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To the editor On October 15, 2022, the IX Scien  tific Conference entitled “Venous thromboem bolism:an underestimated problem” took place iWarsaw in a hybrid form. It attracted a to tal of 366 participants—320 onlineand 46 on  site. The conference has been organized annu  ally since 2014, whenthe World Thrombosis Day was established by the International Society on Thrombosis and Hemostasis (ISTH).It is cele  brated on October 13, the birthdayanniversary of RudolfVirchow, who pioneered the research into the pathogenesis of thrombosis and contributed to our better understanding of this condition.

Our aim is to increase the awareness of throm  bosis, highlighting its significance, risks, as well as signs and symptoms. Thrombosis is still mis  understood and often overlooked by clinicians. Worldwide, 1 in 4 people die from conditions caused by thrombosis. Early identification of an at risk patient facilitates diagnosis and treat  ment, which can often lead to recovery.Pulmo  nary embolism, when left untreated, is associat  ed with a mortality rate of up to 30%, but when treated early, the mortality rate drops to 8%. It is necessary to highlight the burden of venous thromboembolism (VTE), which has serious health consequences if undiagnosed for a long time and insufficiently treated. VTE may also occur at unusual and often critical locations, for example, in the intracerebral, retinal, or intra  abdominal venous circulation, and can result from a variety of inherited or acquired prothrom  botic states. Thrombosis is still the main cause of death in compound mediated disorders, for ex  ample, paroxysmal nocturnal hemoglobinuria.

Thrombosis constitutes a dilemma in pregnant women. To assess the risk of thrombosis during pregnancy and to introduce preventive measures, and sometimes treatment, a gynecologist should have adequate knowledge and experience. In addi tion, an active cooperation with a hematologist is needed. The outbreak of the COVID 19 pandem  ic has brought about new challenges in the diag  nosis of thrombotic complications and antithrom botic treatmentof this disease. Finally, the choice of an anticoagulant regimen is important and may be difficult, especially in older patients with comor  bidities, such as cancer or renal failure.

During the IX Scientific Conference, numer  ous important topics related to thrombosis were presented and discussed by specialists in hema  tology, cardiology, and gynecology. All lectures are available on the educational platformrun by the Group for Hemostasis of the Polish So  ciety of Hematology and Transfusion Medicine (hemostasis.edu.pl).

1. When to considerthromboprophylaxis in pregnancy– Marzena Dębska
2. Complement system inhibition reduces the risk of thrombosis: insights from cases with paroxysmal nocturnal hemoglobinuria (PNH) – Maria

Podolak‑Dawidziak

1. 2022 ISTH updates – Magdalena Łętowska
2. Secondary prevention of venous thromboem‑bolism: target patients,the choice of medication, and duration of treatment in the era of DOACs

– Anetta Undas

1. Different faces of thrombosis—iTTP – Jerzy Windyga 6 Thrombosisin unusual sites – Jacek Treliński
2. Antithrombotic treatmentin patients with COVID‑19: 2022 ISTH guidelines – Jacek Musiał
3. Management of patientsafter acute pul‑ monary embolism: 2022 ESC guidelines – Piotr Pruszczyk

Information on the previous Scientific Confer‑ ences held by the Group for Hemostasis of the Pol‑ ish Society of Hematology and Transfusion Med‑ icine can also be found in Polish Archives of Inter- nal Medicine,1, 2 which actively supports this valu‑ able initiative to reduce thrombosis‑related mor‑bidity and mortality.

None declared.