BL-20 (Pi Shu) Spleen Shu

What does BL-20 Pi Shu do?

Pi Shu BL-20 is the Back-Shu point of the Spleen, and it is the principal point of the body for supplementing the Spleen. Sacred Lotus sources & references record that classification directly, and it organises everything else about the point. The Back-Shu points are the places on the back where each organ's qi is said to infuse the surface, and BL-20 is the Spleen's. In classical theory the Spleen governs the transformation of food into qi and blood, the holding of blood inside the vessels, the transport of fluids, and the muscles and four limbs — so a point that supplements it reaches digestion, energy, bleeding and dampness all at once.

• Tonifies Spleen qi and Spleen yang — the defining action, recorded first in our own action record. For the tired, poorly digesting, cold-and-weak presentation the tradition attributes to Spleen depletion: loose stools, poor appetite, abdominal distension after eating, heavy limbs.
• Resolves dampness — the Spleen is said to dislike damp and to be the organ that fails first when damp accumulates. BL-20 is the point through which that failure is addressed, for oedema, a heavy body, a thick tongue coating, chronic loose stools and damp skin conditions.
• Raises Spleen qi and holds the blood — two aspects of the same containing function. Sinking Spleen qi is the classical explanation of prolapse and dragging heaviness; Spleen qi failing to hold blood is the explanation of chronic bleeding that is pale, prolonged and unforced — heavy or prolonged menstrual bleeding, blood in the stool, bruising under the skin.
• Regulates and harmonises the qi of the middle burner — the middle burner is the digestive centre of the trunk, and BL-20 is used with its Stomach counterpart to settle the whole of it: epigastric pain, nausea, vomiting, belching, distension.
• Nourishes blood — the derived action. Since the Spleen is described as the source from which qi and blood are made, supplementing it is the indirect route to a blood deficiency that has not responded to blood-nourishing points alone.
• Acts as the Spleen's diagnostic point — as with every Back-Shu point, tenderness, a sunken feel or a change in the tissue at BL-20 is read as a sign referring to its organ, and the point is palpated as well as needled.

Source: Sacred Lotus sources & references (channel, Back-Shu classification, existing action record); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 278); Chinese Acupuncture & Moxibustion (p. 179); cross-referenced against multiple online sources.

What is BL-20 Pi Shu used for?

Pi Shu BL-20 is used above all for digestive complaints and for the fatigue, dampness and chronic bleeding that classical theory attributes to a depleted Spleen. The indications below are those carried in Sacred Lotus sources & references together with those set out in the standard reference literature. They describe traditional use, not proven treatment, and this point carries the depth cautions set out under needling.

• Epigastric pain and discomfort
• Abdominal distension and fullness after eating
• Poor appetite and anorexia
• Vomiting and nausea
• Diarrhoea, chronic loose stools and undigested food in the stool
• Dysentery
• Blood in the stool
• Profuse or prolonged menstrual bleeding
• Jaundice
• Oedema and a heavy, waterlogged body
• Fatigue, weak limbs and general depletion
• Backache at the level of the lower ribs
• Chronic bleeding that is pale and unforced, including bruising under the skin

Source: Sacred Lotus sources & references (existing indication record); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 278); Chinese Acupuncture & Moxibustion (p. 179).

Where is BL-20 Pi Shu, and how is it used in practice?

Pi Shu lies on the back, one and a half cun either side of the midline, level with the lower edge of the eleventh thoracic vertebra — that is, level with Ji Zhong DU-06 on the spine itself. Sacred Lotus sources & references give it in both terms. It is a bilateral point, needled on both sides, and it sits in the muscle mass either side of the spine just above the lowest ribs, at the point where the back begins to narrow toward the waist.

In practice BL-20 is almost never used alone. It belongs to a small cluster of back points — Spleen, Stomach, Liver and Gall Bladder — that are treated together as the digestive block, and it is one of the points most strongly associated with moxibustion rather than needling, because nearly everything it is used for is deficiency and cold.

Which points is BL-20 combined with?

