BL-19 (Dan Shu) Gallbladder Shu

What does BL-19 Dan Shu do?

Dan Shu BL-19 is the Back-Shu point of the Gall Bladder — the place on the back where the Gall Bladder's qi is said to infuse the body surface — and it is the point of the back through which the tradition reaches that organ. Sacred Lotus sources & references record that classification directly, and it is the fact that organises everything else on this page. Our own action record gives four things: it clears damp-heat from the Liver and Gall Bladder, clears pathogenic factors from the shaoyang, tonifies and regulates Gall Bladder qi, and tonifies deficiency.

• Clears damp-heat from the Liver and Gall Bladder — the first recorded action and the busiest one. Damp-heat in this pair is the pattern the tradition holds behind jaundice, a bitter taste in the mouth, distension and pain beneath the ribs on the right, and a yellow greasy tongue coating. Our own indication record for BL-19 leads with jaundice and bitter taste, which is exactly this action expressed as symptoms.
• Clears pathogenic factors from the shaoyang — the distinctive one. Shaoyang is the half-exterior, half-interior division of the six-channel scheme, the territory of the Gall Bladder and the San Jiao, and its classical presentation is alternating chills and fever, a bitter taste, dry throat, dizziness and fullness below the ribs. Very few points on the back carry a shaoyang action at all; BL-19 does because the organ it reaches is the shaoyang organ.
• Tonifies and regulates Gall Bladder qi — the deficiency side of the same organ. In classical theory the Gall Bladder governs decisiveness and courage, and Gall Bladder qi deficiency is described as timidity, indecision, being easily startled and waking in the night unable to settle. That is the reasoning behind the point's appearance in prescriptions for fright and disturbed sleep, which otherwise look out of place on a list headed by jaundice.
• Tonifies deficiency — the general supporting action, and the one the classical moxibustion literature leans on hardest. It is the basis of BL-19's role in the Sihua or "Four Flowers" grouping described further down, where BL-19 and its neighbour BL-17 are moxaed together for depletion and exhaustion rather than for anything to do with bile.

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, and that gives them two jobs rather than one. 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. BL-19 is the fifth of the twelve as they descend the back, and it is the only one of them assigned to the Gall Bladder. Whatever a treatment wants to do to that organ from behind, this is the point that does it.

Source: Sacred Lotus sources & references (existing action record, rebuilt here as a proper list; Bladder channel and Back-Shu of the Gallbladder classification queried directly); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 277); Chinese Acupuncture & Moxibustion (p. 179); Shang Han Lun, on the shaoyang presentation; cross-referenced against multiple online sources.

What is BL-19 Dan Shu used for?

Dan Shu BL-19 is used for jaundice and a bitter taste in the mouth above all — the two indications that name the Gall Bladder in classical language — and after that for pain beneath the ribs and the chest, and for the wasting, feverish presentations the older literature calls consumptive. The indications carried in Sacred Lotus sources & references are jaundice, bitter taste in the mouth, pain in the chest and hypochondriac region, pulmonary tuberculosis and afternoon fever. The standard reference literature sets the range out more fully below. These describe traditional use, not proven treatment, and this point carries the safety considerations recorded under needling.

• Jaundice — yellowing of the skin and eyes
• Bitter taste in the mouth
• Distension and pain below the ribs, particularly on the right
• Pain and fullness of the chest
• Alternating chills and fever — the shaoyang presentation
• Dry throat and dry mouth
• Dizziness and blurred vision
• Nausea, vomiting and inability to eat
• Afternoon (tidal) fever and bone-steaming heat
• Pulmonary tuberculosis and the wasting, coughing presentations the classics group as consumptive disorder
• Night sweating
• Timidity, indecision and being easily frightened — the Gall Bladder qi deficiency presentation
• Insomnia and restless sleep accompanying that pattern
• Swelling of the axilla
• Stiffness and pain of the mid-back at the level of the point

Two of these deserve a word. Pulmonary tuberculosis and afternoon fever look like intruders on a Gall Bladder list, and they are not: they are there because BL-19 is half of the Sihua or "Four Flowers" grouping, the classical moxibustion prescription for consumptive depletion, described under how the point is used. And timidity is not a figure of speech in this context — the Gall Bladder is the organ the tradition assigns to decisiveness, so its Back-Shu point inherits a psychological indication that no other digestive Back-Shu point carries.

