DISCUSSION:
Hemothorax is defined as a pleural fluid with a hematocrit level greater than 50% of the patient’s blood. It is a clinical entity caused in most cases by trauma or iatrogenic causes through procedures such as pleural biopsies or central line insertion (3).
Spontaneous hemothorax (SH) involves the accumulation of blood within the pleural space in the absence of trauma or iatrogenic causes(3). It is extremely rare in the pediatric population with data limited to few case reports (4).
Spontaneous hemothorax etiologies in children include connective tissue disease, neoplasia, arteriovenous malformations, multiple exostosis and coagulopathy (3).
Approximately 20%-50% of hospitalized patients with COVID-19 have hematologic changes in coagulation tests (1).
Coagulopathy in Covid 19 infection is associated rather with thromboembolic events than bleeding tendency.
The pathogenesis of SARS-CoV-2-induced coagulopathy is not yet fully understood. It has been proven that the SARS-CoV-2 enters the host via the angiotensin converting enzyme receptor 2, which is expressed in cells including endothelial cells (5).
Recent evidence showed that the virus can induce endothelial activation directly or by an immune-mediated mechanism in the presence of a locally dysregulated inflammation. Activated endothelial cells release high numbers of ultra large von Willebrand factor (vWF) multimers. Under normal circumstances, vWF flows in intact vessels together with platelets and erythrocytes without binding to any blood element. Elevated microcirculatory shear stress due to endothelial cell dysfunction leads the unfolding of vWF from a globular structure to an extended chain structure exposing its binding sites. Long strands of vWF multimers becoming functionally active. It has been proven that a functional imbalance in vWF multimer sizes can lead to either microcirculation bleeding or thrombosis (5).
While a meta-analysis comprising 28,173 patients with COVID-19 estimated an in-hospital prevalence of venous thromboembolism of 14.1% (6), Researchers reported a case of spontaneous retroperitoneal hematoma in a 47-year-old woman with a COVID-19 concurrent infection. She had no medical priors and was not taking any medication(7).
Others reported 6 cases of abdominal bleeding associated with COVID-19 infection. Five of them used low/medium dosage heparin while the sixth took a high dose for pulmonary embolism. Laboratory investigations showed a normal PTT and PT, excluding a possible adverse effect from anticoagulant therapy (8).
In addition, 2 cases of massive intracranial hemorrhage have been reported in patients being treated with VV-ECMO for COVID-19, with normal PTT and in the absence of other risk factors that could predict such complication(9). Patients with chronic kidney disease (CKD) have a paradoxical hemostatic potential with increased rates of bleeding associated with a higher risk of thromboembolic events. Bleeding events have been reported in 24–50% of patients on HD (10). Increased bleeding is essentially due to platelet dysfunction and alterations in the coagulation cascade with deranged vWF and platelet interactions (10).
CKD was the major risk factor of bleeding in our patient. In the absence other relevant findings, we concluded that the spontaneous hemothorax was due to the covid 19 vasculopathy probably by rupture of small chest wall vessels in a predisposed pediatric patient.