LITHUANIAN UNIVERSITY OF HEALTH SCIENCES
MEDICAL ACADEMY
Faculty of Medicine,
Emergency Department
Carlota López Amorín
ACUTE ABDOMEN, TO DO OR NOT TO
DO COMPUTED TOMOGRAPHY?
Final Master Thesis
Medicine
Supervisor: Prof.
Kęstutis Stašaitis
Consultant: Vytautas Aukštakalnis
TABLE OF CONTENTS
1. SUMMARY……….3 2. CONFLICT OF INTEREST………....4 3. ABBREVIATIONS LIST………....5 4. TERMS……….6 5. INTRODUCTION………....66. AIM AND OBJECTIVES OF THE THESIS………..7
7. LITERATURE REVIEW……….8
7.1 Acute abdomen: a rising problem………..8
7.2 What is Computed Tomography?...9
7.2.1 Are there risks?...9
7.3 How to select a patient for Computed Tomography?...11
7.3.1 Clinical history……….11
7.3.2 Physical examination………....13
7.3.3 Laboratory testing……….15
8. RESEARCH METHODOLOGY AND METHODS………..18
9. CONCLUSIONS……….19
10. PRACTICAL RECOMMENDATIONS………..21
11. LITERATURE LIST………....22
1. SUMMARY
Carlota López Amorín. Acute abdomen: to do or not to do Computed Tomography?
In this literature review, the research aim has been to determine which patients, presenting with Acute Abdomen (AA) to the Emergency Department (ED), should be performed a Computed Tomography (CT) scan.
In order to study the different areas that might be involved in the establishment of a criteria to choose what patients should get a CT scan performed, three objectives were proposed:
- To identify the benefits of using Computed Tomography scan in Acute Abdomen - To identify the risks of using Computed Tomography scan and how to overcome them - To analyze what factors and findings can discriminate what patients will benefit from
undergoing a Computed Tomography scan
The methodology used in this study was a literature review of the most recent scientific studies, published within the last 5 years. The databases that have been used are PubMed, Google Scholar, and others. Medical journals and current available guidelines are as well used in this study.
The conclusions obtained are: that CT scan is a very informative image diagnostic tool when it comes to AA; that the radiation exposure when performing a CT is high and therefore measures to reduce radiation dosage must be taken; that performing a CT increases the staying time in the hospital; that good candidates for a CT scan are elderly patients,
paraplegic and quadriplegic patients; that patients suffering from chronic abdominal diseases must be carefully selected in order to avoid unnecessary radiation exposure; that chronic opioid users when presenting to the ED with AA might be suffering from constipation, and therefore they will benefit from simple x-ray; that patients with chronic constipation or obstipation will as well benefit from simple x-ray; that pain localization can be used in order to choose the most appropriate diagnostic method: if the pain is localized in RLQ, LLQ or is non-localised, it is advised to perform a CT scan as a first choice; on the contrary, if the pain is localized in RUQ, ultrasonography should be the first choice; biological markers can be as well used to justify the need of an emergency CT scan: if CRP and WBC are elevated in combination with RLQ pain, it is reasonable to perform a CT,or in the case of concomitant
leukocytosis and lymphopenia . Nonetheless, elevated CRP and elevated WBC alone, do not justify the need of an emergency CT.
The emergency doctor could reasonably order a CT for a patient with AA when: the patient is an elder, paraplegic or quadriplegic; the pain is localized in the RLQ, LLQ, and non-localized pain, in the case of the suspicion of a serious pathology; there is a combination of elevated CRP (>50 mg/L) with elevated WBC (>15 × 109/L) and RLQ pain; there laboratory results show Leukocytosis (>11g/L) and relative lymphopenia (< 15% of total leukocytes).
2. CONFLICT OF INTEREST
The author reports no conflicts of interest.3. ABBREVIATIONS LIST
AA Acute AbdomenACR The American College of Radiology ASIR Adaptive statistical iterative reconstruction CRP C- Reactive protein
CT Computed Tomography ED Emergency Department GI Gastrointestinal
LLQ Left Lower Quadrant
MBIR Model-based iterative reconstruction MDCT Multidetector Computed Tomography RLQ Right Lower Quadrant
RUQ Right Upper Quadrant WBC White Blood Cells
4. TERMS
Iterative reconstruction techniques: refers to an image reconstruction algorithm used in CT that begins with an image assumption, and compares it to real time measured values while making constant adjustments until the two are in agreement.
Computer technology limited early scanners in their ability to perform the iterative
reconstruction. However, this image reconstruction algorithm is now widely used due to the improvement of computer technology over the past decade.
