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Technical Article

Guidelines for Ultrasound in the Radiology Department During the COVID-19 Pandemic

Sheth, Sheila MD; Fetzer, David MD; Frates, Mary MD; Needleman, Laurence MD§; Middleton, William MD; Jones, Jill MD; Podrasky, Ann MD#; Mankowski Gettle, Lori MD, MBA∗∗

Author Information
doi: 10.1097/RUQ.0000000000000526

Abstract

A few weeks after the first cases of pneumonia caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) were reported in Wuhan, China, in December 2019, the outbreak was declared a pandemic by the World Health Organization on January 30, 2020. According to the Johns Hopkins Coronavirus Resource Center, as of May 14, 2020, there are 4,387,438 confirmed cases worldwide and a staggering 298,392 total deaths from the disease thus far. The United States now leads the world in terms of total number of cases (1,395,265) with the number of death in New York alone reaching 27,477 individuals with 84,313 country-wide.1

The toll this highly transmissible disease has taken on overwhelmed hospital systems has been well documented in medical journals and the lay press. Numerous publications in radiology journals are addressing the unique challenges our specialty faces. Many articles focus on the imaging findings of COVID-19 pneumonia and the need for consistent reporting. Others address the extrapulmonary manifestation of the disease including vascular, cardiac, renal, central nervous system, liver, and gastrointestinal tract and dermatological complications. A series of publications share their experience on how radiology departments are adapting and modifying workflow to mitigate spread of the infection to patients as well as technologists and radiologists. As our collective knowledge is evolving rapidly, we wish to share our experience specific to ultrasound workflow in the radiology department in the era of the COVID-19 pandemic.

This document summarizes the personal experience and insight of multiple colleagues who lead ultrasound sections or are experts in the field.

GOALS AND CHALLENGES IN THE NEW ENVIRONMENT

  1. Providing optimal patient care for all patients remains the most important objective. This includes providing ultrasound imaging to patients infected by COVID-19 while continuing to perform ultrasound for all other individuals in a safe environment, including hospitalized patients not infected by COVID-19 as well as outpatients.
  2. Ultrasound has distinct advantages for patients infected with COVID-19, foremost its ability to be performed at the bed side. Point-of-care ultrasound has been used extensively in these patients for diagnosing and monitoring pneumonia, guiding line placement, and draining fluid. This article will not address point-of-care ultrasound, rather it will focus on how to safely and efficiently provide comprehensive ultrasound examinations from radiology departments.
  3. A co-equal priority is to maintain the health and safety of our workforce (both radiologists and sonographers). Because of the hands-on nature of ultrasound, sonographers are particularly vulnerable to exposure to the virus unless strict precautions are implemented. It has become abundantly clear that COVID-19 is highly contagious and spreads through large and small respiratory droplets. A suggested “safe distance” of 2 meters (6 feet) to minimize spread through respiratory particles cannot be maintained during most ultrasound examinations.
  4. Assuring that ultrasound equipment does not become a source of infection is an additional concern that must be addressed. Assessment of residual viral load and survival on inert surfaces demonstrates that the virus is more stable on plastic and stainless-steel surfaces as compared with cardboard and copper, with small amounts of viable virus being detected 72 hours after application on the former surfaces.2

Protection for Sonographers and Radiology Personnel

Leaders of radiology departments across the country have quickly recognized the challenges posed by the pandemic and have taken measures to continue providing appropriate imaging while implementing policies to protect the personal safety of their employees that are adapted to their local circumstances.3 Articles describing step-by-step measures and guidelines published by organizations such as the Radiological Society of North America and the American Institute of Ultrasound in Medicine are in agreement with the principles outlined hereinafter.4–6 Among radiology personnel, sonographers have a high risk of exposure, defined as face-to-face contact within 2 meters in a closed environment for more than 15 minutes.7

