Neonatal renal vein thrombosis

　　In the 1940s, research suggested that infection, congenital heart disease, injury, and changes in umbilical artery after birth are possible causes of neonatal renal vein thrombosis. Since then, continuous observation and research on neonatal renal vein thrombosis have led researchers to propose different views on its possible causes. To date, researchers generally believe that the main causes of neonatal renal vein thrombosis include the following:

　　1. Primary kidney disease

　　Early reports indicate that neonatal renal vein thrombosis is usually caused by local hypercoagulability in the kidney during nephrotic syndrome. However, primary diseases of the neonatal kidney associated with neonatal renal vein thrombosis are rare, and only congenital nephrotic syndrome or kidney tumors are involved.

　　2. Involvement of renal vascular pedicle

　　Postperitoneal abscess or umbilical vein catheterization can cause renal (main) venous circulation obstruction, which can trigger neonatal renal vein thrombosis.

　　3. Increased blood viscosity

　　Under physiological conditions, there are more red blood cells in the peripheral blood of neonates. Reasons such as insufficient feeding, birth trauma, asphyxia, hypoxia, and ischemia can make the blood thick, and the blood viscosity increases exponentially.

　　4. Decreased renal blood flow

　　Infections, shock, maternal pregnancy-induced hypertension syndrome, or diabetes can reduce renal blood flow, thereby triggering neonatal renal vein thrombosis.

　　In addition to its clinical manifestations, neonatal renal vein thrombosis can also cause other diseases. This condition often complicates with hypertension, acidosis, jaundice, renal failure, and some patients may have complications such as hypertensive crisis.

　　The clinical manifestations of renal vein thrombosis in the neonatal period are non-specific and are often masked by the primary disease. Typical renal vein thrombosis has three major symptoms: abdominal pain, hematuria, and renal enlargement, but abdominal pain is difficult to find in the neonatal period and is replaced by thrombocytopenia. The main symptoms of neonatal renal vein thrombosis include the following:

　　1. Dehydration

　　Dehydration includes history, symptoms, and signs of concealed water loss.

　　2. Sudden hematuria and oliguria

　　Sudden appearance of hematuria, oliguria, or anuria, thrombocytopenia, and hypertension that are not directly related to the primary disease. 60% of children have gross hematuria for 24 hours, followed by persistent microscopic hematuria. 36% of children have oliguria or anuria, and proteinuria and acidosis are also common. The blood pressure of the child rises sharply after a sudden drop. Hypertension can last for several days, months, or even longer. Nausea, vomiting, abdominal distension, fever, jaundice, and general edema may also occur. Phenomena such as pulmonary and limb embolism, varicocele, or gastroesophageal varices may also be seen.

　　3. Enlarged kidneys

　　50% to 60% of children can feel enlarged kidneys. The size, thickness, and tension of the kidneys are different from those under physiological conditions. Due to increased tension inside the renal capsule, the hardness of the kidneys increases, and the patient has an uncomfortable avoidance reaction during palpation. Right-sided lesions are more common than left-sided ones, and if both sides are affected, there are differences in the extent of the lesions.

　　Infected or gastrointestinal disorders can often lead to neonatal renal vein thrombosis due to dehydration, so it is necessary to actively prevent and treat gastrointestinal diseases and severe dehydration. In addition, it is necessary to prevent situations that can increase blood viscosity, such as asphyxia, hypoxia, birth trauma, and ischemia. Preventing the causes of reduced renal blood flow such as infection, shock, maternal pregnancy-induced hypertension syndrome, diabetes, and others can help prevent this condition. Oral small-dose enteric-coated aspirin and compound Danshen tablets can reduce platelet aggregation and effectively prevent neonatal renal vein thrombosis.

　　Due to the lack of specificity in the clinical manifestations of renal vein thrombosis in the neonatal period, diagnosis mainly relies on chemical testing methods. The main examinations for neonatal renal vein thrombosis include the following:

　　1. Blood Test

　　Observation of platelet count and the dynamics of platelets helps in the judgment of thrombosis activity.

　　2. Urinalysis

　　Children may have gross or microscopic hematuria.

　　3. X-ray Plain Film

　　All children suspected of having renal vein thrombosis should have an abdominal plain film (anteroposterior and lateral views) taken to estimate kidney size and whether there is calcification shadow in the renal area.

　　4. Ultrasonic Examination

　　Ultrasonic examination, due to its painless, non-radioactive and non-invasive nature, is the preferred diagnostic method and monitoring tool for neonatal renal vein thrombosis.

　　Neonates with renal vein thrombosis should have a low-fat diet, avoid spicy, sweet, greasy foods. Eat less or no animal fats and animal internal organs, such as fatty meat, fatty intestines. The diet should be light, avoid salty, and it is best not to eat pickled vegetables. Avoid drinking stimulants such as coffee and strong tea.

　　Neonatal renal vein thrombosis not only severely affects the daily life of children, but also, if prolonged, can lead to the occurrence of other diseases. Therefore, timely treatment should be provided once diagnosed. The commonly used treatment methods are mainly the following two.

　　First, surgical treatment

　　Nephrectomy can be performed in children with advanced renal atrophy or persistent hypertension. For renal (main) vein and inferior vena cava thrombosis, thrombectomy can be performed to restore the patency of the vein.

　　Second, medical treatment

　　In the past 20 years, conservative medical treatment has been adopted. The application of anticoagulants and thrombolytic agents has significantly improved the cure rate of neonatal renal vein thrombosis.

　　1. Correcting dehydration and electrolyte imbalanceFor children with dehydration, timely fluid replacement should be provided. If there is no increase in urine output after 24 hours of fluid replacement and diuretic use, consider the possibility of acute renal insufficiency, and immediately limit fluid intake.

　　2. Radical cure and symptomatic treatment for underlying diseasesCaptopril (thiopropyl alanine) and other angiotensin-converting enzyme inhibitors can be used to treat hypertension. Hemodialysis can be used for patients with kidney function not recovered.

　　3. AnticoagulantsThe commonly used anticoagulants are heparin and warfarin, especially heparin is more commonly used. After 2 to 3 injections of heparin, fresh plasma should be infused once to replenish coagulation factors and monitor coagulation status.

　　4. Thrombolytic AgentsThe commonly used thrombolytic agents are urokinase.