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Sonographic evaluation of groin and anterior abdominal wall hernias

      Hernias commonly cause pain and/or lumps. Large hernias in thin patients are usually clinically obvious, but the exact type and contents of the hernia might not be clinically apparent. Smaller hernias in obese patients can also cause pain, but may be obscured clinically by thick subcutaneous fat. Sonography can be valuable in determining the presence, type, contents, reducibility, and tenderness of a hernia. There are 5 types of groin hernias—indirect and direct inguinal, femoral, Spigelian, and supravessical. There are 3 types of anterior midline hernias—epigastric and hypogastric linea alba and umbilical hernias. Incisional, laparoscopic trochar site, and parastomal hernias also occur and can be diagnosed with sonography. Most hernias contain only fat and membranes. Only a small percentage contain bowel or peritoneal fluid. Other contents are rare. With sonography, it may not be possible to determine whether a hernia that contains only fat contains intraperitoneal or properitoneal fat unless peritoneal fluid “puddles” when the patient is upright. Fat-containing hernias are of approximately of the same echodensity as surrounding abdominal wall soft tissues and difficult to appreciate unless they can be made to move with dynamic maneuvers such as Valsalva and compression. Compression also helps us determine whether a hernia is partially or completely reducible and whether it is tender. Dynamic maneuvers and upright positioning are critical to the diagnosis of hernias and offer sonography an advantage over CT.