Source: Sacred Lotus sources & references (existing indication record, reformatted here as a list); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 277); Chinese Acupuncture & Moxibustion (p. 179); cross-referenced against multiple online sources.

Where is BL-19 Dan Shu, and how is it used in practice?

Dan Shu lies on the mid-back, one and a half cun either side of the midline, level with the lower border of the spinous process of the tenth thoracic vertebra — that is, level with Zhong Shu DU-07 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 beside the spine at about the level of the lower tip of the shoulder blade and a little below, in the run of Back-Shu points that descends the inner Bladder line.

In practice BL-19 is used in two quite different registers, and keeping them apart is the useful thing. As the Gall Bladder's Back-Shu point it appears in damp-heat prescriptions — jaundice, bitter taste, right-sided rib pain, gallstones — almost always with its Front-Mu point on the chest and a distal point on the Gall Bladder channel. As half of the Sihua pair it appears in a completely separate tradition of moxibustion for depletion, exhaustion and consumptive fever, where the Gall Bladder is barely mentioned. The point's indication list only makes sense once you know it is doing both jobs.

Which points is BL-19 combined with?

• With Ri Yue GB-24 — the Front-Mu point of the Gallbladder, in the seventh intercostal space on the front of the trunk, confirmed held by direct query of the Front-Mu set. Back-Shu with Front-Mu is the classical Shu-Mu pairing for reaching an organ from front and back at once, and this is its Gall Bladder instance. It is the single most important partnership on this page, and the GB-24 record names BL-19 in the same terms from the other side.
• With Yang Ling Quan GB-34 — the He-Sea point of the Gall Bladder channel and the Hui-Meeting Point of the Sinews, on the outer upper calf. Back-Shu with the channel's He-Sea point is the standard shape of a Gall Bladder prescription, and GB-34 is the distal point most often added to BL-19.
• With Gan Shu BL-18 — one level above at T9, the Liver's Back-Shu point. The Liver and Gall Bladder are an interior-exterior pair, and damp-heat is generally spoken of as affecting both, so BL-18 and BL-19 are needled together as a matter of routine. They are also the two Back-Shu points most often confused with one another, and the difference is a single vertebral level.
• With Ge Shu BL-17 — two levels above at T7, the Hui-Meeting Point of Blood. This is the Sihua pairing set out below, and it is the oldest documented use of BL-19.
• With Dan Nang Xue — the modern "Gallbladder Point" on the outer upper calf, an extra point located by tenderness one to two cun below GB-34, held in this library. Where a gall bladder complaint is acute, the tender leg point and the Back-Shu point are used together, and the Dan Nang Xue record names BL-19 for exactly this reason.
• With Zhi Yang DU-09, Yang Gang BL-48 and Zhi Gou SJ-06 — the wider jaundice and damp-heat grouping. Yang Gang BL-48, held here, is BL-19's outer companion three cun lateral at the same T10 level; its name, "Yang Headrope", marks it as the outer-line point of the Gall Bladder as a yang organ.
• In a published gallstone protocol — frequency-changing electroacupuncture was applied at seven points in a trial of 120 patients with cholelithiasis: Qi Men LIV-14, Liang Men ST-21, Ri Yue GB-24, Dan Shu BL-19, Gan Shu BL-18, Yang Ling Quan GB-34 and Dan Nang Xue, against a multi-component comparison regimen, with a reported total effective rate of 86.7 per cent against 68.3 per cent (Zhongguo Zhen Jiu 2006;26(11):772–4, PMID 17165496). It is a seven-point protocol, so nothing in it is attributable to BL-19 alone, and "total effective rate" is a composite outcome of limited reliability — but it shows the Shu-Mu pair being used as the tradition describes.

What are the Sihua or "Four Flowers" points?

