Basics
Description
- Most common non " ôcatheter-related thromboembolism in the neonatal period
- May also be associated with nephrotic syndrome, hypercoagulable states, and oral contraceptive use
- May present with a clinical triad of flank mass, gross hematuria, and thrombocytopenia
Epidemiology
- Most commonly seen in the newborn period
- Slight male predominance
- In neonates, most cases are unilateral, with the left kidney more frequently affected.
Incidence
- Not well-defined due to lack of data
- Ranges from 0.5 to 2.3 per 100,000 live births
Prevalence
Accounts for 16 " ô20% of thromboembolic events in newborns é á
Risk Factors
- Maternal diabetes mellitus
- Birth asphyxia
- Dehydration/blood loss
- Polycythemia
- Cyanotic heart disease
- Hypercoagulable states
- Nephrotic syndrome
- Venous catheter
- Sepsis
- Oral contraceptive use
- Renal transplant recipient
Genetics
- ó ł ╝50% of affected neonates have at least 1 hereditary prothrombotic risk factor.
- Factor V Leiden, protein C/S, and MTHFR mutations and lupus anticoagulant
General Prevention
- Maintaining a high index of suspicion in patients at risk (i.e., infant of diabetic mother, child with nephrotic syndrome)
- Counseling regarding the importance of adequate fluid intake and avoidance of dehydration, especially in newborn infants
- Prophylactic anticoagulation may be indicated in certain populations, although conclusive data is lacking.
Pathophysiology
- Thrombus formation is initiated by endothelial cell injury from hypoxia or other insults.
- In neonates, non " ôcatheter-related renal vein thrombosis is believed to originate in the arcuate or interlobular veins, as evidenced by early ultrasound findings.
- Thrombosis may extend to the main renal veins and inferior vena cava.
- Neonates also have decreased levels of protein C, protein S, antithrombin, and plasminogen, which may make them more susceptible to thrombosis.
- Lower renal blood flow may also predispose neonates to venous thrombosis.
- In older children, thrombosis may be associated with nephrotic syndrome, hypercoagulable states, or cyanotic heart disease.
- Renal venous thrombosis can result in renal enlargement, decreased renal venous flow, and increased arterial resistive indices.
- Adrenal hemorrhage and left varicocele may also result from renal venous thrombosis.
Diagnosis
History
- More than half of neonatal cases present within 3 days of birth and almost all within the 1st month of life.
- Macroscopic hematuria is seen in about half of affected infants.
- The classic triad of flank mass, gross hematuria, and thrombocytopenia is present in less than 25% of patients.
- Signs and symptoms:
- Palpable flank mass
- Abdominal/flank pain
- Hematuria
- Dehydration/shock
- Edema
- Fever
- Hypertension
- Varicocele
Physical Exam
- Palpable enlarged kidney can be found in about half of neonates.
- Abdominal/flank tenderness
- Periorbital/peripheral edema
- Left varicocele
- Hypertension
Diagnostic Tests & Interpretation
Lab
- Urinalysis
- Macroscopic or microscopic hematuria
- Proteinuria
- Complete blood count
- Thrombocytopenia is seen in about half of affected neonates.
- Hemolytic anemia may be present on peripheral blood smear.
- Coagulation tests
- Prothrombin time and partial thromboplastin time may be prolonged.
- Fibrin split products may be elevated.
- Plasma fibrinogen levels may be decreased.
- Tests for hypercoagulable states, such as factor V Leiden or lupus anticoagulant, should be performed.
- Renal function tests
- Increased blood urea nitrogen (BUN) and/or creatinine may be present due to acute kidney injury.
- Electrolyte abnormalities may exist depending on the underlying disease and degree of renal insufficiency.
Imaging
- Ultrasonography
- Pathognomonic echogenic streaks may be seen with early clot formation.
- Progresses to renal enlargement and increased parenchymal echogenicity
- Later findings include loss of corticomedullary differentiation and calcified thrombi in the renal veins.
- Doppler ultrasound
- Demonstrates decreased or absent renal venous flow
- May see increased arterial resistive indices
Differential Diagnosis
- Renal tumors (Wilms, mesoblastic nephroma)
- Pyelonephritis/renal abscess
- Hematoma
- Cystic kidney disease
- Obstructive uropathy
- Thrombotic microangiopathy (hemolytic uremic syndrome [HUS], thrombotic thrombocytopenic purpura [TTP])
Treatment
Medication
- The American College of Chest Physicians Evidence-Based Clinical Practice Guidelines for Antithrombotic Therapy in Neonates and Children (9th edition) recommend the following:
- For unilateral renal vein thrombosis (RVT) in the absence of renal impairment or extension into the inferior vena cava (IVC), either (1) supportive care with radiologic monitoring for extension of thrombosis (if extension occurs, anticoagulation is suggested) or (2) anticoagulation with unfractionated heparin (UFH)/low-molecular-weight heparin (LMWH) or LMWH in therapeutic doses rather than no therapy. If anticoagulation is used, a total duration of between 6 weeks and 3 months rather than shorter or longer durations of therapy.
