When I teach my fellows/residents/students in the Ultrasound office, there is a white board behind me, which I’ll use to draw, write, and place arrows linking one thing to another – it doesnt ever look that great in its final form. Then @LittleMedic - an awesome blogger/student in Sydney Australia - took the pic I posted of my white board scratches and made it read-able! Oh, if you only knew what the board looked like, you would thank him with all your heart, as I do now.
In an official statement by the American Institute of Ultrasound in Medicine (AIUM), they updated their guidelines on cleaning probes: Read below:
“The purpose of this document is to provide guidance regarding the cleaning and preparation of external and internal ultrasound probes. Some manufacturers use the term “transducers” or “imaging arrays.”
Medical instruments fall into different categories with respect to their potential for pathogen transmission. The most critical instruments are those that are intended to penetrate skin or mucous membranes. These require sterilization. Less critical instruments (often called “semicritical” instruments) that simply come into contact with mucous membranes, such as fiber-optic endoscopes, require high-level disinfection rather than sterilization. “Noncritical” devices come into contact with intact skin but not mucous membranes.
External probes that only come into contact with clean, intact skin are considered noncritical devices and require cleaning after every use as described below.
All internal probes should be covered with a single-use barrier. If condoms are used as barriers, they should be nonlubricated and nonmedicated. Although internal ultrasound probes are routinely protected by single-use disposable probe covers, leakage rates of 0.9% to 2% for condoms and 8% to 81% for commercial probe covers have been observed in recent studies (Rutala and Weber, 2011). These probes are therefore classified as semicritical devices.
Note: Practitioners should be aware that condoms have been shown to be less prone to leakage than commercial probe covers and have a 6-fold enhanced acceptable quality level (AQL) when compared to standard examination gloves. They have an AQL equal to that of surgical gloves. Users should be aware of latex sensitivity issues and have non-latex-containing barriers available.
For maximum safety, one should therefore perform high-level disinfection of the probe between each use and use a probe cover or condom as an aid to keep the probe clean. For the purpose of this document, “internal probes” refer to all vaginal, rectal, and transesophageal probes, as well as intraoperative probes and all probes that are in contact with bodily fluids/blood or have a remote chance to be in contact with dry/cracked skin and body fluids, including blood.
All cleaning, disinfection, and sterilization represent a statistical reduction in the number of microbes present on a surface rather than their complete elimination. Meticulous cleaning of the instrument is the key to an initial reduction of the microbial/organic load by at least 99%. This cleaning is followed by a disinfecting procedure to ensure a high degree of protection from infectious disease transmission, even if a disposable barrier covers the instrument during use.
According to the Centers for Disease Control and Prevention (CDC) “Guideline for Disinfection and Sterilization in Healthcare Facilities” (2008):
“Cleaning is the removal of visible soil (eg, organic and inorganic material) from objects and surfaces and normally is accomplished manually or mechanically using water with detergents or enzymatic products. Thorough cleaning is essential before high-level disinfection and sterilization because inorganic and organic material that remains on the surfaces of instruments interfere with the effectiveness of these processes.”
“Disinfection describes a process that eliminates many or all pathogenic microorganisms, except bacterial spores.”
Low-Level Disinfection—Destruction of most bacteria, some viruses, and some fungi. Low-level disinfection will not necessarily inactivate Mycobacterium tuberculosis or bacterial spores.
Mid-Level Disinfection—Inactivation of M Tuberculosis, bacteria, most viruses, most fungi, and some bacterial spores.
High-Level Disinfection—Destruction/removal of all microorganisms except bacterial spores.
“Sterilization describes a process that destroys or eliminates all forms of microbial life and is carried out in healthcare facilities by physical or chemical methods. Steam under pressure, dry heat, ethylene oxide (EtO) gas, hydrogen peroxide gas plasma, and liquid chemicals are the principal sterilizing agents used in health-care facilities. . . . When chemicals are used to destroy all forms of microbiologic life, they can be called chemical sterilants. These same germicides used for shorter exposure periods also can be part of the disinfection process (ie, high-level disinfection).”
The following specific recommendations are made for the cleaning and preparation of all ultrasound probes. Users should also review the CDC document on sterilization and disinfection of medical devices to be certain that their procedures conform to the CDC principles for disinfection of patient care equipment.
1. Cleaning—Transducers should be cleaned after each examination with soap and water or quaternary ammonium (a low-level disinfectant) sprays or wipes. The probes must be disconnected from the ultrasound scanner for anything more than wiping or spray cleaning. After removal of the probe cover (when applicable), use running water to remove any residual gel or debris from the probe. Use a damp gauze pad or other soft cloth and a small amount of mild nonabrasive liquid soap (household dish-washing liquid is ideal) to thoroughly cleanse the probe. Consider the use of a small brush, especially for crevices and areas of angulation, depending on the design of the particular probe. Rinse the probe thoroughly with running water, and then dry the probe with a soft cloth or paper towel.
2. Disinfection—As noted above, all internal probes (eg, vaginal, rectal, and transesophageal probes) as well as intraoperative probes require high-level disinfection before they can be used on another patient.
For the protection of the patient and the health care worker, all internal examinations should be performed with the operator properly gloved throughout the procedure. As the probe cover is removed, care should be taken not to contaminate the probe with secretions from the patient. At the completion of the procedure, hands should be thoroughly washed with soap and water. Gloves should be used to remove the probe cover and to clean the probe as described above.
