How to choose anesthesia for a patient who was scheduled to undergo cesarean section in the emergency department with 5 coagulation tests, abnormal prolongation of TT, and no previous history of coagulation dysfunction?
Before analyzing the etiology of this patient with abnormal TT prolongation, let's first understand the customization of PT, APTT, and TT.
l Prothrombin time (PT): the time required to determine plasma coagulation by simulating all the conditions of exogenous coagulation in vitro.
PT = exogenous pathway coagulation factors + common pathway coagulation factors (I, II, V, X)
l Activated partial thromboplastin time (APTT): the time required to determine plasma coagulation by simulating all the conditions of endogenous coagulation in vitro.
APTT = 内源性凝血因子 + 共同途径凝血因子(I、II、V、X)
l Thrombin time (TT): The time it takes for a fibrin clot to form after the addition of standardized thrombin (an intermediate product of the common coagulation pathway) to plasma. TT reflects changes in the amount or function of fibrinogen.
At the same time, the coagulation system does not exist in isolation, and both the anticoagulation and fibrinolytic systems affect PT, APTT, and TT. The main causes of PT, APTT, and TT abnormalities are as follows:
The patient had no abnormalities in PT and APTT, indicating that there were no abnormalities in the coagulation factors involved in the internal/exogenous coagulation pathway, and the amount of fibrinogen (FIB/Fg) was in the normal range, and the patient could exclude a history of DIC or heparin-like use. Therefore, dysfunction of FIB should be considered in this patient, with a high suspicion of hereditary dysfibrinogenemia (CD).
CD is a genetic disease caused by FIB gene defects resulting in abnormal molecular structure and functional defects of FIB, which belongs to class II defects in FIB deficiency disorder, most of which are inherited by autosomal dominance, and only one parent carries the defective gene to inherit it to its offspring. CD is not a rare disease.
The clinical manifestations of CD patients are diverse, with about 55% of CD patients having no symptoms, 25% having bleeding manifestations, 20% having thrombosis, and some patients having both bleeding manifestations and thrombosis. It should be noted that some asymptomatic patients with CD have a greater risk of bleeding or thrombosis during surgery, pregnancy, postpartum and traumatic emergencies.
At present, there is no unified diagnostic criteria for CD at home and abroad. Commonly used laboratory tests for CD include FIB, PT, APTT, TT. Although FIB is one of the coagulation factors involved in the common pathway (FI), PT and APTT are not sensitive for the diagnosis of FIB-deficient disease, so PT and APTT results are usually unremarkable in patients with CD. TT is a sensitive test for CD, and the vast majority of patients with CD have prolonged TT. Mass spectrometry and DNA sequencing can also be used for the diagnosis of CD with high specificity and accuracy.
In summary, although the patient who was to undergo cesarean section had normal PT and APTT and no previous history of coagulation dysfunction, there was a high suspicion of CD. Since asymptomatic CD patients are at higher risk of bleeding or thrombosis in traumatic situations such as surgery, we believe that general anesthesia is a more optimal choice of anesthetic option.
Bibliography:
Zhou Weijie,Yan Jie,Deng Donghong,Lin Faquan.Diagnosis of hereditary abnormal fibrinogenemia[J].Chinese Journal of Laboratory Medicine,2020,43(4):406-410.DOI:10.3760/cma.j.cn114452-20191120-00681.
Department of Anesthesiology, 903rd Hospital of the People's Liberation Army, Wang Jingyu, Yang Xuezhi
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