Introduction

COVID-19 is a life-threatening infection that originated in Wuhan, the capital of Hubei province in China. ¹ Due to its rapid global spread, the World Health Organization (WHO) has declared it a pandemic. ² As of March 25, 180 countries had been infected. ² Since then, humanity has progressively begun to strictly adhere to recommendations issued by world experts whose guidelines have remained unobjectionable as the pandemic has evolved. Endoscopic procedures are of unusual importance since all of this potentially lethal disease’s transmission mechanisms are simultaneously present in endoscopy rooms. Therefore, our group considers this narrative review based on updated information on the most important aspects of SARS-Cov-2 infection and endoscopic procedures to be particularly appropriate.

Methodology

We searched Pubmed using the following terms: (“COVID-19” OR “coronavirus” OR “SARS-Cov-2”) AND (“gastrointestinal” OR “transmission” OR “intestinal” OR “digestive” OR “endoscopy” OR “esophagogastroduodenoscopy” OR “colonoscopy”). There were no restrictions on date, language, or other factors. We found 2,340 references from which we chose the most relevant for a review of this topic. References in primary articles considered important for this study were also consulted manually.

Until recently, the start of the SARS-Cov-2 epidemic in China was believed to have been on December 31, 2019 when patient zero (0) was identified. At that time, an epidemiological alert was issued in that country because of suspected cases of pneumonia with unknown causes. ³ However, recent publications in the Chinese media have reported that the first confirmed case of the new virus was a 55-year-old man on who was diagnosed on November 17, 2019. ⁴ Whether this patient will be designated “patient zero” is now under study. As of December 31, 2019, there were about 300 COVID-19 patients in Wuhan: soon after there were thousands of fatalities. ² This pandemic has spread very rapidly. In Italy, after the first case was diagnosed on February 18, 2020, the number of infected has grown exponentially, and there are currently hundreds of deaths every day. ²

SARS-Cov-2 is a single-stranded RNA virus whose diameter is between 60 and140 nm. ¹ It belongs to the coronaviruses, whose name derives from the morphology of its envelope which has the form of a “crown” made up of 14 amino acid residues that interact with receptor 2 of the angiotensin-converting enzyme (ACE), which seems to be its receiver. ^5-7 There are six species in the coronavirus family that cause mild respiratory diseases in humans, ^8,9 but in the last two decades two coronavirus species have caused catastrophic diseases with high mortality rates: SARS-Cov in 2002 and MERS-Cov in 2012. ⁹ The names of these viruses derives from the fundamental pathologies they produce followed by Cov (coronavirus). SARS-Cov stands for severe acute respiratory syndrome coronavirus and MERS-Cov stands for Middle East respiratory syndrome coronavirus, a name which also identifies the geographical location of its epidemiology. ¹⁰ SARS-Cov-2 is the abbreviated name of the disease that produces the “SARS-CoV-2 related disease” that originated in 2019. ¹⁰

SARS-Cov-2 was initially called HCoV19 and originally infects bats, civets, badgers, bamboo rats, and wild camels. ^1,11 The jump to humans appears to have originated from the consumption of fresh and live animals at the Wuhan seafood market. ¹¹ Genomic and phylogenetic analysis of broncho-alveolar lavage samples in nine hospitalized patients found that SARS-Cov-2 homology of 88% with the genetic sequence of two bat beta-coronaviruses (bat-SL-CoVZC45 and bat-SL- CoVZXC21). ¹¹ SARS-Cov-2-19 is presumed to have infected the human population from a bat reservoir, although it is unknown which animal may have been an intermediate host between bats and humans. It has recently been postulated that the intermediary could be a pangolin, ¹² a placental mammal physically similar to an armadillo but genetically different and a member of another species. ¹³

Clinical manifestations of COVID-19 range from mild asymptomatic disease to severe disease with respiratory failure, multiple organ dysfunction, septic shock, and death. ^1,2,14 Fever, dry coughing, and fatigue are common symptoms. Diarrhea and other digestive symptoms such as discomfort and dyspepsia have been reported in less than 5% of patients. ¹⁴ However, some authors have found that nausea, abdominal pain, and diarrhea can occur in 50% of patients and may even precede respiratory symptoms. ^15-18 The first case identified in the United States had gastrointestinal symptoms including nausea, vomiting, and diarrhea, and viral RNA was documented in that patient’s stool. ¹⁹ Nausea and vomiting appeared on the fourth day of illness and diarrhea on the sixth day. ¹⁹ A Chinese study of 73 patients hospitalized for COVID-19 found viral RNA in the feces of 53% of the patients. Only 65% ​​had diarrhea, suggesting that fecal infection may occur even if there is no diarrhea. ¹⁸ The stools of twenty percent of COVID-19 patients test positive for viral RNA even after respiratory tract tests are negative. ¹⁴