• With BL-21 Wei Shu — the Stomach Back-Shu point, one level below at T12. This is the essential pairing: in classical theory the Spleen and Stomach are the interior–exterior couple of the middle burner, and the two Shu points are treated as one unit for any digestive complaint.
• With LIV-13 Zhang Men — the Shu-Mu combination. LIV-13, on the side of the trunk at the free end of the eleventh rib, is the Spleen's Front-Mu point, and Back-Shu with Front-Mu is the oldest structured pairing in the medicine: the front and back of the same organ, treated together.
• With SP-03 Tai Bai — the Yuan-Source point of the Spleen channel, on the inner edge of the foot. Back-Shu with Yuan-Source is the classical structure for supplementing an organ, and this is its Spleen instance.
• With ST-36 Zu San Li and REN-12 Zhong Wan — the two great points of the middle burner on the front and the leg. REN-12 is the Stomach's Front-Mu point and the Hui-Meeting point of the fu organs; ST-36 is the Command Point of the abdomen. BL-20 with these two is the standard skeleton of a digestive treatment.
• With SP-06 San Yin Jiao — for dampness, for gynaecological bleeding and for the fatigue of a depleted middle burner, adding the meeting point of the three leg yin channels.
• With BL-17 Ge Shu — the Hui-Meeting point of blood, four levels above at T7. BL-17 with BL-20 is the standard pairing where the Spleen's failure to make or to hold blood is the presenting problem.
• With BL-49 Yi She — "Reflection Abode", on the outer Bladder line three cun lateral at the same T11 level. It is BL-20's outer companion and is named for the yi, the faculty of thought and reflection that the Spleen is said to house; the pairing is used where overthinking and worry are held to be depleting the Spleen.
• With BL-13 Fei Shu and BL-23 Shen Shu — the Lung, Spleen and Kidney trio, the classical three-organ structure for chronic wheezing and for chronic damp-phlegm conditions. This grouping is in current research use: an animal study of point-application therapy for asthma applied a herbal ointment at Feishu BL-13, Pishu BL-20 and Shenshu BL-23 and reported reduced airway inflammation and collagen deposition, with effects traced to the AMPK/mTOR pathway (J Asthma 2026;63(1):15–25, PMID 40920042).

Where does BL-20 sit among the Back-Shu points?

The Back-Shu points run down the inner Bladder line, one and a half cun either side of the spine, one for each organ, in roughly the order the organs sit in the trunk. Sacred Lotus sources & references hold the complete set of twelve:

• Fei Shu BL-13 — Lungs
• Jue Yin Shu BL-14 — Pericardium
• Xin Shu BL-15 — Heart
• Gan Shu BL-18 — Liver
• Dan Shu BL-19 — Gallbladder
• Pi Shu BL-20 — Spleen
• Wei Shu BL-21 — Stomach
• San Jiao Shu BL-22 — San Jiao
• Shen Shu BL-23 — Kidneys
• Da Chang Shu BL-25 — Large Intestine
• Xiao Chang Shu BL-27 — Small Intestine
• Pang Guang Shu BL-28 — Bladder

Each Back-Shu point pairs with its organ's Front-Mu point on the front of the trunk. The Spleen's Front-Mu is Zhang Men LIV-13, on the side of the trunk at the free end of the eleventh rib — which surprises people, since it sits on the Liver channel rather than the Spleen's. Front-Mu points frequently sit on a different channel from their organ; the Spleen and the Kidneys, whose Front-Mu point is Jing Men GB-25, are the two clearest examples. LIV-13 is additionally the Hui-Meeting point of the zang organs, which is a second reason it is reached for whenever the solid organs as a group are being addressed. BL-20 is, after BL-23 Shen Shu, among the most heavily used of the twelve, because Spleen deficiency and Kidney deficiency are the two patterns most often treated.

Source: Sacred Lotus sources & references (BL-20 record; the full twelve-point Back-Shu set and the Front-Mu set queried directly; LIV-13 confirmed as Front-Mu of the Spleen); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 278); Chinese Acupuncture & Moxibustion (p. 179); PMID 40920042; cross-referenced against multiple online sources.

Where is BL-20 located?

• A Manual of Acupuncture (p. 278): 1.5 cun lateral to the lower border of the spinous process of the eleventh thoracic vertebra (T11).
• Chinese Acupuncture and Moxibustion (p. 179): 1.5 cun lateral to Jizhong (DU-6), at the level of the lower border of the spinous process of the eleventh thoracic vertebra.

