Is computed tomography tractography reliable in patients with anterior abdominal stab wounds?
a b s t r a c t
Introduction: The current literature and guidelines recommend that determination of peritoneal violation is done first in cases of anterior abdominal Stab wounds. The primary endpoint of this study was to determine the reli- ability of computed tomographic (CT) tractography to assess peritoneal violation in anterior abdominal stab wounds. The secondary endpoint is to compare local wound exploration between conventional CT and CT tractography in the evaluation of peritoneal violation.
Material and methods: A total of 252 patients who were referred with anterior abdominal Stab wounds were in- cluded in this prospective observational study. Three techniques (local wound exploration, conventional abdom- inal tomography, and CT tractography) were used to evaluate peritoneal violation. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated for each technique to de- termine peritoneal violation.
Results: The results for the local wound exploration were 100% sensitivity, 100% specificity, 100% PPV, 100% NPV, and 100% accuracy. The results for CT tractography were 95% sensitivity, 100% specificity, 100% PPV, 80% NPV, and 96% accuracy. Conventional abdominal tomography results were 87% sensitivity, 50% specificity, 91% PPV, 40% NPV, and 82% accuracy.
Conclusion: Local wound exploration is 100% effective in determining peritoneal violation with anterior abdom- inal stab wounds. CT tractography is better than conventional CT in detecting peritoneal violation. However, we do not recommend CT tractography in anterior abdominal stab wounds due to the false-negative results.
(C) 2018
Introduction
Trauma is currently the primary cause of death in young and middle- aged adults. According to the World Health Organization (WHO), the in- cidence of penetrating trauma has increased not only in Developing countries but also in developed countries due to the increasing number of local wars, starvation, and migration in the world [1-3]. In addition, WHO publications highlight that deaths due to anterior abdominal stab wounds total more than five million around the globe each year, and tens of millions of people visit emergency departments annually for these wounds [4].
Formerly, laparotomy was performed routinely in cases of penetrat- ing abdominal stab wounds. In the 1960s, Shaftan et al. were the first to report that it was possible to conservatively manage penetrating ab- dominal injuries [5]. In subsequent clinical trials, it has been demon- strated that only 50% of all anterior abdominal stab wounds enter the peritoneal cavity, and of those, only 40% cause an organ injury requiring operative repair [6,7]. Therefore, routine laparotomy has largely been
* Corresponding author at: Bahcesehir 1. kisim mahallesi Ispartakule Caddesi Kiptas Vaditepe 4. Bolge Sitesi K1 Blok Daire:16 Basaksehir-Istanbul-Turkiye, Turkey.
E-mail address: [email protected] (I.S. Sarici).
abandoned, and more selective conservative treatments have been adopted in clinical practice [8].
The current literature and guidelines recommend that determina- tion of peritoneal violation is to be done first with local wound explora- tion in cases of anterior abdominal stab wounds, and Hemodynamically stable patients with peritoneal integrity can be safely discharged [9,10]. However, due to surgical site infection and hemorrhage in the injured area and difficulties in the application of local wound exploration in obese patients and those with long and oblique stab wounds, different techniques have been developed. In addition to advances in technology, computed tomography (CT) has begun to be used to assess peritoneal integrity as well as for local wound exploration [11,12]. However, using CT alone cannot clearly visualize the injury to the subcutaneous tissue and facial planes in the wound area.
For this reason, in 2014 Bansalet et al. [13]. defined a CT trachography method for posterior penetrating abdominal injuries. This method is a form of CT in which contrast is injected into the stab wound site just before the scan, and the resulting images can be used to determine the injury tract. In 2015, Ertan et al. [14] found that 90% of cases with positive CT tractography in anterior abdominal stab wounds required laparotomy, and negative CT tractography patients did not require surgery. Recently, Uzunosmanoglu et al. [15] reported
https://doi.org/10.1016/j.ajem.2017.12.065
0735-6757/(C) 2018
that CT tractography was 100% effective in assessing the peritoneal vio- lation in anterior abdominal stab wounds.
