Bladder Meridian
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BL-31
Safety Warnings
- Contraindicated during pregnancy
Needle Depth
0.8–1.5 cun
Needle Angle
90° (Perpendicular), 45° (Oblique)
Body Area
Back — Sacral
Location
In the 1st posterior sacral foramen, about midway between the posterior superior iliac spine (PSIS) 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
Malaria
Vomiting
Impotence
Back pain
Cold knee
Knee pain
Leukorrhea
Infertility
Bloody nose
Lumbar pain
Painful period
Genitalia pain
Uterus prolapse
Seminal emissions
Genitalia itching
Urinary difficulty
Defecation difficulty
Irregular menstruation
Alternating fever and chills
Sensation of cold in the back
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, but Ciliao BL-32 is the most important one with the widest indication.
Shangliao BL-31 is comparatively less important. First of all, it 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.
Furthermore, by removing Dampness from the Lower Burner, it is effective in treating gynecological disorders such as dysmenorrhoea, infertility, irregular menstruation, itching and pain of the genitals as well as white, red and white leukorrhea.
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, BL-31 also strengthens Qi and promotes the Qi ascending so as to treat anus or Uterus prolapse, seminal emission and impotence.
Classical Sources
Zhenjiu Jiayi Jing (《針灸甲乙經》): First recorded the point location as "in the first sacral foramen, one cun below the waist bone, in the depression lateral to the spine."
Suwen - Discourse on Painful Obstructions (《素問·骨空論》): "For lumbar pain that cannot turn, radiating to the genitals, needle the Baliao and above the pain, the Baliao are in the eight spaces at the waist and sacrum."
Zhenjiu Dacheng (《針灸大成》): "The Baliao collectively treat lumbar pain."
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, where Shaoliao BL-31 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
Pregnancy: Needling is contraindicated during pregnancy except when used to promote labor. The Baliao points have strong effects on the pelvic organs and can stimulate uterine contractions. Needling technique: When inserting through the sacral foramen, use a slightly oblique medial and inferior angle to enter the foramen safely. Perpendicular insertion (0.5–1 cun) stimulates locally, while deeper insertion (1.5–2 cun) through the foramen affects pelvic organs. Some classical texts note caution with moxibustion at this point.
Needle Angle
90° (Perpendicular) / 45° (Oblique)
Depth Category
Deep
Standard Depth
0.8–1.5 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
Local soreness and distension in the sacral area. With deeper insertion through the sacral foramen, sensation may radiate to the lower abdomen, perineum, or down the posterior leg. Deqi (arrival of qi) often presents as a deep ache that may spread toward the hip or genitalia.
Moxibustion
Questionable
Duration: 10–20 minutes
Cupping
Recommended
Bloodletting
N/A
Gua Sha
Recommended
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