白環俞 Baihuanshu
“White Ring Transport” · BL30
Foot Taiyang · 30 of 67
Where. Low on the sacrum, level with its fourth hollow, two finger-widths from the centre ridge.
For. Low back and sacral ache; irregular periods.
Press. Reach behind and press with the fingertips, about a minute.
白環俞，在第二十一椎下，兩傍各一寸五分按 · Press with me
Six slow breaths
About a minute. Press as you breathe out, ease as you breathe in.
鄰 · Neighbouring leaves
Where Baihuanshu Sits on the Sacrum
The dataset sets Baihuanshu down at the very base of the spine: on the sacrum, 1.5 cun lateral to the median sacral crest, level with the fourth posterior sacral foramen. Unpacked for hands rather than rulers, that sentence describes a triangle of bone wedged between the two hip bones at the back of the pelvis, closing off the bottom of the spinal column. The sacrum forms from five vertebrae fused so completely in adulthood that their boundaries have all but vanished; what remains visible is the median sacral crest, a knuckled ridge running down the bone’s middle like a seam. A cun is the traditional measuring unit of Chinese point-location — proportional lengths taken from the person being examined rather than from a ruler — so one-and-a-half cun comes to roughly the width of the index and middle fingers pressed together on many adult hands, arithmetic worth trusting only alongside the bony landmarks.
The fourth posterior sacral foramen deserves a closer look, because it anchors everything. Four pairs of small openings pierce the sacrum front to back, arranged in two tidy vertical columns flanking the central crest; these are the posterior sacral foramina, doorways through which nerves leave the spine’s lowest reaches. The fourth pair sits near the inferior end of the bone, just above the sacral hiatus — the little gap where the spinal canal finally runs out of bony roof. Baihuanshu stands beside the fourth opening but pushed outward, onto the firm band of muscle that lies one-and-a-half cun clear of the crest. Its nearest relatives make a neat map: three stations higher up the same line — Xiaochangshu (BL27), Pangguangshu (BL28), Zhonglushu (BL29) — keep company with the first, second, and third pairs of openings; Xialiao (BL34) sits nearer the midline at Baihuanshu’s own level; and below, Huiyang (BL35) keeps watch beside the tip of the coccyx.
Channel cartography explains why this quiet stretch of bone gathers stations at all. The bladder meridian is the longest pathway in the body — sixty-seven stations strong — drawn in the old cartography from the inner corner of the eye, sweeping over the head, then descending the whole back to finish at the little toe. Down the spine it travels in paired vertical routes: an outer road three cun wide of the midline, and an inner road just one-and-a-half cun out — the road Baihuanshu stands on. Across the sacrum this inner road steps from opening to opening before slipping onward into the buttock and down the back of the thigh. Among the five phases the bladder was assigned water, and the tradition packed this lower stretch of the water channel with stations its records associate with the body’s plumbing and storehouses — which is precisely the company Baihuanshu keeps.
A Self-Palpation Walkthrough
Begin by meeting the two most cooperative landmarks on the whole lower back. Stand relaxed before a mirror or lie face-down, and find the pair of shallow dimples many people carry just above the crease of the buttocks, symmetric about the spine — these mark the posterior superior iliac spines, and they sit roughly level with the second pair of sacral openings. From either dimple, walk your fingertips downward along the bumpy midline ridge of the sacrum. The first pair of soft depressions you meet belongs to the third foramen, and one more step down brings you to the fourth — the lowest pair, just above the hiatus near the bottom of the bone. Now step outward from that depression, sideways away from the spine, about the width of two pressed-together fingers onto the firm muscle band alongside. That spot, mirrored on both sides of the midline, is Baihuanshu’s address.
A second anchor confirms the first. Find the tip of the tailbone — the coccyx — at the very bottom of the trunk’s back wall, then slide upward onto the sacrum it continues. Within a thumb-width or so of the bottom edge you will feel the last pair of depressions: those are the fourth foramina, and outward from them, two finger-widths toward the side of the body, lies the same address found from above. Cross-checking both ways costs ten seconds and catches most drift. Touch feather-light as you search and compare sides; many people register a faint, dull awareness at the genuine spot and little sensation a finger-width away. This terrain barely stirs with breathing — unlike the chest or the upper back — so stillness under the fingertips simply tells you the search has stayed in the sacrum’s quiet country.