In this study, we aimed to determine the reliability of CT tractography to indicate peritoneal violation in anterior abdominal stab wounds and to compare local wound exploration, conventional CT, and CT tractography for the evaluation of peritoneal violation.
Materials and methods
This prospective observational study was conducted between No- vember 2015 and September 2017 in a large, urban teaching hospital that is high-volume trauma center. Patients with anterior abdominal stab wounds were included in the study. hemodynamically unstable patients, those with generalized peritonitis, and those with evisceration were excluded from the study, and emergency laparotomy was per- formed. The same algorithm was applied to all anterior abdominal stab wound patients (Table 1). Local wound exploration was first ap- plied to the anterior abdominal stab wound under sterile conditions in the emergency room by a general surgeon. Subsequently, local wound exploration and conventional (with oral and intravenous contrast) ab- dominal tomography (without tractography) were performed on the patient. After the initial conventional CT scan, the Contrast material (iohexol, Omnipaque, GE Healthcare, Ireland) was injected at the injury site or sites (for multiple injuries) with a 50-mL injector in the CT room by a general surgeon (Fig. 1). Conventional CT (without tractography) and CT tractography were evaluated, and an independent assessment was made by both the radiologist and the general surgeon in terms of peritoneal violation and Organ injuries (Fig. 2A-B). Regardless of the peritoneal violation status, all patients were admitted to the general surgery service and followed for at least 48 h conservatively. The pa- tients were followed up every 2 h in the first 12 h and every 4 h in the next 36 h with an Abdominal examination and whole blood count. Dur- ing conservative follow-up, patients who were hemodynamically unsta- ble and whose physical examination findings pointed to acute abdomen were taken for an emergency laparotomy. Patients who were hemody- namically stable and whose abdominal examination did not change after 48 h of follow-up were discharged. For this study, written permis- sion was obtained from the institution. All patients included in the study were informed and consent forms were signed. Patients’ age, gender, body mass index (BMI), wound size, injury localizations, local wound
Fig. 1. Contrast was injected at the injury site with a 50-mL injector in the CT room.
exploration results, conventional abdominal tomography (without tractography), and CT tractography results were recorded. All patients who underwent laparotomy were evaluated for peritoneal violation and organ injury, and laparotomy was considered to be the gold stan- dard for assessing the peritoneal violation.
The primary endpoint of this study was to determine the reliability of CT tractography for assessing peritoneal violation in anterior abdom- inal stab wounds, which is required for the safe discharge of patients. The secondary endpoint was to compare local wound exploration, con- ventional CT, and CT tractography for evaluating peritoneal violation.
Statistical analyses were performed using SPSS15.0 for Windows (SPSS Inc., Chicago, IL). Continuous data were expressed as mean +- standard deviation (SD). Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of local wound exploration with conventional abdominal CT and CT tractography were calculated for peritoneal violation. Categorical data are reported as proportions and 95% confidence intervals (CI).
Algorithm of anterior abdominal stab wound patients.
Fig. 2. A: Initial conventional CT image shows negative peritoneal violation with red arrow. B: CT tractography determining positive peritoneal violation is shown with red arrow. Blue arrow shows intraabdominal contrast.
Results
A total of 252 patients who presented to the trauma and emergency department with anterior abdominal stab wounds of which 58 patients (23%) were taken to emergency surgery due to hemodynamic instabil- ity, generalized peritonitis, and organ evisceration. Local wound explo- ration, conventional abdominal tomography (without CT tractography), and CT abdominal tractography were performed on the remaining 194
Table 2
Patients demographics, wound sizes, injury localizations, and organ injuries.
