Are preoperative CT variables associated with the success or failure of subsequent ventral hernia repair: nested case-control study

Anatomical Variation of Abdominal Wall Musculature: An Objective Assessment Using Cross-Sectional Imaging

Purpose: To determine normal anatomical variation of abdominal wall musculature. Methods: A retrospective analysis of CT scans was performed on adults (>18 years) with normal abdominal wall muscles. Two radiologists analysed the images independently. Distances from three fixed points in the midline were measured. The fixed points were; P1, mid-way between xiphoid and umbilicus, P2, at the umbilicus, and P3, mid-way between umbilicus and pubic symphysis. From these three fixed points the following measurements were recorded; midline to lateral innermost border of the abdominal wall musculature, midline to lateral edge of rectus abdominis muscle, and midline to medial edges of all three lateral abdominal wall muscles. To obtain aponeurotic width, rectus abdominis width was subtracted from the distance to medial edge of lateral abdominal wall muscle. Results: Fifty normal CT scan were evaluated from between March 2023 to August 2023. Mean width of external oblique aponeurosis at P1 was 16.2 mm (IQR 9.2 mm to 20.7 mm), at P2 was 23.5 mm (IQR 14 mm to 33 mm), and at P3 no external oblique muscle was visible. Mean width of the internal oblique aponeurosis at P1 was 32.1 mm (IQR 17.5 mm to 45 mm), at P2 was 10.13 (IQR 1 mm to 17.5 mm), and at P3 was 9.2 mm (IQR 3.0 mm to 13.7 mm). Mean width of the transversus abdominis aponeurosis at P1 was -25.1 mm (IQR 37.8 mm to -15.0 mm), at P2 was 29.4 mm (IQR 20 mm to 39.8 mm), and at P3 was 20.3 mm (IQR 12 mm to 29 mm). Conclusion: In this study we describe normal anatomical variation of the abdominal wall muscles. Assessing this variability on the pre-operative CT scans of ventral hernia patients allows for detailed operative planning and decision making.

Preoperative CT imaging as a tool to predict incisional hernia outcomes following abdominal wall reconstruction: A retrospective cohort analysis

INTRODUCTION

Ventral wall hernia often causes significant morbidity and requires complex abdominal wall reconstruction (AWR). This study aims to determine whether subcutaneous abdominal fat thickness (AFT) measured with preoperative CT scans could predict postoperative outcomes in patients undergoing AWR.

METHODS

A retrospective cohort study was conducted on all patients who underwent AWR at our institution between 2009 and 2021, with a minimum follow-up of 12 months. Using preoperative CT scans, AFT was measured at the xiphoid process, umbilicus, and pubic tubercle, as well as the hernia dimensions. Demographic, operative, and surgical outcome data were also collected and analyzed using statistical tests.

RESULTS

The results showed that 9 of 101 patients (8.9%) experienced hernia recurrence. Smoking was associated with an increased risk of hernia recurrence (p < 0.001) with a predictive odds ratio (OR) of 18.27 (p = 0.041). Increased AFT at the xiphoid (p = 0.005), umbilicus (p < 0.001), and pubic tubercle (p < 0.001) were also associated with hernia recurrence and risk of infection. Only AFT at the pubic tubercle reached significance in the regression model predicting recurrence (OR=1.10; p = 0.030) and infection (OR=1.04; p = 0.021). A cut-off value of 67 mm was associated with a positive predictive value of 42.14% (sensitivity of 67% and specificity of 91%). Hernia defect area was not associated with risk of recurrence or infection.

CONCLUSIONS

Smoking and increased AFT at the pubic tubercle are significant predictive factors for recurrence and infection in patients undergoing AWR, and preoperative optimization should focus on reducing these factors.

Comparison of two-dimensional measurement with three-dimensional volume rendering for the assessment of loss of domain in incisional hernia patients

PURPOSE

We aimed to compare simple two-dimensional (2D) measurement with comprehensive three-dimensional (3D) volume rendering to determine loss of domain (LOD), a clinically important decision-making feature for incisional hernia repair.

METHODS

In this single-center retrospective study, we analyzed the CT scans of a consecutive cohort of adult patients with a midline incisional hernia. The hernia sac- and abdominal cavity volumes were obtained by two different methods. The 2D method estimated the volumes using the corresponding height, width, and depth. The 3D method comprised of a volume rendering tool. For both methods, LOD was calculated according to the Sabbagh ratio (hernia sac volume / (hernia sac volume + abdominal cavity volume)). Taking the 3D method as the reference standard, the performance of the 2D method was expressed as positive predictive value (PPV) and negative predictive value (NPV) for LOD of more than- and less than 20%. The agreement between both methods was expressed as Cohen's kappa coefficient (kappa).

RESULTS

We analyzed 92 CT scans. Agreement between both methods was high (kappa = 0.854, p = 0.0001); all 67 measurements for which the 2D method assessed LOD to be less than 20% were correctly classified (NPV = 100%), and 20 of 25 measurements for which the 2D method assessed LOD to be more than 20% were correctly classified (PPV = 80%).

CONCLUSIONS

The 2D method can exclude patients from perioperative actions needed for a more complex hernia. Since this method is easy to use and less time-consuming, it seems useful for the routine radiological assessment of LOD in clinical practice.