An alternate light source examination identified intradermal injury in 98% of patients with nonfatal strangulation and no externally visible injuries, based on limited evidence from a scoping review.
Nonfatal strangulation is associated with substantial health risks and has been identified as a marker of escalating violence, with one study cited in the review reporting a 7.48-fold higher risk of future homicide among affected patients.
Researchers reviewed 11 databases—including PubMed, CINAHL, Embase, Medline, Cochrane, Scopus, and four legal databases—for peer-reviewed, English-language studies published before June 30, 2021.
Eligible studies included patients aged 18 years and older who had survived a strangulation attempt and examined medical evidence, documentation, or prosecution-related outcomes. After screening, 25 studies met inclusion criteria: 7 addressed medical assessment, 8 addressed documentation, and 12 examined medical evidence in court, with 2 studies contributing to more than one category.
Injury Patterns and Imaging Findings
Across 959 strangulation cases included in medical investigation studies, 701 patients received imaging. External injuries were absent in an average of 44% of patients, with reported ranges from 17% to 93%.
Bruising or hematoma was the most commonly reported injury, present in 55% of assessed cases. Other findings included abrasions (24%), neck tenderness (37%), petechiae (9%), swelling (5%), subconjunctival hemorrhage (4%), and ligature marks (2%).
Strangulation was primarily manual in 79% of reported cases, while 11% involved ligatures and 6% involved chokeholds. Women accounted for 87% of victim-survivors.
Magnetic resonance imaging identified injuries in at least 52% of examined cases, with detection rates varying across studies. In some instances, magnetic resonance imaging (MRI) detected injury when no external findings were present.
One study also reported that a forensic radiologist identified significantly more injuries on MRI than a clinical radiologist, suggesting potential differences in detection based on specialist training.
Computed tomography demonstrated limited sensitivity overall, with injury detected in approximately 8% of examined cases, including as low as 3% in one large study. Computed tomography appeared more effective for detecting bone and cartilaginous injuries, which are less common in strangulation.
The single study evaluating alternate light source technology—which uses ultraviolet, visible, and infrared wavelengths to enhance visualization—identified intradermal injuries in 98% of patients without visible external injury. Researchers noted that this method may allow detection of patterned injuries and support photographic documentation, but emphasized that evidence is limited to a single study.
Documentation Strategies
Across eight studies focused on documentation, researchers consistently recommended standardized tools designed specifically for strangulation assessment. These tools typically include body maps, injury checklists, and structured history-taking.
Detailed questioning was emphasized, including recording patients’ statements verbatim. Suggested questions included what patients believed would happen during the assault and what the perpetrator said. Researchers noted that direct quotations may support legal proceedings, particularly when physical evidence is limited.
Photographic documentation was also recommended, including full-body images, close-up images of injuries with and without measurement tools, follow-up images to capture evolving injuries, and images demonstrating how the strangulation occurred.
Implications for Prosecution
Across 12 studies examining legal outcomes, medical documentation of injuries, symptoms, and patient statements was consistently identified as essential for prosecution.
One retrospective analysis found cases were 40% more likely to be filed when forensic nurse examinations were performed using standardized evidence collection procedures.
Researchers cautioned that absence of visible injury should not be interpreted as evidence that strangulation did not occur, noting that it is common and potentially misleading in legal contexts.
The review also highlighted that corroborating medical evidence may reduce reliance on patient testimony, which can be associated with retraumatization and may not always be available.
Limitations
The researchers noted that most included studies were retrospective, raising the possibility of referral bias in imaging use. They also highlighted limited evidence for some modalities—particularly alternate light source examination—and a lack of studies evaluating computed tomography angiography despite its role in detecting vascular injury.
“Despite these limitations,” the researchers wrote, “this review provides a first and comprehensive review of the literature to guide clinical decision making, referral and criminal prosecution of nonfatal strangulation.”
The study was supported by an Australian Research Council Discovery Project grant (DP200101020). No competing interests were reported.
Source: BMJ Open