Vertically 0.5–1 cun.
Caution: The liver is located on the right, the peritoneum on the left.
Caution during pregnancy.
The Penetrating Vessel is the 'Sea of Blood', 'Sea of the 12 Channel' as well as the 'Sea of the abdomen avenue'. Thus its points are often able to invigorate the Blood and Qi and remove Stagnation, especially in the abdomen.
Youmen KID-21 is one of the most important point for regulating Qi and subduing Rebellious Qi in the Stomach. Typical symptoms includes vomiting of foamy saliva, hiccup, sour regurgitation, retching, morning sickness, epigastric fullness, poor appetite, feeling of fullness below the xiphoid process and difficulty in swallowing.
It is also the point where Penetrating Vessel leaves its superficial pathway and runs interiorly and spreads in the chest and breasts. In fact, it is how it gets its name 'Door of the Darkness'. Therefore, it regulates the Qi entering and exiting of the epigastric and chest area. Manifestations include chest pain, hypochondrial distension and coughing.
KID-21 is also widely used for postpartum breastfeeding issues, especially if the patients suffer from Liver Qi Stagnation in the breasts and chest.