Bladder Meridian
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BL-33
Needle Depth
0.8–1.2 cun
Needle Angle
90° (Perpendicular)
Body Area
Back — Sacral
Location
In the 3rd posterior sacral foramen, between the posterior superior iliac spine and the midline.
Main Actions
- Regulates the Lower Burner and facilitates urination and defecation
- Resolves Dampness and regulates menstruation
- Benefits the lower back and legs
Indications
Diarrhea
Leukorrhea
Infertility
Lumbar pain
Sacrum pain
Coccyx pain
Cold sacrum
Cold coccyx
Constipation
Scanty periods
Urinary retention
Painful urination
Urinary difficulty
Painful lower limbs
Lower limbs atrophy
Abdominal distention
Defecation difficulty
Irregular menstruation
Cold sensation in buttocks
Undigested food in the stools
Commentary
'Liao' means crevice, thus BL-31, BL-32, BL-33 and BL-34 are called 'Siliao'(Four crevices) or 'Baliao'(Eight crevice since there are four crevices on each side). They are called so, due to their location in the four sacral foramina.
Shangliao BL-31 (Upper crevice) is at the highest sacral foramina. Ciliao BL-32 (Second crevice) is at the second. Zhongliao BL-33 (Middle crevice) the third, while Xialiao BL-34 (Lower crevice) is the last one.
All these four points share similar actions. Ciliao BL-32 is the most important one with the widest indications. Zhongliao BL-33 has the strongest effect for some actions.
First of all, BL-33 regulates the Lower Burner and treats urination and defecation difficulties. Kidney Deficiency is an important underlying pattern for this disorder, which is frequently seen in elderly and weak patients. Typical urinary manifestations include painful and difficult urination, dark and retention of urine as well as enuresis. While intestines related symptoms covers difficult defecation, constipation, borborygmi and diarrhoea. BL-33 has the strongest effect on urinary disorders.
Furthermore, by removing Dampness from the Lower Burner, the point is effective in treating gynecological disorders such as dysmenorrhea, infertility, irregular menstruation, labor pain and leucorrhoea.
BL-33 is also indicated for genital disorders, even though Xiaoliao BL-34 has the strongest action. Typical manifestations are swelling and painful vagina, incessant green vaginal discharge, pain of the testicles and etc.
All these four points benefit the lumbar region, lower back and legs. They remove the Painful Obstructions from the Channel by invigorating the Qi and Blood. Ciliao BL-32 and Zhongliao BL-33 have the most effect on this action.
Finally, Zhongliao BL-33 is indicated for "the five taxations, the seven injuries and the six extremes", all forms of extreme exhaustion. This underlines a further aspect of the actions of the eight Liao as a whole, which is to benefit, warm, firm and supplement the Kidneys.
Classical Sources
Zhenjiu Jiayi Jing (Systematic Classic of Acupuncture and Moxibustion): Records BL-33 among the sacral points for treating difficult urination, constipation, and lumbar pain.
Suwen - Gukong Lun (Discourse on Bone Hollows): The four sacral foramina points (Baliao) are mentioned as "in the space between the lumbar region and the buttocks" (腰尻分间), indicated for conditions involving pain that radiates to the genitals.
Zhenjiu Dacheng (Great Compendium of Acupuncture and Moxibustion): Lists BL-33 for treating "the five taxations, the seven injuries, and the six extremes" (五劳七伤六极), referring to various forms of exhaustion and deficiency patterns.
How to Locate
First identify the Tuffier's line which connects the highest points of the iliac crest. The spinous process of the 4th lumber vertebra (L4) mostly falls on this line. Then palpate in an inferior direction, passing L5, and reach the most superior 1st sacral foramen. Palpate further to reach the 3rd foramen, where Zhongliao BL-33 is located. Here is to identify the 4 sacral foramens and the corresponding points at the same time. First locate the 4th sacral foramen on the level of the superior end of the rima ani (sometimes a bit more superiorly or inferiorly). Place the little finger on the 4th foramen, then the ring, middle and index fingers on a slightly V-shaped line in a superior direction, palpating for the depressions of the sacral foramens. With the fingers in this position, the index finger will be resting on Shangliao BL-31 of the 1st foramen, the middle finger on Ciliao BL-32 of the 2nd foramen, the ring finger on Zhongliao BL-33 of the 3rd foramen and the little finger on Xialiao BL-44 of the 4th foramen.
Caution
Use caution during pregnancy, especially with strong reducing techniques, except when intentionally promoting labor. Deep needling (1.5-2 cun through the foramen) requires accurate location to enter the sacral foramen properly. Avoid excessive manipulation to prevent nerve irritation. The point is part of the Baliao group, and strong stimulation of these points can induce uterine contractions.
Needle Angle
90° (Perpendicular)
Depth Category
Deep
Standard Depth
0.8–1.2 cun
Needling Directions
Vertically 0.7–1 cun. Or 1.5-2 cun through the foramen. Caution:Reducing Needling techniques are contraindicated during pregnancy, except for promoting labor.
Expected Deqi Sensation
Sensation of soreness, distension, or heaviness locally in the sacral region. The deqi may radiate downward toward the buttocks, perineum, or lower limbs. In some cases, patients may feel the sensation extend to the lower abdomen or genitourinary area. Deeper needling through the sacral foramen may produce stronger electrical or radiating sensations along the sacral nerve distribution.
Moxibustion
Recommended
Duration: 10–15 minutes
Cupping
Recommended
Bloodletting
N/A
Gua Sha
Questionable
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