The Sihua points are bilateral Ge Shu BL-17 and bilateral Dan Shu BL-19 — four points in a square on the mid-back — and this is the grouping BL-19 belongs to that has nothing to do with the Gall Bladder. The name means "four flowers", from the arrangement of the four moxa sites, and the classical method for locating them is a measuring procedure with a cord rather than a count of vertebrae. Their traditional indication is xu lao — consumptive depletion: wasting, chronic cough, tidal fever, night sweating, exhaustion that does not recover. That is precisely why our own indication record for BL-19 carries pulmonary tuberculosis and afternoon fever alongside jaundice, and it is the answer to why those entries are there.

The grouping is not merely historical. Three indexed clinical studies define the Sihua points in exactly these terms and use them in patients having chemotherapy for non-small-cell lung cancer:

• Direct moxibustion. Eighty patients were randomised to chemotherapy alone or chemotherapy plus direct moxibustion at the Sihua points, defined in the paper as Geshu BL-17 and Danshu BL-19, three cones per point, once daily for ten days. Serum colony-stimulating factor and interleukin-2 were higher and tumour necrosis factor lower in the moxibustion arm, and Karnofsky performance scores fell less (Zhongguo Zhen Jiu 2013;33(3):207–10, PMID 23713299).
• Fire needling, immune markers. Sixty patients with advanced non-small-cell lung cancer were randomised to chemotherapy alone or chemotherapy plus fire-needle stimulation at the Sihua acupoints, again defined as bilateral Geshu BL-17 and Danshu BL-19, once daily for seven days. Interleukin-2 and interferon-gamma rose and interleukin-4 and interleukin-10 fell relative to the control arm, with a smaller decline in performance status (Zhen Ci Yan Jiu 2019;44(2):136–9, PMID 30945491).
• Fire needling, quality of life. Sixty further patients were randomised in the same way, with quality of life assessed by the lung-cancer-specific FACT-L instrument. Tumour response did not differ significantly between the arms; performance status and several quality-of-life subscales did (Zhongguo Zhen Jiu 2017;37(11):1191–5, PMID 29354957).

Three small trials from a narrow research base, all comparing an added treatment against no added treatment rather than against a sham, are not strong evidence and are not offered as such. What they establish is narrower and still worth having: the Sihua grouping is a live, defined, two-point prescription in which BL-19 is one of the two named points, and its modern use follows the classical depletion indication rather than the gall bladder one.

Where does BL-19 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, 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-19 is the fifth of the twelve and sits immediately below the Liver's, which is what the interior-exterior pairing of Liver and Gall Bladder would lead you to expect: the two organs that share a pair share adjacent vertebral levels. Each Back-Shu point pairs with its organ's Front-Mu point on the front of the trunk, and the full set of twelve Front-Mu points is held here as well:

• Zhong Fu LU-01 — Lungs
• Shan Zhong REN-17 — Pericardium
• Ju Que REN-14 — Heart
• Qi Men LIV-14 — Liver
• Ri Yue GB-24 — Gallbladder
• Zhang Men LIV-13 — Spleen
• Zhong Wan REN-12 — Stomach
• Shi Men REN-05 — San Jiao
• Jing Men GB-25 — Kidneys
• Tian Shu ST-25 — Large Intestine
• Guan Yuan REN-04 — Small Intestine
• Zhong Ji REN-03 — Bladder

The Gall Bladder is one of only three organs whose Front-Mu point sits on its own channel — Ri Yue GB-24 is both the Gallbladder's Front-Mu point and the twenty-fourth point of the Gall Bladder channel, the others being LU-01 for the Lungs and LIV-14 for the Liver. That is not the rule. Five of the twelve Front-Mu points sit on the Conception Vessel, the Spleen's sits on the Liver channel at Zhang Men LIV-13, and the Kidneys' sits on the Gall Bladder channel at Jing Men GB-25 — so the tidy BL-19 and GB-24 pairing is one of the easier ones to learn.

