- •
Although the activated partial thromboplastin time (aPTT), prothrombin time (PT), and international normalized ratio (INR) are widely used in routine preoperative testing, these hemostatic tests are not reliable predictors of perioperative bleeding in patients without known bleeding risk factors.
- •
A preoperative bleeding history and physical examination are usually obtained in an attempt to identify important bleeding risk factors. However, current questionnaires used to assess bleeding history
Clinical Use of the Activated Partial Thromboplastin Time and Prothrombin Time for Screening: A Review of the Literature and Current Guidelines for Testing
Section snippets
Key points
aPTT
The aPTT is a global coagulation screening test that is used for assessment of the coagulation status in patients with suspected acquired deficiencies of coagulation factors of the intrinsic and common pathways of the coagulation system. The test is affected by multiple factors, including the levels of factors VIII, IX, XI, XII, X, II, and fibrinogen. The aPTT is widely used for monitoring anticoagulation therapy with low levels of heparin (from 0.1 IU/mL to approximately 1 IU/mL). In a normal
PT and INR
The PT measures the time required for clotting to occur after the addition of a source of tissue factor to recalcified citrated plasma in laboratory instruments and on point of care (POC) devices. The PT is measured by adding thromboplastin (a mixture of tissue factor, calcium, and phospholipid) to a patient’s citrated plasma sample, and clot formation is determined. It is used also as a screening assay to detect deficiencies of one or more coagulation factors (fibrinogen and factors II, V,
Utility of aPTT and PT: evidence from the literature
Findings of previously published reviews of the literature on coagulation testing are summarized in Table 2.2, 10, 11, 12, 13, 14, 15, 16, 17, 18 The overwhelming conclusion from these reviews is that routine preoperative hemostatic testing with aPTT and PT is not useful in asymptomatic patients with no known risk factors. Moreover, with aPTT and PT, the high rate of false-positive and false-negative results may lead to inappropriate precautionary measures or false reassurance, respectively.12
Drugs
As would be expected from their indications, anticoagulant therapies (warfarin, heparin, low-molecular-weight heparins) will prolong aPTT and PT test results to a varying extent, depending on the pharmacologic agent. In addition, the antibiotic daptomycin may impact aPTT reagents leading to falsely prolonged results.58
Test Reagents
As described above, test results may vary with the reagent used. Prolonged aPTT times have been reported with micronized silica, celite, and ellagic acid as activators.59 Even
Preoperative Bleeding History and Physical Examination
A preoperative bleeding history and physical examination should be considered to potentially identify any of the bleeding risk factors summarized in Box 113 because many factors may contribute to the bleeding risk. Of paramount importance, a careful medication history should be obtained, including over-the-counter medicines that may contain aspirin and use of any anticoagulation agents or herbal supplements that may affect hemostasis such as platelet function. Particular attention should be
Summary
Coagulation testing using aPTT and PT/INR tests are not reliable predictors of excessive perioperative bleeding risk in patients without other known risk factors. Although routine preoperative use of these tests is common, the data do not support their utility for screening. However, they are used extensively for anticoagulation monitoring with many different anticoagulation agents. A thorough patient and family history, together with physical examination, is vital to identify patients at
References (89)
- et al.
Effect of body mass index on early outcomes in patients undergoing coronary artery bypass surgery
J Am Coll Cardiol
(2003) - et al.
Lupus Anticoagulant (LAC) testing in patients with inflammatory status: does C-reactive protein interfere with LAC test results?
Thromb Res
(2010) Perioperative coagulation monitoring
Best Pract Res Clin Anaesthesiol
(2010)Preoperative clinical assessment of hemostatic function in patients scheduled for a cardiac operation
Ann Thorac Surg
(1996)- et al.
A prospective multicenter evaluation of preoperative hemostatic screening tests. The French Associations for Surgical Research
Am J Surg
(1995) - et al.
Preoperative evaluation of hemostasis in patients with congenital heart disease
Mayo Clin Proc
(1987) - et al.
Predictors of excessive blood use after coronary artery bypass grafting. A multivariate analysis
J Thorac Cardiovasc Surg
(1989) - et al.
