The symptoms of intestinal perforation are mainly sudden onset of severe and persistent pain in the abdomen, which in the case of duodenal ulcer perforation tends to occur in the upper abdomen. In the case of other perforations, the pain can be most pronounced at the primary lesion and can extend rapidly throughout the abdomen, increasing with deep breathing, coughing or turning. In addition, there can be reflex nausea and vomiting, mainly caused by irritation of the peritoneum, and the vomit is the stomach contents. When perforated, acute diffuse peritonitis can result. Acute diffuse peritonitis can present with an acute critical appearance and the typical triad of peritonitis such as pressure pain, rebound pain, and muscle tension in the abdomen.