Clinical importance of intraperitoneal fluid in patients with blunt intra-abdominal injury

Deep learning for emergency ascites diagnosis using ultrasonography images

PURPOSE

The detection of abdominal free fluid or hemoperitoneum can provide critical information for clinical diagnosis and treatment, particularly in emergencies. This study investigates the use of deep learning (DL) for identifying peritoneal free fluid in ultrasonography (US) images of the abdominal cavity, which can help inexperienced physicians or non-professional people in diagnosis. It focuses specifically on first-response scenarios involving focused assessment with sonography for trauma (FAST) technique.

METHODS

A total of 2985 US images were collected from ascites patients treated from 1 January 2016 to 31 December 2017 at the Shenzhen Second People's Hospital. The data were categorized as Ascites-1, Ascites-2, or Ascites-3, based on the surrounding anatomy. A uniform standard for regions of interest (ROIs) and the lack of obstruction from acoustic shadow was used to classify positive samples. These images were then divided into training (90%) and test (10%) datasets to evaluate the performance of a U-net model, utilizing an encoder-decoder architecture and contracting and expansive paths, developed as part of the study.

RESULTS

Test results produced sensitivity and specificity values of 94.38% and 68.13%, respectively, in the diagnosis of Ascites-1 US images, with an average Dice coefficient of 0.65 (standard deviation [SD] = 0.21). Similarly, the sensitivity and specificity for Ascites-2 were 97.12% and 86.33%, respectively, with an average Dice coefficient of 0.79 (SD = 0.14). The accuracy and area under the curve (AUC) were 81.25% and 0.76 for Ascites-1 and 91.73% and 0.91 for Ascites-2.

CONCLUSION

The results produced by the U-net demonstrate the viability of DL for automated ascites diagnosis. This suggests the proposed technique could be highly valuable for improving FAST-based preliminary diagnoses, particularly in emergency scenarios.

Free Fluid Accumulation following Blunt Abdominal Trauma: Potential for Expansion of the Fast Protocol

Objective

To determine sites of free intra-peritoneal fluid collection following blunt abdominal trauma, with a view to refinement of the Focused Assessment by Sonography for Trauma (FAST) protocol.

Methods

This was a retrospective observational study of CT scans of subjects who had suffered blunt abdominal trauma and had free intra-peritoneal fluid detected on CT scan within 24 hours. The depth from the skin and amount of fluid at 14 abdominal sites were determined.

Results

CT scans of 105 patients were examined: 68 (64.8%) were male, mean age 36.7±18.4 years, mean injury severity score 25.4±11.6. Fluid collected most commonly at three sites: right mid-axillary line at the level of the xiphisternum (52 patients, 49.5%), lateral margin of the right rectus muscle at the level of the anterior superior iliac spine (49 patients, 46.7%) and right mid-axillary line at the level of the umbilicus (40 patients, 38.1%). Mean depth of fluid at these sites were 3.6, 3.6 and 4.2 cm, respectively.

Conclusions

Free fluid collects commonly in the area of the right iliac fossa following blunt abdominal trauma. The inclusion of this site in the FAST protocol may increase the ultrasonographic detection of free fluid in the acute trauma setting.

Bedside US imaging in multiple trauma patients. Part 1: US findings and techniques

OBJECTIVES

The aim of this review article is to present the current views and visions of the role of ultrasound (US) in the management of patients with multiple trauma. The article is divided into two parts. Part 1 (US findings and techniques) will mainly deal with the technical aspects of US imaging in trauma patients and is written also for educational purposes. Part 2 (pathophysiology and US imaging in trauma patients) will deal with integration of US in the clinical and pathophysiological management of multiple trauma patients.

METHODS

A non-systematic review of the literature through PubMed search (restricted to the last 10 years) of original articles and review articles.

RESULTS

80 publications were selected for Part 1. Of these 80 articles, the author selected 50 according to personal criteria on the basis of their innovative or original contents (48 original articles and 2 literature review articles); 19 articles were furthermore extracted from the references of the selected publications. The information extracted from these 69 publications was organized into sections dealing with different fields of applications of US imaging in multiple trauma patients.

