BL-22 (San Jiao Shu) Triple Burner Shu

What does BL-22 San Jiao Shu do?

San Jiao Shu BL-22 is the Back-Shu point of the San Jiao — the "Triple Burner" — and its recorded work is to move and regulate that system, and through it the passage of water and the transformation of dampness. Sacred Lotus sources & references record that classification directly. The San Jiao is not an organ in the anatomical sense but the tradition's name for the three divisions of the trunk and, above all, for the waterways that run through them; BL-22 is the place on the back where its qi is said to infuse the surface, and it sits at the first lumbar vertebra, in the middle of the body, at the join between the middle and lower divisions.

• Moves and regulates the San Jiao — the Back-Shu action and the defining one. Where the tradition holds that the passage of qi and fluid through the trunk has become obstructed, this is the point on the back that addresses it as a whole rather than organ by organ.
• Regulates the water passages and promotes urination — the action that follows directly, and the one BL-22 is most reached for. The San Jiao is described in the classics as the official responsible for the waterways; oedema, difficult urination and fluid retention are the recorded uses.
• Regulates the Spleen and Stomach and resolves dampness — for abdominal distension, borborygmus, indigestion, vomiting and diarrhoea. BL-22 sits between the Stomach's Back-Shu point above and the Kidneys' below, and it takes on the digestive complaints in which fluid and dampness are the issue rather than food.
• Resolves masses — the recorded action behind its classical use for palpable accumulations in the abdomen.
• Strengthens the lumbar region — the local action, for pain and stiffness of the lower back. BL-22 lies in the muscle mass beside the first lumbar vertebra and is used as a local point in its own right.
• Serves as the San Jiao's diagnostic point — as with all Back-Shu points, tenderness, a sunken feeling or a change in the tissue at BL-22 is read as a sign referring to the system it names, and the point is palpated as well as needled.

Source: Sacred Lotus sources & references (existing action record; Back-Shu classification queried directly); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 281); Chinese Acupuncture & Moxibustion (p. 180); cross-referenced against multiple online sources.

What is BL-22 San Jiao Shu used for?

San Jiao Shu BL-22 is used for abdominal distension and digestive upset in which fluid is the problem, for oedema and difficult urination, and for lower back pain and stiffness. The indications carried in Sacred Lotus sources & references are borborygmus, abdominal distension, indigestion, vomiting, diarrhoea, dysentery, oedema, and pain and stiffness of the lower back; the standard reference literature sets them out as follows. They describe traditional use, not proven treatment, and this point carries the depth facts set out under needling.

• Abdominal distension and fullness
• Borborygmus — rumbling and gurgling of the abdomen
• Indigestion and undigested food in the stool
• Vomiting
• Diarrhoea and dysentery
• Oedema and swelling
• Difficult or scanty urination
• Retention of urine
• Pain and stiffness of the lower back
• Weakness of the lumbar region
• Palpable masses and accumulations in the abdomen
• Jaundice
• Emaciation despite eating, attributed to failed transformation

Source: Sacred Lotus sources & references (existing indication record); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 281); Chinese Acupuncture & Moxibustion (p. 180).

Where is BL-22 San Jiao Shu, and how is it used in practice?

San Jiao Shu lies on the lower back, one and a half cun either side of the midline, level with the lower edge of the first lumbar vertebra — that is, level with Xuan Shu DU-05 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 one level above Shen Shu BL-23 and one below Wei Shu BL-21, in the run of Back-Shu points that descends the inner Bladder line.

In practice BL-22 is the least famous of the twelve Back-Shu points, for a straightforward reason: the San Jiao is the hardest of the twelve to picture, having no organ of its own. That has left the point somewhat overshadowed by its neighbours. Where it is genuinely distinctive is in fluid problems — oedema, difficult urination, abdominal distension with a sense of water rather than food — because that is the San Jiao's own territory. It is commonly treated with moxibustion.

Which points is BL-22 combined with?