Its ability to overcome noise associated with filtered back projection without increasing radiation dose has had a significant impact on the computed tomography image
reconstruction industry.
5. INTRODUCTION
Acute abdominal pain is one of the most common reasons for seeking medical help. The clinical picture of the patients presenting with acute abdomen ranges from non-urgent
condition, urgent condition, and life-threatening condition. Determining the most appropriate approach for each patient is a big challenge that the emergency physician faces.
Underestimating the condition could lead to a fatal outcome, and overestimating the condition can lead to unnecessary testing and procedures, longer stay in the hospital and increasing medical costs for the hospital.
It is not an easy task to establish an appropriate diagnosis for the patient presenting with acute abdominal pain. This is because of the several systems and organs that can be involved in the abdominal pain physiology: gastrointestinal system, hepatobiliary system, urinary system and reproductive system. But it is also often that the pain origin is found in extra-abdominal organs like the lungs or the heart. For this reason, the physician will most likely need to perform additional testing on the patient.
Nowadays, the use of Computed Tomography on patients presenting with Acute Abdomen to the Emergency Room, is rising all around the world. This imaging method is very helpful in order to establish a right diagnosis, determine the severity of the condition, and avoid unnecessary surgical interventions. And even though the benefits are many, there is one concerning issue regarding the increasing use of the CT scan. This is the ionizing radiation exposure that the patients are put through when performing the CT on them. As well as, iodine based contrast material is believed to cause “contrast induced nephropathy, and allergic reactions (including anaphylaxis).
Therefore it is necessary to select the patients that will most likely benefit from the CT, and not to perform it as a routinary test, in order to avoid unnecessary radiation exposure.
Finding out what patient, theoretically, will most likely benefit from getting a CT scan could help enormously the physician in order to choose the most appropriate approach and further treatment plan. Therefore, several scientific studies and research have been and are being carried out in order to create guidelines that could be easily be used by the physicians in the Emergency Room. At this moment, there is a lot of data regarding this topic but not enough to make conclusions and put them all together to create an uniformed guideline.
In this literature review, it has been collected and scrutinized all the recent data available about what variables should be taken into consideration when creating guidelines about what patients presenting with AA to the ER will benefit from getting a CT scan.
The aim of this research is to able to decide, according to the most recent literature, which patient, presenting with AA to the ED, should undergo a CT scan and which patient should not.
6. AIM AND OBJECTIVES OF THE THESIS
There is a lot of data available about how to approach a patient who presents to the ER with AA. But there are no clear guidelines when it comes to image testing. There are many diverse
opinions whether to use one image diagnostic method, or another. Or not to use any imaging method at all. In this review, it gathered the data available up to date, focusing on the last 5 years, regarding image diagnostic methods used in AA in the ED setting, in particularly, when it is recommended to use the CT.
CT scan has become an issue in the recent years because of its increased use. Even though CT is a great image diagnostic method, it implies significant risk for the patient, due to the ionizing radiation exposure. Therefore, the medical community considers that is needed to establish a criteria in order to choose what patients should get a CT scan.
In this literature review, the aim has been to determine on which patients, presenting with Acute Abdomen to the Emergency Department, should get a Computed Tomography scan performed.
In order to study the different areas that might be involved in the establishment of a criteria to choose what patients should get a CT scan performed, three objectives were proposed:
- To identify the benefits of using Computed Tomography scan in Acute Abdomen. - To identify the risks of using a Computed Tomography scan.
- To analyze what factors and findings can discriminate what patients will benefit from undergoing a Computed Tomography scan.
7. LITERATURE REVIEW
7.1 ACUTE ABDOMEN: A RISING PROBLEMAcute abdomen (AA) refers to a sudden, severe abdominal pain, which requires emergency medical or surgical consultation. [1] It is essential to differentiate what is the nature of the condition, whether it is urgent or non-urgent, in order to choose the most appropriate approach. This presents a challenge due to the wide range of causes that can be involved in acute abdominal pain. It can be caused by any abdominal organ or abdominal system. However, it can be also caused by extra abdominal organs, such as lungs and heart diseases. Therefore, acute abdomen is considered to be a condition rather than a disease.
Acute abdominal pain of non-traumatic origin is one of the more frequent complaints leading people to the Emergency Department (ED). It comprises 5 to 10% of the ED visits. [2] It is a rising problem for the emergency doctor because of all the challenges that are needed to solve with this condition. It is essential to determine if it is an urgent or a non-urgent situation. Nowadays, it is easier to answer this question with all the new diagnostic methods and techniques that are available, especially inside the imaging field, where Computed
Tomography (CT) is a game changer. Nevertheless, these techniques arise new challenges such as how to select the patients that are candidates to undergo CT, the radiation exposure, the increasing staying time in the hospital while waiting to get the CT done, are the main concerns.
