenchyma. However, the resolution of ultrasound image is poor, and it is affected by the intestinal contents, so it is usually only used as a preliminary examination. More accurate examination methods are CT and intravenous urography (IVU). there are two types of CT, plain and enhanced, and the latter requires intravenous injection of contrast agent, which has certain impact on kidney function. If the patient has renal insufficiency, the enhanced CT examination is not suitable, and likewise the IVU examination is not suitable. Second, hydronephrosis How is the severity of hydronephrosis classified? The severity of hydronephrosis can be divided into 3 levels: mild, moderate and severe. From the perspective of pathological anatomy, mild hydronephrosis means only hydronephrosis in the renal pelvis, moderate is hydronephrosis in both pelvis and calyces, and severe hydronephrosis is when the whole kidney is filled with urine and has lost its normal shape. In clinical practice, ultrasound examination is often used to determine: (1) mild hydronephrosis: kidney morphology and size are not significantly abnormal, renal parenchyma thickness and echogenicity are normal, renal collecting system is separated by 2-3 cm. (2) moderate hydronephrosis: kidney volume is mildly increased, morphology is full, parenchyma is mildly thinned, renal column is not clear, renal pelvis and calyces are significantly dilated, renal collecting system is separated by 3-4 cm. (3) Severe hydronephrosis: the kidney volume increases, the morphology is abnormal, the parenchyma is significantly thinner or cannot be displayed, and the whole kidney area is liquid dark area. If only a single calyx is hydronephrosis and the renal pelvis is normal (e.g., caused by a calyx stone), it is usually classified as mild. How to treat hydronephrosis caused by kidney stones? From a professional point of view, hydronephrosis is not a disease, but a pathological change after the obstruction of the urinary tract, so the key to treat hydronephrosis is to release the obstruction of the urinary tract. For hydronephrosis caused by kidney stones, as long as the stones are cured, the hydronephrosis will be reduced or eliminated naturally. Depending on the size, location and time of obstruction of stones, different methods such as drugs, extracorporeal lithotripsy and surgery can be used to remove the stones. Sometimes in urgent cases, such as acute urinary tract infection or renal insufficiency, in order to relieve the condition as soon as possible, we can first treat the hydronephrosis and drain the urine, while leaving the stones to be treated after the condition improves. The treatment methods are percutaneous renal puncture and drainage and transurethral ureteral built-in tube drainage. Can kidney function be restored after hydrocele is eliminated? Why? After the formation of hydronephrosis, the kidney function on the affected side is inevitably affected, and the degree of the effect depends on the obstruction site, the degree of obstruction, the duration and other factors. After the obstruction is removed, the hydronephrosis can be reduced or disappeared, and the kidney function can be restored, but the amount of restoration depends on the time and age of the obstruction. If the obstruction is incomplete, that is, partial obstruction, urine passage but not smooth, or just individual calyces fluid accumulation, then the impact on renal function is smaller, and renal function will recover faster after fluid elimination. On the contrary, if the obstruction is complete, it will have a greater impact on renal function. Studies have shown that after a few weeks of complete obstruction, irreversible damage to the kidney will occur, and even if the obstruction is lifted, the kidney function cannot be completely restored to normal. Therefore, once hydronephrosis occurs, the obstruction should be removed as soon as possible. In addition, the recovery of renal function is also related to the age of the patient, the younger the age, the easier the recovery of renal function.