Gender n(%) |
|
Male |
228(90) |
Female |
24(10) |
Age (range), y |
22(16-42) |
BMI (mean +- SD) |
25.2 +- 4.9 |
Wound size (mean +- SD) (mm) |
32.52 +- 11.32 |
Location of injury n(%) |
|
97(38) |
|
Right lower quadrant |
76(30) |
73(29) |
|
Left lower quadrant |
29(11) |
Number of Stab wounds n(%) Single |
221(88) |
Multiple |
31(12) |
Organ injury n(%) |
|
Small bowel |
49(40) |
Liver |
21(17) |
Colon |
17(14) |
Stomach |
15(12) |
Spleen |
8(7) |
Renal |
5(4) |
5(4) |
|
Diaphragm |
3(2) |
that all of these 74 patients had peritoneal violation before the opera- tion and, likewise, the technique detected true-negative results in the 12 cases without peritoneal violation. CT tractography showed perito- neal violation in the preoperative period with a true-positive result in 71 of 74 patients. A false-negative result was detected in three patients with CT tractography (Table 3). As in local wound exploration, it was found that CT tractography detected true- negative results for all 12 pa- tients without peritoneal violation. Conventional tomography (without tractography) detected peritoneal violation before laparotomy in 65 of 74 patients, and the technique determined false-negative results in 9 patients. True-negative results were found in 6 of 12 patients without peritoneal violation, whereas false-positive results were found in 6 pa- tients (Table 3). The diagnostic efficiency of the local wound explora- tion, abdominal CT tractography, and conventional abdominal CT (without tractography) to determine peritoneal violation was evaluated (Table 4). The results for the local wound exploration was 100% (95% CI: 96%-100%) sensitivity, 100% (95% CI: 96%-100%) specificity, 100% (95% CI: 96%-100%) PPV, 100% (95% CI: 96%-100%) NPV, and 100% (95% CI:
96%-100%) accuracy. CT tractography had a 95% (95% CI: 91%-98%) sen- sitivity, 100% (95% CI: 96%-100%) specificity, 100% (95% CI: 96%-100%)
Table 3
Comparison of three different techniques with laparotomy results.
patients (76%), and these patients were hospitalized in the general sur- gery service after evaluating them for peritoneal violation and organ in- jury. 108 of 194 (66%) patients were discharged without any problem after 48 h of clinical follow-up. Peritoneal violation was evaluated in
the 108 patients with three different methods: peritoneal violation
Local wound exploration (n)
Peritoneal violation (+) in laparotomya (74 patients)
Peritoneal violation (-) in laparotomya (12 patients)
was observed in 26 (16%) patients, and peritoneal violation was not ob- served in 82 (50%) patients. Since laparotomy was the accepted gold standard detection method for peritoneal violation in the study, the methods used to detect peritoneal violation in this group of patients have not been evaluated. On the other hand, 86 (34%) patients underwent laparotomy due to hemodynamic instability or peritonitis findings during service visits. Patient demographics, wound sizes, injury
Peritoneal violation (+)
Peritoneal violation (-)
CT tractography (n) Peritoneal violation (+)
Peritoneal violation (-)
74 0
0 12
71 0
3 12
locations, and organ injuries are shown in Table 2. Considering laparot-
omy as a gold standard in detecting peritoneal violation, sensitivity, specificity, PPV, NPV, and accuracy were calculated for local wound ex-
Conventional abdominal CT (without tractography) (n)
ploration, conventional tomography (without tractography), and CT tractography. Peritoneal violation was detected in 74 (86%) of the pa- tients who underwent laparotomy, and 12 (14%) patients did not have
Peritoneal violation
(+)
Peritoneal violation (-)
65 6
9 6
peritoneal violation (Table 3). Local wound exploration determined
a Laparotomy considered gold standard for assessing the peritoneal violation.
The diagnostic efficiency of local wound exploration, abdominal CT tractography, and conventional abdominal CT (without tractography).