7.2 WHAT IS COMPUTED TOMOGRAPHY?
Computed Tomography is a computerized x-ray imaging procedure. It consists of a narrow beam of x-rays that are aimed at the patient while rotating around the body. The produced signals are processed by the computer and cross-sectional images are created. These cross-sectional images can be used individually, studying and analyzing each image on its own, or they can be combined together in order to produce a three dimensional image of the body. This possibility of looking at the pieces individually and/or combined it is highly beneficial when studying anomalies that are not so easy to be seen.[3]
CT is very good at showing bone, soft tissue, and blood vessels.
In the study of the abdominal cavity, in order to help in the diagnosis of acute abdomen, it is sometimes needed to administer to the patient a CT contrast agent. This is because CT, as with all X-rays, dense structures within the body are easily imagined, but soft tissues are more difficult to see. For this reason, different contrast media are administered to the patients. In the case of enhancing the image of the digestive system, oral contrast agents are used.
CT scans use x-rays, and all x-rays produce ionizing radiation. Ionizing radiation has the potential to cause biological changes in the living organism. [4] And this risk increases with the number of exposures added up over the life of an individual.
Since CT use is more widely used, new concerns arise. It is undoubted that physicians and patients can benefit from a CT scan by getting a more accurate diagnosis and thus a better medical approach to the condition. But, the conflict lies between deciding when the benefit is higher than the detriment.
Currently, there are several techniques that are being developed, and are starting to be used, in order to reduce the exposure to ionizing radiation.
- Iterative reconstruction techniques: this technique focuses on improving the imaging quality with various image reconstruction algorithms integrated in the computer of the CT scan. This allows to decrease the dose of radiation used during the scan, and still be able to see. But it has few limitations, like texture changes and longer
reconstruction time.[5] Nevertheless, in one scientific study a reduced-dose protocol was studied. It was evaluated for the accuracy of reduced-dose CT by using a new generation model-based iterative reconstruction (MBIR) to diagnose acute renal colic compared with a standard-dose with 50% adaptive statistical iterative reconstruction (ASIR). And it was concluded that a reduced-dose protocol with MBIR allowed to a dose reduction of 84% without increasing noise and without an conspicuous
deterioration in image quality in patients suspected of having renal colic.[6]
- Customized imaging: the amount of radiation used in a CT scan is dependent on several variables like the size of the patient, part of the body being examined, and the diagnostic task. The use of more sensible algorithms within the computer of the scan are being developed, so that the amount of radiation used in the scan will be adjust more appropriately to the patient according to the mentioned parameters. [3]
- Omitting oral contrast: few scientific studies are being carried out in order to see if there is a significant difference in diagnostic accuracy between using oral contrast in the study of the gastrointestinal system (GI) or not. In one retrospective study, it was studied the hypothesis that it is safe to omit the oral contrast media in patients that present with acute abdominal pain in the emergency room and are undergoing
Multidetector Computed Tomography (MDCT). And their conclusion was that, according to their study, oral contrast can be safely omitted in patients presenting with abdominal symptoms in and undergoing a MDCT of the abdomen and pelvis in an emergency setting. [7]
The radiation problem is very concerning nowadays, and therefore several studies are being done, different techniques are being applied, and alternative options are being given in order to minimize the impact of the radiation on the patient. But this is not the only disadvantage that the CT scan presents.
Another concerning issue is whether the patient spends more or less time in the hospital when a CT scan is performed on them. The literature is controversial this matter. Some studies suggest that when oral contrast is used, the time spent in the hospital increases by 60-90 minutes. [7, 8]. Other studies demonstrate that the overall staying time in the hospital is reduced when an early CT is performed in the elderly patients that need the surgical assessment unit.[9] So, whether the time spent in the hospital when a CT is performed increases or not, it is not so clear, and more importantly, it might be not so determinant when deciding whether to perform a CT scan or not.
It is clear that performing a CT scan when a patient presents to the emergency department with acute abdominal pain, can be very befinicial and greatly help to determine the most accurate diagnosis, but as it entails some disadvantages, it is needed to determine what kind of patient can benefit from the CT scan. In order to do that, it is needed to categorize the patient according to the clinical history, risk factors, physical examination, laboratory test results.
