Post COVID-19 guidance | TOE

The global COVID-19 pandemic has led to a significant reduction in all types of echocardiography. 

This has been especially true for transoesophageal echocardiography (TOE) as it is classified as an aerosol-generating procedure (AGP). A key factor in the transmissibility of COVID-19 is the high level of associated viral shedding that occurs in the upper respiratory tract, even among pre-symptomatic individuals. Accordingly, TOE examinations carry an increased risk of COVID-19 transmission, especially when performed in the conscious-sedated patient; due to the potential to generate aerosolised particulate matter as a result of insertion/removal of the probe and coughing during the procedure. For perioperative TOE, the additional airway protection provided by a cuffed endotracheal tube and closed-circuit ventilation probably reduces the risk of aerosol generation. However, it is also possible that the longer duration of the procedure could increase the risk of viral transmission.

Now, as the government looks to ease the most stringent restrictions from the lockdown, there is a requirement to re-start elective TOE studies. This will be a challenging service to resume given the AGP status of TOE, carrying a higher risk of cross-contamination to staff as well as patients.

The aim of this document is to provide a framework for re-introduction of TOE services in a safe and efficient manner. We explore the challenges, from bookings, prioritizing patients, infection control, and effects on training. Consideration is also given to the issues surrounding the use of TOE in the mechanically ventilated patient.

Please note that this will be a framework, from which we expect each department will formulate their own guidelines, in accordance with local considerations and policies. Performing TOE whilst COVID-19 infection remains endemic in society will present a challenge to us all, thus it is recommended that lists are booked accordingly (i.e. reduced) at the onset of resuming services, as it is likely that each study will take a significantly longer period of time than before. Akin to other high-risk procedures performed routinely (e.g. endotracheal intubation), it is also recommended that clinical teams have pre-established protocols and consider the use of in-situ simulation to maximize safety during this procedure.

Similar to recent BSE guidance produced for other forms of echocardiography, this document is divided into five sections:

  1. Screening and triaging patients
  2. Undertaking TOE
  3. Special considerations for TOE in the mechanically ventilated patient
  4. Special considerations in the COVID-19 patient
  5. Example SOP

1. Screening and triaging patients


A scheduling prioritization should be developed based upon patient symptom status and exam indication urgency. For instance, higher priority exams would include patients with acute cardiovascular symptoms and in whom a trans-thoracic echocardiogram (TTE) is insufficient to guide urgent management queries, including the need for urgent surgery or valve interventions. It is worth stating that the threshold for TOE at the present time should be re-visited and only those patients that genuinely need TOE to answer a clinical query that cannot be answered by TTE or a different imaging test should undergo the procedure. We recommend that either a consultant or senior fellow is responsible for triage of TOE requests.

The benefit of performing TOE also has to be factored against the risk of the procedure to the patient, especially if ‘shielding’ is recommended by the Government (see appendix 1). Ideally, those TOEs should be deferred until the pandemic subsides.

Bookings need to be done through contacting the patient on the telephone, in addition to post, explaining to the patient the process. This booking call should include a questionnaire that screens the patient for COVID-19 symptoms – we recommend that this is repeated when the patient arrives in the hospital for the test.

Patients will need to have a COVID swab within 7 days of the test and will need to isolate for 14 days. The result of the swab should be known and confirmed negative prior to the patient attending their appointment. The swab test should ideally be carried out by a healthcare professional, as the yield is higher than if a patient swabs themselves (given the inherent discomfort caused by swabbing the nasopharynx). One way to do this is to liaise with the healthcare professionals who pre-assess patients for other cardiac procedures, and who are already swabbing patients prior to such procedures (e.g. angiography or ablation).

Day of Arrival:

On arrival, the patient should report to a reception desk, where they will be provided with a mask, asked to wash their hands, have their temperature checked and answer the COVID questionnaire again. Ideally, there should be not be a lengthy wait for the patient at this stage and if any waiting is required, strict social distancing needs to be implemented. Putting markers on the flooring and visual signs would help. Patients that answer questions in the COVID questionnaire at this stage that suggest they have developed symptoms since spoken to over the phone should not proceed with the test and should be sent home at this stage.

2. Undertaking TOE

Choosing the right TOE room is essential; ideally a high-efficiency particulate air (HEPA) filtered room or a room with windows should be used. There should be minimal furniture in the room. Non cloth-based furniture is preferable as they are easier to wipe clean (see figure 1 below). The number of staff in the TOE room should be as few as possible, ideally no more than three individuals: the operator manipulating the TOE probe, the individual driving the echocardiography machine for image optimization and acquisition and a nurse to manage the airway. Thus, at present, training of other members of staff (e.g. junior cardiology trainees, student physiologists and student nurses) may need to be postponed, to minimise the risk of infection and use of PPE. This can be re-visited as time passes and TOE services start to increase.

