BL-27 (Xiao Chang Shu) Small Intestine Shu

What does BL-27 Xiao Chang Shu do?

Xiao Chang Shu BL-27 is the Back-Shu point of the Small Intestine — the place on the back where that organ's qi is said to infuse the body surface. Sacred Lotus sources & references record that classification directly, and it organises everything else about the point. Four actions are recorded: it separates the pure from the turbid, it regulates the intestines and the Bladder, it drains turbid dampness and clears damp-heat, and it regulates Small Intestine qi. Every one of them follows from what the Small Intestine is held to do.

• Separates the pure from the turbid — the defining function of the Small Intestine in Chinese physiology, and the action stated first in our own record. The organ receives what the Stomach passes down and divides it: the usable part sent onward and upward, the waste sent to the Large Intestine and the excess fluid to the Bladder. BL-27 is the back point of that sorting process, which is why a point named for the Small Intestine carries urinary indications at all.
• Regulates the intestines and the Bladder — the practical consequence of the above. Lower abdominal pain and distension, dysenteric disorder and diarrhoea on one side; enuresis, blood in the urine and difficult urination on the other. In classical reasoning these are the two directions the separation can fail in.
• Drains turbid dampness and clears damp-heat — the action behind its use for vaginal discharge, for urinary heat and for the heavy, turbid presentations of the lower burner.
• Regulates Small Intestine qi — the Back-Shu action proper, reaching the organ itself rather than a symptom of it.
• Strengthens the lower back and sacrum — the local action. BL-27 lies on the sacrum in the thick fascia and muscle beside it, and lower back pain and sciatica are among the indications carried in our own record.

Source: Sacred Lotus sources & references (channel and Back-Shu classification, and the existing action record — whose broken list markup is corrected here); Deadman & Al-Khafaji, A Manual of Acupuncture, p. 288; Chinese Acupuncture & Moxibustion, p. 181; cross-referenced against multiple online sources.

What is BL-27 Xiao Chang Shu used for?

Xiao Chang Shu BL-27 is used for lower abdominal, intestinal and urinary complaints, and for pain in the sacrum and down the leg. The indications recorded in Sacred Lotus sources & references divide into an intestinal group, a urogenital group and a local group. They describe traditional use, not proven treatment.

• Lower abdominal pain and distension
• Dysenteric disorder; diarrhoea
• Constipation and irregular bowel movement
• Nocturnal emission
• Haematuria (blood in the urine)
• Enuresis (bed-wetting) and urinary incontinence
• Difficult, painful or frequent urination
• Vaginal discharge
• Lower back and sacral pain
• Sciatica — pain radiating from the sacrum down the back of the leg
• Stiffness and weakness of the lumbosacral region

The combination of intestinal and urinary indications in one point is not accidental and is worth understanding rather than memorising: in classical physiology the Small Intestine is the organ that separates the clear from the turbid and passes surplus fluid to the Bladder, so a failure of that function appears at both ends. That is also why BL-27 sits immediately above Pang Guang Shu BL-28, the Bladder's own Back-Shu point, on the same line.

Source: Sacred Lotus sources & references (existing indication record, reformatted here as a list); Deadman & Al-Khafaji, A Manual of Acupuncture, p. 288; Chinese Acupuncture & Moxibustion, p. 181.

Where is BL-27 Xiao Chang Shu, and how is it used in practice?

Xiao Chang Shu lies on the sacrum, one and a half cun out from the midline — about two finger-widths to the side of the spine — level with the first posterior sacral foramen, which is the first of the four pairs of openings in the back of the sacrum. It is the point immediately below Guan Yuan Shu BL-26 at the fifth lumbar level and immediately above Pang Guang Shu BL-28 at the second sacral level. In practice the sacral run of the inner Bladder line is counted downward from the top of the sacrum, and BL-27 is the first of them.

One clarification saves a common confusion. BL-27 is level with the first sacral foramen but does not sit over it — the foramen points are the baliao, BL-31 to BL-34, which lie closer to the midline. BL-27 at one and a half cun lateral lies over solid sacral bone. That distinction matters clinically and it matters for safety, and it is set out under needling.

Which points is BL-27 combined with?

