Pangguangshu (BL28): The Low Back Point Beside the Dimples, for an Aching Sacrum

Where Pangguangshu Sits

This point sits low on the back, on the flat bone at the base of the spine. That bone is the sacrum, a triangle made of five vertebrae that fused together long ago. It sits like a wedge between the two halves of the pelvis. The point lies about two finger-widths out from the centre of that bone, a little below the two dimples you can see above the buttocks.

It belongs to the line that Vietnamese and Chinese texts call the Bladder channel, which comes down the back in two tracks on each side of the spine. The inner track carries a row of points, one for each organ in this tradition. This one, the twenty-eighth stop, belongs to the bladder itself, the organ the channel is named after.

The old texts place it below the nineteenth vertebra, one and a half units out from the spine. Counting from the top of the back, the nineteenth is the second segment of the sacrum. The modern standard from the World Health Organization says the same in today's words: level with the second posterior sacral foramen, one and a half units out from the centre ridge of the sacrum. The foramina are small holes in the back of the bone where nerves come through. You cannot feel the holes themselves, but the second one lies at about the level of the dimples. One and a half units is about the width of your index and middle fingers laid side by side.

Under the skin there is little muscle. The thick tendons of the long back muscles end on this part of the sacrum, and the big buttock muscle begins along its outer edge. Just outside the point lies the sacroiliac joint, where the sacrum meets the hip bone, bound by some of the strongest ligaments in the body. The skin is served by small branches of the upper sacral nerves. Deep in the pelvis, in front of the bone and well out of reach, sits the bladder.

Why This Spot

On the anatomical side, this is where the weight of the upper body passes into the pelvis and on to the legs. Every step sends a small jolt through the joint beside the point, and long hours of sitting press the area into the chair. After fifty, the ligaments here stiffen and the lowest discs lose height. Many people feel a dull, deep ache at the base of the back, worse after sitting. That ache often lives along the edge of the sacrum, where tendon meets bone. This spot sits right on it.

In this tradition, every organ has a transport point on the back, where its energy is said to come close to the surface. This is the one for the bladder. The bladder is described as the organ that stores water and lets it go at the right time, and it is paired with the kidney. When the lower body grows cold and tired with age, this tradition says the bladder holds less firmly. The result is a familiar pattern for people in their 60s and 70s: an ache across the base of the back, legs that feel cold, and a bladder that wakes them two or three times a night. A teacher reaches for this point when those things come together.

The name says what it is. Pangguang is the bladder; shu means to transport. Its Vietnamese name, Bàng Quang Du, carries the same meaning.

What the Old Texts Say About Pangguangshu

The Systematic Classic of Acupuncture and Moxibustion, the Jiayi Jing, compiled by Huangfu Mi in the third century, places this point below the nineteenth vertebra, one and a half units out on each side. It groups the point with the other transport points of the back, each one named after the organ it serves. The modern standard describes the same spot in terms of the sacral holes.

The Vietnamese handbook of points and channels by Ngô Trung Triều, published by Hồng Đức, follows the same count. To find it, the handbook says, draw a line across the tip of the bump on the second segment of the sacrum and meet it with a vertical line one and a half units out from the centre line. It lists the point for pain of the low back and sacrum, bed-wetting, and complaints of the urinary passage.

Notice how the list joins two things that seem unrelated: a sore base of the spine and trouble with passing water. In this tradition both belong to the same lower region, and the same tiredness is said to lie behind both. The old practitioners looked at the person who could not sit comfortably and also woke at night, and reached for one spot.

The point was often warmed as well as pressed, especially for people who felt the cold in their lower back and feet. That reputation rests on long use rather than proof, but it tells you generations of hands found this place useful for a low, heavy ache.

Points That Work With Pangguangshu

The first partner sits right next door, in the same row of small holes in the sacrum but closer to the centre, roughly in the hollow between the dimple and the middle ridge. In this tradition the two are worked one after the other when the whole base of the spine aches and the bladder is restless. One tennis ball, moved a little inward, reaches both.

The second sits higher up, at waist level, two finger-widths out from the spine, beside the second bump of the lower back. It is the kidney's transport point. Because this tradition pairs the kidney and the bladder, the waist point and this one are often pressed together for a back that feels weak and cold, and for waking at night.

