Keywords
Key points
- •SARS-CoV-2 transmission seems to mainly occur via respiratory particles (respiratory droplets and smaller aerosols that are expelled from the respiratory tract during speaking, breathing, and coughing) and close contact with infected persons.
- •WHO and CDC advise using respirator masks, such as N95s, when performing procedures that might pose higher risk for transmission if the patient has SARS-CoV-2 infection (eg, that generate potentially infectious aerosols or involving anatomic regions where viral loads might be higher, such as the nose and throat, oropharynx, and respiratory tract).
- •Endoscopic findings in patients with COVID-19 suggest that SARS-CoV-2 does not seem to behave as a highly invasive and injurious pathogen to gastrointestinal mucosa.
Introduction
The spread of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was declared a pandemic by the World Health Organization (WHO) on March 11, 2020.
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Since the outbreak was first identified in December 2019 in Wuhan, China, the public health and social impact of the disease and the cumulative morbidity and mortality across the world has been enormous. As with any new or emerging pathogen, early in the pandemic, there was limited evidence and understanding of how SARS-CoV-2 was transmitted, limited testing capability, and resource constraints, especially in the availability of personal protective equipment (PPE).2
Endoscopy centers shut down and the volume of endoscopic procedures plummeted save for only urgent, lifesaving, or time-sensitive procedures. In line with international consensus statements and guidelines as well as local state- and health system-level policies, endoscopy centers slowly opened up and increased their volume of procedures with the paramount goal of reducing the potential risk of infection for patients and health care workers (HCWs).3
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Many studies showed drastic reductions in endoscopy volumes during the onset of the pandemic and persistent reductions in procedural volumes for sustained periods thereafter.7
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This article summarizes the evolution of our understanding of SARS-CoV-2 infection, the performance of safe endoscopy, as well as indications and endoscopic findings in patients with COVID-19.Understanding Modes of Transmission of Respiratory Viruses
A critical aspect of managing any pandemic from a respiratory virus requires a clear understanding of how an infectious pathogen is transmitted and the equipment or protection that is therefore needed to minimize transmission. Respiratory viruses are transmitted between individuals when the virus is released from the respiratory tract of an infected person and is transferred through the environment, to infect the respiratory tract of an exposed and susceptible person. The major modes of transmission of a respiratory virus from one person to another include large droplets, aerosols, direct contact, or indirect contact (fomites).
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Often, the relative contributions of different modes to a successful transmission and the relative effects of each mode, as well as modifications of risk by viral, host, and environmental factors, are unknown10
(Table 1).Table 1Transmission patters of respiratory viruses, such as coronavirus
| Definition | Key Attributes of Transmission |
|---|---|
| Large droplets originate in the upper respiratory system and vary in size between 5 and 60 μm |
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| Aerosols are generated in a similar way as large droplets but are smaller |
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| Fomites are the surfaces on which infectious particles cling once deposited |
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Understanding Modes of Transmission of Severe Acute Respiratory Syndrome Coronavirus 2
Our current understanding of SARS-CoV-2 transmission has shifted and evolved since the beginning of the pandemic. According to the WHO, SARS-CoV-2 transmission seems to occur mainly via respiratory particles and close contact with infected symptomatic cases.
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These particles not only include respiratory droplets but also droplets as small as 5 μm, and smaller aerosols that are expelled from the respiratory tract during speaking, breathing, and coughing.World Health Organization. Infection prevention and control of epidemic-and pandemic prone acute respiratory infections in health care. Available at: https://www.who.int/publications/i/item/infection-prevention-and-control-of-epidemic-and-pandemic-prone-acute-respiratory-infections-in-health-care. Accessed November 2022.
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The risk of transmission via aerosols is influenced by many factors including the concentration and mass of particles emitted, the viral load, the proximity and duration of exposure, and the circulation of air in the environment.