• With Guan Yuan REN-04 — the essential pairing. REN-04 is the Front-Mu point of the Small Intestine, three cun below the navel on the midline of the lower abdomen. Back-Shu with Front-Mu, front and back at one organ, is the oldest structured pairing in the medicine, and this is its Small Intestine instance. Our REN-04 record names BL-27 from the other side. Both are held here.
• With Xia Ju Xu ST-39 — the Lower He-Sea point associated with the Small Intestine, on the lower leg. Pairing an organ's Back-Shu point with its lower He-Sea point is the classical structure for a fu-organ disorder, and this is the one for the Small Intestine. Held here.
• With Pang Guang Shu BL-28 — the Bladder Back-Shu point immediately below it, for urinary complaints where the two organs' functions overlap; and with Zhong Ji REN-03, the Bladder's Front-Mu point. Both held here.
• With Da Chang Shu BL-25 — the Large Intestine Back-Shu point two levels above, for intestinal complaints and for lower lumbar pain; and with Tian Shu ST-25, the Large Intestine's Front-Mu point beside the navel. Both held here.
• With Ci Liao BL-32 and the sacral foramen points — for pelvic-organ and lower-back complaints treated locally. BL-32 is the most used of the four foramen points and lies just medial and slightly below. Held here.
• With Wei Zhong BL-40 — the He-Sea point behind the knee and the classical distal command point of the back, for sacral and lumbar pain treated as a channel problem. Held here.
• With San Yin Jiao SP-06 — the meeting point of the three leg yin channels, the standard distal partner for urogenital complaints. Held here.

The Back-Shu points, and where BL-27 sits among them

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, and they are worth seeing together because the arrangement is the point:

• 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

BL-27 is the eleventh of the twelve, and the lowest but one. Two things about its position are worth noticing. First, the set is ordered by the position of the organs in the body, not by any channel logic — and the Small Intestine, a hollow organ of the lower abdomen, therefore appears near the bottom of the run, on the sacrum. Second, there is a gap in the sequence between BL-25 and BL-27: BL-26 Guan Yuan Shu, which lies between them, is not a Back-Shu point despite the shu in its name, and our records classify it as Origin Pass Shu rather than as the Back-Shu of anything.

The Front-Mu points, and BL-27's partner

Each Back-Shu point pairs with its organ's Front-Mu point on the front of the trunk. Sacred Lotus sources & references carry the full set of twelve: LU-01 Zhong Fu for the Lungs, REN-17 Shan Zhong for the Pericardium, REN-14 Ju Que for the Heart, REN-12 Zhong Wan for the Stomach, LIV-14 Qi Men for the Liver, LIV-13 Zhang Men for the Spleen, GB-24 Ri Yue for the Gall Bladder, GB-25 Jing Men for the Kidneys, REN-05 Shi Men for the San Jiao, ST-25 Tian Shu for the Large Intestine, REN-03 Zhong Ji for the Bladder — and REN-04 Guan Yuan for the Small Intestine.

That last one catches most students, and it is worth stating clearly because BL-27 is the other half of it. The Small Intestine's Front-Mu point is on the lower abdomen, on the Conception Vessel, three cun below the navel — nowhere near the Small Intestine channel, which runs along the arm and up the side of the neck and never touches the abdomen at all. Front-Mu points are assigned by where an organ's qi is held to gather, not by which channel passes overhead. BL-27 and REN-04 are therefore a matched pair on the back and front of the pelvis, and neither of them lies on the Small Intestine channel.

Source: Sacred Lotus sources & references (location, Back-Shu classification, and the full twelve-point Back-Shu set, the full twelve-point Front-Mu set, and the BL-25, BL-26, BL-28, BL-32, BL-40, REN-03, REN-04, ST-25, ST-39 and SP-06 records queried directly); Deadman & Al-Khafaji, A Manual of Acupuncture, p. 288; Chinese Acupuncture & Moxibustion, p. 181; cross-referenced against multiple online sources.

Where is BL-27 located?

• A Manual of Acupuncture (p. 288): 1.5 cun lateral to the midline, at the level of the first posterior sacral foramen.
• Chinese Acupuncture and Moxibustion (p. 181): 1.5 cun lateral to the Governor Vessel, at the level of the 1st posterior sacral foramen.