Note: An obvious disruption in condom integrity does not require modification of this protocol. Because of the potential disruption of the barrier sheath, high-level disinfection with chemical agents is necessary. The following guidelines take into account possible probe contamination due to a disruption in the barrier sheath.
After removal of the probe cover, clean the transducer as described above. Cleaning with a detergent/water solution as described above is important as the first step in proper disinfection, since chemical disinfectants act more rapidly on clean and dry surfaces. Wet surfaces dilute the disinfectant.
High-level liquid disinfection is required to ensure further statistical reduction in the microbial load. Examples of such high-level disinfectants are listed in Table 1. A complete list of US Food and Drug Administration (FDA)-cleared liquid sterilants and high-level disinfectants is available at http://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/ucm194429.htm, and other agents are under investigation.
To achieve high-level disinfection, the practice must meet or exceed the listed “High-Level Disinfectant Contact Conditions” specified for each product. Users should be aware that not all approved disinfectants on this list are safe for all ultrasound probes.
The CDC recommends environmental infection control in the case of Clostridium difficile, consisting of “meticulous cleaning followed by disinfection using hypochlorite-based germicides as appropriate” (CDC, 2008). The current introduction and initial marketing of a hydrogen peroxide nanodroplet emulsion might provide an effective high-level disinfectant without toxicity.
Table 1. Sterilants and High-Level Disinfectants Listed by the FDA
|Glutaraldehyde||Organic compound (CH2(CH2CHO)2)
Induces cell death by cross-linking cellular proteins; usually used alone or mixed with formaldehyde
|Hydrogen peroxide||Inorganic compound (H2O2)
Antiseptic and antibacterial; a very strong oxidizer with oxidation potential of 1.8 V
|Peracetic acid||Organic compound (CH3CO3H)
Antimicrobial agent (high oxidization potential)
|Ortho-Phthalaldehyde||Organic compound (C6H4(CHO)2)
strong binding to outer cell wall of contaminant organisms
|Hypochlorite/hypochlorous acid||inorganic compound (HClO)
Myeloperoxidase-mediated peroxidation of chloride ions
|Phenol/phenolate||Organic compound (C6H5OH)
|Hibidil||Chlorhexidine gluconate (C22H30Cl2N10)
The Occupational Safety and Health Administration as well as the Joint Commission (Environment of Care Standard IC 02.02.01 EP 9) have issued guidelines for exposure to chemical agents, which might be used for ultrasound probe cleaning. Before selecting a high-level disinfectant, users should request the Material Safety Data Sheet for the product and make sure that their facility is able to meet the necessary conditions to minimize exposure (via inhalation, ingestion, or contact through skin/eyes) to potentially dangerous substances. Proper ventilation, a positive-pressure local environment, and the use of personal protective devices (eg, gloves and face/eye protection) may be required.
Immersion of probes in fluids requires attention to the individual device’s ability to be submerged. Although some scan heads as well as large portions of the cable may safely be immersed up to the connector to the ultrasound scanner, only the scan heads of others may be submerged. Some manufacturers also note that the crystals of the array may be damaged if, instead of suspending the probe in the disinfectant, it rests on the bottom of the container. Before selecting a method of disinfection, consult the instrument manufacturer regarding the compatibility of the to-be-used agent with the probes. Relevant information is available online and in device manuals. Additionally, not all probes can be cleaned with the same cleaning agents. Although some agents are compatible with all probes of a given manufacturer, others must be limited to a subset of probes.
After soaking the probe in an approved disinfectant for the specified time, the probe should be thoroughly rinsed (especially to remove traces of toxic disinfectants in the case of ortho-phthalaldehyde) and dried.
Adequate probe preparation is mandatory. The level of preparation depends on the type of examination performed. Routine high-level disinfection of internal probes between patients is mandatory, plus the use of a high-quality single-use probe cover during each examination is required to properly protect patients from infection. It would be reassuring for the user to be able to consult manufacturer’s instructions, particularly those that have been validated by the manufacturer for sterilizing devices. Preparation of external probes between patients is less critical and reduced to a low-level disinfection process. For all chemical disinfectants, precautions must be taken to protect workers and patients from the toxicity of the disinfectant.
The AIUM does not endorse or promote any specific commercial products. It is the responsibility of each entity to follow the manufacturer’s guidelines, law, and regulations.
- Amis S, Ruddy M, Kibbler CC, Economides DL, MacLean AB. Assessment of condoms as probe covers for transvaginal sonography. J Clin Ultrasound 2000; 28:295-298.
- Bloc S, Garnier T, Bounhiol C, et al. Ultrasound-Guided Regional Anaesthesia: An Effective Method for Cleaning the Probes. Quincy-Sous-Sénart, France: Service d’Anesthésie, Hôpital Privé Claude-Galien; 2010.
- Centers for Disease Control and Prevention, Hospital Infections Program. National Nosocomial Infections Surveillance (NNIS) report, data summary from October 1986-April 1996: a report from the NNIS system. Am J Infect Control 1996; 24:380-388.
- Frazee BW, Fahimi J, Lambert L, Nagdev A. Emergency department ultrasonographic probe contamination and experimental model of probe disinfection. Ann Emerg Med 2011; 58:56-63.
- Hignett M, Claman P. High rates of perforation are found in endovaginal ultrasound probe covers before and after oocyte retrieval for in vitro fertilization-embryo transfer. J Assist Reprod Genet 1995; 12:606-609.