• With Shi Men REN-05 — the Shu-Mu combination. REN-05, on the lower abdomen, is the Front-Mu point of the San Jiao, confirmed by query in Sacred Lotus sources & references. Back-Shu with Front-Mu — the front and back of one system, treated together — is the oldest structured pairing in the medicine, and this is its San Jiao instance.
• With Wei Yang BL-39 — the complete organ triad. This is the most instructive combination on the page. BL-39, in the popliteal crease behind the knee, is the Lower He-Sea point of the San Jiao. Put together with BL-22 as Back-Shu and REN-05 as Front-Mu, this library holds all three classical points of a single organ — a set very few organs allow, and the clearest demonstration of what each classification is for: BL-22 reaches the system from the back, REN-05 from the front, BL-39 from a distance through the leg. All three designations are confirmed by query, and our BL-39 record carries the same triad from its own end.
• With Shen Shu BL-23 — directly below at L2, the Kidneys' Back-Shu point. The pairing is the standard treatment of the lower back and of water metabolism, since the Kidneys govern water and the San Jiao carries it.
• With Pang Guang Shu BL-28 and Zhong Ji REN-03 — added for urinary retention and difficult urination, bringing in the Bladder's own Back-Shu and Front-Mu points.
• With Yin Ling Quan SP-09 and San Yin Jiao SP-06 — the distal leg points for dampness and oedema, the usual partners where fluid is the presenting problem.
• With Wei Shu BL-21 and Pi Shu BL-20 — above it at T12 and T11, for abdominal distension and indigestion treated as a middle-burner problem.
• With Da Chang Shu BL-25 — for the lower back and for the bowel; a clinical report describes plum-blossom needle tapping at Sanjiaoshu BL-22 and Dachangshu BL-25 combined with needling at the Jiaji points in 43 cases of ulcerative colitis (J Tradit Chin Med 2005;25(2):83–4, PMID 16136930). It is an uncontrolled case series and is named for the combination rather than as evidence of effect.

Where does BL-22 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. This page.
• 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 San Jiao's Front-Mu is Shi Men REN-05 on the lower abdomen, two cun below the navel — a Conception Vessel point, since the San Jiao's own channel runs up the arm and does not cross the abdomen at all. BL-22 is the only one of the twelve whose organ is not an organ, and reading the list makes its oddity visible: eleven of these points name a structure you could hold in your hand, and the twelfth names a function.

Source: Sacred Lotus sources & references (BL-22 record; the full twelve-point Back-Shu set and the twelve Front-Mu points queried directly; REN-05 confirmed as Front-Mu of the San Jiao and BL-39 as its Lower He-Sea point); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 281); Chinese Acupuncture & Moxibustion (p. 180); PMID 16136930; cross-referenced against multiple online sources.

Where is BL-22 located?

• A Manual of Acupuncture (p. 281): 1.5 cun lateral to the lower border of the spinous process of the first lumbar vertebra (L1).
• Chinese Acupuncture and Moxibustion (p. 180): 1.5 cun lateral to Xuanshu (DU-5), at the level of the lower border of the spinous process of the first lumbar vertebra.

How is BL-22 San Jiao Shu needled, and what lies beneath it?

Stated plainly: BL-22 lies in the lumbar region at the level of the first lumbar vertebra, and the kidneys lie retroperitoneally — behind the abdominal cavity and in front of the lumbar muscles — spanning roughly the twelfth thoracic to the third lumbar vertebral levels. BL-22 is therefore within the kidney region, and the depth recorded in the texts is bounded for that reason. 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 perpendicular insertion of 0.5 to 1.0 inch, with moxibustion applicable. That is a shallower ceiling than the 1 to 1.2 inch our records hold for Shen Shu BL-23 one level below.
• Deadman & Al-Khafaji (p. 281) and Chinese Acupuncture & Moxibustion (p. 180) record a comparable perpendicular range, with oblique insertion angled medially toward the spine also recorded, and both attach a caution against deep insertion in this region because of the kidney beneath.
• Moxibustion is recorded as applicable and is heavily associated with the Back-Shu points generally, since most of what they are used for is deficiency and cold.

