Aortic thrombosis in a neonate with COVID-19-related fetal inflammatory response syndrome requiring amputation of the leg: a case report.

Neonatal infection with SARS-CoV-2 is considered to have no major complications. A neonate with lower limb gangrene owing to spontaneous aortic thrombosis in the setting of a fetal inflammatory response syndrome (FIRS) post-intrauterine COVID-19 infection is presented. A healthy full-term newborn discharged from hospital on Day 3 developed irritability and progressive blackish discoloration of the toes of the right lower limb on Day 6 of life. Doppler imaging revealed acute thrombosis of the abdominal aorta with a critically ischaemic right lower limb. On Day 11 of life, SARS-CoV-2 RT-PCR was negative but total antibodies (IgG and IgM) were positive in both mother and neonate. The neonate showed raised inflammatory markers including CRP, ESR, interleukin-6, procalcitonin, ferritin and LDH along with elevated N-terminal pro-brain natriuretic peptide and D-dimer. In the absence of clinical signs of sepsis, FIRS was diagnosed. The neonate was treated with corticosteroids, heparin infusion and recombinant tissue plasminogen activator, and required surgical embolectomy followed by right limb amputation. By Day 31 of life, inflammatory markers showed serial return to normal and the neonate was discharged on oral steroids and aspirin. Intrauterine SARS-CoV-2 infection may trigger a systemic inflammatory response in some fetuses which is similar to post-COVID-19 multisystem inflammatory syndrome in children (MIS-C). Development of lower limb gangrene is a unique COVID-19-related neonatal complication and is attributed to thrombo-inflammation. ABBREVIATIONS CRP: C-reactive protein; FIRS: fetal inflammatory response syndrome; MIS-C: multisystem inflammatory syndrome in children; NT-proBNP: N-terminal pro-brain natriuretic peptide; RT-PCR: real-time polymerase chain reaction.