Which anatomical feature best distinguishes the cystic artery from the cystic vein during dissection of the Calot triangle?

## Anatomical Distinction: Cystic Artery vs Cystic Vein ### Structural Comparison | Feature | Cystic Artery | Cystic Vein | |---------|---------------|------------| | **Origin** | Right hepatic artery (90%) or gastroduodenal artery (10%) | Portal vein or right portal vein branch | | **Number** | Typically single (constant) | Often multiple (variable, 2–3 branches) | | **Course** | Within Calot triangle, anterior and medial | Follows gallbladder bed, drains posteriorly | | **Landmark** | Crosses hepatic artery; key to "critical view of safety" | Not part of critical view; posterior dissection | **Key Point:** The cystic artery is almost always single and arises from the right hepatic artery, making it a reliable landmark. The cystic vein is variable in number and drains into the portal venous system. ### Clinical Pearl **High-Yield:** During laparoscopic cholecystectomy, the "critical view of safety" depends on identifying the single cystic artery crossing the hepatic artery. The cystic vein is not part of this view and is divided later without specific identification. ### Why This Matters **Warning:** Confusion between artery and vein can lead to: - Misidentification of vascular structures during dissection - Failure to achieve critical view of safety - Inadvertent injury to hepatic artery or portal vein The **constancy of the cystic artery** (single vessel from right hepatic artery) versus the **variability of the cystic vein** (multiple branches to portal vein) is the most reliable discriminator.