Sonographic aspects and anatomy of the aponeurosis of transversus abdominis muscle.

BACKGROUND Ultrasound, computed tomography, and magnetic resonance imaging of abdominal wall has increasingly been used for hernia diagnosis when clinical examination is uncertain. Anatomical study of abdominal wall along with the ultrasound of transversus abdominis muscle aponeurosis can help identify a Spigelian hernia in this region, a disease of difficult diagnosis. AIM To compare the ultrasound findings of anterolateral wall of the abdomen, focusing on Spigelian aponeurosis, to the anatomy of abdominal wall studied in cadavers. METHODS The evaluation of the transversus abdominis aponeurosis was performed during routine ultrasound exams of the anterolateral wall of the abdomen in 90 individuals of both genders, over 25 years, and data were correlated with 60 dissections of the abdominal wall, held on cadavers. RESULTS Ultrasound showed no significant defects in the aponeurosis of transversus abdominis muscle in the 90 subjects studied and the width of the Spigelian aponeurosis ranged from 0.83 to 2.93 cm (mean 1.72 cm). During dissections of the transversus abdominis, some defects were found in 14 out of 60 muscles and aponeurosis studied (23.3%) and the width of the Spigelian aponeurosis ranged from 1.5 to 3.5 cm (mean 2.26 cm). Comparisons between age groups and genders evaluated by ultrasound with cadaver dissections performed were not statistically significant. CONCLUSION Sonographic examinations found no defects in the aponeurosis of transversus abdominis muscle compatible with hernias, and anatomical variations and defects found during dissections were not as well accompanied by Spigelian hernias in the studied corpse.