Four slips account for nearly every mislocation here. First, treating the waist dimples themselves as the first pair of openings drops the count high — they are landmarks roughly level with the second pair, so from them you descend only to the third and then the fourth. Second, hunting too far out toward the soft flank: the true spot stays on the spine-side band of muscle over bone, and drifting outward leaves the sacrum entirely. Third, pressing on the knuckled crest itself instead of beside it — the crest is the measuring edge, not the destination. Fourth, forgetting the mirror pair: there are two Baihuanshu, one each side of the midline, and neither substitutes for the other. When doubt outlives every test, return to the coccyx tip, confirm the bottom anchor once more, and work upward slowly rather than guessing from wherever the wandering ended.
Reading the Name: White Ring Transport
Three characters, three small ideas. 白 bái means white — the plainest colour word in the language, the white of snow and of unbleached cloth. 環 huán means ring, circle, or loop — the character pictures links encircling, the way a jade ring encircles a wrist. And 俞 shū belongs to the suffix family shared across the point catalogue for stations of transfer, carrying the old sense of conveying or infusing along a channel. Read together, Baihuanshu is the white-ring transport: the station of the white ring, placed where the tradition chose to keep a conversation with the body’s lowest ground.
What, then, was the white ring? Commentators have offered readings rather than settled answers, and the honest reply is that the name keeps part of its mystery. One reading takes the geography: the pale, belt-like band where the trunk cinches down into the pelvis, the lumbosacral girdle imagined as a ring around the body’s base. Another connects the whiteness with essence itself, noting that classical records reach precisely for this station when essence escapes involuntarily during sleep — the traditional indication modern catalogues record as nocturnal emission. Both readings agree on the important part: whatever the ring named, this lowest station stood nearest its lower arc, where ring meets the body’s floor. All of this is heritage name-lore offered warmly for understanding, not anatomy confirmed — the kind of imagery the tradition folded into its maps without ever filing an exact legend.
Pinyin renders the name Báihuánshū: bai rises on the second tone, huan rises on a second tone as well, and shu rides a flat, high first tone. The hanzi string 白環俞 stays legible at a glance — white, ring, transport — and like many points named for images rather than duties, the label does real work. Where a gate implies watching a threshold and a transport implies delivery, a ring implies enclosure: something held within a boundary, kept from leaking out. Hold that image beside the recorded indications — essence escaping at night, urine escaping in childhood sleep, discharge and descent troubling the womb — and the name reads almost like a job description: the tradition posted a keeper at the bottom arc of the white ring, where holding-on matters most.
Traditional Indications, Explained
The dataset records seven indications: nocturnal emission, enuresis, vaginal discharge, irregular menstruation, uterine prolapse, lumbosacral pain, and hernia. The first pair belong together in the classical frame. Nocturnal emission names the involuntary release of semen during sleep; enuresis names involuntary passing of urine, including the childhood bedwetting that outlasts the usual age. Classical teaching located the securing of essence and of water in the lower burner — the kidney-and-bladder territory of water metabolism — and read involuntary escape as the gates of that territory failing to hold fast. Stations along the sacral stretch of the water channel therefore appear again and again in such discussions, and Baihuanshu, lowest on the inner line, sat naturally among them. Framed plainly: these are traditional readings of the body, recorded in a licensed dataset, not claims about what pressing a point achieves.
The middle cluster — vaginal discharge, irregular menstruation, uterine prolapse — collects the traditional portfolio concerning the womb and the lower storehouse. Classical texts discussed discharge as dampness settling and overflowing where it should be contained; irregularity as the water and blood of the lower burner losing their rhythm; and prolapse as qi sinking, the lifting-and-holding work of the body flagging until things slip downward. Whether the complaint involved essence, water, or womb, the reasoning ran through the same neighborhood, and the sacral stations of the bladder channel served as its addresses. It bears repeating that this is the tradition’s own weather map, preserved here for cultural and historical understanding — the vocabulary of another era, not a diagnosis manual, and nothing in it substitutes for assessment by a qualified clinician.
