Value of the activated partial thromboplastin time for preoperative detection of coagulation disorders not revealed by a specific questionnaire

Preoperative screening for bleeding disorders: A comprehensive laboratory assessment of clinical practice

BACKGROUND

Patients with mild bleeding disorders are at risk of perioperative bleeding, but screening for these disorders remains challenging.

OBJECTIVES

We aimed to assess the prevalence of hemostatic abnormalities in patients with and without reported bleeding symptoms on a preoperative questionnaire, consisting of guideline-proposed questions, and appraised the diagnostic value of several screening modalities for the identification of patients with hemostatic abnormalities.

METHODS

In this observational study, 240 patients with and 95 patients without bleeding symptoms on the preoperative questionnaire were included. Patients with known bleeding disorders, antithrombotic drugs, thrombocytopenia, and anemia were excluded. Preoperatively, all patients underwent elaborate hemostatic testing. Hemostatic abnormalities were defined as coagulation, vWF, or fibrinolysis factor levels below reference range and platelet function defects. Screening modalities included the ISTH Bleeding Assessment Tool (ISTH-BAT), PT, aPTT, TT, Euglobulin Lysis Time (ELT), and Platelet Function Analyser (PFA).

RESULTS

In 21 of 240 (8.8%) patients reporting bleeding symptoms, hemostatic abnormalities were found, including 7 reduced coagulation factor levels, 10 platelet function abnormalities, and 4 reduced vWF levels. In comparison, 10 of 95 (10.5%) patients not reporting bleeding symptoms had abnormalities. The ISTH-BAT could not identify patients with abnormalities, while PT, aPTT, TT, ELT, and PFA had high specificity but low sensitivity to detect abnormalities.

CONCLUSIONS

The prevalence of hemostatic abnormalities in both patients with and without reported bleeding symptoms was 9%-10%. This suggests that the guideline-based questionnaire cannot differentiate between patients with and without abnormalities, while the discriminative power of the screening modalities is also limited.

Pre-interventional haemostatic assessment: Guidelines from the French Society of Anaesthesia and Intensive Care

Recently the French Society of Anaesthesia and Intensive Care (Société Française d'Anesthésie et de Réanimation [SFAR]) issued recommendations for the prescription of routine preoperative testing before a surgical or non-surgical procedure, requiring any type of anaesthesia. Thirty clinical specialists performed a systematic analysis of the literature, and recommendations were then developed using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) system. One part of these guidelines is dedicated to haemostatic assessment. The goal of pre-anaesthetic screening for congenital or acquired haemostatic disorders is to prevent perioperative haemorrhagic complications through appropriate medical and surgical management. Preoperative assessment of bleeding risk requires a detailed patient interview to determine any personal or family history of haemorrhagic diathesis, and a physical examination is necessary in order to detect signs of coagulopathy. Laboratory investigation of haemostasis should be prescribed, not systematically, but depending on clinical evaluation and patient history. Standard tests (prothrombin time, activated partial thromboplastin time, platelet count) have a low positive predictive value for bleeding risk in the general population. Patients with no history of haemorrhagic diathesis and no conditions liable to interfere with haemostasis should not undergo pre-interventional haemostasis testing. Conversely, the existence of a positive history or a disease that could interfere with haemostasis should be an indication for clinically appropriate testing.

[Is a biological assessment necessary to realize an obstetrical epidural anaesthesia in a patient whose interrogation and clinical examination are strictly normal?]

In France, coagulation blood tests are usually ordered before performing an epidural anaesthesia. This French habit obeys to the fear of triggering an epidural haematoma induced by neuraxial anaesthesia. This analysis of literature shows that these practices do not protect anaesthesiologists against this clinical risk or its medico-legal consequences. As shown by epidemiological studies, epidural haematoma in pregnancy is associated to the occurrence of HELLP syndrome. On the opposite, gestational thrombocytopenia is not associated to any bleeding risk. According to the recommendations of the French Society of Anaesthesia (Sfar), only a clinical examination and an interrogatory must be done to diagnose coagulation defects before general or loco regional anaesthesia. Normal pregnancy is not an exception to this rule except for the platelet number which must be evaluated during the 3rd trimester of pregnancy. This platelet numeration might detect a rare idiopathic thrombopenic purpura. This recommendation is valid only for normal pregnancy. The clinician must ensure that pregnancy is still normal by seeking for symptoms of pregnancy-induced pathology such as preeclampsia or HELLP syndrome before setting an epidural anaesthesia. The possibly late occurrence of these complications during the per- or post-partum explain why a coagulation test performed even a few days before anaesthesia may not allow to detect any coagulation defect favouring the risk of epidural haematoma.

[Preoperative evaluation of hemorrhagic risk]

Evaluation of bleeding risk before surgery requires both precise knowledge of epidemiological data relating to haemostasis disorders and a true clinical approach to help guide the diagnosis. The patient's individual and familial history is recovered during both the interview with the anaesthesiologist and the clinical examination. Preoperative haemorrhage risk prevalence is 1/40,000 patients in patients with asymptomatic congenital haemostasis disorders with low bleeding and 1/2,000 patients for acquired asymptomatic haemostasis disorders. Deficits in haemostasis factors, i.e., congenital disorders with haemorrhage potential, have an overall prevalence of 1/6,500 patients. Whatever the clinical case, haemorrhage disorders will arise in patients with either congenital or acquired bleeding abnormalities without symptoms. To work in close collaboration with haemobiologists and to request appropriate biological screening tests, it is therefore important to take into account prevalence data according to the surgical environment from which the patient will benefit.