- Kac G, Podglajen I, Si-Mohamed A, Rodi A, Grataloup C, Meyer G. Evaluation of Ultraviolet C for Disinfection of Endocavitary Ultrasound Transducers Persistently Contaminated Despite Probe Covers. Paris, France: Hygiène Hospitalière; 2010
- Koibuchi H, Fujii Y, Kotani K, et al. Degradation of ultrasound probes caused by disinfection with alcohol. J Med Ultrason 2011; 38:97-100.
- Milki AA, Fisch JD. Vaginal ultrasound probe cover leakage: implications for patient care. Fertil Steril 1998; 69:409-411.
- Mirza WA, Imam SH, Kharal MS, et al. Cleaning methods for ultrasound probes. J Coll Physicians Surg Pak 2008; 18:286-289.
- Muradali D, Gold WL, Phillips A, Wilson S. Can ultrasound probes and coupling gel be a source of nosocomial infection in patients undergoing sonography? An in vivo and in vitro study. AJR Am J Roentgenol 1995; 164:1521-1524.
- Rooks VJ, Yancey MK, Elg SA, Brueske L. Comparison of probe sheaths for endovaginal sonography. Obstet Gynecol 1996; 87:27-29.
- Rutala WA, Weber DJ. Sterilization, high-level disinfection, and environmental cleaning. Infect Dis Clin North Am 2011; 25:45-76.
- Whitehead EJ, Thompson JF, Lewis DR. Contamination and decontamination of Doppler probes. Ann R Coll Surg Engl 2006; 88:479-481.
- US Food and Drug Administration. Cleared liquid chemical sterilants/high-level disinfectants US FDA website; March 03, 2010. http://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/ucm194429.htm.
- Centers for Disease Control and Prevention. Guideline for disinfection and sterilization in healthcare facilities, 2008. Centers for Disease Control and Prevention website; 2008. http://www.cdc.gov/hicpac/pdf/guidelines/Disinfection_Nov_2008.pdf.
- Occupational Safety and Health Administration. Hospital eTool: clinical services. Occupational Safety and Health Administration website. http://www.osha.gov/SLTC/etools/hospital/clinical/pt/pt.html.
Our newest guest post is by one of the best emergency medicine resident educators I know – of course, you dont want to miss his educational pearls on twitter too – Dr. Jacob Avila. He discusses a case that illustrates how bedside ultrasound can help in your unexplained short of breath patient, and even cancel that triage bias that your attending can do to sway you away from the truth. Let’s give it to Dr. Avila for highlighting (with a great literature review) how ultrasound can help you too. Here it is – enjoy! (note: not all images were of this patient, but were taken from other resources)
“You arrive to the emergency department for your first night shift of the month, and as you place your bag on the desk, the attending walks towards you with a chart in his hand. “Do you mind seeing this patient? It’s a COPD’er with dyspnea. It’s probably just a COPD exacerbation.” You look at the chart and see that it’s a 46 year old female with shortness of breath. As you walk into the room, you notice the patient appears slightly pale, is afebrile, has an O2 saturation of 91% and is tachycardic in the 110’s with a blood pressure of 105/76, temperature of 98.5° and respiratory rate of 26. While taking the history, you note that the patient is a smoker and recently returned from a 12 hour car ride to see relatives. Suspecting that this may be something other than simple COPD exacerbation, you grab your ultrasound machine and start with the cardiac echo (as described in the RADiUS protocol) and are able to get the following image:
This apical 4-chamber view shows severe right heart dilation, defined as a RV:LV ratio >1. However, you remember that the patient has a history of COPD, and chronic pulmonary hypertension can cause chronic right ventricular dilation1. At that moment, the patient becomes hypotensive with a systolic blood pressure in the 70’s and develops severe respiratory distress. What should we do?
Early diagnosis of a pulmonary embolism (PE) is exceedingly important, as two thirds of patients with mortality associated with a PE die within the first hour of their presentation2, and intuitively, those who are treated earlier generally have a better prognosis 3. The definitive diagnosis of a PE requires the use of a CT scanner 4, but in a patient who is unstable, like this one, that isn’t an option. Looking at the right ventricular to left ventricular ratio is a maneuver that can rapidly change your differential diagnosis or confirm what you previously suspected. A recent study by Dresden et al found right ventricular dilatation identified by emergency physicians had a specificity of 98% for a PE. That number is impressive, but when you look at the methodology section of the publication, only 10% of the patients they included had coexisting COPD, and all of the false positives in the study were in patients with COPD5. One technique that may help differentiate between chronic and acute dilation is looking at the RV free wall in the subxiphoid view while in end diastole. A free wall size >0.5 cm is more likely to be chronic RV dilation6i. However, this view is not always possible in all patients. Another echo sign you could look for is the McConnell sign (apical winking of the right ventricle during systole), which previously was reported to have an impressive 94% specificity and 77% sensitivity for an acute PE7l, but a subsequent and larger study found the McConnell sign to be only 70% sensitive and 33% specific for a PE8. Take a look at what the McConnell sign looks like”
Another, less commonly seen finding would be directly seeing the clot in the right atrium (RA) or in the pulmonary arteries.
Clot in RA:
Clot in pulmonary artery:
Of more practical use are two other sonographic findings: Deep venous thrombosis (DVT) and distal pulmonary infarction.
