Since the introduction of SARS-CoV-2 vaccines, several cases of vaccine-induced immune thrombocytopenia and thrombosis (VITT) have been described, especially cerebral vein thrombosis. We aimed to retrospectively collect all new cases of acute onset first or recurrent splanchnic vein thrombosis (SVT) following a recent SARS-CoV-2 vaccination within the Vascular Liver Disease Group network.

New cases of SVT were identified from April 2021 to April 2022; follow-up was completed on December 31, 2022. Criteria to define VITT were derived from previous studies. Data from a pre-COVID cohort of patients with SVT (N=436) were used for comparison of clinical presentation, etiology, and outcome. Twenty-nine patients were identified with SVT occurring with a median of 11 days (range 2-76) after the first (48%), second (41%), or third (10%) vaccination (ChAdOx1 nCov-19 (n=12) or BNT162b2 (n=14), other (n=3) Only 2 patients(7%) fulfilled criteria for definite VITT. Twenty (69%) had SVT at multiple sites, including 4 (14%) with concomitant extra-abdominal thrombosis. Only 28% had an underlying prothrombotic condition, compared to 52% in the pre-COVID SVT cohort ( p =0.01). Five patients (17%) underwent bowel resection for mesenteric ischemia, compared with 3% in pre-COVID SVT ( p <0.001). Two patients died shortly after diagnosis (7%).

Although definite VITT was rare, in 72% of cases, no other cause for SVT could be identified following SARS-CoV-2 vaccination. These cases were different from patients with nonvaccine-related SVT, with lower incidence of prothrombotic conditions, higher rates of bowel ischemia, and poorer outcome. Although SVT after SARS-CoV-2 vaccination is rare in absolute terms, these data remain relevant considering ongoing revaccination programs.

It is well-described that the coronavirus disease 2019 (COVID-19) infection is associated with an increased risk of thrombotic complications. While there have been many cases of pulmonary emboli and deep vein thrombosis in these patients, reports of COVID-19 associated portal vein thrombosis (PVT) have been uncommon. We present a unique case of concomitant PVT and splenic artery thrombosis in a COVID-19 patient.

A 77-year-old-male with no history of liver disease presented with three days of left-sided abdominal pain. One week earlier, the patient was diagnosed with mildly symptomatic COVID-19 and was treated with nirmatrelvir/ritonavir. Physical exam revealed mild right and left lower quadrant tenderness, but was otherwise unremarkable. Significant laboratory findings included white blood cell count 12.5 K/μL, total bilirubin 1.6 mg/dL, aminoaspartate transferase 40 U/L, and alanine aminotransferase 61 U/L. Computed tomography of the abdomen and pelvis revealed acute PVT with thrombus extending from the distal portion of the main portal vein into the right and left branches. Also noted was a thrombus within the distal portion of the splenic artery with resulting splenic infarct. Hypercoagulable workup including prothrombin gene analysis, factor V Leiden, cardiolipin antibody, and JAK2 mutation were all negative. Anticoagulation with enoxaparin was initiated, and the patient's pain improved. He was discharged on apixaban.

It is quite uncommon for PVT to present simultaneously with an arterial thrombotic occlusion, as in the case of our patient. Unusual thrombotic manifestations are classically linked to hypercoagulable states including malignancy and hereditary and autoimmune disorders. Viral infections such as Epstein-Barr virus, cytomegalovirus, viral hepatitis, and COVID-19 have all been found to increase the risk of splanchnic venous occlusions, including PVT. In our patient, prompt abdominal imaging led to early detection of thrombus, early treatment, and an excellent outcome. This case is unique in that it is the second known case within the literature of simultaneous PVT and splenic artery thrombosis in a COVID-19 patient.

COVID-19 has significantly affected public health, social life, and economies worldwide. The only effective way to combat the pandemic is through vaccines. Although the vaccines have been in use for some time, safety concerns have still been raised. The most typical adverse effects of receiving a COVID-19 vaccine are localized reactions near the injection site, followed by general physical symptoms such as headaches, fatigue, muscle pain, and fever. Additionally, some people may experience VITT (vaccine-induced immune thrombotic thrombocytopenia), a rare side effect after vaccination. We present the case of a 60-year-old female patient that developed VITT-like symptoms with spleno-portal thrombosis and intestinal ischemia two weeks after the administration of the Ad26.COV2-S vaccine. Surgical treatment consisted of extensive bowel resection with end jejunostomy and feeding ileostomy. Two weeks after the first operation, a duodenal-ileal anastomosis was performed. The patient was discharged five weeks after the onset of the symptoms. Although some rare adverse effects are associated with the SARS-CoV-2 vaccines, the risk of hospitalization from these harmful effects is lower than the risk of hospitalization from COVID-19. Therefore, recognizing VITT is significant for ensuring the early treatment of clots and proper follow-up.