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Use of CT in anterior abdominal stab wounds

Three Part Question

In [patients with anterior abdominal stab wounds] does [CT scanning] reliably detect [intra-abdominal injury / peritoneal perforation]?

Clinical Scenario

A 35-year-old male presents to the Emergency Department with an anterior abdominal stab wound (AASW). He is haemodynamically stable, you want to know what the best method of investigation is for him to detect any intra-abdominal injury or perforation.

Search Strategy

NICE Healthcare Databases (1985-2016) including: AMED, PubMED, BNI, EMBASE, HBE, HMIC, Medline, PsycINFO, CINAHL

Search terms:
(anterior abdominal stab).ti,ab
(abdominal stab investigations).ti,ab

Search Outcome

81 papers found. Abstracts were reviewed for relevance of which 16 were duplicates, 55 were irrelevant and 3 were of insufficient quality for inclusion. 6 papers were relevant and of sufficient quality and are included in this BET. Relevant papers are shown in the table below.

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Biffl WL et al
2011
United States
160 adult haemodynamically stable patients with AASW enrolled from 4 centres (2008-2010). Management was guided by a previously stipulated algorithm which did not include CT, Biffl et al, 2009. 47/160 underwent CT scan, which was counted as a deviation from protocol. Pregnant and incarcerated patients were excluded. 29% had multiple stab wounds. Multi-centre prospective observational studyProgression to laparotomy based on CT28% (13 pts)CT contrast administration protocol was not standardised in all patients. Self-reporting by surgeons regarding therapeutic value of surgery. Limited size of patient group. Possible under reporting of patients discharged after negative local wound exploration (LWE) and CT. Possible bias as study set out to validate a protocol which did not include CT.
False positive (non-therapeutic laparotomy)9% (4 pts) Sensitivity 91%
Immediate discharge based on negative CT34% (16 pts) [despite 60% of the group (47) having no CT findings]
Serial Examinations after CT38%
Negative predictive value (NPV)97%
Plackett TP et al
2011
United States
1,961 patients with AASW (1992 – 2008). Paediatric and adult patients 47 patients in the delayed laparotomy group (268 pts) underwent CT Multi-centre retrospective studyFalse positive (non-therapeutic laparotomy) based on CT12.2% (5 pts) Sensitivity 87.8%Due to long study period and multiple influencing individual factors, the effect of CT scanning can not be definitively measured. Small group of patients undergoing CT.
False positive (non-therapeutic laparotomy) without CT21.9% (58 pts) of delayed group
Biffl WL et al
2009
United States
359 adult patients with AASW (2006-2007). 138 (50%) of haemodynamically stable, asymptomatic patients used CT as primary decision-making tool. Multi-centre prospective observational studyImmediate discharge after negative CT21%Management not controlled prospectively. Management based on individual/ institutional protocol and not defined. Therapeutic assessment of surgery subjectively decided by surgeon. Unequal enrolment. No long-term data.
Progression to laparotomy after CT33% (46 pts)
Positive predictive value (PPV)74.6% (103 pts)
False positive (non-therapeutic laparotomy)24% (11 pts) Sensitivity 74%
Lee GL et al
2015
Germany
118 patients with AASW (2004-2012), 10 patients straight to laparotomy due to instability. 108 patients had CT scans. Retrospective studyCT Sensitivity94.2%Small study group. Cannot clearly correlate need for operation and CT findings, no consistent criteria.
PPV98.8%
False positive (non-therapeutic laparotomy) based on CT1%
Positive CT findings91 pts
Salim A et al
2006
United States
156 consecutive haemodynamically stable AASW patients, 2004-2006. 67 patients in the CT group based on attending preference. 89 admitted for serial clinical examination.Prospective Observational StudyPositive CT findings19 ptsCT scans were obtained from only 43% of the patients and at discretion of surgeon. Only single contrast CT used. CT outcome did not show peritoneal penetration. No comparison on length of stay.
Positive CT result and underwent laparotomy 53%
NPV100%
Sensitivity100%
Specificity81%
PPV42%
Overall accuracy for determining intervention 84%
CT changed patient’s management plan18% (12 pts)

Comment(s)