Two further indications need less interpretation because they are local or categorical. Lumbosacral pain is the plainest entry of all: the point lives on the lumbosacral region itself, and pressure traditions everywhere favour gentle local work for local ache. Hernia looks stranger until the old vocabulary is unpacked — the classical category rendered as hernia in Western translations gathered a whole family of groin and lower-abdominal complaints, swellings and dragging sensations included, and sacral stations recur in those historic discussions. As for modern evidence: where self-applied acupressure has been examined at all, reviews suggest effects are modest and context-dependent, and research specific to any single point remains thin. These indications are offered as the tradition’s recorded reach, not as promises — hold the history lightly, and hold the safety rules firmly.
Self-Care Acupressure at Home
Settle first, because reaching this point comfortably is half the practice. Sitting tall on a firm chair works well: lean slightly forward from the hips, let the low back soften, and reach behind with the hand on the same side, walking the fingertips down the sacrum until the landmark sequence above confirms the spot. Lying curled on one side with a pillow under the head offers a lazier alternative for evening practice. Once located, press with the pad of the thumb or two stacked fingertips — pads, never knuckles or elbows — starting with contact alone for a few slow breaths, then adding small circles, letting the skin glide over the firm tissue beneath. Aim for pleasant dullness or mild warmth, never sharpness; a common home rhythm is one to three minutes per side, once or twice daily, matched to unhurried exhales. Swap hands and mirror the session on the other side.
Quality matters more than duration. Light, patient, regularly repeated contact fits the wellness register this page practises; hard jabbing accomplishes nothing except soreness. Warm your hands first if they run cold, because chilled muscle guards against exactly the touch you want it to welcome. Choose a quiet corner over a screen, and let the practice double as a posture pause: the forward lean that makes the sacrum reachable also undoes an afternoon of slouching, and the slow exhales carry the circles out. People who keep routines often anchor them to existing habits — after the morning wash, before the evening walk — because consistency, not intensity, is what self-care traditions actually ask for. Two minutes done daily for a month teaches more than twenty heroic minutes done once.
Treat the exercise as a small ceremony of attention rather than a treatment session. Notice what changes across weeks: perhaps the sacral muscles feel less guarded, perhaps warmth spreads where pressure lands, perhaps nothing shifts except that you spend two minutes attending to the base of your own spine. Every one of those outcomes fits the honest scope of self-acupressure. What does not fit is escalation — pressing harder, longer, or deeper to force a result the practice never promised. The bony shelf beneath this point tolerates gentle contact graciously and answers enthusiasm with soreness; when curiosity pulls toward force, return to gentleness, or simply stop for the day and let the habit, not the pressure, do the accumulating.
Cautions and Safe Practice
This module begins from an unusual position: the licensed dataset records no special caution for Baihuanshu. That absence deserves careful reading. It reflects how the historical record was kept — some points carry generations of written warnings, others none — and it is not an invitation to force. What protects the home practitioner here is simple geometry: the sacrum forms a broad shelf of bone with muscle laid over it, and gentle fingertip contact engages skin and superficial muscle far short of anything deeper. Nothing about surface pressure approaches the structures the body keeps hidden behind that shelf. The rules that follow are therefore the ordinary universal ones, applied with ordinary care.
Keep pressure light and strictly superficial, using finger pads and nothing harder — no elbows, knuckles, or tools. Skip the point over broken, irritated, or infected skin, and pause the practice during feverish illness or any acute flare of back pain. Stop at once on sharp, electric, or radiating sensation, and do not retry that day. Pregnant readers should consult a qualified practitioner before adding any new point practice — a standing rule across this site, doubly sensible at points around the pelvis. Anyone living with conditions affecting the spine, bladder, or reproductive organs, or recovering from surgery near the low back, should likewise seek a professional’s clearance first. None of these limits diminishes the practice; they are the fence that lets the garden grow.
And the wider rule stands over everything: this page is educational, and acupressure is self-care, not diagnosis or therapy. Some low-back symptoms belong with urgent medical care, full stop — numbness in the saddle area between the legs, new difficulty controlling bladder or bowels, progressive weakness or numbness in a leg, pain following a significant fall or accident, fever arriving with back pain, or pain that worsens relentlessly at night. Seek prompt assessment for those rather than a pressure routine, and bring persistent complaints — anything lasting beyond a few weeks, or returning again and again — to a licensed practitioner, medical or East Asian medical as suits the problem. Baihuanshu’s safest gift to most people is a better acquaintance with their own sacrum, treated kindly and within bounds.