How is BL-20 Pi Shu needled, and what lies beneath it?

Stated plainly: BL-20 lies on the back at the level of the eleventh thoracic vertebra — still within the thoracic band — and the pleural cavity extends further down the back than most people expect, its lowest recess reaching the twelfth rib level behind. Pneumothorax is the documented hazard of needling the mid-back Shu points, and it is the reason the reference texts record an oblique angle and a bounded depth here rather than a perpendicular one. Everything below is recorded as neutral reference data describing what the textbooks and the published imaging studies state. It is not instruction, and this page does not teach technique. Needling is carried out only by a qualified, licensed practitioner.

The angle and depth the texts record

• Sacred Lotus sources & references record oblique insertion of 0.5 to 0.7 inch, with moxibustion applicable. The angle is the substance of the record: an oblique needle angled toward the spine travels through the muscle mass alongside the vertebrae, while a perpendicular one travels toward what lies in front of them.
• Deadman & Al-Khafaji (p. 278) and Chinese Acupuncture & Moxibustion (p. 179) record a comparable oblique range, angled medially toward the spine, and both attach an explicit caution against deep or perpendicular insertion at the thoracic Shu points because of the pleura and lung beneath.
• Moxibustion is recorded as applicable and is the technique most associated with this point, since the great majority of what BL-20 is used for is deficiency and cold. Warming the point avoids the depth question entirely, which is part of why it is so commonly chosen here.
• For comparison within our own records: 0.5–0.7 inch at BL-20 is bounded in the same way as the 0.3–0.5 inch recorded for LIV-14 over the liver and for GB-21 over the apex of the lung, and shallower than the 1–1.2 inch recorded for BL-23 in the lumbar region below the ribs. Depth figures in this literature track the structure underneath, not the size of the region.

The measured anatomy — and what the studies actually measured

• Back-point depths to the pleura have been measured directly by CT. A study of 120 patients, divided into six groups by body weight, height and sex, measured on CT the distance from the skin of the back to the thoracic pleura at the relevant acupuncture locations, and defined that distance as the point's safe depth. Depths did not differ significantly between the sexes, but they differed highly significantly between body-size groups (P < 0.01), and the authors proposed the resulting figures as reference safe depths for back points (Zhong Xi Yi Jie He Za Zhi 1991;11(1):10–13, PMID 2054884). The companion study from the same group did the same for the chest (Zhonghua Yi Xue Za Zhi (Taipei) 1992;50(5):388–99, PMID 1338010). Neither paper's abstract names BL-20 among the points measured, and we are not attributing a figure to this point that has not been published for it; the studies are cited for the principle they establish about the thoracic back as a region, and for the finding that body size, not sex, is what moves the number.
• The same has been done in children, where the margins are smallest. A retrospective study of chest CT images in patients aged 4 to 18 measured the safe depths of 23 upper-back acupoints across the Governing Vessel, Bladder, Small Intestine, Gall Bladder and Spleen channels. Safe depth differed significantly between boys and girls at most of them, and differed significantly by age, weight and body-mass index; multiple regression identified weight as the single most important determinant (Ma YC et al., BMC Complement Altern Med 2016;16:85, PMID 26922245). The paper describes its points as upper back acupoints and its abstract does not list BL-20; it is cited here for the same reason as the adult study — the principle, not a borrowed number.
• No single agreed safe depth exists for any point. Two systematic reviews of the safe-depth literature — 33 studies in the first, 47 in the second, measured by MRI, CT, ultrasound and cadaveric dissection — both concluded that depths measured for the same point differ greatly between subject groups and measuring methods, and that the definition of "safe depth" has never been standardised (J Altern Complement Med 2011;17(3):199–206, PMID 21417806; Evid Based Complement Alternat Med 2013;2013:740508, PMID 23935678). The practical content of that is the same as at every other thoracic point: a textbook depth figure describes an average body, not a constant.
• What lies beneath, in plain terms. At the T11 level the needle passes through skin, subcutaneous tissue and the long muscles of the back. In front of those lie the lower ribs and, between and behind them, the lowest part of the pleural cavity — the posterior costophrenic recess, which extends further down the back than the lung itself does. Below and in front of that sit the diaphragm and, deeper again, the upper pole of the kidney on each side and the spleen on the left. This is the anatomical reason the thoracic Shu points are angled medially and kept shallow.