In a study that included 199 examinations, bedside 2-point compression evaluation of the greater saphenous/femoral vein junction and the popliteal veins of patients with suspected DVT was found to be 100% sensitive and 99% specific for DVT 9. However, it is possible for a patient to present with an acute PE and have a negative DVT, and only about 40-50% of patients with DVT’s will end up having a PE10, 11
DVT on one side diagnosed by noncompressible vein:
More recently, lung ultrasound has been explored for the assessment of a suspected PE. A recent systematic review and meta-analysis by Squizzato et al which included 10 studies and a total of 887 patients found lung ultrasound to have a mean sensitivity of 87% and a mean specificity of 82% for acute PE12. What they looked for in the lung was the presence of triangular, wedge or rounded hypoechoic, pleural based lesions. These lesions are thought to be due to embolic occlusions that resulted in either focal atelectasis with extravasation of blood or focal infarction of the lung parenchyma . However, they state in their publication that “Several methodological drawbacks of the primary studies limit any definite conclusion”.
Instead of looking at just one specific sonographic finding for the diagnosis of acute PE, a better method may the use of multi-organ sonography. Recently, Nazerian et al. published a study utilizing multi-organ sonography in the diagnosis of PE. This study used echo, lung and DVT ultrasound to diagnose PE and found that when the three ultrasounds were combined, they yielded a sensitivity of 90%, which was significantly higher than each of the exams by themselves13.
Like any physical exam finding, lab reports or other radiographic assessments, the sonographic analysis of a patient with a suspected pulmonary embolism should be used as part of your diagnostic quiver, and not the silver bullet. Any of the above mentioned ultrasound findings of acute PE can potentially be found in other, non-PE causes of dyspnea. DVT’s can just be DVT’s, RV enlargement can be chronic or from an RV infarction, and subpleural fluid collections can be seen in contusions, pneumonia and cancer. This doesn’t mean not to use it though. Just think about all the other tests we use in the emergency department, such as EKG’s, chest x-rays, troponins, BNP, and the d-dimer. All of these can be abnormal in PE and in non-PE entities.
Now back to our patient. She is a 46 year-old female with COPD that had right heart enlargement, which we learned above can be seen in COPD without the presence of a PE. You were unable to get a good subcostal view of the heart to measure the lateral wall, mostly because the patient did not tolerate being laid flat. You move on to the lungs and in the lower right thorax and there you find two hypoechoic, pleural based lesions. Heparin and a CT scan are ordered, and the CT scan shows a large clot located in the right main pulmonary artery.
Here is the CT scan showing the clot:
To see a recent podcast by Ultrasoundpodcast on multi-organ US for PE, go here.
- Otto, Catherine M.. Textbook of clinical echocardiography. 5th ed. Philadelphia, PA: Elsevier/Saunders, 2013. Print. p 247
- Wood KE. Major pulmonary embolism: review of a pathophysiologic approach to the golden hour of hemodynamically significant pulmonary embolism. Chest. 2002;121:877-905
- Jelinek GA, Ingarfield SL, Mountain D, et al. Emergency department diagnosis of pulmonary embolism is associated with significantly reduced mortality: a linked data population study. Emerg Med Australas. 2009;21:269-276
- Goldhaber SZ, Bounamenaux H. Pulmonary embolism and deep vein thrombosis. Lancet 2012:379:1835-46
- Dresden S1, Mitchell P2, Rahimi L2, Leo M2, Rubin-Smith J2, Bibi S2, White L3, Langlois B2, Sullivan A4, Carmody K5 Right ventricular dilatation on bedside echocardiography performed by emergency physicians aids in the diagnosis of pulmonary embolism. Ann Emerg Med. 2014 Jan;63(1):16-24. doi: 10.1016/j.annemergmed.2013.08.016. Epub 2013 Sep 27.
- Rudski LG, Lai WW, Afilalo J, Hua L, Handschumacher MD, Chandrasekaran K et al. Guidelines for the echocardiographic assessment of the right heart in adults: a report from the American Society of Echocardiography endorsed by the European Association of Echocardiography, a registered branch of the European Society of Cardiology, and the Canadian Society of Echocardiography. J Am Soc Echocardiogr. 2010;23:685-713
- McConnell MV, Solomon SD, Rayan ME, Come PC, Goldhaber SZ, Lee RT. Regional right ventricular dysfunction detected by echocardiography in acute pulmonary embolism. Am J Cardiol 1996;78:469e73.
- Casazza F, Bongarzoni A, Capozi A, Agostoni O. Regional right ventricular dysfunction in acute pulmonary embolism and right ventricular infarction. Eur J Echocardiogr. 2005;6:11-4
- Crisp JG, Lovato LM, Jang T. Compression ultrasonography of the lower extremity with portable vascular ultrasonography can accurately detect deep venous thrombosis in the emergency department. Ann Emerg Med. 2010;56:601-610
- Kearon C. Natural history of venous thromboembolism. Circulation. 2003;107:22-30
- Moser KM, Fedullo PF, Littlejohn JK, Crawford R. Frequent asymptomatic pulmonary embolism in patients with deep venous thrombosis. JAMA 1994;271:223-225
- Squizzato A1, Rancan E, Dentali F, Bonzini M, Guasti L, Steidl L, Mathis G, Ageno W. Diagnostic accuracy of lung ultrasound for pulmonary embolism: a systematic review and meta-analysis. J Thromb Haemost. 2013 Jul;11(7):1269-78. doi: 10.1111/jth.12232.