The measured anatomy — a study that measured this point itself

• MRI measurement of safe depth at BL-22. An MRI study of 61 healthy subjects measured both the "dangerous depth" and the effective safe depth of perpendicular and oblique needling at the acupoints of the kidney region. The points it measured, named explicitly, were Wei Shu BL-21, San Jiao Shu BL-22, Shen Shu BL-23, Wei Cang BL-50, Huang Men BL-51 and Zhi Shi BL-52 — BL-22 among them, which makes this genuinely point-specific. Left and right sides did not differ. What did differ, substantially, was body size: dangerous and safe depths were significantly greater in the overweight group than in the moderate group, and greater in the moderate group than in the underweight group. The authors concluded that in underweight patients the direction and depth of needling must be restricted to avoid accident (Chen GT et al., Zhongguo Zhen Jiu 2022;42(9):1006–1010, PMID 36075596, DOI 10.13703/j.0255-2930.20210820-k0007). The practical content is that a textbook depth figure describes an average body rather than a constant, and that the margin is narrowest in the thinnest patients.
• What a needle reaches in the lumbar muscle — measured at the neighbouring point. A dissection study inserted a depth-measuring blade perpendicularly in twelve dissected specimens to establish whether the psoas major muscle can be reached from this region. Half the insertions reached psoas, at a mean depth of 38.0 mm (interquartile range 29.0–51.8) in specimens with short-term underlying conditions and 32.0 mm (29.3–42.5) in those with long-term health problems, with depth correlating negatively with body length (Chia KL, Haberberger RV, J Integr Med 2016;14(2):128–33, PMID 26988434). That study measured Shen Shu BL-23, not BL-22. It is cited here for the principle it establishes about the lumbar region — that what a given depth reaches depends on the individual body — and no measurement from it is attributed to this point.
• Where the kidneys actually are. The kidneys are retroperitoneal, lying against the posterior abdominal wall behind the peritoneum and in front of the lumbar muscles, at roughly the T12–L3 levels, with the right kidney sitting slightly lower than the left because of the liver above it. BL-22 at L1 lies within that span, toward its upper end — which is the honest statement, and the reason the kidney is named explicitly in the standard cautions for this point where it is not for the lower lumbar points.
• 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, 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).
• What the case literature documents. Injury to retroperitoneal structures following acupuncture is recorded in the published case literature — including a retroperitoneal haematoma from rupture of a pseudoaneurysm caused by acupuncture (J Urol 1998;159(6):2087, PMID 9598531) and a retroperitoneal abscess complicating acupuncture (J Korean Med Sci 2003;18(5):756–757, PMID 14555834). Systematic reviews of acupuncture adverse events list traumatic organ injury among the small number of genuinely serious events on record and conclude that these overwhelmingly followed improper technique rather than acupuncture as such (Zhang J et al., Bull World Health Organ 2010;88(12):915–921C, PMID 21124716, PMC2995190).
• Honest limit of what we can source. We could not locate a published case report naming BL-22 specifically as the point at which a kidney injury occurred, and none is asserted. What is recorded here is what is documented: a bounded depth in the reference texts, MRI evidence that safe depth at this exact point varies markedly with body size, the anatomical fact that the kidney lies within the L1 span, and a published record of retroperitoneal injury from deep needling in this region.

Risk in proportion

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 bounded depth at the lumbar Back-Shu points exists to keep it that way.

Source: Sacred Lotus sources & references (existing needling record); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 281); Chinese Acupuncture & Moxibustion (p. 180); PMID 36075596; PMID 26988434; PMID 21417806; PMID 23935678; PMID 9598531; PMID 14555834; PMID 21124716 (PMC2995190); PMID 34489268 — each verified resolvable and checked for retraction status before citation.

What does the name San Jiao Shu mean?

San Jiao Shu means "Triple Burner Shu" — san, three; jiao, a burner, scorcher or heater; and shu, a transport point. Sacred Lotus sources & references translate it as Triple Burner Shu. The character shu carries the sense of conveying, and the Back-Shu points are named for exactly that: the places on the back where each organ's qi is transported to the body surface. Like the other eleven Back-Shu names, this one is a description of function rather than a metaphor, which is why the set is among the easiest in acupuncture to learn.

What is the San Jiao, and why does it have a Back-Shu point?

The San Jiao is the one of the twelve "organs" with no physical organ behind it — the classics themselves call it "an organ with a name but no form". It denotes the three divisions of the trunk: the upper burner from the diaphragm up, holding the Heart and Lungs; the middle burner between the diaphragm and the navel, holding the Spleen and Stomach; and the lower burner below the navel, holding the Kidneys, Bladder and Intestines. Its function in classical theory is to keep the passages between those divisions open — above all the waterways, which is why the Su Wen describes it as the official in charge of irrigation.

Giving that function a Back-Shu point is a consequence of the tradition treating the San Jiao as one of the six fu organs, entitled to the same set of classical points as any other. It sits at L1, at the junction of the middle and lower burners — a placement that reads as deliberate. In practice this is what makes BL-22 useful in a way its neighbours are not: where BL-20 and BL-21 above it address digestion and BL-23 below addresses the Kidneys, BL-22 addresses the movement between them, and specifically the movement of fluid.

Why does the complete San Jiao triad matter?

