Q: Describe the significance of "Herald Bleeding" in Primary aortoenteric fistula (PAEF)?

Answer: One of the known characteristic of PAEF is of a "herald" bleeding followed hours, days, or even weeks later by a catastrophic bleeding. The herald bleeding is the result of a small fistula tamponaded by thrombus formation. If the fistula continues to expand or the occluding thrombus is removed, massive hemorrhage results.

Clinical significance: This is probably the only window of opportunity to salvage the patient before massive bleed takes over. Emergency exploratory laparotomy should be done as soon as the diagnosis is considered clinically. Mortality is 100% without surgical intervention.

Communications between the aorta and the intestine resulting from disease at either site are referred to as primary aortoenteric fistulas. Causes include untreated aortic aneurysm, infectious aortitis, erosion of the intestine by prosthetic vascular grafts, esophageal cancer etc. Refer other texts for more detailed descriptions.