7.3 HOW TO SELECT A PATIENT FOR CT?
7.3.1 Clinical history:
Age is a very relevant issue when it comes to considering the risk of radiation exposure. It is not the same to perform a CT scan on an elderly patient than on a young patient. The younger
patients have a higher risk of developing the consequences of radiation exposure, since the radiation accumulates and adds up over the lifetime of a person, and a young person has potentially more possibilities of needing further x-ray imaging later in life, than those that are in their latest years of their lives. Also, even if the elderly will need more x-ray tests later on in their lives, they will probably won't suffer the consequences of radiation, since they take years to develop. [10]
Chronic abdominal diseases, patients suffering from chronic diseases of the abdominal cavity have higher possibilities of needing CT scans during their life-time. Thus, it is necessary to decide whether that patient will really benefit from that scan or if there are other imaging techniques that may help to establish the diagnosis without being exposed to the radiation, like Magnetic Resonance Imaging (MRI) or endoscopic techniques. This is particularly important in patients that suffer from inflammatory bowel diseases. These patients are usually young, particularly if we talk about Crohn's disease. They are diagnosed at a young age and they will need follow-up imaging testing during their life-time, thus meaning high levels of radiation dose exposure accumulated over their life-span. It is needed to optimize the radiation exposure and this is the reason to use other instruments like MRI, or if it is needed to perform a CT, using low-dose CT. [11]
In adults without cancer presenting to the ED with acute abdominal pain, almost 19% were
opioid users [12]. The chronic use of opioids should be taken in consideration when taking
the history of the patient, because those patients may be suffering from chronic constipation because of the chronic use of opioids itself. Therefore, constipation may be the cause of acute abdominal pain. In this case, the patients will benefit from simple x-ray without the need of undergoing CT scan. If after performing the x-ray the diagnostic remains unclear,
ultrasonography could be used.
Patients with paraplegia or quadriplegia with acute abdominal surgical emergencies are more likely to present late and have a significantly higher incidence of postoperative septic
complications and longer hospital stay. Early surgical consultation and aggressive evaluation and postoperative management are warranted in these populations.[13] In this group of
patients it would be justified to select them for CT imaging when they present to the ER and the diagnosis is unclear.
7.3.2 Physical examination:
In Acute Abdomen the physical examination can provide a lot of information and be very revealing. In many cases, only with the physical examination and the clinical history an accurate diagnosis could be done. But, there are cases where the clinical picture is not so clear and it is needed to make other tests, like laboratory testing and imaging testing. The location of pain is often a good starting point in order to choose what testing should be performed. The American College of Radiology (ACR) has developed evidence-based guidelines to help physicians to make the most appropriate imaging decisions for specific clinical conditions.[14]
The abdomen is usually divided in four quadrants, this division allows the localization of pain, tenderness and other elements of interest. Following this division of the abdomen, the ACR guidelines explain which imaging option is the most appropriate depending whether the pain is localized in one of the quadrants, or if it is generalized pain.
Right Upper Quadrant Pain
Acute cholecystitis is the most common cause of new-onset of pain in the right upper quadrant. It is recommended to use ultrasonography as the initial imaging test. Even though cholescintigraphy has more sensitivity and specificity than ultrasonography when diagnosing acute cholecystitis, ultrasonography is more widely available and can identify other potential causes of pain, and does not expose the patient to ionizing radiation. [14]
Computed Tomography has not been widely studied in the right upper quadrant pain, but it may be used when the results of the ultrasonography and the cholescintigraphy were inconclusive.
Magnetic Resonance Imaging has similar sensitivity and specificity than ultrasonography. It could be useful to use when the results of the ultrasonography are inconclusive or to visualize structures that are not well seen in the ultrasonography like hepatic and biliary abnormalities. [14]
Right Lower Quadrant Pain
Acute appendicitis is the most common cause of pain in the right lower quadrant requiring surgery, and this is the main cause of requiring additional imaging in order to establish a diagnosis for the right lower quadrant pain. Computed Tomography is recommended as the initial imaging method, since it has been proven that CT has more sensitivity and specificity than ultrasonography for detecting acute appendicitis. Also, CT provides more consistent results because ultrasonography results are highly dependent on the skills and experience of the technologist and radiologist.[14]
Moreover, the use of CT has reduced the negative-finding appendectomy rate from 24% to 3% .[15]
And it has shown to overall decrease the costs per patient by preventing unnecessary appendectomies and hospital admissions. [16]
Left Lower Quadrant Pain
Acute sigmoid diverticulitis is the most common cause of pain in adults in the left lower quadrant, and is the reason for performing imaging. Diverticulitis is often diagnosed without imaging tests, but it is sometimes needed when the diagnosis is unclear or if there are
complications. In this case, the ACR recommends the use of CT. It has been proven that CT has greater sensitivity than 95% for detecting diverticulitis. [17] Also, it can provide
information about the extent of the disease and a greater visualization of the complications, like in the case of abscess formation. Moreover, CT can reveal diseases other than
Ultrasonography has been studied to have similar sensitivity to diagnose diverticulitis compared to CT, but the results vary depending on the study. This might be because the results of the ultrasonography are highly dependent on the technician and radiologist skills and experience. For this reason, CT results are more reliable.