CONCLUSIONS

US imaging in trauma has evolved from the initial use, i.e., early diagnosis of peritoneal effusion (focused abdominal sonography for trauma), to a wider use known as resuscitative ultrasonography, and is today considered as an extension of physical examination to implement a more effective approach to clinical problems and increase the timeliness and safety of interventions.

Influences on the amount of intraperitoneal haemorrhage after blunt liver injury: a retrospective autopsy study

OBJECTIVE

The amount of intraperitoneal blood loss due to traumatic liver injury is rarely addressed in correlation with concomitant injuries or pre-existing liver disease.

METHODS

We carried out a retrospective review of autopsy reports from 1995 until 2007 at the Institute of Forensic Medicine (Bern, Switzerland), and evaluated 126 cases of blunt liver trauma for the amount of blood in the abdominal cavity, severity of liver injury, pre-existing liver disease and concomitant injuries.

RESULTS

Grades IV and V liver injuries (American Association for the Surgery of Trauma classification) showed greater blood loss than grades I and II liver injuries. Grade III liver injuries showed no significant difference in the amount of intraperitoneal blood compared with grades IV and V liver injuries and 53 cases of liver injuries (42%) did not bleed at all. The amount of blood found in the abdominal cavity ranged from 0 to 4500 ml. Pre-existing liver steatosis showed no significant difference in injury pattern or bleeding from the liver. Three cases with liver haemangiomas and one with a liver cyst showed no lesion to their focal alteration. Because of the small number of cases, no statistical analysis was made concerning concomitant injuries such as head, thoracic or limb trauma.

CONCLUSION

Higher grades of liver injury severity are associated with higher blood loss into the abdominal cavity. In addition, a patient with pre-existing liver steatosis seems not to be at any greater risk of having a larger rupture or having stronger bleeding from the liver after a blunt impact compared with a patient with a normal liver.

Detection of free intraperitoneal fluid in healthy young men

OBJECTIVES

Free intraperitoneal fluid is a secondary sign of abdominal disorders. The detection of small volumes of fluid has been documented as a normal finding in women of childbearing age and also in pediatric sonography. However, the finding of free fluid in asymptomatic men has not been similarly documented by sonography. We postulate that with high-frequency linear probes, small volumes of fluid may be detected in asymptomatic men without underlying abdominal disorders.

METHODS

Ten healthy male volunteers underwent targeted abdominal sonographic examinations after an overnight fast and in an immediate postprandial state. The findings were documented, and representative images were saved for analysis.

RESULTS

We found small slivers or geometric collections of fluid between bowel loops in 4 of the 10 volunteers. No obvious correlation between the detection of fluid and the nutritional or hydration status of the patient was identified.

CONCLUSIONS

The findings suggest that small volumes of pelvic free fluid in healthy men can be normal and do not necessarily indicate underlying disorders. The role of free fluid identification as an indicator of major intra-abdominal disorders must be viewed with caution and with careful clinical correlation.

Performance of abdominal ultrasonography in pediatric blunt trauma patients: a meta-analysis

OBJECTIVE

The objective of the study was to obtain the best estimates of the test performance of abdominal ultrasonography (US) for identifying children with intraabdominal injuries (IAIs).

METHODS

We gathered studies on the use of abdominal US in injured children from the following sources: a MEDLINE and Embase search, hand searches of 5 specialty journals and 4 clinical textbooks, the bibliographies of all identified articles, and contact with experts. Both prospective and retrospective studies were included if they used abdominal US for the detection of intraperitoneal fluid or IAIs in blunt trauma patients less than 18 years of age. All authors independently abstracted data from the selected studies. Disagreements between abstractors were resolved by mutual agreement.