Predictive value of blood clotting tests in cardiac surgical patients
Ann Thorac Surg
(1994) - et al.
Coagulation tests during cardiopulmonary bypass correlate with blood loss in children undergoing cardiac surgery
J Cardiothorac Vasc Anesth
(1999) - et al.
Coagulation profile as a predictor for post-tonsillectomy and adenoidectomy (T + A) hemorrhage
Int J Pediatr Otorhinolaryngol
(1994)
Post-tonsillectomy haemorrhage–do coagulation tests and coagulopathy history have predictive value?
Acta Otorrinolaringol Esp
Value of preoperative prothrombin time/partial thromboplastin time as a predictor of postoperative hemorrhage in pediatric patients undergoing tonsillectomy
Otolaryngol Head Neck Surg
An assessment of preoperative coagulation screening for tonsillectomy and adenoidectomy
Int J Pediatr Otorhinolaryngol
The utility of preoperative hemostatic assessment in adenotonsillectomy
Int J Pediatr Otorhinolaryngol
The need for routine pre-operative coagulation screening tests (prothrombin time PT/partial thromboplastin time PTT) for healthy children undergoing elective tonsillectomy and/or adenoidectomy
Int J Pediatr Otorhinolaryngol
Pre-operative hemostatic assessment and management
Transfus Apher Sci
How to interpret and pursue an abnormal prothrombin time, activated partial thromboplastin time, and bleeding time in adults
Mayo Clin Proc
Stability of prothrombin time and activated partial thromboplastin time tests under different storage conditions
Clin Chim Acta
Implications for cardiac surgery in patients with factor XII deficiency
Ann Thorac Surg
Factor XI deficiency in humans
J Thromb Haemost
Passovoy factor deficiency in five Western Australian kindreds
Pathology
Lack of a scientific basis for routine discontinuation of oral anticoagulation therapy before dental treatment
J Am Dent Assoc
Perioperative management of antithrombotic therapy: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines
Chest
Parenteral anticoagulants: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines
Chest
Fresh frozen plasma: the most commonly prescribed hemostatic agent
J Thromb Haemost
Is administering blood as useless as blood letting?
J Thromb Haemost
The prevalence of moderate and severe FXII (Hageman factor) deficiency among the normal population: evaluation of the incidence of FXII deficiency among 300 healthy blood donors
Thromb Haemost
Routine preoperative testing: a systematic review of the evidence
Health Technol Assess
Guidelines on the assessment of bleeding risk prior to surgery or invasive procedures. British Committee for Standards in Haematology
Br J Haematol
Comparison of four commercially available activated partial thromboplastin time reagents using a semi-automated coagulometer
Blood Coagul Fibrinolysis
Defining, establishing, and verifying reference intervals in the clinical laboratory; approved guideline
Pediatric reference values for molecular markers in hemostasis
J Pediatr Hematol Oncol
Preoperative routines. The Swedish Council on Technology Assessment in Health Care
Int J Technol Assess Health Care
The preoperative bleeding time test lacks clinical benefit: College of American Pathologists' and American Society of Clinical Pathologists' position article
Arch Surg
Role of coagulation testing in predicting bleeding risk
Hematol J
Screening for the risk for bleeding or thrombosis
Ann Intern Med
Predicting hemorrhage using preoperative coagulation screening assays
Curr Hematol Rep
Central laboratory and point of care assessment of perioperative hemostasis
Can J Anaesth
Post-tonsillectomy bleeding: a meta-analysis
Laryngoscope
Prothrombin and partial thromboplastin times as preoperative screening tests
Arch Surg
Value of the preoperative history as an indicator of hemostatic disorders
Ann Surg
A prospective evaluation of the efficacy of preoperative coagulation testing
Ann Surg
Abnormal peri-operative haemorrhage in asymptomatic patients is not predicted by laboratory testing
S Afr Med J
Cited by (0)
Conflict of Interest Statements: Prof. J.H. Levy serves on steering committees for Boehringer Ingelheim, CSL Behring AG, Grifols, Janssen Pharmaceuticals, and The Medicines Company. F. Szlam, Dr AM Winkler, and Dr A.S. Wolberg have no relevant conflict of interest to disclose.