Nazerian P, et al. Accuracy of Point-of-Care Multiorgan Ultrasonography for the Diagnosis of Pulmonary Embolism.Chest. 2014 May 1;145(5):950-7. doi: 10.1378/chest.13-1083
In a publication in WestJEM by Bramante, Raio and team, they discuss two cases of appendicitis found on trans-vaginal ultrasound. Now, this is something that I have been told can happen, but there are few studies on it. It makes sense. First off, the trans-vaginal probe is high frequency, there is an empty bladder and there is a regional evaluation of the pelvis. The appendix can lie low and be visualized, and diagnosed with acute appendicitis. Raio also published a study on this in Emergency Medicine International. They studied 224 females with right lower quadrant pain suspicious for appendicitis excluding those pregnant or under 16yrs old. They had 27 with a positive ultrasound for gyn pathology and 55 had appendicitis per OR report. Of course they wondered if they should have looked for the appendix too! Other studies have shown that with both a transabdominal and a transvaginal ultrasound, you can improve accuracy in appendicitis diagnoses, but that wasnt necessarily to look for the appendix. The Journal of Ultrasound in Medicine published in 2006 about a case of transvaginal US and appendicitis very nicely too. The OB literature also stated how some of their cases of pelvic pain had appendicitis seen on both transabdominal and transvaginal ultrasound.
Ok, back to the case reports in WestJEM by Bramante et al. The 2 cases showed the evaluation and pretty obvious sonographic images seen with acute appendicitis with transvaginal ultrasound after an equivocal transabdominal ultrasound:
Now, this is pretty cool. Imagine doing an ultrasound on someone who is not right where you are, but could be in another hospital, or maybe even in another country? These french engineers has made something that is almost to that level. Read below for the EDMT medical imaging article:
“In a breakthrough that might expand the frontiers of ultrasound examinations, a French company has developed the world’s first industrial-scale remote ultrasound system with a robot arm.
Introduced for radiography, remote imaging is now also used for ultrasound, which accounts for one third of medical imaging procedures, making it the most common such procedure in medicine. Today, ultrasound is the most efficacious of all diagnostic procedures, and on average costs half as much as CT scanning. However, medical exams during pregnancy and detailed investigations of organs, blood vessels, ligaments and the heart require the presence of a highly trained physician at the patient’s bedside as well as hands-on operation of the ultrasound device and interpretation of the resulting images.
Remote medical image scanning using a robot arm that functions as a genuine extension of the physician’s hand was invented by the head of the Department of Nuclear Medicine and Ultrasound at Tours University, Philippe Arbeille, as an outgrowth of manned space flight research that is supported by France’s CNES and by the ESA.
“The main challenge is to resolve the problem of synchronous video transmission. Also, the operator needs to be able to place his hand on the patient virtually,” notes AdEchoTech CEO Éric Lefebvre. The French company recently invested four years and one million Euros in the development of the world’s first industrial-scale remote ultrasound system. AdEchoTech has four patents pending for its Melody robot, two of them with Orleans University’s PRISME mechanical engineering research center.
AdEchoTech’s Melody workstation consists of two elements. For the medical practitioner, the workstation comprises a control box, a mini-console and a virtual probe that remotely controls the ultrasound probe arm. And on the patient side, the operator controls the probe arm remotely. The ultrasound probe, connected to the ultrasound device, is attached to the extremity of the robot arm, whose load is lightened by the arm’s carrier base while at the same time making the arm very easy to manipulate. Thanks to its modularity, the solution is readily adaptable to any given technical environment. Particularly, since operator and patient stations can be operated via satellite, as well as fiber optic 3G+ and 4G hookups. In this regard, the system is compatible with most commercially available ultrasound and video conferencing systems.
“Our R&D also focused on compression algorithms, so as to allow for the communication of information concerning the transmission of ultrasound images, as well as for control of the robot arm and for the realization of video conferences in real time – and all of this in a merely 2 Mbit/s symmetrical bandwidth,” says an AdEchoTech engineer.
The Melody robot, which obtained the CE mark in 2012, allows for 90% concordance with conventional ultrasound, and is useful for solving the growing problems entailed by the performance of ultrasound examinations on islands, in mountainous regions, and on ships or oil drilling platforms, in military zones, for repatriation medicine, and in prisons. Ten Melody stations are already in operation in French hospitals, where they are used for the following procedures: pelvic and abdominal emergencies (investigations of the hepatobiliary system, the urinary system, the abdominal aorta and the pancreas) and examinations during pregnancy. In such settings, the system helps to avoid lengthy trips for pregnant women to major hospitals.
“A second generation of patented Melody robots will benefit from two additional degrees of movement freedom, which will allow for the performance of remote cardiac ultrasound examinations,” says Lefebvre. A third generation of Melody robots, which is expected to be available in 2017, will carry out remote robot-assisted ultrasound for punctures and certain surgical procedures.