What is documented, and how often

Pneumothorax — a punctured lung — is the second most frequently reported serious adverse event in acupuncture. A systematic review of the Chinese case-report literature from 1956 to 2010 identified 1,038 adverse-event cases across 167 articles, of which 307 were pneumothorax, behind only fainting, and attributed them chiefly to improper technique (He W et al., J Altern Complement Med 2012;18(10):892–901, PMID 22967282). The presentation is not always immediate: an emergency-medicine case report describes a healthy 38-year-old woman who developed pleuritic chest pain the day after dry needling of the back, with bedside ultrasound showing absent lung sliding and a lung point on the right (Cureus 2021;13(3):e14207, PMID 33948398). Fatal cases exist: an autopsy report describes bilateral pneumothoraces following electroacupuncture, the authors noting that electrical pulses and the muscle contraction they cause may draw needles deeper than the depth at which they were inserted (J Forensic Sci 2022;67(1):377–383, PMID 34435369). A pneumothorax after needling over the thorax or upper back may declare itself hours later, with sudden chest pain, breathlessness or a persistent dry cough; it is a medical emergency requiring immediate assessment.

The proportion of the risk

A meta-analysis of prospective clinical studies estimated serious adverse events in acupuncture at approximately 1 per 10,000 patients and around 8 per million treatments, placing it among the safer treatments in medicine (Bäumler P et al., BMJ Open 2021;11:e045961, PMID 34489268). The absolute risk is small and it is concentrated in a small number of points; the points over the thorax and upper back, BL-20 among them, are where it concentrates. The bounded oblique depth exists to keep it there.

Source: Sacred Lotus sources & references (existing needling record); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 278); Chinese Acupuncture & Moxibustion (p. 179); PMID 2054884; PMID 1338010; PMID 26922245; PMID 21417806; PMID 23935678; PMID 22967282; PMID 33948398; PMID 34435369; PMID 34489268 — each verified resolvable and checked for retraction status before citation.

What does the name Pi Shu mean?

Pi Shu means "Spleen Shu" — pi, the Spleen, and shu, a transport point. The character shu carries the sense of conveying or transporting, and the Back-Shu points are named for exactly that: the places on the back where each organ's qi is said to be transported to the body surface. Sacred Lotus sources & references translate the name as Spleen Shu. Like the other eleven Back-Shu names, it is a description of function rather than a metaphor, which makes this the easiest group of names in acupuncture to learn — the organ, then the word shu.

Why does the Back-Shu classification matter?

The Back-Shu points are the tradition's most direct route to an internal organ. Each is understood as the place where that organ's qi infuses the back, which gives them two roles at once. They are used to treat the organ, particularly in chronic and deficient conditions; and they are palpated in diagnosis, since tenderness, a sunken feeling or a change in the tissue at a Back-Shu point is read as a sign that its organ is involved. That diagnostic claim is one of the few in acupuncture that has been put to an instrument. Using infrared thermal imaging, a study compared 45 patients with chronic persistent asthma against 45 healthy controls and found the body-surface temperature at bilateral Feishu BL-13, Geshu BL-17, Pishu BL-20 and Shenshu BL-23 to be significantly higher in the patients, concluding that these points show specificity in reflecting lung disease (Zhongguo Zhen Jiu 2023;43(4):439–43, PMID 37068822). A follow-up from the same line of work in 61 asthma patients found the surface temperature at the same four points to differ according to the level of pulmonary ventilation function, and analysed the correlation between the two (Zhongguo Zhen Jiu 2025;45(3):274–279, PMID 40097207). These are small single-centre observational studies and they do not establish that a point diagnoses anything — but they are measurements taken at BL-20 itself, and they test the traditional claim rather than assuming it.

Is there research on BL-20 Pi Shu?

There is no randomised trial isolating BL-20, and that should be said before anything else. Every clinical study we located that used this point used it inside a prescription of several points, which cannot show what BL-20 contributed. What does exist falls into three honest categories.