Figure 1: Types of chair commonly found in NHS hospitals. The chair on the left (with arms) is a fabric chair whereas the chair on the right (no arms) has a plastic covering. These plastic covered chairs are preferable if a chair is in the TOE room as they can easily be wiped clean, unlike fabric chairs.

The echocardiography machine may be covered, as illustrated below in figure 2. If this is not done then thorough decontamination using appropriate local infection control guidance will be required before and after each case.

Figure 2: An example of covering the echocardiography machine. In this example the entire machine is covered, including the middle section of buttons and touch screen panel. If operators find this difficult to “drive” the machine, an alternative is to cover the LCD monitor and the main machine base and leave the middle section open, which can subsequently be cleaned using viricidal wipes.


As mentioned above, TOE is considered an aerosol generating procedure (AGP), which requires appropriate PPE, which includes:

  • A face-fit tested facemask (often called a FFP3 mask)
  • Long sleeve surgical / Isolation gowns
  • Double gloves (inner glove taped to gown)
  • Visor
  • Goggles
  • Head cover

An area of storage of PPE in the TOE room is ideal, along with viricidal cleansing products. The responsibility for replenishing PPE stock should be decided amongst members of the echocardiography department. There should be an emphasis on strict twenty seconds of handwashing by each member of the team, prior to donning PPE.

Donning and Doffing PPE

Appendices 2 & 3 outline the donning (putting on PPE) & doffing (taking off PPE) procedures as per Public Health England guidance. It is important to know that healthcare professionals are MORE likely to contaminate themselves during doffing of ‘dirty’ PPE than they are to be contaminated whilst wearing PPE. Thus, meticulous attention to correct technique for donning and doffing is essential.

  1. Each member of the team should have had training in donning and doffing and have been ‘signed off’ as competent in this process, prior to involvement in the TOE list.
  2. Each member of the team can act as donning and doffing ‘buddies’ to each other, to ensure it is done safely and appropriately. The PPE needs to be disposed of in a waste disposal bin immediately.
  3. A poster of the donning and doffing procedures should be attached to the wall, in the TOE room, and visible to all staff.

Patients should wear a surgical facemask up until local anaesthetic spray is administered. The echo machine including the panel, the keyboard, should undergo wiping with large viricidal wipes and then the screen, touchable parts and the transducer ports are covered by the disposable plastic cover (see figure 2).

When spraying the back of the throat with xylocaine, the operator will need to ensure that everyone else in the team is at least 6ft from the patient. Once the probe is inserted, there should be one person to manipulate the probe and one to acquire images and control the echo machine to prevent cross contamination. TOE studies should follow an abbreviated but adequate pathology-directed protocol to limit personnel exposure time. Where possible, limiting the TOE to mid-oesophageal views would be appropriate, as trans-gastric views could agitate patients and cause them to release more secretions. Adequate sedation should also be provided for this reason.

TOE probe sheaths – to use or not to use?

The use of sheaths on TOE probes varies across the UK. In some centres they are routinely used for patients that are known to carry chronic illnesses such as hepatitis C or HIV whereas in other centres TOE sheaths are very rarely used. Sheaths provide an additional physical barrier to pathogens, but there are no studies assessing risk of cross-infection or cross-contamination in patients undergoing TOE with a sheath used versus without a sheath. Thus, all recommendations are made on the basis of consensus of expert opinion. It is recommended that departments follow their local infection control policies regarding the utilisation of TOE probe sheaths for routine elective TOE patients (that have a negative COVID-19 swab result) but it is recommend that a TOE probe sheath is used in all cases where the patient has known COVID-19 infection. Importantly, the use of a TOE sheath does not change the method of probe cleaning required afterwards. Occasionally, perforations may occur in the sheath (these may be micro-perforations invisible to the naked eye) and thus strict cleaning and decontamination of the TOE probe is still required even if a sheath is used.

Figure 3: Examples of different TOE sheath packages available in NHS hospitals


The operator should inform the team he/she is about to withdraw the probe prior to doing so. Other team members should try to keep their distance from the patient at this time. The probe should be placed straight into its container. The waiting time for the team to start doffing is 20 minutes – during this time period all PPE must be kept on as this time is required for any viral particles to settle on the ground. If a suitable plastic cover has been placed over computer equipment, the operator can report during this time (see figure 4).