By: Bernard Banga, MD Report, France
In a meeting of 15 members of the radiology, Ob/Gyn, and emergency medicine communities, new criteria were set that was published in NEJM Oct 2013 so that we dont prematurely state that a pregnancy is non-viable. This is pretty important, and a subject that I posted about earlier as well when discussing the usefulness (…or useless ness) of the beta hCG. Can you imagine what was done, and I remember this algorithm – you have a patient with 1st trimester pain or vaginal bleeding, no IUP seen on US, low beta Hcg, and OB was called and the patient was given methotrexate??? Well, there have been cases where those patients actually had a viable IUP that showed up a week later… and then the lawsuit happens….scary stuff. It’s different now where we dont care too much about the beta hCG, or whether there is not an IUP, but whether we see anything around the ovary….and even then, very close follow up and rechecks may be considered. Below is the Eurekalert and the AuntMinnie articles on it too:
Medical experts recommend steps to reduce risk of inadvertent harm to potentially normal pregnancies
New criteria aim to prevent misdiagnoses of nonviable pregnancies
A panel of 15 medical experts from the fields of radiology, obstetrics-gynecology and emergency medicine, convened by the Society of Radiologists in Ultrasound (SRU), has recommended new criteria for use of ultrasonography in determining when a first trimester pregnancy is nonviable (has no chance of progressing and resulting in a live-born baby). These new diagnostic thresholds, published Oct. 10 in the New England Journal of Medicine, would help to avoid the possibility of physicians causing inadvertent harm to a potentially normal pregnancy.
“When a doctor tells a woman that her pregnancy has no chance of proceeding, he or she should be absolutely certain of being correct. Our recommendations are based on the latest medical knowledge with input from a variety of medical specialties. We urge providers to familiarize themselves with these recommendations and factor them into their clinical decision-making,” said Peter M. Doubilet, MD, PhD, of Brigham and Women’s Hospital and Harvard Medical School in Boston, the report’s lead author.
Among the key points made by the expert panel:
- Until recently, a pregnancy was diagnosed as nonviable if ultrasound showed an embryo measuring at least five millimeters without a heartbeat. The new standards raise that size to seven millimeters
- The standard for nonviability based on the size of a gestational sac without an embryo should be raised from 16 to 25 millimeters
- The commonly used “discriminatory level” of the pregnancy blood test is not reliable for excluding a viable pregnancy
The panel also cautioned physicians against taking any action that could damage an intrauterine pregnancy based on a single blood test, if the ultrasound findings are inconclusive and the woman is in stable condition.
Kurt T. Barnhart, MD, MSCE, an obstetrician-gynecologist at the Perelman School of Medicine at the University of Pennsylvania and a member of the SRU Multispecialty Panel, added, “With improvement in ultrasound technology, we are able to detect and visualize pregnancies at a very early age. These guidelines represent a consensus that will balance the use of ultrasound and the time needed to ensure that an early pregnancy is not falsely diagnosed as nonviable. There should be no rush to diagnose a miscarriage; more time and more information will improve accuracy and hopefully eliminate misdiagnosis.”
Michael Blaivas, MD, an emergency medicine physician affiliated with the University of South Carolina and one of the panelists, emphasized that “These are critical guidelines and will help all physicians involved in the care of the emergency patient. They represent an up-to-date and accurate scientific compass for navigating the pathway between opposing forces felt by the emergency physician and his/her consultants who are concerned about the potential morbidity and mortality of an untreated ectopic pregnancy in a patient who may be lost to follow-up, but yet must ensure the safety of an unrecognized early normal pregnancy.”
Aunt Minnie article :
“In addition, the authors emphasized that the commonly used “discrimination level” of the pregnancy blood test is not reliable for excluding a viable pregnancy. They also cautioned physicians against taking any action that could damage an intrauterine pregnancy based on a single blood test, if the ultrasound findings are inconclusive and the woman is in stable condition.
“The guidelines presented here, if promulgated widely to practitioners in the various specialties involved in the diagnosis and management of problems in early pregnancy, would improve patient care and reduce the risk of inadvertent harm to potentially normal pregnancies,” the authors wrote.
Not stringent enough
Research over the past two to three years has shown that previously accepted criteria for ruling out a viable pregnancy are not stringent enough to avoid false-positive results, but it has been difficult both to disseminate this information to practitioners and to implement standardized protocols.
The challenge is that physicians from multiple specialties — including radiology, obstetrics and gynecology, emergency medicine, and family medicine — are involved in the diagnosis and management of early-pregnancy complications, according to the authors.
“As a result, there is a patchwork of conflicting, often outdated published recommendations and guidelines from professional societies,” they wrote.
To address the problem, SRU in October 2012 organized the Multispecialty Consensus Conference on Early First Trimester Diagnosis of Miscarriage and Exclusion of a Viable Intrauterine Pregnancy. At the conference, researchers reviewed the diagnosis of nonviability in early intrauterine pregnancy of uncertain viability and, separately, in early pregnancy of unknown location. They focused mainly on the initial or only ultrasound study performed during the pregnancy.
The conference participants developed the following guidelines for transvaginal ultrasound diagnosis of pregnancy failure in a woman with an intrauterine pregnancy of uncertain viability.