Source: Sacred Lotus sources & references (BL-19 record; the full twelve-point Back-Shu set and the twelve Front-Mu points queried directly and reproduced here identically to the sets carried in the BL-23, BL-15, BL-27 and BL-13 records; the GB-24, GB-34, BL-17, BL-18, BL-48, DU-07, DU-09, SJ-06 and Dan Nang Xue records queried directly); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 277); Chinese Acupuncture & Moxibustion (p. 179); PMID 17165496; PMID 23713299; PMID 30945491; PMID 29354957 — each verified resolvable and checked for retraction status before citation; cross-referenced against multiple online sources.

Where is BL-19 located?

• A Manual of Acupuncture (p. 277): 1.5 cun lateral to the lower border of the spinous process of the tenth thoracic vertebra (T10).
• Chinese Acupuncture and Moxibustion (p. 179): 1.5 cun lateral to Zhongshu (DU-7), at the level of the lower border of the spinous process of the tenth thoracic vertebra.

How is BL-19 Dan Shu needled, and what lies beneath it?

Stated plainly: BL-19 lies beside the tenth thoracic vertebra, in the paravertebral band of the back where the reference texts record an oblique angle rather than a perpendicular one. Our own record specifies oblique insertion of 0.5 to 0.8 inch with moxibustion applicable, and the angle is the substance of that record, not a stylistic detail. Beneath this level lie the lower ribs and, behind them, the costodiaphragmatic recess of the pleura, with the liver on the right and the upper pole of the kidney lower and deeper. Everything below is recorded as neutral reference data describing what the textbooks and the published anatomical studies state. It is not instruction, this page does not teach technique, and 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 0.8 inch, with moxibustion applicable — a figure in the same family as the 0.5 to 0.7 inch our records give for Fei Shu BL-13 and Feng Men BL-12 higher up the same line, and shallower than the 1 to 1.2 inch recorded for Shen Shu BL-23 in the lumbar region below the ribs.
• Deadman & Al-Khafaji (p. 277) and Chinese Acupuncture & Moxibustion (p. 179) record oblique insertion directed medially, toward the spine, in a comparable range, and both attach an explicit caution against deep or laterally angled insertion at the thoracic Back-Shu points. The reasoning is geometric: angling toward the vertebral column keeps the needle in the muscle mass with the transverse process and lamina behind it, while angling outward points it at the intercostal space.
• Moxibustion is recorded as applicable and is heavily used at this point — direct moxibustion at BL-19 is the technique the Sihua tradition is built on, and it involves no insertion depth at all.
• What lies beneath, in plain terms. At the T10 level the needle passes through skin and subcutaneous tissue, then latissimus dorsi and the thoracolumbar fascia, then the erector spinae mass beside the vertebra. In front of those lie the tenth and eleventh ribs and their intercostal spaces. Behind the lower ribs the pleura continues downward as the costodiaphragmatic recess — the reserve space into which the lung expands on deep inspiration — so pleural puncture remains possible at this level even though the lung itself does not routinely sit here at rest. Deeper and slightly lower, the liver lies on the right and the upper pole of the kidney behind the peritoneum on both sides. That combination is why the recorded angle is oblique and medial and the recorded depth bounded.

The measured anatomy — and which point each study actually measured

This is where precision matters, because the back has been measured repeatedly and the figures are easy to misattribute.