GENERAL PRINCIPLES

  1. Establish a task force at the department level to design processes minimizing the spread of infection based on recommendations by the hospital infection control unit and/or other COVID-19 infection control centers. These may include separate inpatient and outpatient workflow, new specific sterilization/isolation procedures and processes for identifying, isolating, and transporting patients under investigation (PUI) and COVID-19–positive patients.
  2. Clear messaging must be provided to the sonographers. Charge managers or their designee in each division to write and communicate clear and detailed instructions relevant to how state, local, hospital, and department guidelines and policies are implemented in their particular imaging site. For example, provide the sonographers specific routes to follow to reach isolation units.
  3. Charge managers or their designee in each area to ensure the staff have an adequate supply of appropriate personnel protective equipment (PPE). Availability of face masks, respirator masks, and shields is critical. Detailed instructions for using PPE, including written and/or web-based instructions and learning videos, should be widely disseminated. The importance of proper technique and frequency of hand hygiene should be emphasized.
  4. The staff should have a venue to have questions and concerns answered. Maintaining robust communication channels with all staff including off-hour personnel is critical, as directives can change frequently in light of new knowledge and data.
  5. Include regular “check in” to make sure that the physical as well as mental well-being of the staff is maintained.
  6. Reimagine work space that allows for social distancing during breaks and still maintain social contacts and camaraderie (eg, placing chairs in corridors or unused waiting areas)

MEASURES SPECIFIC TO ULTRASOUND

  1. Inpatient setting
    1. Perform all in patient ultrasound examinations on COVID-19 positive or PUI portably, at the bedside to minimize patient transport and contamination of hallways and radiology examination rooms.
    2. Communicate with the patient care team to schedule an opportune time for the examination and to check the condition and position of the patient. Some patients are prone as it has been shown to improve oxygenation, this may preclude performance of some studies such as lower extremity venous ultrasound.
    3. Strip down the ultrasound machine to include only transducers that are needed for the particular examination. Consider individual single-use packages of gel or creating small aliquots of ultrasound gel into disposable bottles or syringes.
    4. Some suggest covering the machine with large clear drape (such as used in the operating room) if available. This may help prevent recirculating virus in the room from contaminating nontouch areas and will facilitate disinfection at the completion of the examination. However, it is important to check with individual manufacturers as these plastic covers may adversely affect proper functioning of the equipment because of overheating.
    5. Minimize the amount of time with and maximize the distance from the infected patient. Time-saving measures may include refreshing the worklist and entering information into the data page before entering patient's room. Scan the patient in the left lateral decubitus position when possible. Limit conversation with the patient. While scanning, in addition to adhering to limited protocols when appropriate, keep the scanning hand coming in contact with the patient away from the ultrasound machine and use the other “semiclean” hand to operate the controls. If a probe needs to be changed or as soon as the examination is complete, step as far away from the patient as possible before proceeding with turning the machine off and initiating the doffing procedure.
    6. Complex examinations such as evaluation of transjugular intrahepatic portosystemic shunt, liver transplants, etc may best performed by more experienced sonographers.
    7. Have a lower threshold then usual to terminate difficult examinations.
    8. Consider having the radiologist check the examination or answer questions using wireless image transmission and/or hands-free communication before the sonographer leaves the patient room to avoid additional donning and doffing of PPE, conserve PPE, and minimize additional cleanings.
    9. Disinfect the machine and transducers after each use according to manufacturer and institutional guidelines. Remember that US gel can be easily caught in the crevices on a probe or keyboard, and meticulous cleaning is required. Do not forget the cords. Detailed instructions compliant with each institutional guideline should be distributed to all the sonographers. One approach is provided in Appendix 1, http://links.lww.com/RUQ/A228, as an example. Each institution should solicit guidance from the institutional infection control office/department.
    10. If staffing allows, some have found that a “buddy system” with 2 sonographers going to the bedside together or with one inside and one outside of the patient room is valuable, as they can help each other during the examination and with cleaning the machine but as importantly to protect each other and catch any potential misstep during the donning and doffing process.
  2. Outpatient setting
  3. In view of the prevalence of asymptomatic carriers, all patients and visitors should be considered potentially infected. This has led many radiology departments to eliminate or limit elective or nonemergent examinations and procedures during period of high-virus prevalence.
    1. Ultrasound studies and ultrasound-guided procedures may be classified into 2 or more categories such as those considered truly elective (nonurgent) and those deemed immediately medically necessary (urgent) (Appendix 2, http://links.lww.com/RUQ/A229). A mechanism should be put in place to keep track of all postponed requests and allow for prompt scheduling as soon as restrictions are lifted, ideally without imposing additional burden on patients and referring providers.
      1. Urgent examinations need to be performed as soon as schedule allows. These may include diagnostic ultrasound for acute symptoms or significant laboratory abnormalities, for example, acute limb swelling or pelvic/abdominal pain. Examples of urgent ultrasound-guided procedures include rapidly progressing cancer requiring treatment modification, therapeutic paracentesis, and thoracentesis.
        • - Suspected malignant mass can be considered semiurgent, to be scheduled within 2 weeks. Consider discussing these cases with the referring provider for optimal scheduling.
      2. Nonurgent examinations can be safely deferred until the local situation is more stable. Examples are thyroid nodule imaging and fine-needle aspirations, surveillance for hepatocellular carcinoma, follow-up size of uterine myomas, etc.
    2. Outpatient office visits need to be re-engineered. Published guidelines suggest that some of the following measures may be helpful in preventing spread of infection.
      1. Pacing of appointment time to avoid crowding of waiting areas and allowing proper cleaning.
      2. Screening of patients for symptoms associated with COVID-19 and redirecting them to appropriate facilities if necessary.
      3. Requiring all patients to wear masks upon entering the medical facility.
      4. Having patients pre-registered and proceed directly from an outside space such as their car to the examination room.
      5. Limiting the number of individuals in the waiting and subwaiting areas.
      6. Not allowing any visitor (unless essential) or trainees in the examination room.