Baihuanshu, the White Ring Transport, holds the lowest seat on the bladder channel’s inner sacral line, level with the fourth pair of openings in the triangular bone at the spine’s base. Classical practice reached for it when essence escaped unbidden at night or when the sacral low back ached. This guide shows how to find it by touch and press it gently.
Self-care limits
Frequently asked
- How do I find Baihuanshu without knowing anything about cun?
- Use the waist dimples and the tailbone as the whole map. Find the pair of dimples just above the buttock crease, walk down the sacrum’s midline ridge past one pair of depressions, and stop at the next — the lowest pair, near the bottom of the bone. Step outward from there, sideways away from the spine, about two pressed-together fingers’ width onto the firm muscle band. Cun measurements simply encode that same landmark sequence in proportional language.
- Is pressing Baihuanshu myself actually safe?
- Gentle fingertip pressure held on the surface is generally reasonable self-care for healthy adults: the point rests on a padded shelf of bone, and surface contact stays well short of deeper structures. The licensed record notes no special caution for this point, though absence of a warning is never license for force. Respect the stop signals — sharp pain, radiating sensation, or discomfort that worsens all mean finish immediately — and skip the practice over broken skin, during fever, or through an acute back-pain flare.
- Why would a point on the sacrum relate to bedwetting or menstrual patterns?
- Through the channel map and the classical physiology built upon it. In five-phase thinking the bladder channel is the body’s water pathway, descending the back along paired lines whose inner route crosses the sacrum exactly where Baihuanshu stands. Classical teaching placed the securing of essence, water, and the womb’s rhythms in the lower burner, so the sacral stations became natural addresses whenever those gates seemed to loosen. It is traditional reasoning about the body — coherent, historically real, and offered for understanding rather than as treatment claims.
- What did classical practice use Baihuanshu for?
- The recorded list covers nocturnal emission, enuresis, vaginal discharge, irregular menstruation, uterine prolapse, lumbosacral pain, and hernia. Notice how the earlier entries echo the name itself: a station called the white-ring transport was reached for whenever something seemed about to slip past its enclosure. These are traditional uses documented in a licensed dataset and old literature, preserved here as cultural context — not evidence-backed treatment promises.
- When should low-back trouble go to a doctor instead of a pressure routine?
- Promptly, whenever red flags appear: saddle-area numbness, new loss of bladder or bowel control, progressive leg weakness, pain after a significant fall, fever with back pain, or relentless night pain. Persistent ache lasting beyond a few weeks, or pain that keeps returning, also deserves professional assessment even without dramatic signs. Think of self-care and medicine as different floors of the same building: daily gentleness lives downstairs, and the consulting room upstairs exists precisely for the cases downstairs cannot judge.
Sources
- 01WHO Standard Acupuncture Point Locations in the Western Pacific Region (2008), World Health Organization — nomenclature conventions.
- 02A Manual of Acupuncture, Peter Deadman, Mazin Al-Khafaji and Kevin Baker — point-name tradition and bladder-channel context.
- 03aijiu-mpvue (MIT License) licensed dataset, entry for BL30 Baihuanshu — location, actions, and caution record.
Last reviewed
牌記This leaf, for machines
Old books ended with a colophon saying who printed them. Every leaf here carries the same facts as structured data for agents and search, with no layout in the way.
- GET /en/points/bl30/leaf.json
- GET /zh-hant/points/bl30/leaf.json
- GET /zh-cn/points/bl30/leaf.json
- /llms.txt — the index of every leaf
- JSON-LD in the page: MedicalWebPage, MedicalEntity and FAQPage
{
"id": "BL30",
"name": {
"en": "Baihuanshu",
"gloss": "White Ring Transport",
"zh-Hant": "白環俞",
"zh-Hans": "白环俞"
},
"channel": {
"id": "BL",
"order": 30,
"of": 67
},
"location": {
"text": "Low on the sacrum, level with its fourth hollow, two finger-widths from the centre ridge."
},
"for": [
"low back and sacral ache",
"irregular periods"
],
"press": {
"text": "Reach behind and press with the fingertips, about a minute.",
"seconds": 60
},
"cautions": [],
"source": "Zhenjiu Jiayi Jing, book 3",
"url": "https://acupoints.com/en/points/bl30",
"lastReviewed": "2026-08-24"
}