Preliminary data on MRI to diagnose diverticulitis suggest that it may be useful.
Non Localized Abdominal Pain
Although certain diseases are often associated with pain in a localized quadrant, like appendicitis, cholecystitis and diverticulitis, it is also very often when the pain presents generalized, making the clinical picture not so clear and the differential diagnosis broader. When the clinical history, physical examination and laboratory testing are not sufficient to determine the cause of the pain, additional imaging testing is needed. In this case, it is CT typically the chosen method of imaging, when there is significant concern for serious pathology. [14]
It has been studied that performing a CT in patients with non traumatic abdominal pain presenting to the emergency department will alter the leading diagnosis in 49% of patients and change the management plan in 42% patients. [18]
There are other guidelines and scientific studies to help the physicians to decide which imaging method might be more beneficial in each scenario. But a guideline based on the anatomical quadrants of the abdomen, having in mind that this is how the physical evaluation of the patient will be performed, it makes it very simple to be remembered and used in the setting of the Emergency Room (ER).
7.3.3 Laboratory testing:
Laboratory testing can be very informative regarding the current status of the patient at the time of being examined, as well as, the prognosis of the patient.
Nowadays the study of biological markers is one of the main interests within scientific studies. Different studies suggest that certain biomarkers may be used in the early diagnosis of autoimmune diseases, others may be used to properly diagnose rare conditions such as acute mesenteric infarction, and others may be used to select what patients are good candidates for CT investigation.
The conclusions of the studies about individual biological markers are not always statistically relevant, but this changes when the biomarkers are studied in combination with other
biomarkers or with other elements.
Regarding the use of biomarkers to select the patients for CT investigation, there are three interesting studies that may be used by emergency doctors when deciding if the patient should undergo CT testing or not.
1. “C-Reactive Protein and White Blood Cell Count as Triage Test Between Urgent and Nonurgent Conditions in 2961 Patients With Acute Abdominal Pain”:
CRP levels and WBC count are insufficient markers to be used as a triage instrument in the selection for diagnostic imaging: a good criteria in order to decide what cases need or would benefit from imaging testing, is differentiating between urgent cases and non-urgent cases. In urgent cases the use of additional imaging testing in the ER setting would be justified. An accurate triage could help the physician in the ER to prevent unnecessary tests, with its consequent risk of ionizing radiation for the
patient, and additional costs for the hospital. Focusing the resources for those patients who could really benefit from the imaging testing. So that patients with urgent
conditions could get an accurate diagnosis and management strategies. The study examined how accurate two parameters could be that are routinely checked in the ER, White Blood Cells range and C-Reactive protein levels. It was investigated if the high levels of these two parameters could be used to differentiate between urgent and non-urgent cases. The conclusion of the study demonstrates that using CRP (>50 mg/L) and WBC count (>15 ×109/L) as triage test alone would lead to an unacceptably high percentage of missed urgent cases (85.3%) and a substantial overshoot in use of diagnostic imaging because of the high percentage of false-positive cases.[19]
2. “Do C-reactive protein level, white blood cell count, and pain location guide the selection of patients for computed tomography imaging in non-traumatic acute abdomen?”:
Selection of patients for CT investigation: elevated CRP combined with elevated WBC and RLQ pain. Since CRP and WBC count are insufficient to be used alone as a triage, one study, it is believed to be the first, examined whether combining it with the location of pain aids in the selection of patients for CT imaging. From all the
abdominal quadrants and regions that were studied, the number of positive CTs in patients with RUQ and LLQ were the highest, and the lowest were in pelvic pain. No significant difference was found between positive and negative CT groups in terms of CRP levels in patients with pain location other than RLQ. However, further studies are needed, because of the high positive CTs that were obtained in patients with LLQ, flank pain, and RUQ pain; it was suspected that a study with a larger proportion of those groups may be found to have significant differences. In the absence of more evidence regarding the other localizations of pain, it can be concluded by this study that the combination of elevated CRP (>50 mg/L) with elevated WBC (>15 × 109/L) and RLQ pain can be used in the selection of patients for CT investigation. [20]
3. “Concomitant leukocytosis and lymphopenia predict significant pathology at CT of acute abdomen: a case-control study”:
In this study, data was extracted from patient's electronic health records. The aim of the study was to compare the following variants and their ability to predict a
significant pathology: shock index, peritonism, abnormal bowel sounds, fever (> 38 °C), intensity and duration of the pain, leukocytosis (white blood cell count >11G/L), relative lymphopenia (< 15% of total leukocytes), and C-reactive Protein (CRP). Significant pathology was detected on CT in 71 (65%) patients. Only leukocytosis (odds ratio 3.3, p = 0.008) and relative lymphopenia (odds ratio 3.8, p = 0.002) were associated with significant pathology on CT. The joint presence of these two anomalies was strongly associated with significant pathology on CT (odds
ratio 8.2, p = 0.033). Leukocytosis with relative lymphopenia had a specificity of 89% (33/37) and sensitivity of 48% (33/69) for the detection of significant pathology on CT
.
