Abdominal wall hernias: Cross-sectional imaging signs of incarceration determined with sonography

OBJECTIVE. The aim of this study was to determine with sonography whether d istinct cross-sectional imaging signs exist that may differentiate between incarcerated and nonincarcerated abdominal wall hernias. SUBJECTS AND METHODS.The sonographic appearance of 149 consecutive abdomina l wall hernias was prospectively investigated and correlated with subsequen t surgical results. Commercially available 4- to 10-MHz linear transducers and 2- to 5-MHz curved transducers were used to evaluate the hernias. RESULTS. Surgery revealed 126 nonincarcerated and 23 incarcerated hernias. The sonographic signs suggestive of incarceration that we identified includ ed free fluid in the hernia sac, which was observed in 91 % of the incarcer ated hernias and in 3% of the nonincarcerated hernias; bowel wall thickenin g in the hernia, which was detected in 88% of the incarcerated hernias and in none of the nonincarcerated hernias; fluid in the herniated bowel loop, which was detected in 82% of the incarcerated hernias and in 3% of the noni ncarcerated hernias and dilated bowel loops in the abdomen, which occurred in 65% of the incarcerated hernias and in none of the nonincarcerated herni as. These imaging findings allowed the identification of incarceration in a ll 23 cases and led to a false-positive result in two of 126 nonincarcerate d hernias. CONCLUSION. Cross-sectional imaging signs indicating hernial incarceration included free fluid in the hernial sac, bowel wall thickening in the hernia , fluid in the herniated bowel loop, and dilated bowel loops in the abdomen . Sonography is an appropriate cross-sectional imaging modality for detecti ng these signs that are helpful in diagnosing patients with atypical clinic al presentations.