Effects of CT examination in different body positions on the evaluation of abdominal incisional hernia volume

Objective To investigate the effects of computed tomography (CT) examination in different body positions on the evaluation of abdominal incisional hernia volume. Methods The retrospective case-control study was conducted. The clinical data of 23 patients with abdominal incisional hernia who were admitted to the Sixth Affiliated Hospital of Sun Yat-sen University from February to September in 2017 were collected. There were 14 males and 9 females, aged from 47 to 75 years, with an average age of 63 years. All patients underwent CT scan in supine position and lateral position. The volume of hernia sac, abdominal cavity and the volume ratio of hernia sac to abdominal cavity in different body positions were measured by multi-planar reconstruction and volume reappearance on the workstation. Observation indicators: (1) situations of CT examination of patients with abdominal incisional hernia in different positions; (2) correlation analysis of volume ratio increment of hernia sac to abdominal cavity between different positions by CT examination in patients with abdominal incisional hernia. Measurement data with normal distribution were expressed as Mean±SD, and comparison between groups was performed using the pared t test. Count data were expressed as absolute numbers or percentages. Pearson correlation was used to analyze the volume ratio increment of hernia sac to abdominal cavity between different positions by CT examination in patients with abdominal incisional hernia. Results (1) Situations of CT examination of patients with abdominal incisional hernia in different positions: CT examination of 23 patients with abdominal incisional hernia showed that the contents of hernia increased and the abdominal wall deformed in the lateral position compared with conventional supine position, with manifestations as shortened abdominal transverse diameter and longer vertical diameter. The volume of the hernia sac in supine position and in lateral position by CT examination was (623±293)mL and (869±425)mL, respectively, showing a significant difference (t=-7.959, P<0.05). The volume of abdominal cavity in supine position and in lateral position by CT examination was (6 445±1 438)mL and (6 283±1 348)mL, respectively, showing a significant difference (t=2.762, P<0.05). The volume ratio of hernia sac to abdominal cavity in supine position and in lateral position by CT examination was 0.096±0.040 and 0.138±0.061, showing a significant difference (t=-8.093, P<0.05). The volume ratio of hernia sac to abdominal cavity in lateral position increased by 0.042 compared with that in supine position, with an increasing rate of 43.8%. All the 23 patients had volume ratio of hernia sac to abdominal cavity less than 20% in supine position by CT examination, however, 4 patients had volume ratio of hernia sac to abdominal cavity more than 20% in lateral position by CT examination. (2) Correlation analysis of volume ratio increment of hernia sac to abdominal cavity between different positions by CT examination in patients with abdominal incisional hernia: results of Pearson correlation analysis showed a positive correlation of volume ratio of hernia sac to abdominal cavity between supine position and lateral position by CT examination (r=0.742, P<0.05). Conclusions The volume of incisional hernia is influenced by different body positions. Compared with supine position, lateral position by CT examination has a more accurate reflection of abdominal incisional hernia. Key words: Hernia; Incisional hernia; Body position; Computed tomography, X-ray; Hernia sac volume; Abdominal cavity volume; Volume ratio