**4. Endoscopic ultrasound-guided pancreatic fluid collection drainage: technical review**

There are two options of endoscopic drainage method, which are transmural, transpapillary, or even combining these two techniques. In the pseudocyst case, endoscopic ultrasound (EUS) has been widely used for transmural drainage with previous evaluation where direct visualization of cystic lesions through the gastrointestinal (GI) lumen can be easily performed. It has become the most important tool in the management for pancreatic cyst, especially to differentiate benign from malignant condition. However, other than anatomic factor, the presence of ductal communication is also an important factor to decide which route is better to perform. In the WON case, the principle is the same; however, the fluid collection resolution after 72 h is the main consideration for more aggressive endoscopic intervention, which is known as EUS-guided transmural necrosectomy procedure. The drainage procedure can be done either with transpapillary or transmural approach. The needle puncture is performed using 19-G FNA needle. After the tip of the needle entering the cyst cavity, the needle sheath can be left inside by pulling out the needle and the guide wire was inserted through the needle sheath until it is coiled up. Then, the sheath was pulled out with maintaining the wire inside the cyst cavity. The dilatation process will further be performed either with dilator or 5 or 6-fr cystotome to make a larger fistula. Finally, the stent is inserted through the fistula track (plastic or metallic stent) [23–26].
