title: Reduced plasma fibrinolytic potential in patients with recurrent implantation failure after IVF and embryo transfer.
abstract: BACKGROUND
  Recurrent implantation failure (RIF) following embryo transfer (ET) is a major continuing problem in IVF. Women with haemostatic defects may be at increased risk of miscarriage and preclinical pregnancy loss. The fibrinolytic system is considered, at present, the key to new thrombotic pathogenic mechanisms. Patients with unexplained recurrent miscarriage have an impairment of fibrinolysis, as demonstrated by prolonged clot lysis time (CLT) in association with increased plasma levels of thrombin-activatable fibrinolysis inhibitor (TAFI). In this study, we investigated fibrinolytic potential in patients with RIF.
  
  
  METHODS
  Three groups of patients were studied: 30 women with RIF (RIF group), 60 patients undergoing a first successful IVF-ET cycle (IVF group) and 60 healthy fertile women (FER group). Plasma CLT was measured using a global fibrinolysis assay. TAFI antigen plasma levels and polymorphisms in the TAFI gene (+505A/G and +1542C/G) were analysed using enzyme-linked immunosorbent assay and allele-specific PCR, respectively.
  
  
  RESULTS
  CLT was significantly longer (P < 0.0001 and P < 0.0009, respectively) and TAFI antigen levels were significantly higher (both P < 0.0001) in the RIF versus the IVF and FER groups. A direct relationship between CLT and TAFI antigen levels (r = 0.40; P = 0.001) was detected in the whole study population. There were no differences in distribution of TAFI polymorphisms between groups.
  
  
  CONCLUSIONS
  Patients with RIF have reduced plasma fibrinolytic potential, as shown by a prolonged CLT, and this may be explained, at least in part, by increased TAFI antigen levels.
authors.affiliation: Institut Clínic of Gynecology, Obstetrics and Neonatology, Hospital Clínic, Villarroel 170, 08036 Barcelona, Spain.
authors.forename: M Angeles
authors.initials: MA
authors.lastname: Martínez-Zamora
authors.forename: Montserrat
authors.initials: M
authors.lastname: Creus
authors.forename: Dolors
authors.initials: D
authors.lastname: Tassies
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Reverter
authors.forename: Salvadora
authors.initials: S
authors.lastname: Civico
authors.forename: Francisco
authors.initials: F
authors.lastname: Carmona
authors.forename: Juan
authors.initials: J
authors.lastname: Balasch
mesh_terms: D000483:Alleles; D025901:Carboxypeptidase B2 / Q000097:blood / Q000235:genetics; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro; D005342:Fibrinolysis; D006403:Hematologic Tests; D006801:Humans; D007246:Infertility / Q000097:blood* / Q000150:complications / Q000235:genetics / Q000628:therapy*; D007247:Infertility, Female / Q000097:blood / Q000150:complications / Q000235:genetics / Q000628:therapy; D020641:Polymorphism, Single Nucleotide; D012189:Retrospective Studies; D012307:Risk Factors; D013030:Spain; D013927:Thrombosis / Q000150:complications*; D017211:Treatment Failure
chemical_list: D025901:Carboxypeptidase B2