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The relative contribution according to particle size in virus transmission, however, is unknown. Epidemiologic evidence suggests that the risk of transmission is predominantly from short-range exposure from a person who generates significant amounts of virus. The SARS-CoV-2 virus has been detected in the air with a half-life of just more than 1 hour, and this evidence was offered as proof of “viable” virus that could be transmitted via aerosolization. However, this study was significantly limited in that it was conducted in a laboratory setting under an artificially created environment and not representative of real-world data.13
Human-to-human transmission can also occur from unknown infected persons (eg, asymptomatic carriers or individuals with mild symptoms), as well as individuals with virus shedding during the preincubation period before symptoms develop.14
A potentially compounding factor for transmission events is the contagiousness and transfer of SARS-CoV-2 infectious particles from fomites or contaminated surfaces (eg, door handles). As other coronaviruses and respiratory viruses are known to be transmitted this way, spread through fomites may be an additional source of transmission. In early studies of hospitalized patients with COVID-19 positive SARS-CoV-2 samples were identified in various locations around patients’ rooms, including the bed, sink, bathroom, light switches, and doors.
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In addition, positive samples were found on the shoes and stethoscopes of staff exiting patient rooms, but no contamination was found in the anteroom or corridor outside the room. These studies raised concerns about environmental contamination by patients with SARS-CoV-2 through respiratory droplets and fecal shedding.16
Despite the consistent evidence of SARS-CoV-2 contamination and survival of the virus on certain surfaces, there have been no specific reports demonstrating direct fomite transmission and the risk is generally thought to be small.17
People who come into contact with potentially infectious surfaces often also have close contact with the infectious person, thus making the distinction between respiratory droplet and fomite transmission difficult to differentiate.Centers for Disease Control and Prevention. Scientific Brief: SARS-CoV-2 Transmission. Available at: https://www.cdc.gov/coronavirus/2019-ncov/science/science-briefs/sars-cov-2-transmission.html. Accessed November 2022.
Viral SARS-CoV-2 particles have been isolated from various bodily fluids, including feces, urine, saliva, semen, and tears, raising concerns about possible transmission through these routes; however, the presence of viral particles in these fluids has not been shown to correlate with clinical symptoms.
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The detection of viral particles in the stool was of particular importance because coronaviruses can have direct pathogenicity in the gastrointestinal (GI) tract and cause enteric diseases; this raised concerns about fecal-oral spread as well as safety of endoscopy because aerosolization and increased exposure to fecal material may pose additional infectious risk. According to one systematic review of 35 studies that included 1636 patients with laboratory-confirmed COVID-19 who received fecal, anal, and/or rectal swab SARS-CoV-2 RNA examinations, the pooled prevalence of fecal SARS-CoV-2 was 43% with about half of these patients demonstrating persistent shedding even after respiratory samples turned negative, and shedding was found more commonly in patients with GI symptoms.20
Despite these data, no cases of direct fecal-oral transmission were reported thereby questioning the viability and infectivity of SARS-CoV-2 virus found in fecal matter. Importantly, wastewater evaluation has been a useful surveillance strategy for tracking and predicting rates of prevalent COVID-19 for health care utilization.21
The Role of Personal Protective Equipment in Minimizing Risk of Infection from Severe Acute Respiratory Syndrome Coronavirus 2
PPE includes gowns gloves, eye protection (eg, face shield or goggles), and surgical/medical or respirator masks. Surgical masks (also known as medical masks) are fluid resistant and often used for droplet precautions, because they are designed to block large particles, but are less effective in blocking small particle aerosols (<5 μm). Surgical masks provide a barrier to prevent droplets reaching the wearer’s nose, mouth, and respiratory tract. Most masks are not designed to fit closely to the face, which means that airborne particles (aerosols <100 microns) could potentially pass though the gap between the mask and the face. In contrast, respirator masks are designed to block aerosols. Respiratory protection for airborne precautions in health care commonly follows 2 filtering device paths, N95 or N99 masks/respirators or filtering facepiece respirators (such as FFP2 or FFP3) and powered air-purifying respirators (PAPRs). The N95 masks filter at least 95% of aerosols (<5 μm) and droplet-size (5–50 μm) particles and are not resistant to oil. Lightweight, no-hose PAPRs are a highly effective alternative to face masks that force air through a large, multilayer filter housed in the helmet and provide positive pressure within the face-shield compartment. These devices are approved by US National Institute for Occupational Safety and Hazard and can provide high-level protection from common airborne viruses that exceeds that for N95 face masks without the need for “fit-testing” and also have the advantage of providing head and neck protection.