RESULTS

Twenty-five articles met the inclusion criteria, and 3838 children evaluated with abdominal US were included. Abdominal US had the following test characteristics for identifying children with hemoperitoneum: sensitivity, 80% (95% confidence interval [CI] 76%-84%); specificity, 96% (95% CI 95%-97%); positive likelihood ratio, 22.9 (95% CI 17.2-30.5); and negative likelihood ratio, 0.2 (95% CI 0.16-0.25). Using the most methodologically rigorous studies, however, yielded the following test characteristics of abdominal US for identifying children with hemoperitoneum: sensitivity, 66% (95% CI 56%-75%); specificity, 95% (95% CI 93%-97%); positive likelihood ratio, 14.5 (95% CI 9.5-22.1); and negative likelihood ratio, 0.36 (95% CI 0.27-0.47).

CONCLUSIONS

Abdominal US has a modest sensitivity for the detection of children with hemoperitoneum; however, its test performance characteristics worsen when only the most methodologically rigorous articles are included. A negative US examination has questionable utility as the sole diagnostic test to rule out the presence of IAI. Because of the high risk of IAI, a hemodynamically stable child with a positive US examination should immediately undergo abdominal computed tomographic scanning.

Ultrasonic interrogation of tissue vibrations in arterial and organ injuries: preliminary in vivo results

Soft tissues surrounding vascular injuries are known to vibrate at audible and palpable frequencies, producing bruits and thrills. We report the results of a feasibility study where Doppler ultrasound (US) was used to quantitatively estimate the tissue vibrations after induced trauma in an animal model. A software-programmable US system was used to acquire quadrature-demodulated ensembles of received US echoes bypassing clutter filtering and other conventional Doppler processing stages. The waveforms of tissue velocity surrounding the injury site were then estimated from the clutter data using autocorrelation and analyzed to determine vibration characteristics. Six New Zealand white rabbits and two juvenile pigs were used for the study. The femoral artery of the anesthetized animal was punctured with an 18-gauge needle to model a peripheral arterial trauma, and the liver was surgically exposed and incised to model organ trauma. Two types of oscillatory tissue motion were observed: "vibrations" with high frequency (>50 Hz) and low peak-peak amplitude (<1 microm) and "flutter" with low frequency (<50 Hz) and high peak-peak amplitude (>1 microm). Active bleeding in femoral artery punctures produced tissue vibrations at the frequency of 323 +/- 214 Hz (mean +/- standard deviation, pooled for both rabbits and pigs) and the amplitude of 0.24 +/- 0.15 microm. Active bleeding in liver incisions produced vibrations at the frequency of 120 +/- 47 Hz and the amplitude of 0.33 +/- 0.25 microm. Flutter was observed in punctured arteries at the frequency of 28 +/- 13 Hz the amplitude of 2.92 +/- 1.75 microm, and in incised livers at the frequency of 26 +/- 6 Hz and the amplitude of 1.53 +/- 0.76 microm. In a punctured artery, the vibration frequency and phase of tissue surrounding the artery were highly correlated between neighboring locations in tissue (correlation coefficient = 0.98), and with the flow oscillations in the lumen (correlation coefficient = 0.96). This preliminary study indicates that tissue vibrations could provide additional physiologic information for detecting, localizing and monitoring internal bleeding using US.

Staged management and outcome of combined pelvic and liver trauma. An international experience of the deadly duo

Pelvic fracture associated with liver trauma is not an uncommon injury combination in multiple trauma and is associated with high morbidity and mortality. The aim of this study was to examine the characteristics of this specific patient group, to describe the diagnostic and treatment protocols and finally to analyse risk factors associated with mortality. Data were collected over a 6-year period, ending in 2001. The pelvic injury was graded according to the Tile classification system and the hepatic injury was scored using the organ injury scale (OIS). Treatment protocol, associated injuries, complications, length of ICU/Hospital stay and mortality were recorded and analysed. A total of 140 patients (40% female) with a mean age of 35.1+/-15.9 years and a median ISS of 41 were included in this study. The overall mortality rate was 40.7%. Binomial logistic regression analysis revealed age, initial blood pressure, transfusion requirement as well as the severity of head, chest, spleen and liver injury as independent parameters predicting reduced survival rates. This deadly duo of injuries presents a challenge to the trauma surgeon. Rapid assessment and treatment is required to prevent death by haemorrhage. The presence of concomitant injuries renders the patient very sensitive to ongoing or additional physiological disturbance. The principles of 'damage control surgery' must be applied to avoid complications such as acute respiratory distress syndrome (ARDS) and multiple organ dysfunction syndrome (MODS).