Findings diagnostic of pregnancy failure:
- Crown-rump length of ≥ 7 mm and no heartbeat
- Mean sac diameter of ≥ 25 mm and no embryo
- Absence of embryo with heartbeat ≥ 2 weeks after a scan that showed a gestational sac without a yolk sac
- Absence of embryo with heartbeat ≥ 11 days after a scan that showed a gestational sac with a yolk sac
Findings suspicious for but not diagnostic of pregnancy failure:
- Crown-rump length of < 7 mm and no heartbeat
- Mean sac diameter of 16-24 mm and no embryo
- Absence of embryo with heartbeat 7-13 days after a scan that showed a gestational sac without a yolk sac
- Absence of embryo with heartbeat 7-10 days after a scan that showed a gestational sac with a yolk sac
- Absence of embryo ≥ 6 weeks after last menstrual period
- Empty amnion (amnion seen adjacent to yolk sac, with no visible embryo)
- Enlarged yolk sac (> 7 mm)
- Small gestational sac in relation to the size of the embryo (< 5 mm difference between mean sac diameter and crown-rump length)
Pregnancy of unknown location
The panel also determined diagnostic and management guidelines related to the possibility of a viable intrauterine pregnancy in a woman with a pregnancy of unknown location.
For the finding of no intrauterine fluid collection and normal (or near-normal) adnexa on ultrasonography, the authors provided the following key points:
- A single measurement of human chorionic gonadotropin (hCG), regardless of its value, does not reliably distinguish between ectopic and intrauterine pregnancy (viable or nonviable).
- If a single hCG measurement is < 3,000 mIU/mL, presumptive treatment for ectopic pregnancy with the use of methotrexate or other pharmacologic or surgical means should not be undertaken, in order to avoid the risk of interrupting a viable intrauterine pregnancy.
- If a single hCG measurement is ≥ 3,000 mIU/mL, a viable intrauterine pregnancy is possible but unlikely. The most likely diagnosis is a nonviable intrauterine pregnancy, so it is generally appropriate to obtain at least one follow-up hCG measurement and follow-up ultrasonogram before undertaking treatment for ectopic pregnancy.
If ultrasound had not yet been performed, the researchers offered the following key point: “The hCG levels in women with ectopic pregnancies are highly variable, often < 1,000 mIU/mL, and the hCG level does not predict the likelihood of ectopic pregnancy rupture,” they wrote. “Thus, when the clinical findings are suspicious for ectopic pregnancy, transvaginal ultrasonography is indicated even when the hCG level is low.”
Panel member Dr. Kurt Barnhart, an ob/gyn at Perelman School of Medicine at the University of Pennsylvania, said in a statement that the guidelines represent a consensus that will balance the use of ultrasound and the time needed to ensure that an early pregnancy is not falsely diagnosed as nonviable.
“There should be no rush to diagnose a miscarriage; more time and more information will improve accuracy and hopefully eliminate misdiagnosis,” he said in the statement.
By Viveta Lobo, MD and Laleh Gharahbaghian, MD, FACEP
Our latest insert in the ACEP Ultrasound Section newsletter is below – on the FAST scan – the Suprapubic sections. The prior entries was on the FAST scan: The Cardiac views ( go here) and The Upper Quadrants ( go here. ). The ACEP US Section is the go-to site for everything you want to know about starting an US program, credentialing in ultrasound, the policies and politics, and is the home of SonoGuide - an amazing educational resource for bedside ultrasound, and the EMSONO: Ultrasound Test. It is also where we add our entries for their newsletter that goes over tips and tricks, cases, and all things ultrasound in the news. We recently wrote an article for the ACEP Ultrasound Section Newsletter - which is available for all members of the ACEP US Section – and I highly recommend becoming a member – it’s totally worth it.”
It was a TRUE pleasure to record a podcast recently with Dr. Scott Weingart (aka, my hero) on EMCrit (twitter: EMCrit), and writing this article with our newest ultrasound faculty member, Dr. Viveta Lobo, describes some of what was spoken about.
As discussed in our last entry, the FAST exam is undoubtedly the most widely used bedside ultrasound application used in emergency medicine. Its incorporation in the ATLS revised protocol, the RUSH exam, and several other published protocols, makes it an invaluable screening tool for intra abdominal injury causing hemoperitoneum, cardiac injury with pericardial effusion, and unexplained hypotension.(1,2)
We will continue our discussion of the FAST scan by reviewing the pelvis views, and relay some tips and tricks. Refer to the March 2013 Newsletter for our article reviewing tips for scanning the right upper quadrant (RUQ) and left upper quadrants (LUQ), and the June 2013 newsletter for our article reviewing the tips for the cardiac views.
The Suprapubic View
The suprapubic view on the FAST exam is generally the last of the four views performed.
Theoretically, given its dependent anatomical position, one might logically conclude that it should in fact be the most sensitive view to visualize free fluid; unfortunately, the literature has negated this theory – and in fact this can often be the least sensitive view, largely in part of human error, and especially in pelvic fractures.(1,2,4) Anatomically, when we scan the suprapubic area in both transverse and longitudinal planes, there’s a lot that we see –the bladder, bowel, pelvic bones, pelvic organs, and rectum to name a few. This might make it harder for us to visualize free fluid, and separate it out from these other structures. But here’s a few tips to help overcome these limitations. Begin by placing your phased array or curvilinear probe just above the pubic symphysis, aiming inferiorly/caudad into the pelvis.
Tips for the Suprapubic View:
1. Look through a full bladder. A full bladder - The suprapubic view is visualized using a filled bladder as the acoustic window. Not all trauma patients come in with a full bladder and we will not likely go back to the days when a foley catheter used to be placed in order to fill the bladder for visualization. While we are sure our patients appreciate us not doing this anymore – its important to note, that if your patient has an empty bladder, it is best to hydrate them up with the fluids, and repeat the scan when the bladder is more full.(5) With an empty bladder your ability to adequately discern free fluid is very limited. Mostly due to gas scatter from bowel, inadequate depth adjustments, and inability to discern bowel fluid from free fluid. Click Here for a Video of A Normal Female.
