PAGF is an abnormal communication between aorta and gastrointestinal tract, which is a rare but life-threatening cause of gastrointestinal bleeding, characterized by significant mortality, even with early diagnosis and intervention. The mortality rate is high, the mortality rate of untreated patients is close to 100%, and that of surgical patients is 30%, 40%[7, 8]. The pathophysiological mechanism is not clear, it is believed that due to the continuous beating of aneurysms, constantly squeezing and eroding the digestive tract, resulting in ischemia and necrosis, the formation of fistula between the two is a rare cause of gastrointestinal bleeding, accounting for less than 0.2%[9]. PAGF are most commonly caused by abdominal aortic aneurysms and 85% are caused by atherosclerosis. Other rare causes include infection (aortic arteritis caused by bacteria, syphilis and tuberculosis), tumors, radiation injuries, peptic ulcers, diverticulitis and foreign bodies (such as needle, fishbone or chicken bone). Fistulas can form between the aorta and anywhere from the esophagus to the sigmoid[8]. In our patients, case 1 had a primary aortic aneurysm, which formed hematoma after bleeding, the beginning of the inferior mesenteric artery was compressed by hematoma, which caused intestinal ischemia. Fistula was formed between the aorta and intestine in Case 2, and esophagus in case 3. Clinical manifestations of PAGF are variable, including low-grade fever associated with obscure infected lesions and classical triad of abdominal or chest pain, GI bleeding, and abdominal pulsating mass[10]. In our patients, all had GI bleeding, only one patient had abdominal pain. The sentinel hemorrhage is the initial bleeding prior to catastrophic exsanguinations, and is usually minor and self-limiting owing to formation of thrombus plugging the fistula as a result of hypotension. However, the plug may be dislodged of its canal, leading to further bleeding after the patients become normotensive. Sentinel hemorrhage occurs in a repetitive fashion, the time interval between the initial hemorrhage and final exsanguination ranges from hours to months[8–10]. In our study, this time interval ranges from 11 hours to 4 days. Hypovolemic shock occurred in case 2 during the first sentinel hemorrhage, resulting in death. A high index of suspicion is essential for prompt diagnosis of PAGF. In the absence of clinical suspicion, no single examination can reliably make the diagnosis. Endoscopy is the most useful investigation for origins of GI bleeding, but it can be misleading in finding out coexisting pathological entities. The lack of awareness of PAGF, together with the inaccessibility to distal duodenum and underlying overt GI lesions, are probably responsible for misdiagnosis and delayed appropriate management. If endoscopy failed to reveal informative findings, then CT scan is usually performed which may give a reported detection rate of 30–61%[11]. A definitive diagnosis at the time of the initial bleeding is essential for timely, life-saving surgery. Absence of an identifiable source of massive GI bleeding strongly prompts a surgical exploration, in order to establish diagnosis and salvage the patients. All cases in our study were discovered during an exploration, and 2 patients survived the operation. Therapeutic approaches in patients with PAGF may be either open surgery or endovascular repair. Menezes et al. showed that there are no differences in overall mortality when comparing endovascular with open aortic aneurysm repair (7.69% versus 11.89%, P = 0.263)[12]. However, patients with a ruptured or inflammatory aortic aneurysm were excluded from this cohort. In our study, two cases were treated with endovascular aortic repair (EVAR) by placing aortic stent. While study of Leonhardt showed that the immediate success rate at stopping bleeding was 80% using stent grafts. Despite the inital success, 80% rebled after 2 weeks or longer. 30-day mortality was 40%, which doubled at 6 months[13]. This supports the conclusion that EVAR should be considered only as bridging measure prior to definitive surgical repair. As the risk of infection is high, patients require antibiotic cover following EVAR. Bacteria in the digestive tract may translocate or enter the blood directly, causing septicemia, if blood culture is negative, antibiotics are recommended for 7–10 days, if blood culture is positive, antibiotics should be selected according to the results of drug sensitivity test, and antibiotics should be used for about 6 weeks after operation. In spite of this, postoperative infection complications and fistula recurrence are still possible. In our study, case 1 and case 3 were treated with antibiotics for a month after placing endovascular stent, and so far, the prognosis is good.