SUGGESTED WORKFLOW MODIFICATIONS FOR COVID-19–POSITIVE PATIENTS OR PATIENTS UNDER INVESTIGATION IN INPATIENT AND EMERGENCY DEPARTMENT SETTING

  1. Enhanced scrutiny of the indication for the ultrasound requested.
    1. Unlike the prepandemic environment where ultrasound may have been integrated into many diagnostic algorithms, ultrasound requests should be scrutinized to ensure that:
      1. The order indication warrants imaging. For example, mild elevation in liver function tests (LFTs) is a known and common adverse effect of antiviral medications, can be seen with the cytokine inflammatory response, and rarely has an imaging correlate. Daily trending of LFTs may prove to be more useful that immediate imaging evaluation.
      2. The most appropriate ultrasound examination is performed that would answer the clinical question. For example, for unilateral leg swelling, and unilateral as opposed to a bilateral deep vein thrombosis (DVT), an examination should be considered.
      3. The examination has not been or may be more appropriately answered by another modality. For example, for suspected portal vein thrombosis, a preceding contrast-enhanced CT may confirm vessel patency. Defer a gallbladder examination if there is a recent abdominal CT that demonstrated a normal gallbladder. Review chest CT to see whether the area in question was included.
      4. The results will alter patient management. For example, if the patient is currently on anticoagulant therapy, a repeat DVT examination may not alter the plans for continuing medication.
    2. Ultrasound examinations that are unlikely to provide significant benefit should be discouraged. This helps minimize sonographer exposure and also helps preserve PPE.
    3. Depending on the indication, direct communication between the radiologist and requesting provider may be necessary for ultrasound requests for COVID-19–positive patients and of PUI. For this latter group, the urgency of the ultrasound should be discussed with the clinical team to determine whether waiting until after the COVID test result is available, to confirm a negative result, and may minimize use of PPE.
  2. Design of targeted ultrasound protocols for COVID-19–positive patients

There is a general consensus among ultrasound experts to encourage abbreviated protocols and targeted examinations in COVID-19–positive and PUI patients. This limits the time the sonographer needs to complete the examination, thus minimizing exposure. Ideally, the ultrasound physician leader should provide a modified written protocol to sonographers for clarity and consistency. The sonographer should have a clear understanding of the clinical question that the ultrasound examination is addressing and acquire sufficient imaging to result in a diagnostic study. The sonographers, interpreting radiologists, and referring providers should understand the extent and intent of the new protocols and the reports should reflect the more targeted approach.

If pathology is encountered, appropriate diagnostic images should be obtained to evaluate the abnormality. For example, if a liver mass is identified on a limited right upper quadrant ultrasound, the mass should be imaged in 2 planes and color Doppler should be applied. However, clearly benign entities such as simple cysts may not need to be measured.

The abbreviated protocols described hereinafter cover the most commonly encountered ultrasound examinations in COVID-19–positive inpatients. For other examinations, a radiologist should review the indication to ensure that the appropriate imaging study is performed. Furthermore, the ultrasound should be tailored to answer the clinical question, for example, eliminating Doppler for female pelvis and scrotal US unless the indication is pain or a lesion is identified. Video clips should be encouraged. Video/cine loops will increase the amount of information for the same amount of scanning time compared with static images.

At the present time, we do not encourage changing ultrasound protocols for the general population in an outpatient setting. An exception might be slight modification of obstetrical ultrasound describe hereinafter.

