Role of Fast in Patient with Blunt Abdominal Trauma
Dr. RaedBassimAbdulbaki, 1 Dr. Sssd Abdullah Sarsam, 2 Dr. Haider I. Aleime. 3
1M. B. Ch. B, residents’ doctor at surgical Department/Baghdad Teaching Hospital
2CABS, FRCS, FACS, Consultant doctor at surgical Department/ Baghdad Teaching Hospital
3Specialist doctor at surgical Department/Baghdad Teaching Hospital Corresponding author: Dr. Haider I. Aleime.
ABSTRACT Background
Blunt abdominal trauma is a common cause of presentation to surgical emergency department. The Focused Assessment Sonographic examination in Trauma patient (FAST) is a rapid bedside sonographic test that sequentially surveys for hemopericardium and then the right upper quadrant (RUQ), left upper quadrant (LUQ), and pelvis for hemoperitoneum in patients with potential truncal injuries.
Objective: This study aimed to assess the efficacy of FAST in managing patients with blunt abdominal trauma regarding specificity, sensitivity, positive and negative predictive values.
Patients and Method: This is a prospective observational study performed in Baghdad teaching hospital during thirteen months’ period involving 103 patients with blunt abdominal trauma presenting to the emergency department of Baghdad teaching hospital aged 15 years and above.
Results: 103 cases of Blunt abdominal trauma were received through this period.From these cases were 74.7% (n=77) males and 25.3% (n=26) were females. In these 103 cases, 88.35%
(n=91) of them showed negative FAST result and 11.65% (n=12) of them showed positive FAST results, 0.97% (n=1) patient had false positive and 1.95% (n=2) patients had false negative results. Sensitivity was calculated to be (84.6%), specificity (98.8%), with the accuracy of (97%), the negative predictive value was (95.6%) and the positive predictive value was (91.6 %).
Conclusion: FAST scan is a useful diagnostic tool in the initial assessment of blunt abdominal trauma patients. It is easy to perform, readily available; no risk of radiation, reproducible, and noninvasive. It guides the surgeons for further management of patients with blunt abdominal trauma.
Keywords: FAST, blunt abdominal trauma, emergency, laparotomy Introduction:
Blunt trauma is the direct energy transfer to a body part by impact, injury or physical attack [1]. It is a major cause of morbidity and mortality in all age groups and it can happen during acceleration or deceleration part of energy transfer [2]. The deceleration part is the most common cause of intra-abdominal organ injury in velocity of the patient leading to organ being either torn by shear stress or impact on other body parts [3]. 85% of abdominal trauma are blunt in character and 15% penetrating [4].
The Patient may present with pain, tenderness, vital instability, peritoneal hemorrhage and / or peritoneal signs. There may also be some specific signs indicating the probability of an abdominal and visceral injury for example seat belt marks steering wheel marks which occur in RTA, ecchymosis involving the loins (Grey turner sign), or per umbilical ecchymosis (Cullen sign) both indicate retroperitoneal hemorrhage [5].
However, clinical examination by itself is not adequate because the patient may suffer from other distracting injuries or may have altered mental status [6]. The management of blunt
1970s, the structure of the work up and treatment of life threating injuries was very much dependent on the physician’s diagnostic abilities. The introduction of ATLS by Steiner and Collicott was a turning point in the management style as since 1965 diagnostic peritoneal lavage was the procedure of choice for determining which patient with blunt trauma would require an intervention and which would require only observation [7]. That is until the introduction of FAST in the evolution of abdominal trauma by Kristensen and colleagues in 1971[8].
Another major advance in the management of the blunt abdominal trauma is the introduction of the CT scan in 1980s especially in hemo-dynamically stable patients and using contrasts Enhancement [9].
FAST: is an abbreviation of focused assessment with sonography in trauma which is a rapid bedside sonographic examination done by doctors and sometimes even trained paramedics as a screening test for fluid (typically blood or hollow viscus content in 4 parts (per hepatic, per splenic, pericardium and pelvic) [10].
For FAST to be (+ve) positive minimal volume of free fluid must be present intraperitoneally, this volume is dependent on the operative experience the quality of the equipment and the position of the patient and it ranges between 100cc to 500cc [11, 12].
The approach to patients with blunt abdominal trauma is largely derived from guidelines presented by the Washington state department of health office of community health system.
Emergency medical services and trauma section set forth by the national Guideline clearing house [13]. These guidelines are modified to better suit the capabilities of Iraqi hospitals as seen in the following flowcharts.
Indications
Indications for the FAST exams include:
•Blunt and/or penetrating abdominal and/or thoracic trauma.