Figure 4: Plastic cover (an x-ray cover) over monitor, keyboard and mouse allows reporting of the TOE study during the 20minutes waiting time after a TOE has been completed. The plastic cover is disposed of between each test.

As mentioned above, we recommend doffing with a colleague (‘buddy’) to help ensure safe removal of PPE. Once removed, PPE should be disposed of straight away into a clinical waste bin. The covers for the echo machine should be disposed of in the same manner. The container carrying the TOE probe should be wiped and taken as soon as possible by the infection team for decontamination as per local guidelines.

Recovery of the patient begins during the 20 minutes of waiting to doff PPE, after which time it continues in the usual recovery area. The nursing staff overseeing the patient’s recovery should have the non-AGP (standard) PPE, which includes a surgical facemask and gloves.

There should be an adequate time gap between each patient on the list. The gap depends on the local infection guidance and the size and ventilation properties of the room used for TOE. However, in general, for non-HEPA filtered rooms, the time between cases should be 2 hours.

3. Special considerations for TOE in the mechanically ventilated patient

In common with all invasive procedures, peri-operative or critical care TOE should only be performed if there is a favourable risk: benefit ratio. This analysis should be done not just for the patient but also for the echocardiographer and other members of the team (giving consideration to high risk groups such as those with cardiovascular disease, diabetes mellitus, chronic kidney disease, immunocompromised patients, BAME background and staff members living with at risk individuals). The incidence of asymptomatic or pre-symptomatic COVID-19 positive patients remains one of the unanswered questions about the pandemic. This uncertainty is further complicated by false-negative test results and the recognised presence of viable virus in asymptomatic individuals. It is therefore acknowledged that the evidence base on which to base decisions is extremely sparse whilst also being confounded by an inability to separate the different procedures performed intraoperatively (i.e. endotracheal intubation, pre and post cardio-pulmonary bypass TOE or bronchoscopy).

If possible, a goal-directed, focused TOE is performed by a single operator who performs all aspects of the exam including probe insertion, manipulation, image acquisition, and probe removal. This could be the same physician who performs the endotracheal intubation thus limiting provider and staff exposure.  

Since TOE is being performed in an anaesthetised, paralysed and intubated patient, the risk might be considered to be lower although this has not been quantified yet.  However, contact and droplet transmission from oral secretions, close physical proximity of patient, blood and body fluid splash events can occur. Extra care must be taken to prevent contamination during trans-gastric views, removal of the “dirty” TOE probe from the oesophagus and accidental extubation of the endotracheal tube, and disconnection of the anaesthetic circuit. 

Changing gloves, a transparent plastic cover (such as image intensifier covers) placed over the TOE machine controls, sterilisation of the probe and thorough wipe down of the echo machine should reduce the risk of spread. 

Finally, it is difficult to make strong recommendations about PPE due to the lack of good evidence. This is likely to change as the evidence base evolves. A high index of suspicion of COVID-19 is encouraged and we recommend continued use of full PPE (FFP3 mask) throughout the perioperative phase at this stage. 
However, in lower risk patients (i.e. COVID-19 test negative, asymptomatic and adequate, preoperative self- isolation), a pragmatic but hitherto untested approach would be to use full PPE for endotracheal intubation and pre-bypass TOE. A lower level of PPE may be worn later if the overall risk is deemed to be low for that particular situation based on a personal risk benefit analysis with an aim to avoid the discomfort of full PPE. This decision should take into account the probability of COVID-19 infection in the patient, the possibility of false negative tests and the individual risk factors of the operator and other individuals in the area.

4. Special considerations in the COVID-19 positive patient

If possible, TOE should be avoided in COVID-19 positive patients. Alternative imaging modalities should be considered to answer a clinical question if TTE images are deemed insufficient (e.g. CT scan to exclude aortic root abscess). 

If TOE has to be performed in a COVID-19 patient, all of the above precautions are recommended and, in addition, we recommend performing the scan as a focussed study directed to answer the clinical question (i.e. the minimum number of images required to answer the clinical query).

5. Example standard operating procedure for TOE (from the University Hospital Southampton)

1. Purpose of this document

To set out and standardise a template for booking and undertaking transoesophageal echocardiograms within our echocardiography Department, University Hospital Southampton, as strict lockdown measures are eased in the midst of endemic COVID-19 infection.

2. Scope of this SOP

Applies to all University Hospital Southampton NHS Foundation Trust employed staff who may need to undertake a TOE as requested by a clinician and after approval by a senior member of the echocardiography staff (i.e. Dr D Rakhit or Dr B Shah).

