This study employs a prospective, randomized, double-blind, placebo-controlled design. It aims to compare the efficacy of etamsylate versus placebo in preventing bleeding complications in patients with thrombocytopenia following hematopoietic stem cell transplantation.

This study employs a prospective, randomized, double-blind, placebo-controlled design. It aims to compare the efficacy of etamsylate versus placebo in preventing bleeding complications in patients with thrombocytopenia following hematopoietic stem cell transplantation. The primary endpoint is the incidence of death or bleeding events (WHO grade ≥2) within 30 days. Secondary endpoints focus on the safety profile of etamsylate versus placebo.

Inclusion Criteria:

1. Age between 18 and 70 years (inclusive), regardless of gender;
2. Patients diagnosed with a hematological disease requiring hematopoietic stem cell transplantation;
3. Expected platelet count ≤ 10 x 10⁹/L persisting for 5 days or more;
4. Normal coagulation function;
5. Adequate organ function: Aspartate Aminotransferase (AST) and Alanine Aminotransferase (ALT) ≤ 3 times the Upper Limit of Normal (ULN), Total Bilirubin ≤ 2 x ULN; Serum Creatinine ≤ 2 x ULN; Creatinine Clearance ≥ 50 mL/min (calculated using the Cockcroft-Gault formula); Left Ventricular Ejection Fraction (LVEF) ≥ 50% as measured by Echocardiography (ECHO);
6. Voluntary provision of signed informed consent, with the ability to understand and comply with all study requirements.

Exclusion Criteria:

1. Diagnosis of acute promyelocytic leukemia confirmed according to WHO diagnostic criteria;
2. Pregnant or breastfeeding women, and women of childbearing potential unwilling to use effective contraception;
3. Presence of active bleeding or infection;
4. History of diagnosed primary immune thrombocytopenia or hemolytic uremic syndrome;
5. Patients with known hereditary or acquired hemorrhagic disorders;
6. Patients receiving anticoagulant or antiplatelet therapy;
7. Patients with severe cardiac insufficiency (left ventricular ejection fraction [EF] < 60%); or severe arrhythmias: history of clinically significant QTc prolongation (male > 450 ms; female > 470 ms), ventricular tachycardia, atrial fibrillation, second-degree heart block; myocardial infarction within 1 year prior to enrollment; or symptomatic coronary artery disease requiring medication; patients with severe liver impairment (liver function indices [ALT, TBIL] > 3 times the upper limit of normal [ULN]);
8. Patients with severe pulmonary insufficiency (obstructive and/or restrictive ventilatory defects);
9. Patients with severe renal insufficiency (renal function index [Cr] > 2 times ULN); or 24-hour urinary creatinine clearance rate (Ccr) < 50 ml/min;
10. Patients with mental disorders or other conditions preventing provision of informed consent and compliance with study treatment and procedural requirements;
11. Other reasons deemed by the investigator to make the patient ineligible for inclusion.