This search revealed three prospective studies and three retrospective studies with no randomised control trials comparing CT to other investigation methods. One prospective study was protocol-based, where CT was considered a deviation from protocol. However, this study had been included due to the fact that moderate numbers of CTs were performed despite the protocol. None of the studies reported CT scanning in haemodynamically unstable patients. Within the haemodynamically stable population with AASW, sensitivity of CT scanning ranged from 70 – 100%. Specificity is harder to assess as few studies assessed the number of false negatives, however those that did found it to be between 81 – 100%. Despite the high rate of true negative results, a negative CT did not automatically result in patient discharge, Biffl et al, 2011, reported only 34% of patients with a negative CT scan were discharged home. However, Berardoni et al reported that in the 80% of patients with a negative CT scan that had hospital admission, the majority was for either psychiatric reasons, intoxication or associated injuries. From these studies the impact on increasing patient ED discharge rate and decreasing length of stay cannot be fully determined but suggests it has an influence if there are no other circumstances that require admission. False positive rate for non-therapeutic laparotomy in CT ranged from 9-30%, which was less or similar to other methods of investigation reported by Biffl et al, 2009, which included diagnostic peritoneal lavage, 31%, and local wound exploration, 54%. The discussion on which method of investigation should be chosen over another appears to be centred on cost-effectiveness and the ability to discharge patients from the Emergency Department. This will vary between hospitals depending on access to CT, access to ward based care for AASW patients and the skill set required to perform alternative investigations such as local wound exploration and serial clinical examinations. Additionally patient factors such as obesity which may affect results of certain investigations such as local wound exploration need to be considered All studies commented on the difficulty in attributing clear correlation between CT scan results and need for theatre due to variability in surgeon preferences. Consistency in the decision to request a CT was also reported to be variable, making it difficult to understand what factors influenced a patient to receive a CT scan. Additional factors, not reported, could have also influenced the decision making process such as risk of radiation exposure and patient risk factors for likely intra-abdominal injury. CT scanning for AASWs in a haemodynamically stable patient was found to be used as an investigation method in all studies and showed benefit even where studies had a differing protocol. These studies suggest CT scanning is a viable method of investigation and can be a valuable addition to clinical examination and judgement in a haemodynamically stable AASW patient’s management plan. In addition to clinical factors, it is likely that organisational factors e.g. skill set and availability of resources are also likely to be taken into consideration. More evidence is needed including defined patient selection protocol and randomised controlled trials to definitively recommend CT scanning as an optimum investigation of AASW.

Clinical Bottom Line

Although evidence is limited, it appears CT scanning should be considered for use in conjunction with clinical judgement and examination. It can be an adjunct to clinical examination for assessing the need for laparotomy in haemodynamically stable patients, as well as decreasing the number of non-therapeutic laparotomies. It also may have an influence in identifying patients that can be discharged direct from the ED.

References

  1. Biffl WL, Kaups KL, Pham TN, Rowell SE, Jurkovich GJ, Burlew CC, Elterman J, Moore EE. Validating the Western Trauma Association algorithm for managing patients with anterior abdominal stab wounds: a Western Trauma Association multicenter trial. J Trauma 2011;71(6):1494–1502
  2. Plackett, Timothy P. DO; Fleurat, Jonathan MD; Putty, Brad MD; Demetriades, Demetrios MD, PhD; Plurad, David MD. Selective Nonoperative Management of Anterior Abdominal Stab Wounds: 1992:2008 Journal of Trauma-Injury Infection & Critical Care 2011; 70(2):408-414
  3. Biffl WL, Kaups KL, Cothren CC, et al. Management of patients with anterior abdominal stab wounds: A Western Trauma Association multicenter trial. J Trauma 2009;66:1294-1301
  4. Lee GJ, Son G, Yu BC, Lee JN, Chung M. Efficacy of computed tomography for abdominal stab wounds: a single institutional analysis. European Journal of Trauma and Emergency Surgery 2015; vol. 41 (no. 1); p. 69-74
  5. Berardoni NE, August DL, Kopelman TR, et al. Use of computed tomography in the initial evaluation of anterior abdominal stab wounds. American Journal of Surgery Dec 2011; vol. 202 (no. 6); p. 690-696
  6. Salim A, Sangthong B, Martin M, et al. Use of computed tomography in anterior abdominal stab wounds: Results of a prospective study. Archives of Surgery 2006; vol. 141 (no. 8); p. 745-750