ABSTRACT
Gastrointestinal tract perforations can occur for various causes such as peptic ulcer, inflammatory disease, blunt or penetrating trauma, iatrogenic factors, foreign body or a neoplasm that require an early recognition and, often, a surgical treatment.Ultrasonography could be useful as an initial diagnostic test to determine, in various cases the presence and, sometimes, the cause of the pneumoperitoneum.The main sonographic sign of perforation is free intraperitoneal air, resulting in an increased echogenicity of a peritoneal stripe associated with multiple reflection artifacts and characteristic comet-tail appearance.It is best detected using linear probes in the right upper quadrant between the anterior abdominal wall, in the prehepatic space.Direct sign of perforation may be detectable, particularly if they are associated with other sonographic abnormalities, called indirect signs, like thickened bowel loop and air bubbles in ascitic fluid or in a localized fluid collection, bowel or gallbladder thickened wall associated with decreased bowel motility or ileus.Neverthless, this exam has its own pitfalls. It is strongly operator-dependant; some machines have low-quality images that may not able to detect intraperitoneal free air; furthermore, some patients may be less cooperative to allow for scanning of different regions; sonography is also difficult in obese patients and with those having subcutaneous emphysema. Although CT has more accuracy in the detection of the site of perforation, ultrasound may be particularly useful also in patient groups where radiation burden should be limited notably children and pregnant women.
ABSTRACT
BACKGROUND: Intestinal ischemia is an abdominal emergency that accounts for approximately 2% of gastrointestinal illnesses. It represents a complex of diseases caused by impaired blood perfusion to the small and/or large bowel including acute arterial mesenteric ischemia (AAMI), acute venous mesenteric ischemia (AVMI), non occlusive mesenteric ischemia (NOMI), ischemia/reperfusion injury (I/R), ischemic colitis (IC). In this study different study methods (US, CT) will be correlated in the detection of mesenteric ischemia imaging findings due to various etiologies. METHODS: Basing on experience of our institutions, over 200 cases of mesenteric ischemia/infarction investigated with both US and CT were evaluated considering, in particular, the following findings: presence/absence of arterial/venous obstruction, bowel wall thickness and enhancement, presence/absence of spastic reflex ileus, hypotonic reflex ileus or paralitic ileus, mural and/or portal/mesenteric pneumatosis, abdominal free fluid, parenchymal ischemia/infarction (liver, kidney, spleen). RESULTS: To make an early diagnosis useful to ensure a correct therapeutic approach, it is very important to differentiate between occlusive (arterial,venous) and nonocclusive causes (NOMI). The typical findings of each forms of mesenteric ischemia are explained in the text. CONCLUSION: At present, the reference diagnostic modality for intestinal ischaemia is contrast-enhanced CT. However, there are some disadvantages associated with these techniques, such as radiation exposure, potential nephrotoxicity and the risk of an allergic reaction to the contrast agents. Thus, not all patients with suspected bowel ischaemia can be subjected to these examinations. Despite its limitations, US could constitutes a good imaging method as first examination in acute settings of suspected mesenteric ischemia.
