BL27 Small Intestine Shu

Reviewed by · Licensed Acupuncturist & TCM Physician · Last reviewed June 2026

BL27 (Xiǎo Cháng Shū, “Small Intestine Shu”) is the Back-Shu Point point of the Bladder Meridian. It is located in the sacral region, 1.5 cun lateral to the midline, at the level of the first posterior sacral foramen (S1). This corresponds to the level below the 18th vertebra in classical counting. It regulates the Small Intestine, separates the clear from the turbid, clears Damp-Heat from the Lower Jiao, benefits the lumbar region and legs, and dispels pathogenic factors like heat and cold from the three jiao.

Location

In the sacral region, 1.5 cun lateral to the midline, at the level of the first posterior sacral foramen (S1). This corresponds to the level below the 18th vertebra in classical counting.

Needling

Perpendicular insertion 0.8 to 1.2 cun. Needling into the posterior sacral foramen can be done with an oblique medial and inferior insertion of 1.0 to 1.5 cun.

TCM functions

Regulates the Small Intestine, separates the clear from the turbid, clears Damp-Heat from the Lower Jiao, benefits the lumbar region and legs, and dispels pathogenic factors like heat and cold from the three jiao..

Indications

Lumbar and spinal pain, lower abdominal pain pulling to the testicles and spine, hernia pain rushing to the heart, urinary difficulty, reddish-yellow urine, dripping and difficult urination (lin syndrome), urinary incontinence, bloody stools, dysentery with pus and blood (red and white dysentery), tenesmus, hemorrhoids, leg swelling, headache, deficiency and exhaustion, unquenchable thirst with dry mouth, summerheat stroke, heat in the three jiao and bladder, cold in the three jiao, cold in the large and small intestines, diarrhea with undigested food, abdominal distention, borborygmus, female leucorrhea, heart vexation and shortness of breath, mouth and tongue dryness with inability to eat..

Back-Shu Point

Clinical notes

As the Back-Shu point of the Small Intestine, BL27 is a primary point for disorders of its paired Fu-organ. Its function of separating clear from turbid fluids makes it essential for treating urinary disorders like difficult, painful, or frequent urination, especially those with a Damp-Heat component. It is also a key local point for lumbosacral pain and sciatica, and its influence extends to treating dysentery and hemorrhoids, reflecting the Small Intestine's role in fluid and waste processing in the lower jiao.

On the Bladder channel

BL27 is one of 67 points on the Bladder Meridian. Nearby points:

Frequently asked questions

Where is BL27 located?

BL27 (Xiǎo Cháng Shū) is located in the sacral region, 1.5 cun lateral to the midline, at the level of the first posterior sacral foramen (S1). This corresponds to the level below the 18th vertebra in classical counting.

What is BL27 used for?

BL27 regulates the Small Intestine, separates the clear from the turbid, clears Damp-Heat from the Lower Jiao, benefits the lumbar region and legs, and dispels pathogenic factors like heat and cold from the three jiao. Common clinical indications include lumbar and spinal pain, lower abdominal pain pulling to the testicles and spine, hernia pain rushing to the heart, urinary difficulty, reddish-yellow urine, dripping and difficult urination (lin syndrome), urinary incontinence, bloody stools, dysentery with pus and blood (red and white dysentery), tenesmus, hemorrhoids, leg swelling, headache, deficiency and exhaustion, unquenchable thirst with dry mouth, summerheat stroke, heat in the three jiao and bladder, cold in the three jiao, cold in the large and small intestines, diarrhea with undigested food, abdominal distention, borborygmus, female leucorrhea, heart vexation and shortness of breath, mouth and tongue dryness with inability to eat.

How is BL27 needled?

Perpendicular insertion 0.8 to 1.2 cun. Needling into the posterior sacral foramen can be done with an oblique medial and inferior insertion of 1.0 to 1.5 cun.

Which meridian is BL27 on?

BL27 is a point on the Bladder Meridian (Zú Tài Yáng Páng Guāng Jīng).

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⚠️ This page is for general education and is not medical advice. Acupuncture is a traditional practice; evidence varies by condition and study quality, and individual results differ. It does not replace diagnosis or treatment by a licensed professional. Always consult a qualified acupuncturist or physician.