The high specificity of the association between leukocytosis and relative lymphopenia amongst the study population suggests that these parameters would be sufficient to justify an emergency CT. However, none of the parameters could be used to rule out a significant pathology. [21]8. RESEARCH METHODOLOGY AND METHODS
The research methodology has consisted of a literature review from the following data bases that the Lithuanian University of Health Science is subscribed to: Pubmed, Google Scholar and UpToDate. Gathering information from handbooks, being the main one The American College of Radiology. Websites and electronic journals like The Journal of Trauma and Acute Care Surgery, The American Journal of Emergency Medicine, etc.
In order to select the literature the following terms were used: “Acute Abdomen”,
“Emergency Department”, “Computed Tomography”, “Diagnostic Imaging”, “Biological Markers”, and “Ionizing Radiation”. During the literature search filters were applied, discarding the articles that were not written in the English language and those articles that were past more than 5 years since the publication date, with the exception of four of them that were older. Also, it was only used in articles focused on adults of +19 years.
The program RefWorks was used in order to manage the found scientific literature
references, which can be found at the end of this paper are cited according to the Vancouver System.
The object of this literature review is to be able, according to the available literature until this date, to select which patients presenting with Acute Abdomen should get a CT scan in the emergency department setting.
The paper has been organized in 3 chapters:
- In the first chapter, it is described what is acute abdomen and its importance. Focusing on the challenge that it presents for the emergency physician to appropriately choose the most appropriate management and treatment.
- In the second chapter, it is described what is a computed tomography scan, and what are the main advantages and disadvantages of performing it. Different techniques and new approaches regarding how to use the CT scan are explained in detail.
- Lastly, in the third chapter it is proposed a criteria of how to choose who are the patients that will, most likely, benefit from getting a CT scan. For that, the patients are chosen according to their clinical picture, physical examination, and laboratory tests results.
9. CONCLUSIONS
After this research, based on the data available up to date, the following conclusions are formulated:
1. The CT scan is one of the most informative imaging methods. CT scan in patients with non traumatic abdominal pain presenting to the ED will alter the leading diagnosis in 49% of patients and change the management plan in 42% patients. The overall staying time in the hospital is reduced when an early CT is performed in the elderly patients that need the surgical assessment unit.
2. The CT scan use on patients presenting with AA to the ED is increasing. This increase concerns the scientific community because of increased ionizing radiation exposure. In order to reduce the ionizing radiation dosage new techniques are developed. Iterative reconstruction techniques: improves the imaging quality with various image reconstruction algorithms integrated in the computer of the CT scan. It was concluded that a reduced-dose protocol with MBIR allowed a dose reduction of 84% without
increasing noise and without any conspicuous deterioration in image quality in patients suspected of having renal colic.
Customized imaging: more sensitive algorithms are developed in order to adjust the radiation dose used by the CT scan, to the size of the patient, the part of the body being studied and the object of the study.
Omitting oral contrast: oral contrast can be safely omitted in patients presenting with abdominal symptoms in and undergoing a MDCT of the abdomen and pelvis in an emergency setting.
Performing a CT scan and using oral contrast increases the time spent in the hospital by 60-90 minutes.
3. The group of patients that it would be justified to select them for CT imaging when they present to the ER with AA and the diagnosis is unclear are: elderly patients, paraplegic and quadriplegic patients.
The group of patients that are at higher risk of getting exposed to higher ionizing radiation dosage, because of the probable need of future CT scans in their lifespan, are: patients with chronic abdominal diseases.
