Results

Study population

Of the total number of 411 cases with fatal traffic accidents 224 patients received a postmortem CT-scan, for excluded patients and subgroups see Fig. 2.

Fig. 2: Flowchart of the study population. 6 patients were excluded because of severe thermic destruction of the abdominal wall. The group “other road traffic accidents” included 56 pedestrians, 37 cyclists, 28 motorcyclists and 6 patients with occupying other vehicles like horse-drawn carriages

Characterization of study population

The complete study population (218 patients with diagnostic non-enhanced CT scans) consisted of 71 (32.6%) female and 147 (67.4%) male patients. Male patients had an average Body Mass Index (BMI) of 28.4 +- 6.0 kg/m2 (n = 138), missing data was due to amputation of the lower extremities, dismemberment or decapitation or scale defects. The average age was 50.9 +- 20.2 years (range 2 to 90 years). The female patients had an average BMI of 28.6 +- 7.9 kg/m2 (n = 69, range 15.5 to 48.8 kg/m2) and an average age of 53.8 +-24.9 years (3 to 88 years). BMI and age showed no significant difference between the two sexes. Chest compressions in the course of resuscitation measures were documented in 63 cases (28.9%).

Incidence

In the total cohort of 218 traffic accident victims, a TAWH was identified in 45 cases (20.6%). The incidence of TAWH did not differ significantly between female patients (19 of 71; 26.7%) and male patients (26 of 147; 17.7%) (p = 0.121). Similarly, no significant association was found between TAWH and age group; the incidence was 13.9% (5 of 36) in younger adult patients aged 18–35, compared to 24.0% (17 of 70) in the elderly over 65 (p = 0.211). Of the patients with TAWH, only two were under the age of 21 (one aged 17 and one aged 20).

When analyzed by accident mechanism, the incidence was highest among pedestrians in railway collisions, where a TAWH was present in 8 of 19 cases (42.1%). Among these eight patients, the hernia was located on the right side in five cases (26.3%), the left side in one case (5.3%), and was bilateral in two cases (10.5%).

Fig. 3: Four axial images of different motor vehicle occupants in a soft tissue window. The pathology is indicated with white arrows. (A) pmCT of a right sided TAWH in a 73-year old female motor vehicle occupant seated in the front passenger seat with a BMI 38.5 kg/m². (B) pmCT of a left sided TAWH in a 46-year old male motor vehicle occupant seated in the front passenger seat with a BMI 38.5 kg/m² with hematoma in the left flank region. (C) pmCT of a left sided TAWH in a 80-year old female motor vehicle occupant seated in the driver’s seat with a BMI 26.5 kg/m² with small bowel loops as content of the hernia. (D) pmCT of bilateral TAWH in a 81-year old female motor vehicle occupant seated in the front passenger seat with a BMI of 29.4 kg/m²

Within the MVO subgroup (n = 72), the incidence was 19.4% (n = 14). Of these, eight were located on the left side (11.1% of all MVOs), four on the right side (5.6%), and two were bilateral (2.8%). In the remaining 127 victims of other traffic accidents, the TAWH incidence was 18.1% (n = 23) see Fig. 3.

A weak but statistically significant correlation was observed between the presence of a TAWH and a higher Body Mass Index (BMI) across all accident types (Mann-Whitney U, p = 0.049). Patients with a TAWH had a mean BMI of 29.98 kg/m2 (SD 6.35, n = 42), compared to 28.13 kg/m2 (SD 6.72, n = 163) for those without.

Subgroup motor vehicle occupants

From the total cohort of 218 patients, a subgroup of 72 patients was identified as MVO. Within this subgroup, 14 individuals (19.4%) were diagnosed with a TAWH on postmortem CT analysis. None of the MVO with TAWH were younger than 21 years old.

There was no statistically significant association between the occurrence of a TAWH and patient age (Mann-Whitney U test, p = 0.071) or sex (Pearson’s χ² test, p = 0.123). The mean age for patients with a TAWH was 34.4 years (SD 7.2), compared to 29.8 years (SD 7.0) for those without a TAWH. Chest compressions were documented in 17 patients (23.6%).

Precise information about seatbelt usage could be acquired with certainty in only 34 of the 72 MVOs (47.2%). Of these, 30 patients were wearing a seatbelt and 4 were not. A TAWH was identified in 7 of the 30 seatbelted patients (23.3%), whereas no TAWH was found in the 4 non-seatbelted patients.

Among the 14 patients with a TAWH, seven were drivers and seven were passengers.

In the driver group (n = 7), the TAWH was located on the right side in five cases, the left side in one case, and was bilateral in one case.Among the passengers with a TAWH (n = 7), the hernia was on the right side in three cases, the left side in three cases, and was bilateral in one case. The seating positions of these passengers were: right front seat (n = 4), right rear seat (n = 2), and rear middle seat (n = 1).

The presence of a TAWH was found to be significantly and positively correlated with several other traumatic injuries, particularly those affecting the pelvic girdle and thoracic cage. The strongest correlation was observed with injuries to the right sacroiliac joint. All statistically significant correlations are detailed in Table 1. Chest compression during resuscitation was considered a confounding factor for rib and sternal fractures. In these cases, the analysis was therefore performed separately on MOV patients without documented chest compressions. (Sternal fracture N = 54, n = 15, p = 0.005; serial rib fractures N = 45 n = 35 p = 0.016)

Associated injury | n | N | ϕ | p-value
Pelvic injuries
Right sacroiliac (SI) joint injury | 7 | 72 | 0.549 | < 0.001
Left sacroiliac (SI) joint injury | 9 | 72 | 0.345 | 0.003
Spinal injuries
Lumbar transverse process fracture (right) | 26 | 72 | 0.361 | 0.002
Lumbar transverse process fracture (left) | 36 | 72 | 0.351 | 0.003
Thoracic vertebral body fracture (T5-T8) | 14 | 71 | 0.379 | 0.001
Thoracic injuries
Sternal fracture | 20 | 71 | 0.419 | < 0.001
Serial rib fracture | 47 | 71 | 0.312 | 0.008

Injuries without a correlation with the occurrence of TAWH are shown in Table 2.

Associated injury / finding | n | N | ϕ | p-value
Intraperitoneal blood | 29 | 68 | 0.149 | 0.224
Clavicular fracture (either side/bilateral) | 18 | 70 | 0.114 | 0.346
Sacrum fracture (right) | 14 | 72 | 0.202 | 0.089
Sacrum fracture (left) | 12 | 72 | -0.031 | 0.794
Thoracic vertebral body fracture (T1-4) | 9 | 70 | 0.021 | 0.861
Thoracic vertebral body fracture (T9-12) | 7 | 72 | -0.043 | 0.721
Ilium fracture (left) | 7 | 72 | 0.076 | 0.528
Ilium fracture (right) | 5 | 72 | - | -
Lumbar vertebral body fracture (L1-3) | 2 | 72 | - | -
Chance fracture | 1 | 72 | - | -
Lumbar vertebral body fracture (L4-5) | 0 | 72 | - | -

In the MVO with TAWH group’s analysis of the accident procedure, 8 of the 14 accidents were head-on collisions, 3 were side impacts and the remaining 3 had an intermediate angle between head-on collisions and side impacts. Reliable speed documentation was unavailable in 13 out of 14 cases but all accidents occurred on streets outside urban areas suggesting high velocity accidents. All MVO in this subgroup were travelling in a passenger car. Most accidents occurred when two passenger cars collided (9/14); three collisions were with a truck, one with a delivery van, and one with a tree.