CHAPTER 19: Hematologic Evaluation

PREOPERATIVE IDENTIFICATION AND PROPHYLAXIS OF THE HYPERCOAGULABLE PATIENT

Clinical Considerations¹

• Renal artery thrombosis, renal artery stenosis, and renal vein thrombosis are serious complications, requiring prompt diagnosis and management.

• Uncommon but can lead to graft loss.

• Vascular thrombosis presentation: Sudden anuria or oliguria, tenderness, swelling, ipsilateral extremity edema.

• Ultrasound with Doppler is the initial study of choice.

• Ultrasound findings: Edematous and enlarged kidney, decreased echogenicity, altered parenchymal architecture.

• Doppler findings: Peaked systolic signals with retrograde signal on diastole and absent venous signal.

Major Clinical Thrombophilic Risk Factors

• History of ≥2 arteriovenous access thromboses

• Prior allograft thrombosis

• Multiple miscarriages (in the setting of antiphospholipid syndrome and hereditary thrombophilia)

• Prior deep vein thrombosis (DVT) or pulmonary embolism (PE)

• Collagen vascular diseases

• Diabetic nephropathy

• Positive family history of thrombosis

Additional Clinical Risk Factors

• Estrogen replacement

• Malignancy

• Age over 40 years

• Obesity

• Nephrotic syndrome

• Chronic tobacco use

• Hepatitis C virus

Mechanical Risk Factors²

• Arterial diameter size (differs with body size)

• Multiple renal arteries

• Stenosis of the donor renal artery

• Atherosclerosis in donor or recipient

• Surgical trauma

• Acute rejection

• Prolonged cold ischemia time with reperfusion damage

Pharmacologic Risk Factors

• Erythropoietin can increase thrombosis risk

• Calcineurin inhibitors like cyclosporine A (CSA) and tacrolimus (FK-506) increase thrombophilia

• CSA can increase factor VIII and tissue factor (TF), in addition to reducing protein C

• Antithymocyte globulins (ATGs) can cause platelet activation, thrombosis, and thrombocytopenia

Types of Hereditary and Acquired Thrombophilia

• Activated protein C (APC) resistance (factor V Leiden [FVL])

• Prothrombin gene mutation

• Decreased Proteins C and S and antithrombin III (ATIII) deficiency

• Lipoprotein(a)

• Antiphospholipid syndrome (APLS): Elevation of Beta 2 glycoprotein 1 (B2GP1), and/or anticardiolipin (ACL), and/or lupus anticoagulant positivity.

• Heparin-induced thrombocytopenia (HIT)

Reported Effects of Hereditary and Acquired Thrombophilia

• FVL:

  • 3 X increased risk of DVT

  • 3.3 X increased risk of graft loss when compared to those without FVL

• Prothrombin gene mutation

  • 3.1× increased risk of DVT

  • 7.4× increased risk of graft loss

• Protein S deficiency is associated with renal graft loss and arterial and venous thromboses.

• Hyperhomocysteinemia increases the occurrence of coronary artery disease threefold if levels of homocysteine surpass 30 μmol/L. It may increase the occurrence of DVT, but increase in graft loss has not been reported.

• APLS: Up to 19% serology positive prevalence in chronic renal failure (CRF).

• APLS in combination with hepatitis C virus (HCV) infection with high titers exceeding 40 IgG phospholipid units (GPL) has been found to increase incidence of graft loss and DVT.

• Risk is enhanced in patients with a prior history of thrombosis.

Incidence of Posttransplant Thrombosis³

• Renal transplant is associated with an 8% risk of DVT/PE within the ...