• Point-property measurement at BL-20 itself — the two infrared thermography studies described above (PMID 37068822; PMID 40097207). These are the most genuinely point-specific findings attached to BL-20.
• Trials in which BL-20 is the added ingredient. The cleanest design we found: 64 patients with post-stroke tracheotomy were randomised to a base treatment of diaphragmatic pacing plus a fixed conventional acupuncture prescription, or to that same base plus needling at bilateral Feishu BL-13, Pishu BL-20 and Shenshu BL-23. The group receiving the three Back-Shu points showed greater improvement in lung function measures, diaphragm ultrasound parameters and balance scores, and a higher extubation success rate (Zhongguo Zhen Jiu 2025;45(6):745–750, PMID 40518777). It is a single-centre unblinded trial and the added element was three points rather than one, but the comparison is between two arms differing only in those three points, which is more informative than most.
• Historical and modern point-selection analyses, where BL-20 recurs. A data-mining study of the earliest ancient acupuncture prescriptions for epigastric pain found the highest-frequency points to be Zhongwan REN-12, Shangwan REN-13, Zusanli ST-36, Neiguan P-06, Gongsun SP-04, Pishu BL-20 and Weishu BL-21 — and found that the commonest structures were Back-Shu points paired with each other, and Back-Shu points paired with Front-Mu points, exactly as the textbooks describe (Zhongguo Zhen Jiu 2025;45(2):253–61, PMID 39943771). A complex-network analysis of 156 clinical studies of acupuncture for inflammatory bowel disease found ST-25, ST-36, REN-04, REN-12 and BL-20 to be the five most-used points (Zhen Ci Yan Jiu 2024;49(3):315–323, PMID 38500330). And an analysis of 106 articles and 158 prescriptions for chronic cough placed Pishu BL-20 among the ten highest-frequency points (Zhongguo Zhen Jiu 2025;45(9):1347–1359, PMID 40954069). These measure what practitioners have chosen over two thousand years, not whether it worked — but the convergence of the ancient and the modern lists on the same point is itself worth recording.
• Preclinical work. The asthma point-application study noted above applied its ointment at BL-13, BL-20 and BL-23 in rats and traced its effects to the AMPK/mTOR pathway (PMID 40920042). It is an animal, three-point protocol and is recorded for completeness rather than as evidence about the point in humans.

What is missing should be said plainly: there is no sham-controlled randomised trial of BL-20 alone for any of its principal traditional uses — digestive weakness, chronic diarrhoea or fatigue. The point's standing rests on the classical record, on continuous clinical use, and on a small amount of measurement taken at the point itself.

How does BL-20 compare with the points around it?

Wei Shu BL-21 lies one level below at T12 and is the Stomach's Back-Shu point; the two are the digestive pair and are almost always used together, with BL-20 leaning toward transformation, dampness and fatigue and BL-21 toward the stomach itself — epigastric pain, nausea, poor appetite. Dan Shu BL-19 above at T10 and Gan Shu BL-18 at T9 are the Gall Bladder and Liver Shu points, added where constrained Liver qi is held to be disturbing digestion. Ge Shu BL-17 at T7 is the Hui-Meeting point of blood and BL-20's partner wherever blood is the issue. San Jiao Shu BL-22 at L1 and Shen Shu BL-23 at L2 continue the line below. Yi She BL-49 is BL-20's outer companion three cun lateral at the same level. Tai Bai SP-03 at the foot is its distal Yuan-Source partner, and Zhang Men LIV-13 on the side of the trunk is its Front-Mu counterpart on the front of the body. Where a treatment needs the Spleen reached from the front and below rather than from the back, Zhong Wan REN-12 and Zu San Li ST-36 are the points that do it.

Source: Deadman & Al-Khafaji, A Manual of Acupuncture (p. 278); Chinese Acupuncture & Moxibustion (p. 179); Sacred Lotus sources & references (BL-20 record; Back-Shu and Front-Mu point sets and the neighbouring points queried directly); PMID 37068822; PMID 40097207; PMID 40518777; PMID 39943771; PMID 38500330; PMID 40954069; PMID 40920042 — each verified resolvable and checked for retraction status before citation; cross-referenced against multiple online sources.