How is BL-27 Xiao Chang Shu needled?

Said plainly, and it is the honest answer: BL-27 is a low-hazard point. It lies over the sacrum — solid triangular bone — one and a half cun from the midline, so there is bone between the needle and the pelvic cavity. There is no pleural, visceral or great-vessel consideration at this point of the kind that governs the thoracic and abdominal points. Sacred Lotus sources & references record perpendicular insertion of 0.8 to 1.2 inches, with moxibustion applicable. Everything below is recorded as neutral reference data describing what the textbooks and the published anatomical studies state. It is not instruction, and this page does not teach technique.

The angle and depth the texts record

• Sacred Lotus sources & references record perpendicular insertion of 0.8 to 1.2 inches, with moxibustion applicable — the same figure our records give for the four sacral foramen points BL-31 to BL-34.
• Deadman & Al-Khafaji (p. 288) and Chinese Acupuncture & Moxibustion (p. 181) record perpendicular insertion in a comparable range. The reason the recorded depth here is roughly double what the texts allow at the thoracic points a foot higher up is simply that the anatomy permits it: over the sacrum the needle meets bone, not lung.
• Moxibustion is recorded as applicable and is common at this point, as it is throughout the sacral and lumbar region.
• For comparison within our own records: 0.8–1.2 inches at BL-27 against 0.5–0.7 inch oblique at Fei Shu BL-13 over the lung and 0.3–0.5 inch at Que Pen ST-12 over the lung apex. Depth figures in this literature track what lies underneath, and here what lies underneath is the sacrum.

What is measured near this point, and what those measurements are of

This region has a real measurement literature, and it is easy to misattribute — so each figure below is labelled with the point it actually belongs to.

• The CT reconstruction figures belong to the foramen points, not to BL-27. A retrospective study of 100 prone pelvic CT scans, reconstructed in three dimensions, measured the angle and depth at which a needle follows the axis of each posterior sacral foramen. For the second sacral foramen — that is, Ci Liao BL-32 — it reported an angle to the skin surface of 57.57 ± 10.01 degrees, an angle to the posterior midline of 18.58 ± 7.76 degrees, and an effective depth of 44.57 ± 11.55 mm; for the first foramen — Shang Liao BL-31, the level at which BL-27 sits — it reported 61.04 ± 12.15 degrees, 24.54 ± 6.21 degrees and 58.16 ± 12.43 mm. Depth correlated positively with body mass index but not with sex or weight alone (Zhen Ci Yan Jiu 2017;42(6):537–41, PMID 29318863). None of these figures is BL-27's. They describe the oblique path a needle takes when it is deliberately directed into a foramen, at points one to two cun closer to the midline than this one. BL-27 lies over the bone beside the first foramen and no needle at it enters a foramen at all.
• Why the distinction is worth making at all. Because the two techniques are genuinely different procedures with genuinely different depths, and conflating them is how a reader ends up with the wrong number. The deep baliao method that those CT figures describe uses long needles following the channel of the foramen toward the sacral nerve, and the Chinese clinical literature on it says openly that its effects depend on that depth and that the classical descriptions of location and manipulation are vague enough to have limited the technique's use (Zhongguo Zhen Jiu 2014;34(3):285–8, PMID 24843976). None of that applies to BL-27.
• The relevant structures here are nerves and muscle, not organs. At BL-27 the needle passes through skin, subcutaneous tissue, the thoracolumbar fascia and the erector spinae mass where it attaches to the sacrum, meeting the bone beneath. The recorded phenomena at the sacral points generally are local soreness and, where a needle reaches a nerve branch, radiating sensation into the buttock or down the leg — which is unsurprising given that sciatica is one of the point's own indications.
• Depth still varies with the person. Two systematic reviews of the safe-needling-depth literature — 33 studies in one, 47 in the other, using MRI, CT, ultrasound and cadaveric dissection — concluded that measured depths for the same point differ greatly between subject groups and between measuring methods, and that "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). No imaging study measuring BL-27 itself was located, and no figure is invented for it.

