Features of multi-slice spiral CT examination of indirect and direct and femoral inguinal hernia in adults

Objective To explore the features of multi-slice spiral computed tomography (MSCT) examination of indirect, direct and femoral inguinal hernia. Methods The retrospective cross-sectional study was conducted. The clinical data of 106 patients with indirect, direct and femoral inguinal hernia who were admitted to the First Affiliated Hospital of Xinxiang Medical University between December 2014 and August 2017 were collected. All the patients were diagnosed as inguinal hernia by MSCT examination and multi-planar reconstruction. Observation indicators: (1) sensitivity, specificity, positive and negative predictive values and diagnostic accordance rate of indirect, direct and femoral inguinal hernia by MSCT; (2) inguinal anatomic presentation in MSCT examination; (3) relationship between hernial sac and surrounding structures in MSCT examination; (4) hernia contents and quadrants of hernial sac in the quadrant partition with "cross intersect" method and complications. Count data were described as absolute number or percentage. Comparison of count data was done using the chi-square test with row multiplied by column. Results (1) Sensitivity, specificity, positive and negative predictive values and diagnostic accordance rate of indirect, direct and femoral inguinal hernia by MSCT: of 106 patients, 66, 22 and 18 were diagnosed as indirect hernia, direct hernia and femoral hernia with 70, 27 and 20 hernial sacs respectively. Sensitivity, specificity, positive and negative predictive values of inguinal hernia by MSCT were respectively 95.7%, 96.3%, 98.5%, 89.7% in indirect hernia patients and 96.3%, 95.7%, 89.7%, 98.5% in direct hernia patients and 100.0%, 100.0%, 100.0%, 100.0% in femoral hernia patients, and diagnostic accordance rate of femoral hernia was also 100.0%. Diagnostic accordance rate of inguinal hernia was 95.9%, and correct index was 0.920. (2) Inguinal anatomic presentation in MSCT examination: transverse, coronal and sagittal imagings of inferior epigastric artery, inguinal ligament, musculus rectus abdominis, femoral vein and other anatomic structures can be identified, and internal ring of inguinal canal of 6 patients cannot be observed clearly. For relationship between internal ring of inguinal canal and inferior epigastric artery, coronal view was the best, transverse view was the next, and sagittal view was rarely observed. For relationship between inguinal ligament and hernial sac, sagittal view was the best, coronal view was also observed clearly by continuous planes, and transverse view was poor. The oblique coronal view was the best for the direct hernial triangle and internal ring of inguinal canal, and coronal view of femoral triangle was the best. The lateral crescent sign and quadrant partition of "ross intersect" method needed to be observed in transverse plane. (3) Relationship between hernial sac and surrounding structures in MSCT examination: indirect hernia entered into the inguinal canal through internal ring of inguinal canal, and hernial sac was located at the outside of inferior epigastric artery; direct hernia was out through triangle hernia, and hernial sac was located at the inside of inferior epigastric artery, 92.6%(25/27) patients were accompanied by lateral crescent sign. The indirect hernia and direct hernia went along the upper front of inguinal ligament; femoral hernia was out through femoral triangle hernia, and hernial sac was located at the lower back of inguinal ligament and the outside of the pubic tubercle. (4) The hernia contents and quadrants of hernial sac in the quadrant partition with "cross intersect" method and complications: the most common hernia content was small intestine, including partial patients with hernia content composed of various substances; indirect hernia contents included small intestine (35), mesentery (29), effusion (25), intraabdominal fat (9), colon (8) and ovary (1) in turn; direct hernia contents included small intestine (14), intraabdominal fat (11), effusion (6), mesentery (6), colon (3) and bladder (2) in turn; femoral hernia contents included small intestine (12), intraabdominal fat (8), effusion (3) and mesentery (2) in turn. There was a statistically significant difference in the hernia contents among indirect hernia, direct hernia and femoral hernia (χ2=28.389, P<0.05). The main hernial sac located at antero-external quadrant was respectively occurred in 70 hernial sacs of indirect hernia and 27 hernial sacs of direct hernia and 15 hernial sacs of femoral hernia, and 5 hernial sacs of femoral hernia were located at postero-external quadrant. There was a statistically significant difference in comparison of the quadrant partition with "cross intersect" method (χ2=78.904, P<0.05). The intestinal obstruction was respectively occurred in 8 patients with indirect hernia and 14 patients with direct hernia and 12 patients with femoral hernia, with a statistically significant difference (χ2=26.674, P<0.05). Conclusions Indirect hernia, direct hernia and femoral hernia have characteristic signs of imaging. MSCT can display precisely the anatomical details of inguinal region, which plays an important role in diagnosis and differential diagnosis of indirect hernia, direct hernia and femoral hernia, especially in display of hernia contents and diagnosis of complications, thus it can provide important information for evaluating risk and making operation plan. Key words: Inguinal hernia; Direct hernia; Indirect hernia; Femoral hernia; Multi-slice spiral computed tomography; Multiple planar reconstruction