Extremity Venous Doppler Ultrasound

COVID-19 is a hypercoagulable state and elevated D-dimer is a common laboratory abnormality. Thromboembolic events, including pulmonary emboli, strokes, and ischemic cardiac events, are thought to contribute significantly to morbidity and mortality in this population.8 It is currently postulated that the virus may damage the endothelium and trigger microvascular thromboses.9 Regardless of the underlying mechanisms, elevated D-dimer is a common abnormality in this population. As a result, venous Doppler ultrasound is a common examination requested in these patients.10 However, experts stress the importance of a pragmatic approach. Venous Doppler imaging should be reserved for symptomatic patients with, for example, limb swelling or pain.10 If there is clinical concern for pulmonary embolism (PE) due to worsening hypoxemia, the use of screening venous ultrasound as a surrogate for CT pulmonary angiogram needs to be discouraged. Bilateral lower extremity venous ultrasound has been shown to have a limited value in this setting with a reported sensitivity of 44%, specificity of 86%, positive predictive value of 58%, and negative predictive value of 77%.11 Computed tomography with contrast remains the imaging study of choice. An exception to consider would be those patients with high suspicion of PE who are not able to undergo CT, either because of iodinated contrast allergy, markedly impaired renal function, or inability to be transported from the intensive care unit. If the clinical team would like to also evaluate the lower extremity veins at the time of CT chest for PE, delayed images through the pelvis and lower extremities can be performed at the same time obviating the need for a lower extremity Doppler US.

Indications

  • - Unilateral leg swelling and/or pain.
  • - Unilateral arm swelling especially if there is a vascular access in that arm.
    • - Bilateral asymmetric leg swelling if more common causes of bilateral leg swelling such as congestive heart failure are not present. Consider performing only unilateral venous ultrasound of the more symptomatic limb after discussion with the referring clinician.
    • - Bilateral asymmetric arm swelling would be a rare indication.

Technique

Abbreviated Lower Extremity Venous US

  • - Spectral Doppler of bilateral common femoral veins or external iliac veins (even on unilateral examinations).
  • - Transverse compression cine clips of common femoral, femoral, and popliteal veins.
  • - No scanning of calf veins unless there are specific symptoms that need evaluation.
  • - If there is clot, document central extent of clot with no need to look distally (“clot then stop” protocol).

For sites with Intersocietal Accreditation Commission (IAC) certification, a recent statement from the board of directors of the IAC allows for protocol variation when considering sonographer safety: https://www.intersocietal.org/vascular/main/newsroom.htm.

Upper Extremity Venous Ultrasound

  • - Recommend unilateral protocol if the patient has venous access or one arm is symptomatic.
  • - If scanning centrally to distally and clot is identified, document central extent of clot with no need to look distally unless specific symptoms need investigation.
  • - If the examination is requested for generalized upper extremity swelling or to evaluate venous access for line placement, an examination limited to bilateral internal jugular veins and subclavian veins may be performed.

Renal Ultrasound

Acute renal insufficiency and proteinuria are being reported in hospitalized patients with severe COVID-19 infection.12,13 Unsurprisingly, preexisting conditions such as diabetes and baseline chronic renal insufficiency are predisposing factors. In a small series of patients, autopsy findings revealed acute injury to the proximal tubules.14 Ominously, acute renal insufficiency seems to be a harbinger of poor prognosis and death.

Indications

  • - Acute kidney injury with concern for obstruction.
  • - Renal size in preparation for renal biopsy.

Abbreviated Renal US Protocol

  • - Sagittal and transverse cine clips through both kidneys.
  • - Consider measuring renal length on the cine clip or one still image.
  • - Color Doppler only no spectral Doppler.
  • - Do not measure simple cysts.
  • - Consider limited imaging of the bladder with cine clip.
  • - If indication warrants renal Doppler, more limited examination. Color image with a single spectral Doppler waveform of the main renal artery and vein is sufficient to document renal flow and exclude major vascular thromboses.

Right Upper Quadrant Ultrasound

Elevated LFTs, particularly elevated elevations of serum alanine aminotransferase or aspartate aminotransferase levels, have been described in more than 70% of hospitalized patients.15 Hepatotoxic effect from antiviral drugs, cytotoxin storm, and hypoxia have been suggested as underlying mechanisms.16 Ultrasound examination of the liver is therefore unlikely to contribute to patient management and should be discussed with the clinical team. However, liver and biliary ultrasound may be warranted without delay in patients with rising bilirubin or alkaline phosphatase and leukocytosis.