• Honest limit, stated first. No imaging, ultrasound or cadaveric study measuring a safe needling depth at BL-19 specifically could be located. Points above it and points below it have been measured; this one has not. No figure taken elsewhere is attached to it here.
• The paediatric chest-CT study did NOT measure BL-19, and this needs saying precisely. A retrospective study measured skin-to-pleura distance directly from chest CT at 23 named upper-back acupoints in 319 patients aged 4 to 18 (205 boys, 114 girls) at a single Taiwanese hospital, with weight the strongest determinant at all 23 points (Ma YC et al., BMC Complement Altern Med 2016;16:85, PMID 26922245, PMC4769822). Its full text — not its abstract, which omits the list — names those 23 points in Tables 2 to 6: DU-09 to DU-14, BL-11 to BL-17, BL-41 to BL-46, SI-14, SI-15, GB-21 and SP-21. Dan Shu BL-19 is not among them. The inner Bladder line in that paper stops at Ge Shu BL-17, three levels above this point, and the outer line stops at BL-46. So the study yields no figure for BL-19 and none is quoted — neither by borrowing BL-17's number nor by implying a measurement exists where it does not.
• The kidney-region MRI study measured its neighbours below, not BL-19. 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 — 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. Left and right sides did not differ; body size did, substantially, the depths being significantly greater in overweight subjects than in moderate-weight subjects and greater again than in underweight subjects, with the authors concluding that in underweight patients the direction and depth of needling must be restricted (Zhongguo Zhen Jiu 2022;42(9):1006–1010, PMID 36075596). BL-19 is two levels above the highest point in that list. The finding is cited for what it says about the region and about body size, not as a number for this point.
• The pleural-dome dissection named BL-11, not BL-19. A dissection study of 46 adult bodies mapped the dome of the pleura against the commonly used points around it, naming Da Zhu BL-11, Tian Tu REN-22, Jian Jing GB-21, Qi She ST-11 and Ding Chuan. The dome's projection varied widely between individuals, extending beyond the medial third of the clavicle in almost 60 per cent of bodies, and the authors concluded that when a point is located and angled as the standard describes the pleura is not reached, but that exceeding the recorded depth breaches the pleural membrane (Chen Y et al., Zhongguo Zhen Jiu 2006;26(5):346–8, PMID 16739850). That study concerns the top of the pleura, nine vertebral levels above BL-19; its operative conclusion about angle and depth transfers, its measurements do not.
• The adult back CT study does not name its points. A CT study of 120 patients, grouped by weight, height and sex, measured the distance from the skin of the back to the thoracic pleura at the relevant acupuncture locations and defined that distance as the safe depth, finding no significant difference between the sexes but highly significant differences between body-size groups, P < 0.01 (Zhong Xi Yi Jie He Za Zhi 1991;11(1):10–13, PMID 2054884). The abstract does not list which back points were measured, so no figure from it can honestly be attributed to BL-19, and none is.
• The GB-21 measurements are GB-21's. Ultrasonography in 101 adults measured the depth from skin to the pleural line at Jian Jing GB-21 at a mean of 17.4 mm in men and 14.6 mm in women (PMID 29936338), and a second ultrasound study of 52 volunteers found that depth at GB-21 varied with posture and breathing, with within-subject variation exceeding between-group variation and the authors warning against applying a depth on the basis of sex or body-mass index alone (Evid Based Complement Alternat Med 2018;2018:2308102, PMID 29507586, PMC5817322). Both sets of figures belong to GB-21, on the shoulder over the lung apex, and neither describes BL-19. They are recorded here only for their general lesson, which is the second study's: an individual body is not the average body.
• 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 "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). A textbook depth figure describes an average body, not a constant.

What the adverse-event literature documents

Pneumothorax 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 — with 35 deaths across the whole series; the authors attributed the events chiefly to improper technique and judged most avoidable through standardised training (He W et al., J Altern Complement Med 2012;18(10):892–901, PMID 22967282). A companion review of 115 Chinese-language articles reporting 479 adverse events including 14 deaths reached the same conclusion about traumatic complications, and lists traumatic injury to internal organs among the small number of genuinely serious events on record (Zhang J et al., Bull World Health Organ 2010;88(12):915–921C, PMID 21124716, PMC2995190). Presentation may be delayed: 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 confirming pneumothorax (Cureus 2021;13(3):e14207, PMID 33948398, PMC8086747), and an autopsy report describes fatal bilateral pneumothoraces after 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). Sudden chest pain, breathlessness or a persistent dry cough in the hours or days after needling over the back is a medical emergency requiring immediate assessment.

What will not be claimed here. None of those reviews identifies the individual points involved in its cases, and no published case report naming Dan Shu BL-19 as the point at which an injury occurred was located. No such claim is made. The honest statement is the one the anatomy already makes and our own record makes with it: this is a lower thoracic paravertebral point, the pleural recess and the liver lie beyond the ribs in front of it, and the recorded angle is oblique and the recorded depth bounded for that reason.

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, with about half of all recorded events being bleeding, pain or flare at the needle site, placing acupuncture among the safer treatments in medicine (Bäumler P et al., BMJ Open 2021;11:e045961, PMID 34489268). Both facts belong together: the overall rate is low, and the events that do occur concentrate in the band of points over the trunk to which BL-19 belongs. The bounded oblique depth exists to keep it that way.