3. Competencies required

The healthcare professional performing the TOE must:

  • Be fully trained in both the practical and reporting aspects of echocardiography, and have current British Society of Echocardiography (BSE) TOE accreditation
    Understand the current PPE guidance as appropriate to TOE and demonstrate competency in safe donning and doffing
  • Hold a current competency in Immediate or advanced life support and be familiar with the location and layout of the Resuscitation Trolley and the updated resuscitation guidance given the current COVID-19 situation
  • Demonstrate a high level of communication with the patient in explaining the procedure and putting the patient at ease
  • Ensure the patient details are entered correctly including name, hospital number and date of birth
  • Be aware of any contraindications to performing the test
  • Clean the equipment and patient environment in line with current guidance to reduce the risk of contamination during the COVID-19 pandemic

4. Who Can Attend for an Outpatient TOE

This will be decided in line with the changes in Government restrictions and Trust initiatives but is likely to begin with more urgent referrals and patient groups that are not ‘shielding’ due to underlying health concerns where possible.

The senior echo team / imaging consultants will triage and select appropriate patients to be booked.  If the patient has referrals for other tests these should be performed on the same day if at all possible to avoid repeat hospital attendances. In order to maintain social distancing, only the patient will be able to attend the appointment and wait in the waiting room – relatives and carers will be asked to wait in the car / outside the department.

5. Booking procedure

A member of the admin team will contact the patient by telephone to discuss attendance for the appointment. They must ask the following:

1. Have you or anyone you live with had a letter from the NHS informing you that you are at higher risk of COVID-19 and should not leave your home?

If the patient answers Yes:

Whilst this group of patients remain vulnerable, current advice is that they may leave their home if they wish, as long as they are able to maintain strict social distancing. However, the invasive nature of a TOE mean that this is not currently possible. Therefore they should not attend the hospital at this time. Patients who are shielding should be advised to ring the department when they are able to leave the house and attend for the appointment. The patient should be reassured that they will not be taken off the waiting list. If the patient has still not attended for the appointment after 3 months from the referral date, the request will be sent back to the referrer for review.

If the patient answers No: proceed to question 2.

2. Have you or anyone you live with had a high temperature, new or continuous cough, loss or change to your sense of smell or taste? (i.e. symptoms of COVID-19 as outlined by the NHS)

If the patient answers Yes:

They cannot attend for their appointment until they and the other occupants of their home have been symptom-free for 14 days – they will need to contact us with an update before we will proceed to an appointment. They should use the online 111 service or GP for further advice

If the patient answers No: proceed to question 3,

3. Are you able to get yourself to the hospital for an appointment? (i.e. ensure they do not need transport or require several buses and that a family member is able to drive them to the hospital and drive them home after the test).

If the patient answers No:

We will have to wait until further relaxation of lockdown measures to proceed with their appointment.

If the patient answers Yes:

Offer them the next available appointment and inform them that only they will be able to attend the department.

Advise the patient:

As the patient will not be permitted to drive home after the test (as they will have had sedation), where possible a member of their household must drive them to their appointment and wait in the car/outside for them or go home and return after 3 hours to pick the patient up.

Before ending the call inform them that if they or a person they live with develop symptoms between now and the appointment time they must phone the department to re-schedule.

Ensure the outcomes of all calls are documented – if patients were called but the patients were self-isolating/shielding or repeatedly not answering this needs to be logged on CHARTS (e-docs).

6. Appointment Schedule

TOE appointments should be scheduled with a 120-minute appointment slot as below. This unusually long time period is required as it allows us to perform the test, allows for the 20minute time period required in the room prior to doffing PPE and permits the team to recover the patient and report the test all in the same room, whilst also having sufficient time to clean all equipment and surfaces appropriately after each patient.

Time Slot Echo Room 5
8:30 am TOE room, Cath Lab Day Unit
10:30 am TOE room, Cath Lab Day Unit
13:30 pm TOE room, Cath Lab Day Unit
15:00 pm TOE room, Cath Lab Day Unit

7. Arrival at UHS – on the day

The patient should be dropped off by a relative at the C level, North Wing entrance where they will be met by a member of our team who will be wearing a mask, gloves, apron and visor. They will determine which appointment the patient is attending the hospital for – either with us, cardiac MRI/CT or cardiology outpatient clinic.

The patient’s temperature should be measured:

If it is more than 37.8°C:

They should be advised to return home and contact NHS 111 - they must not enter the department.