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Maximum protection is achieved only with proper donning and doffing techniques.Requirements for Personal Protective Equipment During Endoscopy
Owing to the high risk of human-to-human transmission and the potential for transmission of infection with SARS-CoV-2 during routine performance of endoscopy, there was a lack of clarity regarding the necessity of PPE.
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Since the initial SARS infection in the early 2000s, there was ongoing recognition that certain medical interventions, labeled aerosol-generating procedures (AGPs), increased the risk of potential infection due to aerosol generation.24
According to the WHO, an AGP is any medical or patient care procedure that results in the production of airborne particles, or aerosols that are “associated with an increased risk of pathogen transmission” and therefore require enhanced precautions.25
Per the WHO, the following procedures were considered AGPs: open airway suction, sputum induction, cardiopulmonary resuscitation, endotracheal intubation and extubation, noninvasive ventilation such as bilevel positive airway pressure and continuous positive airway pressure, bronchoscopy, and manual ventilation. The quantitative evidence to support this categorization was, however, limited to retrospective cohort/case-control studies that were all deemed as very low quality.World Health Organizatiion. Infection prevention and control of epidemic-and pandemic prone acute respiratory infections in health care. available at: https://www.who.int/publications/i/item/infection-prevention-and-control-of-epidemic-and-pandemic-prone-acute-respiratory-infections-in-health-care. Accessed November 2022.
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The gastroenterology community had a significant controversy as to whether upper or lower endoscopy qualified as AGPs.
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AGP classification was critical in informing infection prevention and control policies, specifically the requirements for respiratory protective devices, such as N95 or N99 masks/respirators or filtering facepiece respirators (such as FFP2 or FFP3) or masks at endoscopy.28
In the context of COVID-19, a classification of a procedure as an AGP necessitated a higher grade of PPE to protect against aerosolized virus and potential airborne transmission risk. Although certain interventions such as intubation and bronchoscopy were acknowledged as high risk, there was a lot more uncertainty about endoscopic procedures. Possible sources of aerosolization during endoscopy include intubation and removal of the endoscope, coughing, belching during endoscopy, heavy breathing from sedation, patient expulsion of gas and liquid, and dispersion of contaminated fluid during insertion and removal of tools through the working channel of the endoscope, adjustment of the air/water button, retrieval of tissue from a biopsy channel, and during precleaning of the endoscope.Centers for Disease Prevention and Control. CoronavIrus 2019. Available at: https://www.cdc.gov/coronavirus/2019-ncov/index.html. Accessed November 2022.
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Our knowledge of the role of aerosol generation during endoscopy has expanded during the course of the pandemic. Several investigators, using various techniques, have studied this phenomenon to help us better understand the degree and quantity of aerosolization that is generated during routine endoscopy. These newer studies are summarized in Table 2.Table 2Recent studies that have aimed to assess the possibility and quantity of aerosol generation during upper and lower gastrointestinal endoscopy
| Particle-counting approach: aerosols from patients undergoing upper gastrointestinal endoscopy were measured by a handheld optical particle counter before, during, and after the procedure. Particle sizes were reported to be in the range of 0.3 to 10 μm. 10 , 11 , World Health Organization. Infection prevention and control of epidemic-and pandemic prone acute respiratory infections in health care. Available at: https://www.who.int/publications/i/item/infection-prevention-and-control-of-epidemic-and-pandemic-prone-acute-respiratory-infections-in-health-care. Accessed November 2022. 12 | |
| Sagami et al, 30 2021 |
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| Chan et al, 31 2020 |
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| Air sampling approach: aerosols were measured in a sample of air | |
| Gregson et al, 32 2022 |
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| Phillips et al, 33 2022 |
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A major criticism of this approach to categorizing AGPs into discrete dichotomous categories (AGP vs non-AGP and high-risk vs low-risk AGPs) is that this categorization does not consider the continuum of procedure-related aerosol generation and the different levels of transmission risks. Thus, there is likely a hierarchy of AGPs with each intervention conveying a different degree of transmission risk.