Chronic opioid users, patients suffering with chronic constipation or obstipation, will most likely benefit from simple x-ray without the need of undergoing CT scan. If after performing the x-ray the diagnostic remains unclear, ultrasonography could be used. When pain is localized in the Right Lower Quadrant, CT is recommended as the initial imaging method.
When pain is localized in the Left Lower Quadrant, CT is recommended as the initial imaging method.
When the pain is non-localised, CT is typically chosen as a method of imaging, when there is significant concern for serious pathology.
When the pain is localised in the Right Upper Quadrant, ultrasonography should be the initial imaging test.
Using CRP and WBC count as triage test alone would lead to an unacceptably high percentage of missed urgent cases and a substantial overshoot in use of diagnostic imaging because of the high percentage of false-positive cases.
The combination of elevated CRP (>50 mg/L) with elevated WBC (>15 × 109/L) and RLQ pain can be used in the selection of patients for CT investigation.
Leukocytosis (>11g/L) and relative lymphopenia (< 15% of total leukocytes) would be sufficient to justify an emergency CT.
The study has gone some way towards enhancing the understanding of what is important to take in consideration when selecting a patient for a CT scan.
These are the conclusions that derive from the scrutinization of the available literature. They can be valuable for the physician for the selection of patients that will most likely benefit from a CT scan when presenting with AA to the ED. Nonetheless, more studies and scientific research are needed in order to identify what other factors can be used in the selection
criteria.
10. PRACTICAL RECOMMENDATIONS
According to the conclusions obtained in this literature review, the following practical recommendations are suggested:
1. The emergency doctor could reasonably order a CT for a patient with AA when: - The patient is an elder, paraplegic or quadriplegic.
- The pain is localized in the RLQ, LLQ, and non-localized pain, in the case of the suspicion of a serious pathology.
- There is a combination of elevated CRP (>50 mg/L) with elevated WBC (>15 × 109/L) and RLQ pain.
- There laboratory results show Leukocytosis (>11g/L) and relative lymphopenia (< 15% of total leukocytes)
10. LITERATURE LIST
1. John W. Patterson; Elvita Dominique, 2019. Acute abdomen. https://www.ncbi.nlm.nih.gov/books/NBK459328/
2. John L Kendall, MD, FACEPMaria E Moreira, MD, 2020. Evaluation of the adult with abdominal pain in the emergency department.
https://www.uptodate.com/contents/evaluation-of-the-adult-with-abdominal-pain-in-t he-emergency-department
3. Paul Stark, MD, Nestor L Muller, MD, PhD, Geraldine Finale, MD, 2019. Principles of computed tomography of the chest.
https://www.uptodate.com/contents/principles-of-computed-tomography-of-the-chest? search=CT&source=search_result&selectedTitle=1~150&usage_type=default&displa y_rank=1
4. Christoph I Lee, MD, MS, Joann G Elmore, MD, MPDH, 2019. Radiation-related risks of imaging.
https://www.uptodate.com/contents/radiation-related-risks-of-imaging?search=princip les%20of%20CT&source=search_result&selectedTitle=12~150&usage_type=default &display_rank=12
5. A. Padole, Ranish Deedar Ali Khawaja, Mannudeep K. Kalra and Sarabjeet Singh, 2015. CT Radiation Dose and Iterative Reconstruction Techniques.
https://www.ajronline.org/doi/full/10.2214/AJR.14.13241
6. Mikael Fontarensky , Agaïcha Alfidja, Renan Perignon , Arnaud Schoenig, Christophe Perrier, Aurélien Mulliez, Laurent Guy, Louis Boyer, 2015. Reduced Radiation Dose with Model-based Iterative Reconstruction versus Standard Dose with Adaptive Statistical Iterative Reconstruction in Abdominal CT for Diagnosis of Acute Renal Colic. https://pubs.rsna.org/doi/full/10.1148/radiol.2015141287
7. Abdullah Alabousi, Michael N. Patlas, FRCPC, Niv Sne,Douglas S. Katz, MD, FACR, FASER, 2015. Is Oral Contrast Necessary for Multidetector Computed
Tomography Imaging of Patients with Acute Abdominal Pain?.
https://journals.sagepub.com/doi/full/10.1016/j.carj.2015.03.003
8. Nova L. Panebianco, MD, MPH a, Katherine Jahnes, MD b, Angela M. Mills, MD a, 2017. Imaging and Laboratory Testing in Acute Abdominal Pain.
