What is kidney biopsy?
Kidney biopsy is called renal puncture biopsy, which is a special tool used by doctors to remove a small piece or pieces of kidney tissue from the kidney and examine it through pathology in order to make a correct diagnosis of kidney disease. It can be said that the development of renal pathology examination is a leap in the development of nephrology. At present, the results of renal pathology examination have become the golden indicator for the diagnosis of kidney diseases.
Why kidney biopsy is needed for kidney disease patients?
There are many kinds of kidney diseases with complex etiology and pathogenesis, and the clinical manifestations of many kidney diseases are not completely consistent with the histological changes of the kidney. For example, the clinical manifestation of nephrotic syndrome, the pathology can present as microscopic lesions, focal segmental sclerosis, membranous nephropathy and many other changes, and their treatment options and prognosis are extremely different. Repeat renal pathology is sometimes required to understand the effect of treatment or to understand the progression of pathology (e.g., crescentic nephritis, lupus nephritis, etc.). In summary, the significance of renal pathology examinations are mainly as follows.
1. to clarify the diagnosis: renal diseases, especially glomerular diseases (also commonly known as nephritis), in many cases the clinical manifestations are almost similar, but there are many types of pathology, through kidney biopsy can clarify the pathological type of the disease and make a correct diagnosis.
2. guide the treatment: the treatment principles of different pathological changes can be completely different, if the treatment is only according to the clinical manifestations, it may cause some patients ineffective, delay the timing of treatment, over-treatment and other adverse consequences, while the pathological results obtained by kidney biopsy can guide the treatment. And through pathological observation, experienced renal pathologists can often also suggest whether the kidney disease is secondary to the changes, guiding clinicians to look for the primary cause. In addition, some patients with mild microscopic hematuria or a small amount of proteinuria have a heavy psychological burden, and having a renal biopsy to determine that the lesion is indeed mild can reduce the heavy psychological pressure; and many patients with mild clinical manifestations have been confirmed by renal biopsy that the pathological changes are not mild, and the rapid development of a treatment plan or revision of the original plan to control the development of nephritis can maintain stable renal function.
3. Estimation of prognosis, the prognosis is different with different pathological manifestations. Pathological findings can also determine whether acute or chronic renal failure and renal function impairment is likely to be reversed? Moreover, once chronic nephritis progresses to uremia, pathological diagnosis is also an important reference to determine whether the patient is suitable for kidney transplantation. Repeat kidney biopsy can also observe the effect of treatment so that the treatment plan can be revised.
What are the methods of kidney biopsy?
Renal biopsy is one of the most important means of obtaining pathological specimens of the kidney and there are four main methods.
Open renal biopsy: surgical exposure of the lower pole of the kidney, direct visualization and hemostasis, which is less blind, has a high success rate of sampling, can be taken from multiple sites, and is conducive to the diagnosis of focal renal lesions, but has many complications.
Transvenous biopsy: A tube is placed through the right internal jugular vein to reach the lower pole of the kidney, a transvenous nephrostomy needle is placed, and the material is taken by negative pressure suction, which has the advantage that the puncture bleeding flows into the circulation, but the operation is cumbersome.
Transperitoneal biopsy: With the maturation of laparoscopic technology, some studies have used laparoscopic retroperitoneal kidney biopsy. As with open renal biopsy, trans-laparoscopic renal biopsy may be considered only when percutaneous renal biopsy has failed or is contraindicated and a renal biopsy is necessary.
Percutaneous renal puncture biopsy: It is the most popular method at home and abroad.
Our department adopts the “B-ultrasound real-time guided oblique angle needle 1-second rapid kidney biopsy technique, which is operated by experienced chief physicians, convenient and fast, with high safety. So far, more than 30,000 kidney biopsies have been performed without any major complications leading to nephrectomy or death.
What are the conditions that require kidney biopsy?
1. primary kidney disease: acute nephritis syndrome, primary nephrotic syndrome, asymptomatic hematuria, asymptomatic proteinuria.
2. Secondary or hereditary kidney disease: kidney biopsy should be done when clinical suspicion cannot be confirmed or when the diagnosis has been confirmed clinically, but the renal pathology information is important for guiding treatment or determining prognosis.
3. acute renal failure: renal biopsy should be done promptly when the cause cannot be determined by clinical and laboratory examination (including chronic kidney patients with rapid deterioration of renal function).
4. transplanted kidney: when the cause of significant renal function decline is unclear, severe rejection reaction to decide whether to remove the transplanted kidney, suspected recurrence of the original kidney disease in the transplanted kidney.
Which patients belong to the high-risk group for renal biopsy?
Patients with a history of sarcoid hematuria, especially recurrent sarcoid hematuria, are most likely to develop sarcoid hematuria after surgery. Patients with a long history of hypertension and poor blood pressure control. Diabetic nephropathy, especially with hypertension and renal insufficiency. Chronic renal insufficiency, due to diabetic nephropathy, hypertension, IgA nephropathy and chronic interstitial nephritis. Patients with coagulation disorders, such as cirrhosis, preoperative anticoagulant use, and impaired coagulation tests.
What are the contraindications for kidney biopsy?