The San Jiao is one of the few systems for which this library holds all three of the classical point types, and seeing them together is the best available illustration of what those classifications are for. Confirmed by query in Sacred Lotus sources & references:

• Back-Shu — San Jiao Shu BL-22, on the lower back at L1. Reaches the system from behind; used in chronic and deficient conditions and palpated in diagnosis.
• Front-Mu — Shi Men REN-05, on the lower abdomen two cun below the navel. Reaches it from the front; the "alarm" point, where tenderness signals involvement.
• Lower He-Sea — Wei Yang BL-39, in the crease behind the knee. Reaches it from a distance. The Lower He-Sea points are the classical route to the six fu organs from the leg, set out in the Ling Shu, and BL-39 is the San Jiao's.

Notice that not one of the three sits on the San Jiao channel itself, which runs from the ring finger up the arm to the head and never crosses the trunk below the shoulder. Two are on the Bladder channel and one on the Conception Vessel. That is the same lesson the Front-Mu set teaches elsewhere: these classifications are assigned by where an organ can be reached, not by which line runs over the spot.

Is there research on BL-22 San Jiao Shu?

The honest answer is that BL-22 has very little point-specific research, and the most substantial study naming it is an anatomical one rather than a clinical one. That should be stated plainly rather than padded out with whole-protocol trials.

• The anatomical study measured this point. The MRI safe-depth study of 61 subjects described under needling measured BL-22 explicitly among the six kidney-region points, and established that safe depth at it varies significantly with body size (PMID 36075596). For this point, as for several safety-constrained points, the anatomical literature is the research literature.
• An honest negative in an imaging study. Infrared thermography was used to compare body-surface temperature at the lumbosacral region and at the lumbar Back-Shu points in 50 patients with low back pain from lumbar disc herniation against 45 healthy controls. The points measured were bilateral Sanjiaoshu BL-22, Shenshu BL-23, Qihaishu BL-24, Dachangshu BL-25, Guanyuanshu BL-26, Xiaochangshu BL-27 and Pangguangshu BL-28. Left-right temperature differences were significantly greater in the patients than the controls at BL-23, BL-24, BL-25, BL-26 and BL-27 — and the authors concluded that BL-23 and BL-25 showed relative specificity (Zhongguo Zhen Jiu 2024;44(4):423–427, PMID 38621730). BL-22 was measured and did not show the effect. That is worth recording exactly as it stands: the finding is consistent with the traditional picture, in which BL-22 is not primarily a low-back-pain point, and reporting it is more useful than omitting it.
• A small uncontrolled clinical series. Forty-three cases of ulcerative colitis were treated with acupuncture at the Jiaji points EX-B2 combined with plum-blossom needle tapping at Sanjiaoshu BL-22 and Dachangshu BL-25 (J Tradit Chin Med 2005;25(2):83–4, PMID 16136930). A case series with no control group and a multi-point protocol; it establishes that the point is used this way, not that it works.

What is missing should be said plainly: there is no randomised trial of BL-22, no sham-controlled study of it, and none of its fluid, urinary or digestive indications has been tested at this point specifically. Where BL-22 appears in the trial literature it is one point among many in a protocol, and nothing in those studies is attributable to it.

How does BL-22 compare with the points around it?

Wei Shu BL-21 lies one level above at T12 and is the Stomach's Back-Shu point; it takes the digestive complaints in which food rather than fluid is the issue. Shen Shu BL-23 lies one level below at L2, is the Kidneys' Back-Shu point, and is by a wide margin the most used point of the twelve — where BL-22 carries the waterways, BL-23 carries the constitutional reserve, and the two are constantly used together for oedema and urinary complaints. Huang Men BL-51 is BL-22's outer companion three cun lateral at the same L1 level. Xuan Shu DU-05 lies directly medial on the midline at the same level. Shi Men REN-05 on the lower abdomen is BL-22's Front-Mu counterpart, and Wei Yang BL-39 behind the knee its Lower He-Sea partner, completing the triad. For readers looking for the San Jiao channel's own points, note that they are all on the arm — Wai Guan SJ-05 at the wrist is the usual distal choice — and that none of BL-22's classical partners is among them.

Source: Sacred Lotus sources & references (name, translation, Back-Shu classification, the Back-Shu and Front-Mu sets, and the REN-05 and BL-39 records queried directly); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 281); Chinese Acupuncture & Moxibustion (p. 180); Ling Shu, on the Lower He-Sea points; Su Wen, on the San Jiao as the official of irrigation; PMID 36075596; PMID 38621730; PMID 16136930 — each verified resolvable and checked for retraction status before citation; cross-referenced against multiple online sources.