Pregnancy. Sacred Lotus sources & references record no pregnancy contraindication at BL-19, and none is added here. The caution that governs this point in every source we hold is the anatomy behind the ribs, and it applies to everyone. Standard clean-needle practice applies.

Source: Sacred Lotus sources & references (existing needling record); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 277); Chinese Acupuncture & Moxibustion (p. 179); PMID 26922245 (PMC4769822 — full text Tables 2–6 read; BL-19 not among the 23 measured points); PMID 36075596; PMID 16739850; PMID 2054884; PMID 29936338; PMID 29507586 (PMC5817322); PMID 21417806; PMID 23935678; PMID 22967282; PMID 21124716 (PMC2995190); PMID 33948398 (PMC8086747); PMID 34435369; PMID 34489268 — each verified resolvable and checked for retraction status before citation.

What does the name Dan Shu mean?

Dan Shu means "Gallbladder Shu" — dan, the gall bladder, and shu, a transport point. Sacred Lotus sources & references translate it exactly that way. The character shu carries the sense of conveying or transporting, and the twelve Back-Shu points are named for precisely that: the places on the back where each organ's qi is said to be transported to the body surface. The name is a description of the point's function rather than a metaphor, which sets the Back-Shu group apart from most of the repertoire — "Gallbladder Shu" tells you what the point is and what it does in two syllables, where a name like "Sun and Moon" or "Jumping Round" tells you neither.

Why is the Gall Bladder's Back-Shu point at T10?

Because the Back-Shu points descend the back in roughly the order the organs occupy the trunk, and because the Liver and Gall Bladder are an interior-exterior pair whose points sit next to each other. Gan Shu BL-18, the Liver's, is at T9; Dan Shu BL-19 is at T10; Pi Shu BL-20, the Spleen's, is at T11. Three consecutive vertebral levels carry three consecutive organs, and the pairing of Liver above and Gall Bladder immediately below mirrors the pairing of the organs themselves. In practice this closeness is the commonest source of error with BL-19: one level too high is the Liver's point, one level too low is the Spleen's, and the three are used for overlapping but distinctly different patterns.

What are the "Four Flowers" and why does BL-19 belong to them?

The Sihua or "Four Flowers" are bilateral Ge Shu BL-17 and bilateral Dan Shu BL-19 — four moxa sites arranged in a square on the mid-back — and they are the oldest documented use of this point. The classical method locates them by a measuring procedure with a cord looped round the body rather than by counting vertebrae, which is why older texts sometimes describe the Sihua points without ever naming BL-17 or BL-19; the modern identification with those two points is settled and is stated in exactly those terms in the current clinical literature (PMID 23713299, PMID 30945491, PMID 29354957). Their traditional indication is xu lao, consumptive depletion: emaciation, chronic cough, tidal fever, night sweating and exhaustion that will not lift.

This matters for reading BL-19's indication list. Our own record carries pulmonary tuberculosis and afternoon fever alongside jaundice and bitter taste, and those two entries look anomalous on a Gall Bladder point until the Sihua tradition is put beside them. They are not Gall Bladder indications at all; they are Sihua indications, inherited by BL-19 through a grouping that treats it as a depletion point rather than as an organ point. It is one of the clearer cases in the repertoire of a point carrying two separate lineages of use in one indication list.

Is there research on BL-19 Dan Shu?

There is a small but genuinely point-named body of work — measurement and point-selection research rather than efficacy research — and no trial isolates BL-19. That should be said before anything else.