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Further complicating this issue is that numerous studies have shown that certain respiratory events, such as coughing, can generate vastly greater numbers of droplets and aerosols, considerably more aerosol particles than aerosols generated from currently classified AGPs.35
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In addition, some studies have found that traditional AGPs pose no greater risk than talking or breathing.40
It is difficult to infer risk of infection from these studies because aerosols may not necessarily contain viable virus material, and the amount and quantity of aerosol generation does not equate to infectivity from endoscopy.In summary, aerosol generation occurs as a continuum and endoscopy is associated with variable degrees of aerosolization. Risk of infection from aerosolized viral particles is, however, associated not only with the degree of aerosolization but also with other factors such as quantity of infective virus, proximity to source, and room ventilation. Based on these studies, however, there is increasing consensus that upper GI endoscopy should be classified as an AGP and periprocedural management including PPE recommendations should follow the AGP protocols to minimize transmission.
Current recommendations by the WHO and Centers for Disease Control and Prevention (CDC) advise the use of respirator masks, such as N95s or N99s, when performing surgical procedures that might pose higher risk for transmission if the patient has SARS-CoV-2 infection. These procedures generate potentially infectious aerosols or involve anatomic regions where viral loads might be higher, such as the nose and throat, oropharynx, or respiratory tract. Respirator masks are warranted in caring for individuals with COVID-19 or when community transmission levels increase, but standard surgical masks are adequate for routine care not involving aerosol-generating procedures.
25
,World Health Organizatiion. Infection prevention and control of epidemic-and pandemic prone acute respiratory infections in health care. available at: https://www.who.int/publications/i/item/infection-prevention-and-control-of-epidemic-and-pandemic-prone-acute-respiratory-infections-in-health-care. Accessed November 2022.
41
A systematic review of 172 observational studies on COVID-19, SARS-CoV-1, and Middle East respiratory syndrome coronavirus indicated that people, including HCWs, are strongly protected by wearing surgical face masks (adjusted odds ratio, 0.15 95% confidence interval, 0.07–0.34), with eye protection potentially conferring additional benefit.42
Early Impact of the Coronavirus Disease 2019 Pandemic on Endoscopy Units
In March 2020 when the COVID-19 outbreak was declared a global pandemic all endoscopy services came to a virtual halt.
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Considering the escalating rates of hospitalizations and deaths, limited PPE availability, limited COVID-19 test availability, and the burden on the health care system, routine elective endoscopy services were temporarily discontinued. HCWs, physicians, and nursing staff were redeployed, and protocols were developed for triaging of endoscopies to identify and perform only endoscopic procedures for urgent or emergent indications. Although there were variations in how procedures were prioritized, many centers limited procedures for the following indications: active GI bleeding, acute cholangitis, food impactions, GI obstructions, and cancer diagnosis/staging/treatment. This strategy was aimed to reduce the risk of spreading infection, reducing use of limited PPE supplies, and reducing use of hospital resources.Numerous studies from the United States, United Kingdom, The Netherlands, Canada, China, Spain, Japan, and Taiwan reporting on endoscopy volumes during the initial 3 to 4 months of the pandemic demonstrated reductions in total number of upper endoscopies and colonoscopies of 51% to 72% and 59% to 85%, respectively (compared with the same period from prior years).
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After the initial phase, many centers resumed limited endoscopy services with the implementation of stringent infection prevention and control policies and worked to reduce the backlog of colonoscopies by offering patients noninvasive stool-based tests for colorectal cancer screening.50
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- Moraveji S.
- Thaker A.M.
- Muthusamy V.R.
- et al.