Anosmia, dysgeusia or ageusia are recently identified manifestations which may be related by tropism of SARS-Cov-2 with brain tissue. This would make it a neuroinvasive virus. ²⁰ Central nervous system compromise may also play a role in severe respiratory failure through compromising the cardiorespiratory center of the brain stem and neurologically reaching mechanoreceptors and chemoreceptors in the lungs and lower respiratory tract. ²⁰

A breakdown of clinical characteristics of more than 44,000 confirmed cases in China found that 81% had mild cases without pneumonia or mild pneumonia; 14% had severe pneumonia with dyspnea, respiratory rates ≥30, O2 saturation ≤ 93%, fractions of inspired oxygen (FiO2) <300, and/or pulmonary infiltrates > 50%) within 24 to 48 hours; and 5% were critical and suffered respiratory failure, septic shock, and/or multiple organ dysfunction. ²¹ Clinical suspicion is essential because of the rapid evolution of complicated cases and the fact that 60% or more cases are transmitted by asymptomatic people. ²² SARS-Cov-2 is transmitted from person to person by respiratory secretions, feces (oral-fecal), ^14,23,24 and contaminated surfaces. ¹ In addition, a 2005 study conducted in China during the SARS epidemic found viral SARS-CoV RNA in wastewater from hospitals that were treating patients with SARS. Even though it was not viable virus, it was found that it could remain for up to 14 days at 4° C and for 2 days at 20° C. ²⁵

The most important transmission modes, and the modes that have been studied most, are droplets of saliva and aerosols. ²⁶ A drop has a diameter greater than 5 µm and contains water. ²² Drops can come into contact with surfaces at a distance of one meter. ²⁶ A sneeze releases about 40,000 microdroplets at a speed of 100 m/s while a cough releases 3,000 drops at a speed of 200 m/s. They remain viable as an aerosol for up to 3 hours. ^26,27 Saliva’s viral load is similar to that of fecal matter, but the virus can persist for up to 48 hours longer in feces than in respiratory secretions. ^18,24,27 It remains viable in aerosols for 3 hours. ²⁷ The number of copies of the virus in aerosols is not clear, nor is the infective dose. In the case of the influenza virus, concentrations between 48 to 300 copies of the viral RNA have been documented per positive sample filter. This corresponds to a production rate on exhalation of 3.2 to 20 copies of viral RNA per minute. In each cough droplet, there are about 16 copies of the virus. ^28,29

SARS-Cov-2 has an affinity for angiotensin-converting enzyme 2 (ACE2) receptors to which its protein S binds. ⁵ Angiotensin-converting enzyme 2 is not only expressed in alveolar type II cells (AT2) but is also expressed in cells of the oral mucosa, esophagus, ileum, colon, and bile duct. ^5-7,30,31,32 Affinity for these digestive system cells may explain transmission through the feces. ^17,18 After entering the cytoplasm of digestive system cellss, viral proteins and viral RNA are synthesized and new viruses are assembled. These are released into the intestinal lumen and later reach the feces. ¹⁸ The affinity of SARS-Cov-2 with ACE2 receptors has led to a hypothesis now circulating that people taking ACE2 inhibitors may face high risks from COVID-19. ³³ Nevertheless, this relationship has not been demonstrated, and the American and European Cardiology Associations recommend continuing ACE inhibitors in patients with COVID-19. ^34,35

As mentioned, the epidemiological impact of transmission occurs through aerosols, close contact, inanimate surfaces, and fecal matter. All upper digestive endoscopies and colonoscopies generate aerosols ^36,37. Upper digestive endoscopies produce aerosols from coughing and retching from nausea, and colonoscopies produce aerosols from flatus. All of these can contaminate nearby surroundings. ³⁷ The importance of aerosols in the field of medical procedures has been emphasized in an extensive WHO guide on rational use of personal protective equipment for SARS-Cov-2. It contains very strict and precise instructions for health care professionals who perform procedures that generate aerosols. ³⁸ In addition to generating aerosols, other potential sources of contact exist in endoscopy rooms. They include as close person-to-person contact; contact with environments contaminated by splashes of gastrointestinal fluids such as stretchers, pillows, sheets, blankets, floors and walls; and contact with accessories that are removed or inserted through the working channel of endoscopes. Contact with fluids that flow out of a patient that can even contaminate doctors’ shoes, as demonstrated in China. ³⁹ These observations require us to consider endoscopy rooms to be contaminated environments. ⁴⁰

Endoscopic procedure guidelines are absolutely necessary and must be widely disseminated. Because of the special characteristics of this infection in the gastrointestinal tract, and because endoscopy rooms bring together the most important SARS-Cov-2 transmission mechanisms (aerosols, fecal matter, contaminated surfaces and close contact) in one place, these procedures have high risks for medical and nursing personnel involved in them. Moreover, they could easily become a focus of dissemination of this infection within hospital institutions and their communities.

