A 52-year-old woman undergoes laparoscopic cholecystectomy for symptomatic cholelithiasis. During dissection of Calot's triangle, the surgeon identifies a small arterial branch arising from the right hepatic artery and crossing anterior to the cystic duct. Which feature best distinguishes this as the cystic artery rather than an aberrant right hepatic artery branch?

Explanation

## Cystic Artery vs. Aberrant Hepatic Artery Branches ### Anatomical Context The cystic artery is the sole arterial supply to the gallbladder and arises from the right hepatic artery in ~90% of cases. However, anatomical variations are common, and aberrant hepatic artery branches may also cross Calot's triangle, creating potential for confusion during surgery. ### Best Discriminating Feature: Terminal Vascular Distribution **Key Point:** The **destination and termination pattern** of the vessel is the most reliable discriminator: - **Cystic artery:** Enters the gallbladder at the neck or along the body; supplies only the gallbladder wall (mucosa, muscularis, serosa) - **Aberrant hepatic branches:** Continue toward and supply hepatic parenchyma; do not terminate in the gallbladder ### Comparative Table | Feature | Cystic Artery | Aberrant Hepatic Branch | |---------|---------------|------------------------| | **Termination** | Gallbladder wall only | Liver parenchyma | | **Surgical consequence** | Safe to ligate; no hepatic ischemia | Ligation causes liver infarction | | **Identification method** | Trace to gallbladder fundus/body | Trace toward liver hilum | | **Diameter** | Usually small (1–3 mm) | Variable, often larger | | **Course after duct** | Ends at GB | Continues into liver | ### Clinical Pearl **High-Yield:** The **critical view of safety** in laparoscopic cholecystectomy requires the surgeon to trace any arterial branch to its destination. If it enters the gallbladder, it is safe to ligate. If it continues toward the liver, it must be preserved to prevent hepatic ischemia. ### Surgical Significance Misidentification of an aberrant right hepatic artery as the cystic artery and ligating it can result in ischemic hepatic necrosis, a serious intraoperative complication. Tracing the vessel to its endpoint is the gold standard for safe identification. [cite:Standring Anatomy 42e Ch 67; Sabiston Textbook of Surgery 21e Ch 51]