Protocols, personal protective equipment use, and psychological/financial stressors in endoscopy units during the COVID-19 pandemic: a large survey of hospital-based and ambulatory endoscopy centers in the United States.
Gastroenterology. 2020; 159: 1568-1570 e5
Resumption of Endoscopy with a Focus on Safety During the Coronavirus Disease 2019 Pandemic
An important framework for managing health and safety interventions used by the CDC to develop infection control policies was the Hierarchy of Controls, which recommended using strategies to reduce risks of exposure to the virus in addition to the use of PPE.
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Such strategies included eliminating hazards by avoiding admission/treatment of people with active infection and using COVID-19 testing to segregate patients with the infection. Engineering controls such as physical barriers, and administrative controls to facilitate physical distancing, were also included in the hierarchy. And finally given the physical proximity required to deliver many elements of care, the use of PPE was also a required control measure within the health care environment.Following the hierarchy of controls framework, various operational changes were implemented across endoscopy suites and centers to safely reopen endoscopy units while mitigating the risk of infection.
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These changes were implemented based on local factors such as availability of resources, local prevalence of COVID-19, patient demographics, procedure indication, and hospital/endoscopy unit policies. The common goals of these changes were to maintain endoscopic volume and efficiency, while minimizing risk of transmission and infection to patients, staff, and HCWs. Sources of human-to-human transmission could occur from unknown infected persons (eg, asymptomatic carriers or individuals with mild symptoms), as well as individuals with virus shedding during the presymptomatic incubation period. Sources of risk during endoscopy included aerosols generated during endoscopy, which could increase the potential for subsequent airborne transmission, infection from respiratory secretions from patients, and potential contamination from other sources of bodily fluid (stool and patient saliva). Many authorities issued guidance on how to safely restart routine endoscopy and advocated for stringent infection control policies that included universal masking of patients, symptom screening before endoscopy, COVID testing before endoscopy, and use of high-level PPE54
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(Box 1).Box 1
Overview of modifications implemented across various endoscopy centers during various stages of the pandemic before the availability of vaccines
- Preprocedure modifications
- Triage and risk stratification used a screening questionnaire for (1) symptoms of COVID-19 (such as cough, shortness of breath, and persistent fever), (2) known history of contact with a patient with COVID-19, and (3) travel to high risk areas. These were performed in all cases at least 24 to 72 hours before endoscopy
- Preprocedure SARS-CoV-2 testing: individualized protocols for outpatient preprocedural testing of patients 24 to 72 hours before the scheduled appointment depending on local prevalence rates and institutional policies. Reverse transcription-polymerase chain reaction testing was performed in all asymptomatic patients before endoscopic procedures to risk stratify and determine PPE needs (see section later).
- •Patient reassurance about safety precautions taken to decrease transmission from patient to patient
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- Procedural modifications for patients
- All patients required to wear surgical masks and keep at least 1 to 2 m distance from others.
- Arrangements made in advance to reduce patient congestion in the waiting area.
- Chairs and beds spaced to avoid the transmission of viral particles to noninfected patients.
- Informed consent includes informing individuals about the possible risk of nosocomial infection (COVID-19 infection) during endoscopy
- Patients informed to report back if experiencing any de novo symptoms postprocedure.
- Triage and screening questionnaire: at the time of presentation to the endoscopy, questions asked again regarding (1) symptoms of COVID-19 (such as cough, shortness of breath, and persistent fever), (2) known history of contact with a patient with COVID-19, and (3) travel to high-risk areas. These were performed in all cases at least 24 to 72 hours before endoscopy
- High-risk patients, classified by the presence of respiratory tract symptoms, previous travel to COVID-19 locations in the past 14 days, and close contact with COVID-19-positive patients, prompted procedure cancellation and self-quarantine
- Temperature measurements before entering the endoscopy unit
- Patient’s relative/caregiver or driver required to wait offsite and return after the procedure is completed.
- If this is not feasible, the waiting area should be appropriately distanced.
- Procedural modifications for HCWs
- Barriers such as glass or plastic walls/shields set up in check-in areas
- Safe distancing in the preoperative area as well as decreased numbers of patients that nursing staff can receive for preprocedure care.