Prehospital ultrasound imaging improves management of abdominal trauma

BACKGROUND

Blunt abdominal trauma with intra-abdominal bleeding is often underdiagnosed or even overlooked at trauma scenes. The purpose of this prospective, multicentre study was to compare the accuracy of physical examination and prehospital focused abdominal sonography for trauma (PFAST) to detect abdominal bleeding.

METHODS

Six rescue centres took part in the study from December 2002 to December 2003, including 230 patients with suspected abdominal injury. The accuracy of physical examination at the scene and PFAST were compared. Later examinations in the emergency department (ultrasonography and/or computed tomography) were used as the reference standard.

RESULTS

The complete protocol and follow-up was obtained in 202 patients. The sensitivity, specificity and accuracy of PFAST were 93 per cent, 99 per cent and 99 per cent, respectively, compared with 93 per cent, 52 per cent and 57 per cent for physical examination at the scene. Scanning with PFAST occurred a mean(s.d.) 35(13) min earlier than ultrasound in the emergency department. Abdominal bleeding was detected in 14 per cent of patients. Using PFAST led to a change in either prehospital therapy or management in 30 per cent of patients, and a change to admitting hospital in 22 per cent.

CONCLUSION

In this study, PFAST was a useful and reliable diagnostic tool when used as part of surgical triage at the trauma scene.

Is definitive abdominal evaluation required in blunt trauma victims undergoing urgent extra-abdominal surgery?

OBJECTIVES

To evaluate the utility of routine abdominal computed tomographic (CT) scanning for abdominal evaluation of blunt trauma patients before urgent extra-abdominal surgery.

METHODS

In this observational cohort study, we prospectively enrolled all blunt trauma patients at least 8 years of age presenting to the emergency department of a Level 1 trauma center who were initially considered to require urgent extra-abdominal surgery within 24 hours of presentation. Patients were excluded if they had any of the following: 1) isolated extremity trauma, 2) signs or symptoms of intra-abdominal injury (including systolic blood pressure < 90 mm Hg; abdominal, flank, or costal margin tenderness; abdominal wall contusion or abrasion; pelvic fracture; and gross hematuria), or 3) unreliable findings on abdominal examination (Glasgow Coma Scale score < 14, paralysis, or mental retardation). Clinical data were documented on a data sheet before abdominal CT scanning.

RESULTS

A total of 254 patients, with a mean (+/-SD) age of 32.3 (+/-16.1) years, were enrolled. A total of 201 patients ultimately underwent urgent extra-abdominal surgery for the following procedures: orthopedic, 182 (91%); facial, 17 (8%); laceration, 7 (3%); vascular, 6 (2%); neurosurgical, 3 (1%); urology, 2 (1%); and ophthalmology, 1 (0.4%). Three patients (1.2%; 95% confidence interval = 0.2% to 3.4%) were found to have intra-abdominal injuries. Two patients had splenic injuries that required only observation. One patient (0.4%; 95% confidence interval = 0% to 2.2%) underwent laparotomy. This patient sustained multiple injuries in a motorcycle crash, including splenic, kidney, and pancreatic injuries, and underwent a splenectomy.

CONCLUSIONS

Abdominal CT scanning has a low yield in trauma patients whose sole indication for diagnostic abdominal evaluation is the need for general anesthesia for urgent extra-abdominal surgery. A small percentage of these patients, however, will have important intra-abdominal injuries such that further refinement of the recommendations for diagnostic study in this select population is needed.

[Traumatic perforation of the sigmoid colon: role of computed tomography]

The authors report a case of a delayed traumatic perforation of the sigmoid colon, presenting three days after a motor vehicle accident. A review of the literature is presented.

