What does Cullen's sign indicate?

Cullen's sign is characterized by a bluish discoloration around the umbilicus, which typically indicates the presence of bleeding under the skin in that area. This sign is associated with conditions such as intra-abdominal hemorrhage, particularly when blood gathers in the peritoneal cavity. It can result from various causes, including trauma, ectopic pregnancy, or issues related to the pancreas.

The other options provided represent conditions that do not specifically correlate with Cullen's sign. Renal failure does not typically manifest with this particular symptom. Gallbladder rupture and pancreatitis can present with abdominal pain and other systemic signs, but they do not specifically lead to the bruising around the umbilicus seen in Cullen's sign. Thus, the presence of this sign is a significant indicator for clinicians, as it can guide the investigation into potential underlying causes of abdominal bleeding.