- Endoscopy staff with preexisting conditions at higher risk of contracting COVID-19 have been assigned nonclinical duties
- Use of PPE mandated by all health care systems to minimize the risk of transmission
- All endoscopy team members required to wear surgical masks, gloves, hair coverings, face shields or goggles, water-proof disposable gowns, and shoe covers or boots.
- Initially use of highest level of PPE mandated by all health care systems to minimize the risk of transmission
- Eventually PPE for endoscopy personnel adjusted according to patient risk stratification with full PPE required for high-risk or confirmed COVID-19-positive patients.
- In low-resource settings, reusable respirators, face shields, goggles, and boots deemed acceptable after appropriate sterilization and decontamination methods
- Training and adherence to strict precautions of properly donning and doffing
- Staff required to complete questionnaire about symptoms before their daily work. Similar distances should be maintained between individuals.
- Staff required to keep at least 1 to 2 m of distance from staff and patients
- For COVID-19-positive (or suspected) cases, procedures performed in a negative pressure endoscopic unit, if available, or portable industrial-grade high-efficiency particulate air filters placed in endoscopy rooms
- In low-resource situations, adequate ventilation of the room was acceptable
- As much as possible, all required documentation should be performed outside the endoscopy room.
- Minimal number of workers should be in procedure room to minimize risk
- Team switching during procedures discouraged to minimize PPE usage and decrease contamination risks
- Postprocedure modifications
- Procedural downtime and room turnover time needed to allow for dispersion of potential virus-laden aerosols depends on rate of air changes per hour. The precise time needed for closure of the room depends on the use of negative pressure and air-exchange rate
- Patients with COVID-19: some centers used only negative pressure rooms (room maintained under negative pressure for at least 30 minutes, and in the absence of negative pressure, for 60 minutes, before the next patient)
- Initially patients are monitored in the recovery area, with no family available in the waiting room
- Eventually limited family available in the waiting room with adequate spacing between seats and requirement of face masks
- Postprocedure telephone follow-ups with patients used to enquire about developing any new COVID-19-related symptoms (traced and contacted after 7 and 14 days)
Endoscopy Room and Endoscope Cleaning
Enhanced cleaning procedures with cleaning of all horizontal surfaces, especially frequently touched surfaces, with particular emphasis on areas within a few feet of the patent (using standard hospital-grade disinfectant solution with viricidal agents) were implemented by most endoscopy units.
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Endoscope cleaning and decontamination processes remained unchanged; as per guidelines, mechanical and detergent cleaning followed by high-level disinfection (a process that eliminates or kills all vegetative bacteria, mycobacteria, fungi, and viruses, except for small numbers of bacterial spores, and reduces the number of microorganisms and organic debris by 4 logs, or 99.99%).62
Preprocedure Testing: Changing Recommendations Through the Course of the Pandemic
The use of preprocedure testing in asymptomatic individuals became a common path to triage for risk stratification. A critical aspect of resuming endoscopy services included providing reassurance to patients and importantly to reassure HCWs, including endoscopists, nurses, and staff. At the pandemic onset, in the absence of available diagnostic tests and knowledge of treatments for COVID-19, one of the earliest evidence-based guidelines was developed by the American Gastroenterological Association (AGA); the guideline panel members made a strong recommendation to use N95 (or N99 or PAPR) masks (along with gowns, shoe covers, goggles, and face shields) instead of surgical masks for all HCWs performing upper endoscopies. Recommendations also included wearing double gloves and using negative pressure rooms, placing a high value on minimizing risks to HCWs, despite having low or very low certainty of evidence for risk of transmission of infection, because of documented community spread during a pandemic. In addition to limited resources for testing, limitations of PPE availability necessitated reuse or prolonged use of N95 masks. Finally, the decision to extend the recommendation to lower GI tract procedures was based on limited evidence of possible aerosolization during colonoscopy and the uncertain risks associated with evidence of the presence of SARS-CoV-2 RNA in fecal samples. These recommendations assumed the absence of widespread reliable testing for the diagnosis of COVID-19 infection or immunity and unclear data on prevalence.