- For unilateral RVT that extends into the IVC, anticoagulation with UFH/LMWH or LMWH for a total duration of between 6 weeks and 3 months
- For bilateral RVT with evidence of renal impairment, anticoagulation with UFH/LMWH or initial thrombolytic therapy with tissue plasminogen activator (tPA) followed by anticoagulation with UFH/LMWH
- However, the overall evidence supporting these recommendations is weak. Also, no recommendations exist for patients with unilateral RVT and renal impairment or patients with prothrombotic risk factors.
Additional Treatment
General Measures
- Treatment of the underlying disease process, if present
- Management of acute kidney injury (i.e., fluid imbalance, electrolyte abnormalities, hypertension)
Issues for Referral
Patients with renal venous thrombosis should be evaluated by a nephrologist and hematologist. é á
Surgery/Other Procedures
- Surgery is rarely indicated, except possibly for malignancy-related cases or refractory hypertension or infection.
- Local thrombolytic therapy via an angiocatheter has been reported for severe IVC thrombosis and bilateral RVT causing renal failure.
Inpatient Considerations
Initial Stabilization
Supportive therapy for the underlying process, correction of fluid/electrolyte imbalance, and pain control é á
Admission Criteria
- Admission for treatment of an underlying cause, if present
- Renal impairment
- Pain management
- Thrombolytic therapy
Ongoing Care
Follow-up Recommendations
Patient Monitoring
Long-term monitoring for development of hypertension, renal atrophy, or chronic renal insufficiency é á
Prognosis
- Treatment with anticoagulants may not change renal outcomes.
- RVT has a low mortality rate but may result in significant complications.
- Patients require long-term follow-up to screen for development of hypertension, renal atrophy, proteinuria, or renal insufficiency.
- Hypertension develops in ó ł ╝20% of patients with neonatal RVT.
- Chronic kidney disease has been reported to develop in up to 71%.
- However, end-stage renal disease is uncommon and is more commonly associated with bilateral RVT.
- Death is uncommon and is usually related to the underlying disease process.
- Certain findings may be linked to worse outcomes, such as the following:
- Kidney size >6 cm at presentation
- Decreased overall renal perfusion by Doppler ultrasound
- Subcapsular bleeding
- Patchy hypoechogenicity or
- Irregular pyramids
Complications
- Hypertension
- Renal atrophy
- Proteinuria
- Renal insufficiency
Additional Reading
- Brandao é áLR, Simpson é áEA, Lau é áKK, et al. Neonatal renal vein thrombosis. Semin Fetal Neonatal Med. 2011;16(6):323 " ô328. é á[View Abstract]
- Goldenberg é áNA. Long-term outcomes of venous thrombosis in children. Curr Opin Hematol. 2005;12(5):370 " ô376. é á[View Abstract]
- Lau é áKK, Stoffman é áJM, Williams é áS, Canadian Pediatric Thrombosis and Hemostasis Network. Neonatal renal vein thrombosis: review of the English-language literature between 1992 and 2006. Pediatrics. 2007;120(5):e1278 " ôe1284. é á[View Abstract]
- Messinger é áY, Sheaffer é áJW, Mrozek é áJ, et al. Renal outcome of neonatal renal venous thrombosis: review of 28 patients and effectiveness of fibrinolytics and heparin in 10 patients. Pediatrics. 2006;118(5):e1478 " ôe1484. é á[View Abstract]
- Monagle é áP, Chan é áAK, Goldenberg é áNA, American College of Chest Physicians. Antithrombotic therapy in neonates and children: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines Chest. 2012;141(2)(Suppl):e737S " ôe801S. é á[View Abstract]
Codes
ICD09
- 453.3 Other venous embolism and thrombosis of renal vein
ICD10
- I82.3 Embolism and thrombosis of renal vein
SNOMED
- 15842009 thrombosis of renal vein (disorder)
FAQ
- Q: Which population is most susceptible to renal vein thrombosis?
- A: Neonates have the highest risk, especially those with a history of maternal diabetes mellitus, birth asphyxia, or dehydration.
- Q: What is the classic presentation of renal vein thrombosis?
- A: Flank mass, gross hematuria, and thrombocytopenia. However, this "triad " Ł is present in less than 25% of patients, so a high degree of suspicion must be maintained.
- Q: How is renal vein thrombosis diagnosed?
- A: Renal Doppler ultrasound can show renal enlargement, increased echogenicity, or absent renal venous flow.
- Q: What are the current treatment recommendations for renal vein thrombosis?
- A: Supportive therapy and monitoring is recommended, except for bilateral involvement, IVC extension, or evidence of renal impairment. The role of anticoagulation is otherwise still controversial.