1. Absolute contraindications: massive ascites; late pregnancy; severe bleeding tendency; severe hypertension not yet controlled; mental impairment unable to cooperate; isolated kidney; hemodialysis treatment with heparin anticoagulation for less than 24 hours; renal hypoplasia or obvious atrophy of the kidney.
2. Relative contraindications: renal parenchymal infection (such as renal tuberculosis, abscess and active pyelonephritis); polycystic kidney or renal cystic lesion; inability to cooperate and to lie prone; severe anemia, blood volume deficiency; those with cardiac insufficiency, new cerebral thrombosis.
What are the preparations before kidney biopsy?
Check the coagulation time of test tube method, blood routine (platelets, hemoglobin) and prothrombin time to understand whether there is a bleeding tendency. If you have used anticoagulant drugs, such as aspirin, bimatoprost, etc., you should stop using them for more than 5 days and recheck the coagulation function before performing renal biopsy.
Kidney function should be checked and ultrasound examination of the kidney should be performed to clarify the size and structure of the kidney.
Preoperative medication: give eszopiclone 1 mg orally in the evening before surgery, which can effectively improve sleep quality to prevent preoperative blood pressure fluctuations and relieve tension. Intramuscular injection of midazolam 5-10 minutes before surgery can effectively relieve the patient’s nervousness during the operation, quietly adjust the breathing status to cooperate with the operation, and reduce the risk of bleeding complications.
Sign the consent form and kidney biopsy catharsis. Patients practice breath-holding (brief breath-holding is required during renal puncture) and bed-resting for urination (bed-resting is required for 6~24 hours after renal puncture).
How is a kidney biopsy performed?
The patient is placed in a prone position with a 5-10 cm high cotton pillow under the abdominal rib cage (equivalent to the kidney area) to reduce kidney movement, with both upper limbs on either side and the head tilted to one side. 1% iodine disinfectant is used to disinfect the skin at least three times or more. Real-time ultrasound guidance allows the operator to observe the entry path and depth of the puncture needle.
Local layer-by-layer anesthesia. Oblique angle of needle entry manual negative pressure suction puncture to remove a small amount of kidney tissue. The kidney tissue is sent for light microscopy, electron microscopy and immunopathological examination, respectively.
Postoperative precautions?
The patient is placed in a supine position and is strictly prohibited from moving, getting out of bed to urinate, defecate or cough. Blood pressure and pulse should be measured every 15 minutes for the first hour after puncture, and thereafter every hour for 3 to 4 consecutive times, and then once every 4 hours until 24 hours if there is no abnormality.
Retain urine to observe the color of urine and pay attention to the presence of hematuria and blood clots. In addition, we should observe whether there are symptoms of back pain and abdominal pain.
Generally, you can turn over in 4 hours after surgery, move around in bed in 8 hours, and get out of bed in 24 hours, but those who have concomitant hematuria, lumbago or abdominal pain should stay in bed longer until the symptoms disappear.
For those who have concomitant sarcoid hematuria, lumbar pain or abdominal pain, monitor the changes of hemoglobin and hematocrit, stay in bed absolutely, brake, avoid actions that increase abdominal pressure, and use hemostatic drugs until the sarcoid hematuria disappears. Use laxative drugs or enemas for constipation.
Post-operative complications and management of renal biopsy?
Hematuria: The incidence of postoperative microscopic hematuria is 100% and disappears within 1~2 days. Carnal hematuria 2~12%, turn to microscopic hematuria in 1~3 days, about 0.5% last 2~3 weeks. Most of the sarcoid hematuria has no change of pulse, blood pressure and hemoglobin, no blood transfusion is needed, only prolonged bed rest can be done. Sarcopenic hematuria mostly disappears within one day, and more than 80% disappear within three days, but a few cases (5%) can last for one week. The most common cause of flesh hematuria is a high puncture site or deep puncture needle entering the renal calyces. The patient should be absolutely bedridden and braked, avoiding coughing and increasing abdominal pressure; increase urine volume sufficiently to prevent clots from obstructing the ureter; enhance hemostasis and coagulation; and dynamically observe changes in the patient’s blood pressure and hematocrit. Generally do not use hemostatic allergy to avoid increasing the chance of clot formation in the ureter.
Perirenal hematoma: Perirenal hemorrhage can occur in almost every biopsy patient. If a sensitive test such as CT is performed, the incidence of perirenal hematoma is quite high, but the vast majority of patients have no clinical symptoms. If there is a postoperative decrease in hemoglobin and hematocrit, a bedside ultrasound should be performed to clarify the diagnosis and to observe the size of the hematoma and assess the amount of bleeding. Patients should be on absolute bed rest, and bleeding may stop on its own after conservative treatment. The hematoma is mostly completely absorbed within 1 month, during which there may be hypothermia. In a few patients, blood transfusion is required if the hemoglobin drops more. In severe cases, the hematoma continues to increase in size and requires surgery to stop the bleeding.
Arteriovenous fistula: The incidence is about 10% and most patients are asymptomatic. Selective renal arteriography is the most sensitive and reliable method to detect complications. 95% of arteriovenous fistulas heal within 3 to 30 months. Treatment is now mostly chosen by embolization of the renal artery branches.
Infection: incidence <0.2%, strict asepsis, active pyelonephritis prohibits penetration.
Other things such as loose kidney stones, renal colic, and accidental injury to other organs are less common.