As the number of COVID tests that received Emergency Use Authorization approval increased, preprocedure testing became more readily available, and questions arose regarding the role of routine preprocedure testing of all individuals to minimize risk for patients and HCWs. At the individual patient level, testing in symptomatic patients helped identify individuals who could be isolated to prevent the spread of disease. At the population level, widespread testing of individuals (symptomatic and asymptomatic) was critical to determine the true prevalence of disease and the provision of health care services, and to reintroduce endoscopy across health care systems and ambulatory care centers. Recommendations developed by the AGA provided a framework for routine preprocedure testing before endoscopy (for all asymptomatic persons) that accounted for local contextual factors such as the local prevalence of SARS-CoV2 and availability of PPE and weighed the pros and cons of a pretesting strategy. Based on a systematic review and meta-analysis of the tests (available at that time), the authors of this guideline conducted and made conditional recommendations against endoscopy centers adopting routine preprocedural testing to triage patients into low- and high-prevalence settings because of concerns about the accuracy of test results and the potential downsides for individuals with false-positive or false-negative test results. It was suggested that all HCWs wear N95s (or higher) masks, if available, and forego testing. For endoscopy centers where the prevalence of asymptomatic SARS-CoV-2 infection was intermediate (0.5%–2%), the AGA suggested implementing a pretesting strategy, if tests were available, to determine the type of PPE (such as use of surgical masks in individuals who tested negative). Alternatively, in settings where the logistics of testing were challenging and the downsides outweighed the benefits, HCWs could choose to wear N95 (or higher) masks and again forego testing. The changing prevalence of COVID-19 was an important factor as new variants emerged and created documented new waves of infection.
The rapid development of vaccines and the widespread implementation of vaccination programs worldwide helped decrease morbidity and mortality from COVID-19. Another important positive change was the availability of relatively effective treatments. Furthermore, within the GI community, as our understanding of disease transmission increased and data on infection rates from endoscopy and universal screening and testing became available, and PPE became widely available, many endoscopy centers again revised their testing policies. In contrast to early reports of high rates of HCW infections early in the pandemic (in the setting of limited PPE) accumulating evidence demonstrated low rates of COVID-19 infections among HCWs performing endoscopy.
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This evidence along with data demonstrating the relative effectiveness of vaccines in decreasing rates of transmission of infection prompted a recommendation against routine preprocedure testing emphasizing the downsides of testing at the patient level (of burden, cost, and access) and at the population level (low rates of screening and surveillance endoscopies leading to lower rates of screening, surveillance, and diagnosis of various GI cancers).Endoscopic Indications and Findings
In patients with COVID-19, several systematic reviews and meta-analyses have described the prevalence of GI symptoms including diarrhea (8%–17%), nausea or vomiting (4%–20%), loss of appetite (2%–21%), abdominal pain (3%–20%), anorexia (8%–10%), abdominal distension (1%) and loss of taste (1%–3%).
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Most GI symptoms associated with COVID-19 are mild. Diarrhea caused by SARS-CoV-2 may be the initial symptom in patients with COVID-19. A small subset of patients with COVID-19 may develop isolated GI symptoms throughout the disease (2.9%–16%).71
Our understanding of the endoscopic findings in COVID-19 is limited. Several case series and retrospective and prospective cohort studies have helped us to understand the direct and indirect effects of COVID-19 on the GI tract.