2. Adjust your depth - More often than not, when it is time to scan the suprapubic area, your depth is set too deep from scanning the upper quadrants or cardiac views. We often find that a depth of about 13cm to 16cm optimizes your view. The goal is to have your bladder centered on the screen, to easily visualize the areas surrounding the bladder
3. Adjust your gain - The bladder is a fluid filled structure, and as mentioned before, fluid is the “lover” of ultrasound, allowing structures deep to it to be well visualized, however this often creates an artifact called “posterior acoustic enhancement” that produces a hyperechoic and bright area deep to the bladder. This makes it hard to visualize anechoic or black free fluid. One of the biggest pitfalls is not decreasing your gain to accommodate for this, and limiting your ability to pick up anechoic free fluid.
A good rule of thumb, is to ensure that you can easily visualize pelvic organs. If you are able to identify a uterus or a prostate easily, that usually means you have adjusted your gain appropriately. Click Here for a Video of Posterior Acoustic Enhancement.
4. Look everywhere - Unlike in your upper quadrants, free fluid in the pelvic cavity can in fact collect anywhere – anterior, lateral, and posterior to the bladder as well as anterior, lateral, and posterior to the uterus in female patients. This often is dictated by your patient’s position, the lay of the uterus, how full the bladder is, and the size of the prostate to name a few. We suggest looking in four areas –
a. Look anterior and cephalad to the bladder. Click Here for Video of Free Fluid Anterior to the Bladder. This is especially true if the bladder is empty. At times, free fluid will be mistaken for the bladder and thought to be a septated bladder, when in fact it is free fluid cephalad to the bladder. Click Here for Video of Free Fluid Easily Mistaken for Bladder.
b. Look adjacent/lateral to your bladder; free fluid will collect into a “wedge” shape or triangular shape in between bowel folds which will be most evident with appropriate fanning through the region. Click Here for Video of Wedge of Free Fluid.
c. Look deep/posterior to the bladder between it and your pelvic organs. Click Here for Free Fluid Posterior to the Bladder. Especially in females, you can see a collection of free fluid between the bladder and the uterus. This often looks like boxed shaped anechoic structures that as you fan through will appreciate it not being a “contained” structure.
d. Look posterior to your pelvic organs. Free fluid can collect deep to your uterus or prostate. Click Here for Video of Free Fluid Posterior to the Uterus.
5. Seminal vesicles are also anechoic/black - In males, don’t be fooled by the seminal vesicles. These lie immediately posterior to the bladder, and often appear like a anechoic “bow-tie” shape, with contained fluid and equal on each side.
They will always appear in the same location, and you should fan slowly and carefully through the region to ensure that this is a contained structure and not mistake it for free fluid.
6. Physiological free fluid in females - In menstruating females you can appreciate some physiological free fluid that may be normal. This is hard to differentiate truly from traumatic free fluid, and you will need to consider the clinical picture – Is there any abdominal pain? Is there abdominal or pelvic trauma? Are her vital signs abnormal? Also, the amount and location of free fluid can help – physiological free fluid is found deep to the uterus, and along its border – it should not be greater than 1/3 the length of the border, anything greater than 1/3 should be considered pathological.
7. Fan slowly - While fanning is always important in evaluating any region by ultrasound – we cannot stress it enough when evaluating the suprapubic area. It is impressive and often surprising just how much free fluid can “hide” behind and around the many structures present in this region, and not be visualized unless you dedicatedly fan through the area. It is strongly encouraged to view the suprapubic area in 2 planes – horizontally and longitudinally and fan through each section slowly to make sure you don’t miss any free fluid!(3)
8. Quick Pregnancy Test- In female patients of reproductive age, while performing the pelvic view, take a quick look inside the uterus. You just may quickly get your answer to whether she is pregnant or not but visualizing a gestational sac with fetal pole or yolks sac. However, if you only see a gestational sac and you are performing a FAST scan for unexplained hypotension or shock, this could be an identifier for a pseudosac of an ectopic pregnancy.
Look out for the next and last entry on the FAST scan – the Lung Views in the next newsletter.
- Abrams BJ, Sukumvanich P, Seibel R, et al. Ultrasound for the detection of intraperitoneal fluid: the role of Trendelenburg positioning. Am J Emerg Med. 1999;17(2):117-20.
- Friese RS, Malekzadeh S, Shafi S, et al. Abdominal ultrasound is an unreliable modality for the detection of hemoperitoneum in patients with pelvic fracture. J Trauma. 2007;63(1):97-102.
- Ma OJ, Kefer MP, Mateer JR, et al. Evaluation of hemoperitoneum using a single- vs multiple-view ultrasonographic examination. Acad Emerg Med. 1995;2(7):581-6.
- Von Kuenssberg Jehle D, Stiller G, Wagner D. Sensitivity in detecting free intraperitoneal fluid with the pelvic view of the FAST exam. Am J Emerg Med. 2003;21:476-8.
- Blackbourne LH, Soffer D, McKenney M, et al. Secondary ultrasound examination increases the sensitivity of the FAST exam in blunt trauma. J Trauma. 2004;57:934-8.