The pandemic forced health-care workers (HCWs) to the frontline. They faced many unknowns and confusion. At the beginning, the elective surgeries were usually postponed and only high-priority and urgent operations have been continued [1] . But, as time progresses, surgical interventions and pre-operative screening became a clinical problem to be solved particularly for asymptomatic cases [2] . We reviewed the pre-operative preparations for elective surgical procedures during the pandemic.
The American College of Surgery established the "Elective Surgery Accurity Scale" to define the priority of the interventions in which they recommend only cancer and high acuity cases be performed [3] . Resumption of the surgical procedures should be considered if a significant reduction in the incidences of COVID-19 cases and the hospitalizations occurred within the last fourteen days [4] . This became an established approach in order to ensure an appropriate health-care service, including enough intensive care units (ICU), non-ICU beds, personal protective equipment (PPE), ventilators, and trained staff [2] .
Patient evaluation for COVID-19 symptoms, sometimes with the support of telemedicine, rather than laboratory testing and radiologic imaging procedures, is encouraged by the joint statement of American College of Surgeons, American Society of Anesthesiologists, Association of periOperative Registered Nurses American Hospital Association and Royal Australasian College of Surgeons [2] , [5] . What is more, the symptom questionnaire is evaluated to be a very important tool in the future in diagnosing COVID-19 and even determining whether PCR screening should be performed [6] . Assessment of the patients before surgery includes the questionnaire of exposure to a COVID-19 patient in the past fourteen days or COVID-19 related symptoms within the prior two weeks [7] .
Testing patients for SARS-CoV-2 is a crucial component of patient evaluation for protecting both HCWs and patients [8] . As the prevalance of asymptomatic and presymptomatic patients is unknown, the common opinion is testing every case with RT-PCR before surgery by following the local recommendations [1] , [4] , [7] , [9] , [10] , [11] . Hovewer, it is also recommended that testing should be determined according to the indication of surgery and the type of procedure [2] . According to the guideline by Royal Australasian College of Surgeons preoperative testing for COVID-19 is not needed in patients with no risk factors regarding the evaluation of the symptoms and history of the patient [5] .Retesting is not recommended, however, by considering the false-negative test rates the need for retesting should be considered in terms of the institutional and local settings [2] , [4] , [5] . There is not a given time when to test patients before the surgery, but the common approach is to perform the test 1-2 days prior to surgery. It is recommended to consider it according to the availability, accuracy, and turnaround time for test results [2] , [11] . Self-quarantine until the day of the surgery after being tested is also recommended [9] . SARS-CoV-2 is probably associated with increased postoperative mortality and pulmonary complications [12] . In case a patient has a SARS-CoV-2 positive result before the elective surgery, it is recommended to delay the operation until the patient is not infectious and has demonstrated recovery from COVID-19 [7] .
Antibody testing is primarily used for screening of the population to detect the development of immunity [13] . The antibodies against SARS-CoV-2 develop as earliest in five days and have the potential of cross-reaction with other coronaviruses, therefore they have a limited role for preoperative screening [1] .
The European Association of Urology presents the joint testing of PCR and chest computerized tomography (CT) as a practical approach [10] . According to the report of the Royal College of Radiologists, routine pre-operative chest CT screening for COVID-19 is not indicated because of a 20% false-negative rate in symptomatic patients makes it of limited value. This method is also not recommended for the detection of COVID-19 in asymptomatic, isolated and tested patients before surgery [14] , [15] . Because of chest CT scanning's low sensitivity, it is only recommended in patients whose preoperative assessment and status indicate that they will need level II/III critical care after the surgeries such as thoracic and upper gastrointestinal ones [16] . Another approach was to use CT screening or chest X-Rays where PCR testing is not available [17] , [18] .
In PCR testing, the positive rate of lower respiratory samples such as sputum could be higher than the nasopharyngeal sample. Tracheal aspiration to collect lower respiratory tract specimens of intubated patients in operating room might be a good option to increase the detection of SARS CoV-2 [19] . Thus, post-surgical management of the patient and HCWs' compliance with isolation precautions might improve, however, we need more data to define this technique's right place in clinical practice.
Providing specific spaces for invasive/surgical treatments for all patients with COVID-19 is recommended if it is available [1] . Reducing the number of staff in operating rooms (OR) and entering and exiting the OR are strongly recommended to avoid transmission [1] , [8] , [18] . High-risk aerosol-generating procedures usually take place in laparoscopic operations, otolaryngological, maxillofacial and thoracic surgeries [20] . Yet, all the suspected and confirmed cases should be operated in negative pressure rooms at least during the intubation and extubation procedures [1] , [8] . If this is not available, in order to be sure that the 99% of the air of OR has exchanged with regard to air circulation cycling time, OR members are recommended to wait outside the room (except for the anesthesia provider and assistant) [4] , [8] . Ultraviolet light is recommended for air column disinfection as it is known to be effective against health care-associated viral infections [21] . Because of the possibility of leakage of gas during the exit of the trocar in laparoscopies, laparotomy with extensive fluid drainage is thought to be a safer option [1] . Surgical smoke still remains a concern. Minimizing energy use from electrocautery devices, use of insufflation systems with ultra-low particulate air (ULPA) filters and two-way pneumoperitoneum insufflators are recommended to reduce the risk of aerosolization [1] , [8] .
Standard precautions, droplet precaution and contact precaution are mandatory for every patient [22] , [7] , [10] , [23] . Whether to use a surgical mask or a respirator during the operation may be the J o u r n a l P r e -p r o o f major dilemma among HCWs. Because patients may be asymtomatic and false negatives may occur with testing, droplet precautions should be used by OR and for intubation and extubation at a minimum, respirators are recommended regardless of the result of the preoperative screening [2] , [7] , [8] , [23] , [24] .
The decision about resuming the elective surgeries should be updated according to the incidence of the COVID-19 cases and their hospitalization. The sypmtom questionnaire plus PCR testing is an important tool for screening preoperative patients and possibly symptom questionnaire will be more directive in the future. The sensitivity of PCR is estimated to be around 66-80% and positive predictive value ranges from 47,3% to 84.3% in low endemic areas (<10%) [25] . Thus, it should be reconsidered by the authorities according to the institutional and local settings before defining it as a screening method alone. Routine CT scan has no added value.