If it is less than 37.8°C:

They must be asked:

1. Have you or anyone you live with had a persistent cough, temperature or tested positive for COVID-19 within the last 14 days?

If the patient answers Yes:

They should be advised to return home and contact NHS 111 - they must not enter the department.

If the patient answers No:

Ask them to alcohol gel their hands, provide the patient with a facemask and they will then be escorted up to the Cath Lab Day Unit (CLDU).

8. CLDU Procedure

The patient will be asked to change from their home clothes into a gown, as usual, and escorted to a trolley. As per our usual protocol, they will be cannulated and go through the pre-procedure checklist with a CLDU staff member. Patients should be consented on CLDU before being taken into the TOE room.

Staff should be wearing a basic (surgical) face mask and gloves when they escort the patient, in their trolley, from CLDU into the TOE room. Once the usual pre-procedural checks have been completed, staff should don their PPE as described in Appendix 1. Once PPE has been donned by all in the room, the patient’s facemask can be removed and local anaesthetic spray administered. The patient should lay on their left side after 2-3 minutes and receive intravenous sedation. The TOE should then be performed, aiming to obtain the maximum amount of information with the minimal number of views (i.e. pathology0-directed or focussed studies). 

9. Recovery and going home

After the initial 20 minute wait in the room after removing the TOE probe, the patient will be moved back to CLDU to continue their recovery. They are free to go home once they have recovered fully from sedation and the CLDU nursing staff are happy with observations and patient mobilisation, as per our usual policy. The patient should be escorted back to the same entrance at which they arrived, where a relative should be waiting to collect them.

Learning and Training in TOE – A special note

Training has been interrupted for cardiology registrars/fellows and advanced cardiac physiologists, as well as student nurses training in TOE. As mentioned above, reducing the number of staff in the TOE room is important in the early days of restarting the service. At this time, we do not recommend that student nurses or junior / novice trainees in TOE are in the room (in addition to the primary personnel). The increased use of simulators – where available – may be helpful at this time. More experienced trainees / physiologists can continue to help with the TOE list, if they are able to perform (most of) the study independently.

As for those working towards their BSE TOE accreditation, there will be significant disruption in many ways:

  1. There will be less cases performed as there will be fewer patients on the list.
  2. The studies will be more focused to reduce the time of contact with the patient. Therefore, ‘full’ TOE studies might not be feasible in most cases.
  3. Some trainee doctors / physiologists might have an associated medical condition requiring ‘shielding’, that may prevent from them from collecting TOE cases at present.

The society has already stated that 12 month extensions for those currently accruing logbook cases for accreditation purposes will be granted.

Table.1 COVID-19 Questionnaire

Appendix 1

People at very high risk – these patients will have had a letter informing them they should be shielding – i.e. not leaving their homes for any reason:

  • have had an organ transplant
  • are having chemotherapy or antibody treatment for cancer, including immunotherapy
  • are having an intense course of radiotherapy for lung cancer
  • have blood or bone marrow cancer (such as leukaemia, lymphoma or myeloma)
  • have had a bone marrow or stem cell transplant in the past 6 months, or are still taking immunosuppressant medicine
  • have been told by a doctor that they have a severe lung condition (such as cystic fibrosis, severe asthma or severe COPD)
  • are taking medicine that render them much more likely to get infections (such as high doses of steroids)
  • have a serious heart condition and are pregnant

People at high risk – should only leave their homes for essential reasons:

  • are 70 or older
  • are pregnant
  • have a learning disability
  • have a lung condition that is not severe (such as asthma, COPD, emphysema or bronchitis)
  • have heart disease (such as heart failure)
  • have high blood pressure (hypertension)
  • have diabetes
  • have chronic kidney disease
  • have liver disease (such as hepatitis)
  • have a condition affecting your brain or nerves (such as Parkinson's disease, motor neurone disease, multiple sclerosis, or cerebral palsy)
  • have a problem with their spleen or have had their spleen removed
  • are taking medicine that can partially affect the immune system (such as low doses of steroids)
  • are very obese (a BMI of 40 or above)


1. NHS. (2020). Who's at higher risk from coronavirus. Available at: [Accessed 12 May 2020]

Appendix 2 – Donning PPE Guidance from Public Health England (PHE)

Appendix 3 - Doffing PPE Guidance from Public Health England (PHE)


The BSE is grateful to Mahesh Prabhu, Sandeep Hothi, Tom Ingram, Mohammad Almajali, Dhrubo Rakhit, Linda Drummond and Benoy Shah for their extensive contributions to this document.