Ultrasound detection of blunt urological trauma: a 6-year study

The objective of this study was to assess the utility of emergency ultrasonography in the detection of blunt urological injury. A retrospective review was conducted of all consecutive emergency blunt trauma ultrasonograms (US) obtained at a level I trauma centre from January 1995 to January 2001. Among the 4320 emergency ultrasonograms performed, 596 patients (14%) had intraabdominal injury and, of these, 99 patients (17%) had urological injuries. The sensitivity of ultrasound for all urological injuries was 67%, and specificity was 99.8%. For isolated urological injuries, sensitivity and specificity were 55.6 and 99.8%, respectively. Ultrasound was most accurate in the detection of grade III renal injuries, identifying 14/15 (93%), and 13 underwent laparotomy. For isolated urological injuries, 15 of 25 (60%) patients with a true-positive US underwent laparotomy compared to 3 of 20 (15%) with a false-negative US. Isolated urological injury was significantly associated with an ultrasonographic pattern of free fluid in the left upper quadrant and the left pericolic gutter (odds ratio=55.1; P<0.001), followed by isolated fluid in the left pericolic gutter (odds ratio=8.6; P=0.04). Although emergency ultrasonography is useful in the triage of patients with blunt urological trauma, it may miss significant urological injury requiring further intervention. As most renal injuries may be managed non-operatively, further studies such as contrast-enhanced CT or angiography should be obtained in the stable patient with suspected blunt urological injury.

Assessment of Nonoperative Management of Blunt Spleen and Liver Trauma

An 8-year analysis of nonoperative management (NOM) of spleen and liver trauma was done in a level 1 trauma center. Spleen and liver trauma was diagnosed in 279 patients: 93 children (<18), 137 younger adults (18–54), and 49 older adults (≥ 55). Nineteen patients who failed resuscitations died within 0–60 minutes of arrival and were excluded from treatment analysis. Operative management (OM) was done in 39 (15%) and NOM in 221 (85%) patients with failure (NOMF) in 11 (5%). NOM and NOMF was 82 per cent and 5.6 per cent in spleen, 74 per cent and 14.3 per cent in combined spleen/liver, and 96 per cent and 1.5 per cent in liver trauma ( P value <0.001). NOM was done in 99 per cent of children, 81 per cent of younger adults, and 68 per cent of older adults with 0 per cent, 8 per cent, and 10 per cent NOMF. Higher grades of splenic trauma and CT fluid had higher OM rate. NOM success rates were 93.8 per cent in grade 3 and 90.3 per cent in higher grades of spleen trauma. There was no NOMF in higher grades of liver trauma. CT fluid grade had no impact on NOMF. Female patients had higher mean injury severity score, age, and mortality compared to cohorts. NOM should be attempted in hemodynamically stable patients. Age over 55, higher grades of injury, and large hemoperitoneum were not predictors of failure of NOM.

Performance of abdominal ultrasonography in blunt trauma patients with out-of-hospital or emergency department hypotension

STUDY OBJECTIVES

We determine the test performance of abdominal ultrasonography for detecting hemoperitoneum in blunt trauma patients with out-of-hospital or emergency department (ED) hypotension.

METHODS

We reviewed the medical records of all blunt trauma patients hospitalized at a Level I trauma center. Patients were included if they were older than 6 years and had out-of-hospital or ED hypotension (systolic blood pressure < or =90 mm Hg) and underwent ED ultrasonography. The initial interpretation of the abdominal ultrasonography was recorded, including the presence or absence of intraperitoneal fluid and the specific location of such fluid. Presence or absence of intra-abdominal injury was determined by abdominal computed tomography scan, laparotomy, or clinical follow-up.