Pregnancy, and risk in proportion

Sacred Lotus sources & references carry no pregnancy contraindication for BL-27, and none is added here. Our own point records were queried directly on this. It should be noted for context that the sacral foramen points BL-32 and BL-33 do appear on the classical lists of points to avoid in pregnancy, on the reasoning that they act on the uterus, and our BL-32 record carries that; BL-27 is not among the points those lists name. A review of the scientific evidence for the so-called forbidden points found no objective evidence of harm across 15 clinical trials (823 women), a cohort of 5,885 pregnant women, and animal work (Carr DJ, Acupunct Med 2015;33(5):413–9, PMID 26362792), while a later systematic narrative review of randomised trials identified the historically forbidden group as SP-06, LI-04, GB-21, BL-60, BL-67, BL-32 and BL-33 (Med Acupunct 2019;31(6):346–360, PMID 31871522, PMC6918516).

A meta-analysis of prospective clinical studies estimated serious acupuncture-related adverse events at approximately 1 per 10,000 patients and around 8 per million treatments, with about half of all recorded events being bleeding, pain or flare at the needle site (Bäumler P et al., BMJ Open 2021;11:e045961, PMID 34489268). The traumatic complications that dominate the serious end of that literature — pneumothorax above all — are complications of needling over the chest and upper back, not over the sacrum. BL-27 belongs among the straightforward points, and saying so is more useful than manufacturing a caution.

Source: Sacred Lotus sources & references (existing needling record; the BL-13, BL-31 to BL-34 and ST-12 records queried directly for comparison; pregnancy fields across the point records queried directly); Deadman & Al-Khafaji, A Manual of Acupuncture, p. 288; Chinese Acupuncture & Moxibustion, p. 181; PMID 29318863; PMID 24843976; PMID 21417806; PMID 23935678; PMID 26362792; PMID 31871522 (PMC6918516); PMID 34489268 — each verified resolvable and checked for retraction status before citation.

What does the name Xiao Chang Shu mean?

Xiao Chang Shu means "Small Intestine Shu" — xiao chang, the small intestine, 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 Small Intestine Shu and classify the point as the Back-Shu of the Small Intestine. Like the other eleven names in the set, it is a description of function rather than a metaphor, which is why the twelve Back-Shu points are among the easiest names in acupuncture to learn.

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: they are used to treat the organ, particularly in chronic conditions, and they are palpated in diagnosis, since tenderness, a change in temperature or a change in the tissue at a Back-Shu point is read as a sign that its organ is involved. That second role is not merely traditional assertion — two modern studies have measured it at this point specifically, and they are described under research below.

What the classification does not mean is that BL-27 sits over the small intestine. It does not; the small intestine is in the abdomen, a long way in front of and above the sacrum. The Back-Shu points are placed by the classical anatomy of qi rather than by organ position, and BL-27 is the clearest example of the gap between the two. The nearby foramen points BL-31 to BL-34 are the opposite case — points whose position is fixed by an actual hole in a bone — and our BL-32 record notes explicitly that BL-32 is not a Back-Shu point and should not be described as one. The two systems sit side by side on the sacrum and are worth keeping apart.

Is there research on BL-27 Xiao Chang Shu?

There is no clinical trial of this point, and that should be said plainly. What does exist is a small and genuinely interesting body of work in which BL-27 appears as a measurement site — studies asking whether a Back-Shu point actually changes when its organ or its region is diseased.

