Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in peritoneal fluid of coronavirus disease 2019 (COVID-19) patients-Prevalence and significance.

To the Editor:

We read the manuscript entitled Peritoneal swab test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) patients in abdominal surgery: Is it a reliable practice? with great interest.

The authors suggest that intraperitoneal presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) might remain undetected. In our study, peritoneal fluid was sampled in syringes at the procedural beginning and/or end and analyzed in the virology laboratory on site. We expected to enable detection of intraperitoneal viral RNA via reverse transcriptase–polymerase chain reaction (RT-PCR). Our findings are in line with the majority of literature data reporting its absence in intraperitoneal fluid. In a series of 10 peritoneal dialysis (PD) patients, quantitative RT-PCR tests and additional analyses performed on PD effluent demonstrated absence of infective viral particles along with undetectable viral RNA.

Surgery carries a high risk of morbidity and mortality, and only emergency procedures should be performed during acute coronavirus disease 2019 (COVID-19) infections. Consequently, patients amenable to analysis of intraperitoneal SARS-CoV-2 presence are rare. Intraperitoneal viral RNA detection was reported in 4 COVID-19 patients only. Intraperitoneal swab testing, , intraoperative fluid sampling, and PD effluent enabled SARS-CoV-2 RNA detection by RT-PCR. The PD effluent remained SARS-CoV-2 positive, associated with peritoneal membrane malfunction (PD failure). Viral peritoneal cavity contamination could indeed be owing to increased peritoneal permeability during serositis or transmural bowel inflammation, representing an advanced COVID-19 stage. We cannot yet say whether high pathogenicity results from specific virus strains, mutations, host immune, or circulatory reactions. The detection of intraperitoneal SARS-CoV-2 RNA should lead to sequencing studies, in order to gain insight on whether specific strains or mutations resulted in a virulence involving a breach of the peritoneal barrier.

While research in COVID-19 is ongoing, comparison with feline coronavirus provides additional insight. In case of inflammation, feline coronavirus can leak from the bloodstream into effusions, entailing positive intraperitoneal testing. Similarly, to feline infectious peritonitis (FIP), the infection of macrophages could favor disease progression and explain dysregulated immune responses in COVID-19. Antiviral drugs used in FIP are strong COVID-19 treatment candidates.

It remains unclear whether viral RNA detection is equivalent to presence of contagious virus. The majority of articles on intraperitoneal coronavirus detection concern FIP, where RT-PCR performed on effusions has a high specificity, and a RT-PCR assay was developed to identify actively replicating virus by detecting its mRNA.

Systematic transdisciplinary sampling in nephrological/surgical/gynecologic and autopsy settings is needed to assess the overall viral prevalence in peritoneal fluid and to discriminate between infectious material versus shedding of noninfectious viral particles. Cross-sectional data in the COVID-19 patient population are much needed to achieve a proper risk quantification for viral transmission during both laparoscopic and open surgical approaches. Based on 4 patients with intraperitoneal RNA detection, as opposed to millions of SARS-CoV-2 infections worldwide, we cannot encourage to perform open surgery instead of laparoscopy. Confirmation of effluent contagiousness was suggested before imposing specific procedures, as the dissemination risk during PD seems very low. Transmission factors during surgery can be multifactorial, notably ventilation-associated factors in addition to peritoneal access-related ones, underlining the importance of general precautions recommended by surgical societies.

Funding/Support

This work was supported by French state funds managed within the “Plan Investissements d’Avenir” and by the ANR (reference ANR-10-IAHU-02).

Conflicts of interest/Disclosure

The authors declare that they do not have any conflicts of interest.