• Pressure-pain threshold measured at BL-19 in patients. Sixty patients with irritable bowel syndrome and 34 healthy adults had pain thresholds measured at the five-shu, Front-Mu, Yuan-Source, Luo-Connecting and Back-Shu points of several channels using a pressure algometer. Thresholds at Danshu BL-19 were markedly lower in the patients than in the healthy group, alongside Zu San Li ST-36, Wei Shu BL-21, Yang Ling Quan GB-34, Pi Shu BL-20, Nei Guan P-06, Tai Chong LIV-03, Tai Xi KI-03, San Yin Jiao SP-06 and Qi Hai REN-06, all P < 0.05. The authors' framing is that when an organ's function is disturbed the pain thresholds of related points fall — the point becomes sensitised rather than remaining quiet (Zhongguo Zhen Jiu 2016;36(8):835–839, PMID 29231570). This is an observational measurement in 94 people, not evidence of treatment effect. Its interest is that it is a direct test, at this point, of the diagnostic half of the Back-Shu idea: that a Back-Shu point becomes tender when there is trouble in its territory.
• The Sihua trials. Three randomised studies of moxibustion or fire needling at BL-17 with BL-19 in patients undergoing chemotherapy for non-small-cell lung cancer are described under how the point is used (PMID 23713299; PMID 30945491; PMID 29354957). They are small, from a narrow research base, and compare an added treatment against no added treatment rather than against a sham — but BL-19 is one of only two points in the protocol, which is unusually specific for this literature.
• An animal study naming BL-19 as a measurement site. In rats of three strains, antidromic electrical stimulation of the nerve supplying "Pishu" BL-20 was used to mimic electroacupuncture, and recordings were taken from the nerves supplying the adjacent points "Danshu" BL-19 and "Weishu" BL-21. C and A-delta units at the adjacent points were sensitised — mechanical thresholds fell and discharge rates rose — with the effect strongest in one strain (Guo Y et al., Chin J Integr Med 2016;22(7):537–44, PMID 26631142). An animal neurophysiology study, recorded for completeness and not as evidence about people; its relevance is that BL-19 is a named recording site rather than an incidental member of a prescription.
• A gallstone protocol including BL-19. The seven-point electroacupuncture trial in 120 patients with cholelithiasis described under how the point is used (PMID 17165496) includes both BL-19 and its Front-Mu partner GB-24. Nothing in it is attributable to either point alone.

What is missing should be said plainly: there is no sham-controlled randomised trial of BL-19 alone for jaundice, for gall bladder disease or for any other of its recorded uses, and no imaging study has measured a needling depth at it. Every clinical study that names it uses it inside a prescription, so the results describe the prescription. The point's standing rests on the classical record, on the Back-Shu classification, and on a small amount of measurement made at the point itself.

How does BL-19 compare with the points around it?

Gan Shu BL-18 lies one level above at T9 and is the Liver's Back-Shu point — the interior-exterior partner, used with BL-19 as a matter of course, and the point BL-19 is most often confused with. Pi Shu BL-20 lies one level below at T11 for the Spleen, and takes the digestive and damp complaints that belong to the middle burner rather than to bile. Ge Shu BL-17 two levels above at T7 is the Hui-Meeting Point of Blood and is BL-19's partner in the Sihua grouping — the only pairing on this page in which the Gall Bladder is irrelevant. Yang Gang BL-48 is BL-19's outer companion three cun lateral at the same T10 level; its name, "Yang Headrope", marks it as the outer-line point of the Gall Bladder read as a yang organ, in the same way that Hun Men BL-47 above it marks the Liver's hun. Zhong Shu DU-07 lies directly medial on the midline at the same level. Ri Yue GB-24 on the front of the trunk is BL-19's Front-Mu counterpart and the most important point on this page after BL-19 itself. Yang Ling Quan GB-34 at the outer knee is the channel's own He-Sea point and the usual distal partner, and Dan Nang Xue, the modern extra point an inch or two below it, is the tender leg point added when a gall bladder complaint is acute. All are held in this library. Every point in the thoracic paravertebral band shares the angle-and-depth considerations recorded under needling.

Source: Sacred Lotus sources & references (name and Back-Shu classification; the BL-17, BL-18, BL-20, BL-48, DU-07, GB-24, GB-34 and Dan Nang Xue records queried directly); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 277); Chinese Acupuncture & Moxibustion (p. 179); PMID 29231570; PMID 23713299; PMID 30945491; PMID 29354957; PMID 26631142; PMID 17165496 — each verified resolvable and checked for retraction status before citation; cross-referenced against multiple online sources.