RESULTS

Four hundred forty-seven patients with a mean age of 36.0+/-17.5 years were enrolled. One hundred forty-eight (33%) patients had intra-abdominal injuries, and 116 (78%) of these patients had hemoperitoneum. Abdominal ultrasonography had the following test performance for detecting patients with intra-abdominal injury and hemoperitoneum: sensitivity 92/116 (79%; 95% confidence interval [CI] 71% to 86%), specificity 316/331 (95%; 95% CI 93% to 97%), positive predictive value 92/107 (86%; 95% CI 78% to 92%), and negative predictive value 316/340 (93%; 95% CI 90% to 95%). The positive likelihood ratio was 15.8, and the negative likelihood ratio was 0.22. One hundred five (91%) of the 116 patients with intra-abdominal injuries and hemoperitoneum underwent a therapeutic laparotomy. Abdominal ultrasonography demonstrated intraperitoneal fluid in 87 (sensitivity 83%; 95% CI 74% to 90%) of these 105 patients.

CONCLUSION

Of patients with out-of-hospital or ED hypotension, abdominal ultrasonography identifies most patients with hemoperitoneum and intra-abdominal injuries. Hypotensive patients with negative abdominal ultrasonography results, however, must be further evaluated for sources of their hypotension, including additional abdominal evaluation, once they are hemodynamically stabilized.

Emergency ultrasound in trauma patients

US will be used more frequently in the future for the evaluation of traumatized patients. Previously,the main focus of the sonographic examination was for the detection of free fluid. Unstable patients with free fluid often can be triaged to the operation room without further imaging tests. In patients who are more stable or in whom US results are negative, CT is required. Based on recent studies, sonography has a sensitivity rate of approximately 40% in direct detection of solid organ injuries. In the future, however, with the use of contrast-enhanced agents, sonography may more reliably detect solid organ injuries. Within the chest, US has been shown to be helpful in detecting pleural effusions and may be useful in detecting pericardial effusions. US has been shown to be sensitive in detecting pneumothoraces in traumatized patients.

Sonographic patterns of intraperitoneal hemorrhage associated with blunt splenic injury

OBJECTIVE

To determine the correlation between sonographic detection of free fluid in the left upper quadrant and blunt splenic injury.

METHODS

A retrospective review was conducted of all consecutive emergency blunt trauma sonograms obtained at a level I trauma center from January 1995 to January 2001. Data were collected on demographics, free fluid location, and patient outcome. Injuries were determined from computed tomography, diagnostic peritoneal lavage, laparotomy, or a combination thereof.

RESULTS

A total of 4320 blunt trauma sonograms were obtained, and 596 patients (14%) had intra-abdominal injuries. The mean age was 33.7 +/- 19.1 years (range, 1-95 years), with 294 (49%) male and 302 (51%) female. There was no statistical difference between age, sex, or mechanism for all subgroups. There were 409 true-positive, 187 false-negative, 88 false-positive, and 3636 true-negative findings. Sensitivity of sonography for detecting all intra-abdominal injuries was 68%, and specificity was 97.6%; sensitivity for detecting isolated splenic injuries was 73.8%. Locations of free fluid in patients with nonsplenic injuries were compared with those in patients with splenic injuries. Isolated left upper quadrant free fluid was significantly associated with splenic injury (odds ratio = 3.0; P = .002), followed by diffuse free fluid (odds ratio = 2.1; P = .005). A subanalysis of isolated splenic injuries also revealed a significant association with left upper quadrant free fluid (odds ratio = 3.1; P = .007) and diffuse free fluid (odds ratio = 2.7; P = .0007).

CONCLUSIONS

Free fluid in the left upper quadrant is significantly associated with splenic injury. This finding should triage patients more rapidly to computed tomography, angiography, embolization, and laparotomy.

Pathophysiology and management of bowel and mesenteric injuries due to blunt trauma

Injuries to the bowel and mesentery are uncommon in blunt trauma and rarely occur in isolation. Delay to diagnosis has a significant impact on morbidity and mortality. The literature tends to focus on the diagnosis of hollow viscus and mesenteric injury, with little written on its management. Studies are usually retrospective with a paucity of comparative trials. The use of computerized tomography (CT) scanning in blunt abdominal trauma has overshadowed other reports. Early-generation scanners had a relatively poor sensitivity in detecting bowel-related injuries, but the CT scan is now the primary modality for imaging stable patients. However radiological signs can be subtle and should be regarded as complementary to meticulous clinical assessment.