To prevent transmission of SARS-Cov-2 within endoscopy units, it is equally important that all those involved in endoscopic procedures strictly adhere to protection protocols as all will inevitably be exposed to secretions and patient fluids and that they follow with interest and responsibility recommendations published by international experts in gastroenterology and endoscopy as they are published and updated. ⁴¹

Experts from China, Italy and Spain, who have accumulated extensive and respectable experience in the present pandemic, suggest that the following strategy be chosen at this time to avoid transmission of the disease from asymptomatic patients to hospital staff or to healthy patients who undergo endoscopic procedures. Very importantly, this will also reduce health care expenses to free up hospital resources necessary to combat the pandemic. ⁴²

Table 1 Indications for therapeutic endoscopies 

Figure 1 Flow chart of decision-making for endoscopic procedures in the COVID-19 pandemic. Adapted from ⁴⁹  

Table 2 COVID-19 Protection in endoscopy units 

Taken from the recommendations of the Sociedad Española de Endoscopia Digestiva (SEED) and modified

At this moment of pandemic patients already scheduled for appointments should be contacted in order to explain the risks of an endoscopy room. Some may also have pathologies that warrant special treatment that can be identified in the interview. In Colombia, isolation has been initiated in a timely manner in order to avoid even minimal contact between and among people. The rationale for isolation is that most SARS-Cov-2 infections are transferred by asymptomatic individuals. Another consideration is that the face-to-face consultation should be suspended as long as social isolation lasts. These consultations should continue to be done virtually by internet or telephone and the physician should update the patient’s medical history in the usual way.

Risk stratification during scheduling of appointments^41,45-48

Preventive measures during procedures^50,51

Table 3 Biosecurity items recommended for health care personnel ⁶³  

* Health care worker: person whose work requires contact with patients.

Post-procedure recommendations

Reprocessing of post-endoscopy equipment

Commonly described infections associated with endoscopy include bacteria, fungi, parasites, and viruses, but adherence to guidelines of international endoscopy organizations has minimized or eliminated these risks for practically all patients and health care personnel who are present during procedures in endoscopy rooms. ⁵² Duodenoscopes that have a “nail” or elevator in their distal end are an exception. Because disinfection is more laborious and even impossible in some cases, ⁵³ a disposable distal end has been designed for these endoscopes. ⁵³

The safety of endoscopy procedures is guaranteed if established high-level disinfection guidelines for endoscopy equipment and accessories such as tweezers and papillotomes are complied with, ⁵⁴ and if cleaning and disinfection procedures for endoscopy units are followed during and at the end of the session. This will directly protect patients and guarantee the safety of personnel who perform procedures as well as their assistants. ^55-57

Instructions for washing and disinfecting equipment have not been modified because of the COVID-19 pandemic. Existing instructions are sufficient for the elimination of the virus. ^58,59 On the other hand, there are new recommendations to avoid the spread of contagion to patients and health care personnel involved in the procedure. As mentioned, the main recommendations include elimination of diagnostic procedures and limiting performance solely to urgent therapeutic procedures using the measures for protection discussed in this article. Characteristics of antiseptics and susceptibility of the virus must be considered for cleaning work areas, surfaces, elements and hands. In the first instance, removal of organic material must be guaranteed by using soaps and detergents and by rubbing with the cleaning material. Table 4 lists antiseptics and their respective concentrations that guarantee reduction of the virus by at least 3 to 4 logarithms (Table 1). ⁵⁸

Table 4 Antiseptic concentrations that reduce the concentration of coronavirus by three or more logarithms* 

* Virucidal activity for SARS-CoV ⁵⁸

Gastroenterology residents

Additional general recommendations⁶³

These recommendations and the allocations they require should be the responsibility of epidemiological surveillance departments and the infectious disease departments.

SARS-Cov-2 is very stable on surfaces. It has been found to remain viable in aerosols for 3 hours and on plastic and stainless steel for up to 72 hours although no viable virus is found on copper after 4 hours. No viable virus was found on cardboard after 24 hours. SARS-Cov-2’s stability is similar to that of SARS-CoV-1 for most substances. ²⁷

The persistence of SARS-Cov-2 is shown in Table 5 while chemical agents that neutralize it are shown in Table 6. ⁶²

Table 5 Persistence of SARS-Cov-2 on various surfaces ⁶²  

Table 6 Chemical agents that reduce viral infectivity ⁶²  

Endoscopy services must maintain their independence from potential pressure from hierarchically superior administrative authorities. These recommendations are based on the most recently published scientific literature about clinical characteristics and modes of transmission as well as recently published universal guidelines on management of the COVID-19 pandemic by the WHO and by experts from the American Association of Gastrointestinal Endoscopy (ASGE), the Chinese Association of Gastroenterology, the Spanish Association of Digestive Diseases plus the experience of gastroenterologists and endoscopists.