Peri-operative SARS-CoV-2 infection increases postoperative mortality. The aim of this study was to determine the optimal duration of planned delay before surgery in patients who have had SARS-CoV-2 infection. This international, multicentre, prospective cohort study included patients undergoing elective or emergency surgery during October 2020. Surgical patients with pre-operative SARS-CoV-2 infection were compared with those without previous SARS-CoV-2 infection. The primary outcome measure was 30-day postoperative mortality. Logistic regression models were used to calculate adjusted 30-day mortality rates stratified by time from diagnosis of SARS-CoV-2 infection to surgery. Among 140,231 patients (116 countries), 3127 patients (2.2%) had a pre-operative SARS-CoV-2 diagnosis. Adjusted 30-day mortality in patients without SARS-CoV-2 infection was 1.5% (95%CI 1.4-1.5). In patients with a pre-operative SARS-CoV-2 diagnosis, mortality was increased in patients having surgery within 0-2 weeks, 3-4 weeks and 5-6 weeks of the diagnosis (odds ratio (95%CI) 4.1 (3.3-4.8), 3.9 (2.6-5.1) and 3.6 (2.0-5.2), respectively). Surgery performed ≥ 7 weeks after SARS-CoV-2 diagnosis was associated with a similar mortality risk to baseline (odds ratio (95%CI) 1.5 (0.9-2.1)). After a ≥ 7 week delay in undertaking surgery following SARS-CoV-2 infection, patients with ongoing symptoms had a higher mortality than patients whose symptoms had resolved or who had been asymptomatic (6.0% (95%CI 3.2-8.7) vs. 2.4% (95%CI 1.4-3.4) vs. 1.3% (95%CI 0.6-2.0), respectively). Where possible, surgery should be delayed for at least 7 weeks following SARS-CoV-2 infection. Patients with ongoing symptoms ≥ 7 weeks from diagnosis may benefit from further delay.

SARS-CoV-2 has been associated with an increased rate of venous thromboembolism in critically ill patients. Since surgical patients are already at higher risk of venous thromboembolism than general populations, this study aimed to determine if patients with peri-operative or prior SARS-CoV-2 were at further increased risk of venous thromboembolism. We conducted a planned sub-study and analysis from an international, multicentre, prospective cohort study of elective and emergency patients undergoing surgery during October 2020. Patients from all surgical specialties were included. The primary outcome measure was venous thromboembolism (pulmonary embolism or deep vein thrombosis) within 30 days of surgery. SARS-CoV-2 diagnosis was defined as peri-operative (7 days before to 30 days after surgery); recent (1-6 weeks before surgery); previous (≥7 weeks before surgery); or none. Information on prophylaxis regimens or pre-operative anti-coagulation for baseline comorbidities was not available. Postoperative venous thromboembolism rate was 0.5% (666/123,591) in patients without SARS-CoV-2; 2.2% (50/2317) in patients with peri-operative SARS-CoV-2; 1.6% (15/953) in patients with recent SARS-CoV-2; and 1.0% (11/1148) in patients with previous SARS-CoV-2. After adjustment for confounding factors, patients with peri-operative (adjusted odds ratio 1.5 (95%CI 1.1-2.0)) and recent SARS-CoV-2 (1.9 (95%CI 1.2-3.3)) remained at higher risk of venous thromboembolism, with a borderline finding in previous SARS-CoV-2 (1.7 (95%CI 0.9-3.0)). Overall, venous thromboembolism was independently associated with 30-day mortality ). In patients with SARS-CoV-2, mortality without venous thromboembolism was 7.4% (319/4342) and with venous thromboembolism was 40.8% (31/76). Patients undergoing surgery with peri-operative or recent SARS-CoV-2 appear to be at increased risk of postoperative venous thromboembolism compared with patients with no history of SARS-CoV-2 infection. Optimal venous thromboembolism prophylaxis and treatment are unknown in this cohort of patients, and these data should be interpreted accordingly.

The implantation of a non-absorbable polypropylene mesh during hernia repair causes chronic foreign body reaction involving the surrounding tissue. In case of inguinal hernia repair using mesh techniques, the spermatic cord is potentially affected by this chronic inflammatory tissue remodeling. This effect has been investigated using standardized animal models (pig and rabbit). Fifteen adult male pigs underwent transinguinal preperitoneal implantation of a polypropylene mesh. The contralateral side with a Shouldice repair served as control. After 7, 14, 21, 28, and 35 days, three animals were sacrificed. The spermatic cords were resected and analyzed histologically. In a second experiment Lichtenstein repair using the same polypropylene mesh and Shouldice repair on the contralateral side was done in eight chinchilla rabbits. Three animals served as controls. Three months after operation, the analysis included testicular size, testicular temperature, and testicular and spermatic cord perfusion. We added histological evaluation of the foreign body reaction and the spermatogenesis using the Johnsen score. In the pig, we observed a certain foreign body reaction with diffuse infiltrating inflammatory cells after mesh implantation. Venous thrombosis of the spermatic veins occurred in five of 15 cases. One animal presented focal fibrinoid necrosis of the deferent duct wall. The side of Shouldice repair showed only minor postoperative changes. In the rabbit, we also observed a typical foreign body reaction at the interface between mesh and surrounding tissue, which was not detectable after Shouldice repair. The mesh repair led to a decrease of arterial perfusion, testicular temperature, and the rate of seminiferus tubules with regular spermatogenesis classified as Johnsen 10 (Lichtenstein: 48.1%, Shouldice: 63.8%, controls: 65.8%). Testicular volume increased about 10% after each operation. The implantation of a polypropylene mesh in the inguinal region induces major response of the structures of the spermatic cord. This may have an influence also on spermatogenesis. Due to this a strict indication for implantation of a prosthetic mesh during inguinal hernia repair is recommended.

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Titanium and its alloys are used worldwide in surgery. The favorable characteristics that make this material desirable for implantation are corrosion resistance and biocompatibility. Concerning hernia repair, a mesh modification has been developed using titanium layering of a polypropylene mesh implant, which is said to lead to an improved biocompatibility compared to commercially available mesh materials. To analyze the pure effect of titanium coating, two different mesh structures were studied using a standardized animal model. The titanium-coated monofilamentous, large porous, and lightweight mesh made of polypropylene and coated with titanium (PP+T) was compared to a pure polypropylene mesh manufactured with a similar structure and amount of material serving as a control (PP). In Sprague-Dawley rats, mesh samples were placed in a subcutaneuous position. Then 56, 84, and 182 days after mesh implantation, three animals from each group were sacrificed for morphological observations (amount of inflammatory and connective tissue formation, percentages of proliferating and apoptotic cells, percentage of macrophages). Both mesh modifications investigated showed an overall good biocompatibility. Macroscopic clinical observation after implantation of up to 182 days was uneventful. The tissue response to the PP as well as to the PP+T mesh was characterized by a moderate inflammatory tissue reaction limited to the perifilamentary region as is known for low weight, large porous, and monofilamentous mesh structures. No significant improvement of biocompatibility was found when analyzing the effect of titanium coating compared to the pure polypropylene mesh structure.