•Undifferentiated shock and/or hypotension (as part of the Rapid Ultrasound for Shock and Hypotension (RUSH) exa) [14].
Contraindications: There are no absolute contraindications to the FAST. However, FAST should not delay resuscitative efforts for patients in extremis [14].
Aim of study:
This study aimed to assess the efficacy of FAST in managing patients with blunt abdominal trauma regarding specificity, sensitivity, positive and negative predictive values.
Patients and methods:
This is a prospective observational study performed in Baghdad teaching hospital in the period from (first of October 2017) to (thirty first of October 2018) involving 103 patients with blunt abdominal trauma presenting to the emergency department of Baghdad teaching hospital aged from 15 years to above, during the call of the supervising consultant, 5th floor.
Emergency protocols were followed according to ATLS ensuring Airway, Breathing, Circulation, Disability and exposure and performing FAST examination along the way to all patients within the 1st ½ hour of arrival and repeated 15 – 30 minutes later according to the patient clinical and vital signs.
Intra-abdominal views on FAST are based on 4 dependent areas in which free fluid is most likely to accumulate when the patient is in the supine position [15,16]
FAST examination was performed by the radiology resident, emergency medicine specialist or general surgery senior house officer.
Patients who were hemodynamically stable with +ve FAST were referred for CT scan of abdomen, if +ve and the patient was indicated for laparotomy, laparotomy was performed and the findings were recorded, if the patient is not indicated for laparotomy then the patient is admitted for observation. Both situations were considered true +ve FAST
If CT scan results was –ve, the patient was successfully treated without operative intervention, the results of the FAST are considered False +ve.
If FAST examination was –ve and the patient was hemodynmiaclly unstable and no other source of bleeding was identified and clinical signs points toward an intra-abdominal source of bleeding, laparotomy was performed and the results considered false –ve .
All the data were recorded using a special Data sheet prepared by the researcher and the supervising specialist
Statistical analysis: The analysis was carried by using the SPSS software version 23, after data entering and revised for many times by the researcher.
Results:
This study took thirteen months from the first of October 2017 to the thirty first of October 2018. 118 trauma cases were received through this period. There were 15 cases of penetrating abdominal injury excluded. 103 cases of blunt abdominal injury were performed by FAST scans.
Cases of blunt abdominal trauma are summarized in table (1) as distributed according to age.
Table (1): Age related to mechanism of injury.
Age(year) RTA FFA Fight Other Total
15-25 18 6 5 10 39
26-35 23 6 3 2 34
36-45 12 2 2 3 19
≥46 9 1 0 1 11
Total 62 15 10 16 103
There were 77 (74.7%) males and 26 (25.3%) females as shown in Figure (1).
Figure (1): Patient gender ratio.
There were 62 (60.2 %) cases of road traffic accident, 15 (14.6 %) cases of fall from height, 10 (9.7 %) cases of fight 16 (15.5 %) cases with other types of injuries Figure (2).
[CATEGORY NAME]
74.7%
[CATEGORY NAME]
25.3%
Patient gender
Male Femal
Figure (2): Mechanism of injury ratio.
From (103) cases there was (12) cases of positive FAST scan; (5) of them were hemodynamically unstable and transferred to the emergency operation theater for urgent laparotomy without C.T. scan
All of them had serious injuries of laparotomy two of them had splenic injury, two of them had liver injury and one had small mesenteric injury.
The remaining seven cases were hemodynamically stable and evaluated by CT scan,6 of them had hemoperitoneum ;( 4) cases of them had major organ injury whom underwent emergency laparotomy {three liver injury and one spleen injury} and (2) cases of them had no major injury and were treated conservatively
The seventh case was found to have a negative CT scan (false positive FAST scan) and was admitted to the ward for follow up and discharged well from hospital 5 days later as shown in Figure (3).
60.2%
14.6 9.7%
15.5
Mechanism of injury
RTA FFH Fight Others
Figure (3): Flow chart of patients with Blunt abdominal traumawho had FAST scan (+ve).
There were (91) negative FAST scan cases; four of them were hemodynamically unstable two of them had major thoracic trauma without hemoperitoneum which received by the cardiovascular team; the other two cases were unstable with signs of peritonitis and no extra abdominal source of hemorrhage so laparotomy was done to them and revealed bleeding from tear in gastro colic ligament.
The remaining (87) cases of negative FAST scan were stable; (85) of them followed up until discharge from the hospital and the other two cases had head injuries which received by
Observation and discharge to
home
Figure (4):Flow chart of patients with Blunt abdominal trauma who had FAST scan (-ve).
In this study FAST positive 12 cases (11.65%); true (+) 11 cases, false (+) 1 case and FAST negative 91 cases (88.35 %); true (-) 89 cases, false n(-) 2 cases Table (2), Figure (5).