Local wound exploration |
CT tractography |
Conventional abdominal CT (without tractography) |
|
Sensitivity (%) |
100 (96-100) |
95 (91-98) |
87 (81-94) |
Specificity (%) |
100 (96-100) |
100 (96-100) |
50 (42-56) |
PPV (%) |
100 (96-100) |
100 (96-100) |
91 (88-93) |
NPV (%) |
100 (96-100) |
80 (78-83) |
40 (37-43) |
Accuracy (%) |
100 (96-100) |
96 (93-99) |
82 (77-86) |
95% CI values are given in parenthesis.
Abbreviations: PPV: Positive predictive value, NPV: Negative predictive value.
PPV, 80% (95% CI: 78%-83%) NPV, and 96% (95% CI: 93%-99%) accuracy.
Conventional abdominal tomography results were 87% (95% CI: 81%-
94%) sensitivity, 50% (95% CI: 42%-56%) specificity, 91% (95% CI 88%-
93%) PPV, 40% (95% CI: 37%-43%) NPV, and 82% (95% CI: 77%-86%)
accuracy.
Discussion
Since Shaftan first described selective conservative management in penetrating abdominal injuries in 1965, most of the centers applied this approach over the last four decades [5-7]. However, this method has led to some debates in clinical practice about determining which pa- tients should be safely discharged and which should receive laparot- omy. In the current literature and several trauma guidelines, the emergency surgical approach is accepted in patients with hemodynam- ically unstable and acute abdomen findings [9,10]. On the other hand, the optimal management for an asymptomatic patient with an anterior abdominal stab wound remains controversial and there are two main questions to be answered in the treatment of these patients. The first issue in anterior abdominal stab wounds is determining whether or not the patient has positive peritoneal violation. The most common method for detecting peritoneal violation is local wound exploration. In addition, currently in the literature, high-resolution and slice-thick- ness CT and CT tractography methods were applied in the detection of peritoneal violation [11-15]. These techniques can guide an early and safe decision in 40% of patients who present without peritoneal viola- tion [6,7]. Determining peritoneal violation is important if patients will be managed conservatively because if peritoneal violation is not present, the possibility of intraabdominal organ injury is ruled out. The second issue is the detection of the intraabdominal organ injury in patients with positive peritoneal violation. However, positive local wound exploration findings have poor specificity for detecting organ in- jury. Patients with positive peritoneal violation have been examined with Diagnostic peritoneal lavage (DPL), laparoscopy, ultrasound (US), CT, or serial clinical evaluation to further select those who are likely to have an organ injury that requires surgical intervention [16-18]. This strategy successfully reduces the number of unnecessary laparotomies by 45% [19]. In our study, we compared three different methods to de- tect peritoneal violation due to anterior abdominal stab wounds to de- termine which method is more reliable.
Local wound exploration, which detects an intact posterior rectus fascia or transversalis fascia, allows the safe discharge of patients with abdominal stab wounds from the hospital with no false-negative lapa- rotomies. Unfortunately, previous studies have shown that unnecessary laparotomy rates are high when local wound exploration is positive [20]. Thus, some authors recommend conventional abdominal CT to de- termine and evaluate both peritoneal violation and intraabdominal in- jury [10,11]. However, in recent years, studies have shown that conventional CT has poorer accuracy in the detection of peritoneal vio- lation than does local wound exploration [15]. For this reason, CT tractography has begun to be applied by researchers [13-15]. The phi- losophy behind the use of this technique is better assessment of the ab- dominal wall layers (anterior and posterior fascia, Rectus abdominis, transversalis fascia, and peritoneum) by applying the contrast from
the local wound area, and this may help the clinician more accurately evaluate the presence of peritoneal penetration. However, the compar- ison of these three techniques to determine peritoneal violation has not been done in any studies until now. Ertan et al. [14] were the first to apply CT tractography in 20 patients with anterior abdominal stab wounds. According to this study, 10 (50%) patients were positive for peritoneal violation in CT Tractography, and 10 (50%) patients were negative for peritoneal violation. All patients without peritoneal viola- tion were discharged conservatively. In addition, intraabdominal organ injury was also detected in 90% of the patients who had peritoneal violation detected in CT tractography. Another study was performed by Uzunoglu et al. [15] regarding anterior abdominal stab wounds. In this study, 35 patients were evaluated for peritoneal violation using con- trast-enhanced CT, and 38 patients were evaluated with CT tractography. According to the results, they found that CT had an 80% sensitivity, 88% specificity, 95% PPV, 61% NPV, and 82% accuracy. For CT tractography, the results were 100% sensitivity, 100% specificity, 100% PPV, 100% NPV, and 100% accuracy for detecting peritoneal viola- tion. Unfortunately, this study had some limitations in the comparison of conventional CT and CT tractography in different patients in terms of peritoneal violation. We performed local wound exploration, conven- tional CT, and CT tractography, respectively, to hemodynamically stable anterior abdominal wound patients to determine peritoneal violation, and the presence or absence of peritoneal violation in these patients was confirmed by accepting laparotomy as the gold standard method of evaluation. According to our results performing three different tech- niques for the evaluation of peritoneal violation; local wound explora- tion was better accuracy to detect peritoneal violation than conventional CT and CT tractography.
