Renal arteriovenous malformation is an uncommon kidney abnormality with an unusual link between renal artery and vein. 

Renal arteriovenous malformations cause hematuria and hypertension due to intrarenal arterial-venous communication. 

It is first described in 1928. Renal artery is a branch from the aorta. 

Types of AVM are: 

Congenital 

Acquired 

Cirsoid AVMs are over 1 cm near collecting system, while angiomatous AVMs are under 1 cm on periphery. 

Renal AVMs are abnormal vessels that connect arteries directly to veins without capillary network. 

Inborn abnormalities caused due to abnormal fetal vascular system development from birth. 

Lobar arteries divided into interlobar arteries within renal parenchyma near collecting system. 

Rate in large autopsy series is less than 1 case per 30000 patients. Incidence of 1 case per 1000 patients noted in clinical studies using urologic and vascular imaging techniques. 

Renal AVMs are less than 1% of all AVMs while congenital AVMs are less than one third of total cases. 

Percutaneous renal interventions such as surgery and biopsies contribute to the global incidence of renal AVMs. 

Cirsoid congenital AVM has artery-vein communications that creates coiled channels and a mass in renal parenchyma. 

Tortuous and dilated vessels are beneath renal urothelium lamina propria. Cluster of vascular channels form mass with arterial supply that originate from renal arteries. 

Arteries and veins match normal soft tissue features under microscope. Uncommon congenital AVM has one artery feeding into single cystic chamber with draining vein. 

Percutaneous renal biopsy can lead to acquired renal AVF in 15-50% of cases. Renal AVMs may develop in one third of hypertensive patients. 

AVF is common in 80% with posttraumatic hypertension due to penetrating trauma. Renal cell carcinoma shows vascular involvement, including parasitic tumor vessels, due to its vascular predilection. 

Idiopathic AVFs arise from the spontaneous erosion or rupture of a renal artery into a renal vein. 

Embolization therapy preferred for AVFs and AVMs to preserve renal parenchyma in endovascular treatment. 

AVMs in hard-to-reach areas or near vital structures in the kidney complicate treatment and risk tissue damage. 

Symptomatic patients with untreated AVM may face poor prognosis without treatment. 

Common treatment for renal AVMs is endovascular embolization and success requires complete occlusion of abnormal vessels without harm. 

Detailed information including presenting symptoms and medical history of patient should be gathered. 

• Abdominal Examination 
• Cardiovascular Examination 
• Genitourinary Examination 
• Neurological Examination 

Acute symptoms are: 

Severe Hematuria, Flank Pain, Fatigue and Anemia and Acute Kidney Injury 

Chronic symptoms are: 

Intermittent Hematuria, Flank Discomfort, Progressive Hypertension, Chronic Anemia 

Renal AVMs cause pain due to clot obstruction in the collecting system or renal capsule expansion from hemorrhage. 

Conservative therapy can be safe in some cases and observation recommended if ablation is not done during arteriography. 

Angiography confirmed disappearance of malformation without intervention needed. 

Optimize outcome with medical management to address pain, hypertension, and heart failure before surgery. 

First-line treatment for AVMs is embolization, using various substances to destroy the malformation. 

Absolute alcohol is the best material for embolization due to its cost and ease of injection through a catheter. 

Super selective embolization using coils and microspheres cautioned against coil migration to prevent potential pulmonary embolism in AVMs. 

Vascular Medicine

Patients should avoid activities such as contact sports, heavy lifting, or high-risk falls to prevent abdominal trauma. 

Patients should take a low-sodium diet control to reduce high blood pressure. 

Patients should consume adequate water intake to avoid stress on kidneys. 

Patients should record their blood pressure at home regularly and follow good hygiene practices to reduce the risk of infections. 

Proper awareness about renal AVM should be provided and its related causes with management strategies. 

Appointments with a physician and preventing recurrence of disorder is an ongoing life-long effort. 

Vascular Medicine

Lisinopril: 

It decreases certain chemicals that tighten the blood vessels, to flow blood more smoothly and efficiently. 

Metoprolol: 

It relaxes blood vessels and slows heart rate to improve blood flow and decrease blood pressure.  

Amlodipine: 

It affects the movement of calcium into the cells of the heart and blood vessels.  

Vascular Medicine

Acetaminophen: 

It targets the heat-regulating area of the brain to decrease elevated temperature and fever. 

Vascular Medicine

Endovascular embolization is the most preferred procedure for treating renal AVMs. It is a minimally invasive technique performed under an interventional radiologist. 

Sclerotherapy involves the administration of injection of a sclerosing agent directly into the AVM to induce fibrosis and occlusion of the abnormal vessels. 

Vascular Medicine

In the initial diagnosis phase, evaluation of medical history, laboratory finding and diagnostic test to confirm diagnosis. 

Pharmacologic therapy is effective in the treatment phase as it includes use of antihypertensive agents and analgesics. 

In supportive care and management phase, patients should receive required attention such as lifestyle modification and intervention therapies. 

The regular follow-up visits with the physician are scheduled to check the improvement of patients along with treatment response