Table (2): The results of FAST scans in Blunt abdominal cases.
(-ve) laparotomy or CT
(+ve) Laparotomy or CT
12 1
11 FAST (+)
91 89
2 FAST ( - )
103 90
13 Total
In this study sensitivity (84.6%), specificity (98.8%), positive productive value (91.6%), negative productive value (97.8%) and accuracy (97%) Figure (5).
Figure (5): Flowchart of patients.
Discussion
One of the most common causes of health problems and death is trauma. The Abdomen is the most commonly injured region. The percentage of patients that need surgical operations is 25% to preserve life. The diagnosis of blunt abdominal trauma is difficult because the clinical signs are sometimes missed and/or not evident in comparison with penetrating abdominal trauma which can be diagnosed easily [17].
There are many causes that explain the need of rapid and accurate imaging tool to diagnose intra-abdominal injuries. Such as disturbed level of consciousness, hemodynamic instability, and other injuries in skull, chest, pelvis or extremities [18].
In the treatment of blunt abdominal trauma patients, the right decision is crucial at the right time. The test can be pivotal when it is reliable, economic, bedside, and rapidly performed screening. It depends on the patient state which may be needing emergency laparotomy, having better off with additional diagnostic workup, or having further superfluous diagnostic workup, without jeopardizing the patients’ clinical outcome. Diagnostic peritoneal lavage is replaced by sonography in European trauma centers for abdominal trauma as the primary screening test [19-20].
Sonography has the advantage of speed, accuracy, noninvasive, without complications, repeatability, cost-competitiveness, portable, and lack of ionizing radiation [19-20].
The time is very important to identify the patient's state. The FAST scan can be done in short time and can detect as little as 100 ml of the free intra-peritoneal fluid [21]. This can be repeated at least 4-6 hours to observe the condition of the patient.
In this study, there were 77 males (74.7%) and 26 females (25.3%). The age range was from 15 to 60 years. There were 45.45 %( 5 cases) of cases having liver injury, 27.27% (3 cases) had splenic injury a, 9.1% (1case) small bowel injury and 18.18 %( 2 cases) gostro- colic ligament injury.
FAST scan showed little limitations for detecting certain types of injuries [22-23]. So that CT can be done after negative FAST to overcome these limitations.
The causes of false negative and false positive may be depending on the following limitations [22-23]:
• Radiology resident, emergency medicine specialist or senior house officer.
• Device accuracy.
• Presence of bowel gas.
• Obesity and subcutaneous emphysema.
• Less accurate FAST for free fluid due to ascites or pelvic inflammatory disease.
The Patients with hemo-dynamically unstable and FAST negative must be evaluated for other extra-abdominal sources of bleeding. The FAST exam and/or other techniques such as CT scan must be repeated after appropriate period of resuscitation [24].
The following table compares the results of this study with other regional and international studies Table (3).
Table (3): Comparison of FAST results in blunt abdominal trauma patients in different studies.
Study
No. ofPt. Sensitivity (%)
Specificity (%)
PPV (%)
NPV (%)
This study 103 84.6 98.8 91.6 97.8
Read Wiwit,
SaadSarsam,SalahTajer[25] 64 92.3 96 86 98
Michael et al [26] 65 43 100 100 94
J Brenchley et al [27] 153 78 99 _ _
Natarajan et al[28] 2105 41 99 95 95
Miller et al [29] 372 42 98.7 67 92
Lee et al [30] 2029 85 96 99 94
It has seen from the above table there are four studies show that lower sensitivity and comparable specificity this can be attributed to many factors , First ; differences in sample sizes , Second; most of our blunt abdominal trauma patients were brought to the emergency department along with mass casualties ,naturally we had high tendency for considering a test to be (+) leading to higher sensitivity , Third ; most of the time the FAST operator is a resident radiologist on call rather than the surgeon or emergency doctor (the radiologist is more trained in identifying abnormal fluid collection) .
Conclusions.
FAST examination is a very good diagnostic tool to be used in cases of blunt abdominal trauma, with fairly high sensitivity, specificity, positive and negative predictive value, it is also easy to perform and can be repeated, however it has its own limitation as it is operator dependent, and needs good equipment.
Recommendation.
All emergency doctors should be trained to perform FAST examination, especially surgical trainees.
Guidelines should be dictated by every emergency department on dealing with trauma patients including FAST examination in accordance with international guidelines since Iraqi hospitals is one of the highest traumas receiving centers in the region.
No conflicts of interest Source of funding: self
Ethical clearance: was taken from the scientific committee of the Iraqi Ministry of health
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