Can ruptured abdominal aortic aneurysm be accurately diagnosed as the cause of death without postmortem computed tomography when autopsies cannot be performed?

Accuracy of presenting symptoms, physical examination, and imaging for diagnosis of ruptured abdominal aortic aneurysm: Systematic review and meta-analysis

OBJECTIVES

Ruptured abdominal aortic aneurysm (rAAA) is a life-threatening condition, and rapid diagnosis is necessary to facilitate early surgical intervention. We sought to evaluate the accuracy of presenting symptoms, physical examination signs, computed tomography with angiography (CTA), and point-of-care ultrasound (PoCUS) for diagnosis of rAAA.

METHODS

We searched six databases from inception through April 2021. We included studies investigating the accuracy of any of the above tests for diagnosis of rAAA. The primary reference standard used in all studies was intraoperative diagnosis or death from rAAA. Because PoCUS cannot detect rupture, we secondarily assessed its accuracy for the diagnosis of AAA, using the reference standard of intraoperative or CTA diagnosis. We used GRADE to assess certainty in estimates.

RESULTS

We included 20 studies (2,077 patients), with 11 of these evaluating signs and symptoms, seven evaluating CTA, and five evaluating PoCUS. Pooled sensitivities of abdominal pain, back pain, and syncope for rAAA were 61.7%, 53.6%, and 27.8%, respectively (low certainty). Pooled sensitivity of hypotension and pulsatile abdominal mass were 30.9% and 47.1%, respectively (low certainty). CTA had a sensitivity of 91.4% and specificity of 93.6% for diagnosis of rAAA (moderate certainty). In our secondary analysis, PoCUS had a sensitivity of 97.8% and specificity of 97.0% for diagnosing AAA in patients suspected of having rAAA (moderate certainty).

CONCLUSIONS

Classic clinical symptoms associated with rAAA have poor sensitivity, and their absence does not rule out the condition. CTA has reasonable accuracy, but misses some cases of rAAA. PoCUS is a valuable tool that can help guide the need for urgent transfer to a vascular center in patients suspected of having rAAA.

Traumatic brain injury: Comparison between autopsy and ante-mortem CT

PURPOSE

The aim of this study was to compare pathological findings after traumatic brain injury between autopsy and ante-mortem computed tomography (CT). A second aim was to identify changes in these findings between the primary posttraumatic CT and the last follow-up CT before death.

METHODS

Through the collaboration between clinical radiology and forensic medicine, 45 patients with traumatic brain injury were investigated. These patients had undergone ante-mortem CT as well as autopsy. During autopsy, the brain was cut in fronto-parallel slices directly after removal without additional fixation or subsequent histology. Typical findings of traumatic brain injury were compared between autopsy and radiology. Additionally, these findings were compared between the primary CT and the last follow-up CT before death.

RESULTS

The comparison between autopsy and radiology revealed a high specificity (≥80%) in most of the findings. Sensitivity and positive predictive value were high (≥80%) in almost half of the findings. Sixteen patients had undergone craniotomy with subsequent follow-up CT. Thirteen conservatively treated patients had undergone a follow-up CT. Comparison between the primary CT and the last ante-mortem CT revealed marked changes in the presence and absence of findings, especially in patients with severe traumatic brain injury requiring decompression craniotomy.

CONCLUSION

The main pathological findings of traumatic brain injury were comparable between clinical ante-mortem CT examinations and autopsy. Comparison between the primary CT after trauma and the last ante-mortem CT revealed marked changes in the findings, especially in patients with severe traumatic brain injury. Hence, clinically routine ante-mortem CT should be included in the process of autopsy interpretation.

The pseudo-SAH sign: an imaging pitfall in postmortem computed tomography

Postmortem computed tomography (PMCT) of the brain has an important role in detection of subarachnoid hemorrhage (SAH), which has a high mortality rate. However, a phenomenon known as "pseudo-SAH," or high-attenuation areas along the cisterns mimicking SAH, may be seen on CT. The aim of this study was to evaluate the diagnostic accuracy of brain PMCT for SAH and to identify the characteristics of pseudo-SAH. Findings on PMCT (sulcal effacement, asymmetry, maximum thickness of SAH signs, presence of acute/subacute intraventricular/intraparenchymal hemorrhage) and clinical history (left ventricular assist device [LVAD] implantation, anticoagulation therapy/coagulation disorder, global ischemia) were compared between subjects with true SAH and those with pseudo-SAH. Twenty eight of 128 enrolled subjects had positive signs of SAH on PMCT, 20 (71.4%) had SAH on autopsy, and 8 (28.6%) did not. The sensitivity, specificity, positive predictive value, and negative predictive value of SAH signs seen on PMCT were 95.2, 94.6, 71.4, and 99.3%, respectively. Asymmetry of SAH signs and acute/subacute intraventricular and intraparenchymal hemorrhage were significantly more common in true SAH cases than in pseudo-SAH cases. The maximum thickness of SAH signs was significantly greater in true SAH cases. A history of LVAD implantation, anticoagulation therapy, and/or a coagulation disorder were more common in true SAH cases but not significantly so. A history of global ischemia was significantly more common in pseudo-SAH cases. If signs of SAH are observed on PMCT, it is important to look for other signs on PMCT and carefully review the clinical history to avoid a diagnostic error.