• Pain threshold at BL-27 in irritable bowel syndrome. A study compared pressure pain thresholds at a large set of points on the Large Intestine, Small Intestine, Stomach, Spleen and Gall Bladder channels between 60 patients with irritable bowel syndrome and 34 healthy adults. The thresholds of the five shu-transport points, the Front-Mu point and the Yuan-Source point of the Small Intestine channel were all significantly lower in the patient group, and three points fell furthest of all: Zhi Zheng SI-07, Xia Ju Xu ST-39 and Xiao Chang Shu BL-27 (all P < 0.01). The authors' conclusion was that when an organ's function is disturbed, the pain thresholds of the related points fall — that the points become sensitised rather than remaining quiescent (Zhang S et al., Zhongguo Zhen Jiu 2016;36(8):835–839, PMID 29231570). This is an observational study, not a treatment trial, and it says nothing about whether needling BL-27 helps. But it measured this point, and the two points that fell alongside it are exactly the two the classical system pairs with it: the Small Intestine channel's own Xi-Cleft point and its Lower He-Sea point.
• Surface temperature at BL-27 in low back pain. Infrared thermography compared 50 patients with low back pain from lumbar disc herniation against 45 healthy subjects, measuring surface temperature over the lumbosacral region and the bilateral Back-Shu points from BL-22 down to BL-28. The left-right temperature difference was significantly greater in the patient group at BL-23, BL-24, BL-25, BL-26 and BL-27; the strongest specificity, however, belonged to Shen Shu BL-23 and Da Chang Shu BL-25, which were the two points also showing a raised temperature on the affected side (Yuan X et al., Zhongguo Zhen Jiu 2024;44(4):423–427, PMID 38621730). Honest reading: BL-27 registered a measurable asymmetry, but it was not one of the two points the authors singled out.
• An animal study, and it is a dog study — flagged as such. Duplex Doppler ultrasonography measured duodenal motility in 15 healthy Beagle dogs before, during and after electroacupuncture at ST-36 and BL-27. Motility frequency increased by about 20 per cent during stimulation at ST-36 and fell afterwards, while at BL-27 it decreased by about 31 per cent during stimulation and rose by about 18 per cent afterwards, the difference between the during- and post-stimulation values being significant (Choi M et al., J Vet Sci 2001;2(3):221–6, PMID 12441692). Two limits must be stated: this is veterinary work in dogs, and canine point locations are transposed from the human map rather than identical to it. It is recorded here because it names the point and reports a directional effect, not as evidence about people.

A point-code caution, recorded because it was met while assembling this. Searching for "Xiaochangshu" or "BL-27" returns a modest set of records, and most of them are trials of lumbar disc herniation, obesity or neurogenic bladder in which BL-27 is one point inside a long protocol and is never the tested variable. Every record used above was read to confirm that it concerns this point rather than merely containing the string, and the veterinary paper above is flagged by species for the same reason. Nothing was counted; the small number of results is the honest total.

What is missing: no randomised trial isolates BL-27, and none of the intestinal, urinary or lumbar indications recorded for it has been tested at this point specifically. Its clinical standing rests on the classical record and on its Back-Shu classification, and this site does not claim otherwise.

How does BL-27 differ from the points near it?

Guan Yuan REN-04 on the lower abdomen is its counterpart on the front of the body — the Front-Mu point of the same organ, and by a wide margin the better known and more used of the pair; where BL-27 is a local sacral point with an organ classification, REN-04 is one of the great tonification and moxibustion points of the body. Pang Guang Shu BL-28 lies directly below BL-27 at the second sacral level and is the Bladder's Back-Shu point; the two overlap heavily in their urinary indications and are frequently used together. Guan Yuan Shu BL-26 lies directly above at L5 and is not a Back-Shu point despite its name — a distinction our own records preserve. Da Chang Shu BL-25 two levels above is the Large Intestine's Back-Shu point and the more usual choice for lower lumbar pain proper. Shang Liao BL-31 and Ci Liao BL-32 lie medial and below on the sacral foramina — the same region, an entirely different kind of point, defined by holes in bone rather than by an organ. Shen Shu BL-23 higher up is the Kidney Back-Shu point and the principal point for the lumbar region. Zhi Shi BL-52 is the outer-line point at the L2 level, and the extra point Shi Qi Zhui Xia sits on the midline just above the sacrum. All of these are held in Sacred Lotus sources & references.

Source: Sacred Lotus sources & references (name, channel, Back-Shu classification, and the full Back-Shu and Front-Mu sets plus the BL-23, BL-25, BL-26, BL-28, BL-31, BL-32, BL-52, REN-04, ST-39 and Shi Qi Zhui Xia records queried directly); Deadman & Al-Khafaji, A Manual of Acupuncture, p. 288; Chinese Acupuncture & Moxibustion, p. 181; PMID 29231570; PMID 38621730; PMID 12441692 — each verified resolvable and checked for retraction status before citation; cross-referenced against multiple online sources.