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GI endoscopy for GI bleeding in patients with COVID-19 is reviewed in the article by Cappell and Friedel in this issue. Mechanistically, viruses in the GI tract, including coronaviruses, can contribute to disease by interacting with the mucous layer, epithelial cells, and potentially lamina propria immune cells. SARS-CoV-2 infection can disrupt the tight and adherent junctions of the endothelium and intestinal epithelium, which may lead to a leaky gut, local and systemic invasion of normal microbiota, and consequent immune activation.76
In one retrospective, single-center study of 95 laboratory-confirmed cases of SARS-CoV-2 infection from Zhuhai, China, 6 patients with GI symptoms underwent upper endoscopy and 2 underwent proctoscopy. Biopsies were taken from the esophagus, stomach, duodenum, and rectum for viral RNA detection. One patient with severe symptoms of GI bleeding localized to the esophagus and attributed to multiple round herpetic erosions and ulcers, each with a diameter of 4 to 6 mm. SARS-CoV-2 RNA was detected in the esophageal erosions and bleeding site, as well as in the stomach, duodenum, and rectum. In the other 5 patients (cases 2–6) no erosions, ulcers, or bleeding was noted. SARS-CoV-2 RNA could also be detected in the esophagus, stomach, duodenum, and rectum of another patient with severe COVID-19 infection (case 2). In contrast, the virus was only detected in the duodenum of the nonsevere case 3 and could not be detected in any GI specimens of the nonsevere cases 4 to 6.
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In a case report of a patient with COVID-19 who underwent endoscopy, biopsies revealed no damage to the epithelium of the esophagus, stomach, duodenum, and rectum, but infiltrates of occasional lymphocytes were observed in esophageal squamous epithelium and numerous infiltrating plasma cells and lymphocytes with interstitial edema were observed in the lamina propria of the stomach, duodenum, and rectum.
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In a retrospective study from Lombardy, Italy, 38 patients with confirmed SARS-CoV-2 underwent endoscopic evaluation (24 EGDs, 20 colonoscopies). Endoscopic lesions were observed in 18 of 24 EGDs (75%) and in 14 of 20 colonoscopies (70%). The main findings were esophagitis (20.8%), bulbar ulcer (20.8%), erosive gastritis (16.6%), neoplasm (8.3%), and Mallory-Weiss tear (4.1%). Colonoscopy revealed segmental colitis associated with diverticulosis (25%), colonic ischemia (20%), diffuse hemorrhagic colitis (5%), and colonic neoplasms (5%).
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Finally, in a multicenter cohort of ∼2000 hospitalized patients with COVID-19 across a geographically diverse network of medical centers in North America, only 1.2% of patients (n = 24) underwent endoscopy despite a high prevalence of GI symptoms and substantial burden of critical or prolonged illness. Most endoscopic procedures were performed for either emergency cases (eg, ongoing GI bleeding or biliary obstruction) or for placement of enteral access tubes. Among those who underwent endoscopy, the indications and findings were judged more likely to reflect overall systemic illness or related to prolonged hospitalization rather than direct viral injury from COVID-19. The investigators did not observe inflammatory pathology and concluded that SARS-CoV-2 did not seem to behave as a highly invasive and injurious pathogen to GI mucosa.
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Summary
In summary, the unprecedented COVID-19 pandemic led to significant disruptions in gastroenterology practice necessitating endoscopy centers to be adaptive, reactive, and innovative. With the emergence of new variants and the ever-present threat of new pandemics, lessons learned during these past few years will help maintain the safe practice of endoscopy and prepare for new and emerging pathogens. Although mechanistically SARS-CoV-2 may contribute to enteric disease, endoscopic findings in patients with COVID-19 are likely to reflect the underlying critical illness rather than the direct effect of the virus.
Clinics care points
- •Aerosolization during upper and lower endoscopy occurs along a continuum, and respirator masks, such as N95s, along with eye protection, gowns, and gloves are an important strategy to minimize risk of viral transmission
- •Endoscopy centers should incorporate several strategies based on the Hierarchy of Controls Model to reduce the risk of viral transmission
- •The role of preprocedure testing should be based on local prevalence, testing availability, PPE availability, and patient burden
- •Although SARS-CoV2 can be detected in stool, there have been no reports of infection via the fecal-oral route
- •Endoscopic and histologic findings in patients with COVID-19 are more consistent with prolonged and severe systemic illness and suggest no direct viral or inflammatory pathogenic effects
Disclosure
The author has nothing to disclose.
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Published online: November 21, 2022
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