Local wound exploration is a simple procedure in patients with a low or typical BMI, in whom the presence of peritoneal violation is obvious. No false-negative results due to local wound exploration were detected in our study. This is probably due to the fact that the local wound exploration is done by general surgery specialists. Based on our experience, we suggest that surgeons should do local wound exploration. Although the specificity and PPV were 100% in CT tractography for the detection of peritoneal violation, unlike in other studies, three (4%) of the patients who underwent CT tractography in our study had a false-negative result. In two of these three patients, a stomach anterior surface injury was detected in laparotomy, and peritoneal hemorrhage was detected in one pa- tient. Ertan et al. [14] and Uzunoglu et al. [15] did not show any false-negative results when assessing peritoneal violation by CT tractography. The possible causes of these false-negative rates in CT tractography is non-sedation of the patient, who on feeling the peri- toneal pain contracts the abdominal muscle groups and causes over- lapping of the surrounding fascias, resulting in the inability of the contrast medium to pass into the abdomen from the peritoneal vio- lation area (Table 5). Furthermore, because of the inadequate amount of contrast, several staff (i.e., radiology technician, radiolo- gist, assistant, surgeon) may apply several techniques (e.g., injector, Foley cannula) for contrast application, leading to false-negative false results. Another reason for false-negative results is evaluation of CT tractography images by different radiologists (Table 5).
Potential causes of false-negative results and problems with CT tractography in clinical fol- low-up.
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One of the most important problems of CT tractography is in clinical follow-up of selected conservative patients, whose peritoneal violation is positive (Table 5). In the case of acute abdomen development or he- modynamic deterioration in service follow-up, additional imagings (CT or US) will be required, and it can be difficult to make a distinction in the new images as to whether it is new fluid or the fluid seen in the CT tractography in the first admission. This can lead to confusion for the cli- nician. In addition, application of selected conservative patients whose peritoneal violation is positive may cause difficult decision making for the clinician in the first admission. Detection of intraabdominal contrast may instead be that leaked into the abdomen from a small intestine or colon injury, rather than CT tractography contrast. Also, contrast given during CT tractography can change the DPL results in the case of a pos- sible peritoneal violation, and the sterility of the contrast given in emer- gency conditions is insufficient and may be a source of secondary peritonitis and intraabdominal sepsis.
Conclusion
In conclusion, local wound exploration performed by general sur- geons is 100% effective in detecting peritoneal violation with anterior abdominal stab wounds. CT tractography is 100% specific, has a 100% PPV, is 96% accurate, and is 95% sensitive; unfortunately, is has an only 80% NPV. Conventional CT has poor accuracy, and the false-negative rate is high. CT tractography is better than conventional CT to detect peritoneal violation. However, we do not recommend CT tractography in anterior abdominal stab wounds due to the false-negative results.
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