Indications

  • - Right upper quadrant pain, suspected cholecystitis, and suspected biliary obstruction.
  • - Rising bilirubin or alkaline phosphatase and leukocytosis.
  • - Portal vein thrombosis.

Abbreviated Protocol

  • - Limit images to area of concern rather than full right upper quadrant or abdominal US. Consider eliminating the pancreas and inferior vena cava from the protocol.
  • - Only 1 image of the right kidney to compare liver echotexture.
  • - Gallbladder and bile ducts if suspected cholecystitis. No need for left lateral decubitus images if adequate supine images.
  • - If indication is an elevated LFT: liver, gallbladder, and bile ducts should be imaged.
  • - For vascular occlusion, concentrate on portal vein. Color flow of left, right, and main portal vein for patency and direction. Spectral Doppler of main portal vein only. Make sure that suspected thrombosis is confirmed with gray scale. Make sure the Doppler angle is acceptable (scans near or at 90 degrees may give false-positive results). This may require scanning from a different direction such as right axillary line or right side up scan. Power Doppler or B-flow imaging may be helpful.

Obstetrical Ultrasound

These examinations are time sensitive and may not be able to be deferred during the current COVID-19 pandemic. Nuchal translucency and anatomy scans should be performed at the appropriate gestational age. If possible, the examinations can be scheduled at a clinic with less patient traffic to avoid possible exposure. It is not known whether pregnant patients are at higher risk for COVID-19, but in general, they are treated as such. Assigning a sonographer to a single room or scanner will reduce overall exposure to both the sonographer and patient.

Indications

  • - Nuchal translucency.
  • - Anatomy scans.
  • - Dating and viability. Defer to combine dating with nuchal translucency study when possible.
  • - Symptomatic patients (ie, pain, vaginal bleeding, decreased fetal movement)
  • - Follow-ups as clinically necessary in particular biophysical profile and growth assessment for high-risk patients.

Technique

  1. No visitors allowed with the patients. Some sites are allowing brief FaceTime or other real-time communication with partners during the study or allowing patients to briefly record a portion of the study. This typically required a radiologist participation to ensure that the study is normal before any recording.
  2. Limit additional scanning. Examples of appropriate back scanning may include the following: decreased fetal movement, possible placenta previa, and challenging cardiac views. Video/cine clips may be used to document more challenging anatomy such as the heart.
  3. Every attempt should be made to complete the study at a single visit, rather than having the patient return, for example, to finish a fetal survey.

In conclusion, the authors hope that this document, intended as guidelines, can provide a framework and help the ultrasound community continue to provide excellent care while protecting both patients and sonographers. We recognize that the situation is fluid and adjustments will be inevitable as more information becomes available.

REFERENCES

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9. Oudkerk M, Büller HR, Kuijpers D, et al. Diagnosis, prevention, and treatment of thromboembolic complications in COVID-19: report of the National Institute for Public Health of the Netherlands. Radiology. 2020;201629.
10. Obi AT, Barnes GD, Wakefield TW, et al. Practical diagnosis and treatment of suspected venous thromboembolism during COVID-19 pandemic. J Vasc Surg Venous Lymphat Disord. 2020;8:526–534.
11. Killewich LA, Nunnelee JD, Auer AI. Value of lower extremity venous duplex examination in the diagnosis of pulmonary embolism. J Vasc Surg. 1993;17(5):934–938.
12. Pei G, Zhang Z, Peng J, et al. Renal involvement and early prognosis in patients with COVID-19 pneumonia. J Am Soc Nephrol. 2020;31:1157–1165.
13. Fanelli V, Fiorentino M, Cantaluppi V, et al. Acute kidney injury in SARS-CoV-2 infected patients. Crit Care. 2020;24(1):155.
14. Su H, Yang M, Wan C, et al. Renal histopathological analysis of 26 postmortem findings of patients with COVID-19 in China. Kidney Int. 2020;98:219–227.
15. Cai Q, Huang D, Yu H, et al. COVID-19: abnormal liver function tests. J Hepatol. 2020;S0168-8278(20):30218–X.
16. Feng G, Zheng KI, Yan Q-Q, et al. COVID-19 and liver dysfunction: current insights and emergent therapeutic strategies. J Clin Transl Hepatol. 2020;8(1):18–24.
Keywords:

COVID-19; pandemic; targeted ultrasound protocols; work-flow adaptation; ultrasound

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