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A 44-year-old woman presents to the emergency room shortly after developing compressive chest, which is causing severe shortness of breath. She explains that she had no previous health problems. Her surgical history includes two births by cesarean section.

Her blood pressure is 170/110 mm Hg, her temperature is 37ºC, her heart rate is 110 bpm, and her oxygen saturation is 85% while breathing ambient air.

Physical examination is indicative of normal cardiopulmonary function – her pulse is regular and she has normal bilateral air entry on chest auscultation.

Laboratory test results are as follows:

• White blood cell count: 15 × 10⁹/L

• Hemoglobin: 13.3 g/dL

• Creatinine: 0.78 mg/dL

• C-reactive protein: 2

• Troponin: 7 ng/L

• D-dimer test: positive

The electrocardiogram (ECG) shows T-wave inversion in the anteroseptal ECG leads and sinus tachycardia. No acute cardiopulmonary abnormalities are observed in the chest x-ray.

Transthoracic echocardiography performed in the emergency room reveals dilation of the right ventricle with pulmonary arterial hypertension of 45 mm Hg, a normal left ventricular ejection fraction of 65%, with no wall motion abnormalities. Pulmonary computed tomography (CT) angiography shows bilateral proximal pulmonary embolism with an abnormal renal cortex.

Given this patient's previously healthy status, clinicians performed tests to identify the underlying cause of bilateral pulmonary embolism. Tests for acquired or inherited coagulopathy, and mammography and bilateral lower extremity duplex ultrasonography returned normal results.

An enhanced CT of the abdomen and pelvis reveals a blood clot in the right renal vein extending into the lumen of the inferior vena cava (Figure).

Treatment and Outcome

Treatment with oxygen support and intravenous heparin infusion is followed by 1 year of rivaroxaban, a direct-acting oral anticoagulant (DOAC). A follow-up assessment 3 months after her discharge from hospital finds her fully recovered – she has returned to her usual daily activities without any difficulty, and has an oxygen saturation of 97% in room air.

Discussion

Clinicians reported this rare ¹ of unilateral right renal vein thrombosis (RVT) complicated by bilateral pulmonary embolism in a previously healthy 44-year-old woman without comorbidities. Uncharacteristically, the patient does not have nephrotic syndrome, which is often associated with RVT.

RVT is a rare clinical condition, with the causes varying by the age of the patient. Older adults tend to develop the condition following trauma, infection, or malignancy, while in young adults and children RVT is most often linked with nephrotic syndrome, especially membranous glomerulonephritis.^2,3

While RVT is usually bilateral, in unilateral cases it is more likely to involve the left renal vein than the right renal vein,^2,3 the clinician authors noted.

Advances in management of RVT have meant that medical treatment often replaces invasive strategies such as nephrectomy or thrombectomy. Treatment is determined based on the underlying etiology. In most cases reported in the literature, the condition is associated with nephrotic syndrome.^2,3

In patients with nephrotic syndrome complicated with RVT, atorvastatin, angiotensin-converting enzyme inhibitors, or angiotensin II receptor blockers may help slow the progression of kidney injury and reduce proteinuria.^4,5

In treatment of membranous glomerulonephritis, steroids, cyclosporine, and immunosuppressive therapies are beneficial; surgery is reserved for cases of RVT associated with early-stage renal cell carcinoma,^4,5 the authors noted.

Although there are no clinical guidelines for use of thrombolysis in RVT, have been made for management of pulmonary thromboembolism and pulmonary hypertension.⁴

In patients with RVT who experience recurrent thromboembolic events despite medical treatment, clinicians may consider an inferior vena cava filter placed below or above the renal veins.⁴ Warfarin therapy has also been recommended for prevention of thromboembolism in patients with RVT.⁶

A recent study reported that the DOAC apixaban was effective in of thromboembolic events in patients with nephrotic syndrome.⁶

Other data suggest that patients with RVT complicated with pulmonary embolism or other thromboembolic events should receive anticoagulation with either warfarin or novel oral anticoagulants (DOACs) continued for at least 1 year or until nephrotic syndrome resolves.^4-10

The case report authors pointed to the unusual characteristics of this particular case -- that it was unilateral, affecting the right renal vein, and complicated by bilateral pulmonary embolism. In addition, the patient did not have nephrotic syndrome.

The authors noted that in the absence of clinical management guidelines, the clinicians used rivaroxaban as it was previously described in studies of patients with nephrotic syndrome and coagulopathies.^9,10

Initial treatment with intravenous heparin infusion, followed by DOAC with rivaroxaban for 1 year resulted in the good clinical outcome for this patient, the case authors concluded.

References

1. Matta A, et al: A case of isolated unilateral right renal vein thrombosis associated with bilateral pulmonary embolism treated with rivaroxaban a direct-acting oral anticoagulant. Am J Case Rep 2019; 20: 1152-1154

2. Asghar M, et al: Renal vein thrombosis. Eur J Vasc Endovasc Surg 2007; 34: 217–23

3. Kerlin BA, et al: Epidemiology and pathophysiology of nephrotic syndrome associated thromboembolic disease. Clin J Am Soc Nephrol 2012; 7: 513–520

4. Singhal R, Brimble KS: Thromboembolic complications in the nephrotic syndrome: Pathophysiology and clinical management. Thromb Res 2006; 118:397–407

5. Laskowski I: Renal vein thrombosis. Medscape 2018. https://emedicine.medscape.com/article/460752-overview

6. Sexton D, et al: Direct-acting oral anticoagulants as prophylaxis against thromboembolism in the nephrotic syndrome. Kidney Int Rep 2018; 3(4): 784–793

7. Han THC, Thet Z: Warfarin vs. new oral anticoagulant in primary adult nephrotic syndrome associated venous thromboembolism. Nephrology 2017;22: 64

8. Kamran HEF, et al: Venous and arterial thromboses in nephrotic syndrome: Where only warfarin has walked. J Gen Int Med 2016; 31

9. Zhang L, et al: Rivaroxaban for the treatment of venous thromboembolism in patients with nephrotic syndrome and low AT-III: A pilot study. Exp Ther Med 2018; 15: 739–744

10. Dupree LH, Reddy P: Use of rivaroxaban in a patient with history of nephrotic syndrome and hypercoagulability. Ann Pharmacother 2014; 48: 1655–1658

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