https://abdominalkey.com/and-laboratory-testing-in-acute-abdominal-pain/?fbclid=Iw
AR3wwlFy3aWbut0k8lQmnzrQKKlaXgSV9Phxn1jZyf8XxT5-WgdfUJ9Qgqw
9. RW Radwan, AM Tang, WD Beasley, 2018. Computed tomography as a first-line investigation for elderly patients admitted to a surgical assessment unit.
https://publishing.rcseng.ac.uk/doi/full/10.1308/rcsann.2017.0231?url_ver=Z39.88-20 03&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub%3Dpubmed&
10. Massimo Tonolini, Elena Valconi, Angelo Vanculli, Roberto Vianco, 2018. Radiation overexposure from repeated CT scans in young adults with acute abdominal pain.
https://link-springer-com.ezproxy.dbazes.lsmuni.lt/article/10.1007/s10140-017-1554-y
11. Richard G. Kavanagh, John O´Grady, Brian W. Carey, Patrick D. McLaughlin, Siobhan B. O´Neill, Michael M. Maher, Owen J. O´Connor, 2018. Low-Dose
Computed Tomography for the Optimization of Radiation Dose Exposure in Patients with Crohn's Disease. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6234436/
12. D. Khemani, M. Camilleri, A. Roldan, A. D. Nelson, S.-Y. Park, A. Acosta, A. R. Zinsmeister, 2016. Opioid analgesic use among patients presenting with acute abdominal pain and factors associated with surgical diagnosis
https://onlinelibrary-wiley-com.ezproxy.dbazes.lsmuni.lt/doi/full/10.1111/nmo.13000
13. Benjamin, Elizabeth MD, PhD; Haltmeier, Tobias MD; Karamanos, Efstathios MD; Inaba, Kenji MD; Lam, Lydia; Demetriades, Demetrios MD, PhD, 2015. Paraplegic and quadriplegic patients undergoing emergency abdominal surgery.
https://journals.lww.com/jtrauma/Abstract/2015/04000/Paraplegic_and_quadriplegic_ patients_undergoing.18.aspx
14. Sarah L. Cartwright, MD, Mark P. Knudson, MD, MSPH, Wake Forest Baptist Medical Center, Winston-Salem, North Carolina, 2015. Diagnostic Imaging of Acute Abdominal Pain in Adults.
15. Raman SS, Osuagwu FC, Kadell B, Cryer H, Sayre J, Lu DS, 2008. Effect of CT on false positive diagnosis of appendicitis and perforation.
https://www.researchgate.net/publication/5547754_Effect_of_CT_on_False_Positive_ Diagnosis_of_Appendicitis_and_Perforation
16. Rao PM, Rhea JT, Novelline RA, Mostafavi AA, McCabe CJ, 1998. Effect of computed tomography of the appendix on treatment of patients and use of hospital resources.https://www.ncbi.nlm.nih.gov/pubmed/9428814
17. Sai VF, Velayos F, Neuhaus J, Westphalen AC, 2012. Colonoscopy after CT diagnosis of diverticulitis to exclude colon cancer: a systematic literature review
https://www.ncbi.nlm.nih.gov/pubmed/22517956
18. Abujudeh HH, Kaewlai R, McMahon PM, et al, 2011. Abdominopelvic CT increases diagnostic certainty and guides management decisions: a prospective investigation of 584 patients in a large academic medical center.
https://www.ncbi.nlm.nih.gov/pubmed/21257870
19. Sarah L. Gans, MD, Jasper J. Atema, MD, Jaap Stoker, MD, PhD, Boudewijn R. Toorenvliet, MD, PhD, Helena Laurell, MD, PhD, and Marja A. Boermeester, MD, PhD, 2015. C-Reactive Protein and White Blood Cell Count as a Triage Test Between Urgent and Nonurgent Conditions in 2961 Patients with Acute Abdominal Pain.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4553955/
20. E. Ozan, G.K. Atac, T. Evrin, K. Alisar, L.O. Sonmez, A. Alhan, 2017. Do C-reactive protein level, white blood cell, and pain location guide the selection of patients for computed tomography imaging in non-traumatic acute abdomen?
https://link-springer-com.ezproxy.dbazes.lsmuni.lt/article/10.1007/s10140-016-1439-5
21. Alexandra Platon, Chloe Frund, Laura Meijers, Thomas Perneger, Elisabeth Andereggen, Minerva Becker, Alice Halfon Poletti, Olivier T. Rutschmann & Pierre-Alexandre Poletti, 2019. Concomitant leukocytosis and lymphopenia predict significant pathology at CT of acute abdomen: a case-control study.
https://bmcemergmed-biomedcentral-com.ezproxy.dbazes.lsmuni.lt/articles/10.1186/s 12873-019-0227-4