The third sits in the middle of the crease at the back of the knee. It is one of the most used points for back pain in this tradition and is easy to reach sitting in a chair. Pair it with this one when the base of the back is stiff and the legs feel heavy.

How to Find and Press Pangguangshu

Getting Into Position

Be honest about reach. Almost nobody can press their own sacrum well with their hands. That is normal. Stand with your back to a wall, feet about a foot out from it, knees soft, and use a tennis ball between your back and the wall. A stick with a rounded end, reached around the hip, is another way.

How to Find It

Reach behind you and feel for the two dimples just above the buttocks, one on each side. They mark the back corners of the hip bones. Between them, in the middle, is the hard ridge of the sacrum. The point lies on each side of that ridge, two finger-widths out, a little below the level of the dimples.

Place the ball there and lean back into it slowly. Shift in small steps, a little up, down, in and out. Much of the area will feel like ordinary pressure on bone and tendon. One spot will sting: a small, sharp, pinpoint tenderness under the ball. That spot is the point, and it is often along the edge where the tendon meets the bone. Two balls tied in a sock let you work both sides at once, with the centre ridge resting in the gap between them.

How to Press It

Once you are on the stinging spot, stay on it. Bend and straighten your knees a little so the ball rubs in small circles about the size of a coin, roughly one each second, without rolling away. With a stick, hold the handle steady, place the rounded tip on the spot and make the same small circles. If you can reach with a thumb tip, press in and slightly toward the centre. Do not press on the hard centre ridge itself, and do not press on the tailbone at the very bottom.

How Much Pressure

A sharp sting under the ball is right. When you step away, it should fade within moments. If the pain stays after you lift off, spreads, or the area turns swollen, hot or red, stop and leave it for several days. Stop at once for any pain shooting down a leg or any numbness. If you are holding your breath, you are pressing too hard. Step your feet a little closer to the wall, so less of your weight goes into the ball, until you can breathe slowly through the sting.

How Long

One to three minutes on each side. Keep the first sessions to about a minute, because the base of the back has little padding and can feel bruised the next day. Add a little time over the following days, up to three minutes. Work both sides, even when only one complains. Once or twice a day is plenty. Longer sessions bring more soreness, not more benefit.

When to Do It

Late afternoon suits the ache that builds after a day of sitting or standing. Before bed is the best time if the bladder wakes you, as part of winding down: empty your bladder, press both sides, then go to bed. Do not press in the middle of the night. If you wake at two or three in the morning to pass water, getting up to lean on a wall will only wake you further. Go back to bed, keep warm, and save the pressing for the day and the evening.

What This Won't Do

It will not change the structure of a bladder or prostate. An enlarged prostate, a bladder that has grown less stretchy with age, or weak pelvic floor muscles are real changes, and no point reverses them. Pressing here can ease a sore, stiff base of the back and may help some people feel more settled at bedtime. Results vary from person to person. What helps night waking more is plainer: less to drink in the two hours before bed, less tea, coffee and alcohol in the evening, feet up in the late afternoon if your ankles swell, and pelvic floor exercises taught by a nurse or physiotherapist.

It is also no substitute for a diagnosis. See a doctor the same day for burning when you pass water, a fever, pain in the side of the back, or blood in your water. See a doctor soon if you get up more than twice a night, if the urge is new or getting worse, if your stream has become weak, or if you leak. Go to hospital at once for numbness between the legs or around the back passage, new trouble controlling your bladder or bowels, or a leg that turns weak. After a fall onto your bottom, especially with thin bones, get the pain checked before pressing here.

Safety First

If you are pregnant, skip this one. Points over the sacrum carry a traditional caution in pregnancy. Do not press over skin that is broken, burned, infected, badly bruised or rashy, and do not press over a pressure sore or a cyst at the top of the buttock crease. Leave the area alone after a recent fall, with a known fracture of the sacrum or tailbone, after recent back or hip surgery, or with unexplained swelling or a lump. If you take blood thinners, bruise easily, have thin bones or reduced feeling in your legs, use a softer ball, lean in less, keep sessions short, and ask your doctor first.

Stop at once if pain stays after you lift off, spreads, or brings tingling or numbness. Nothing here requires you to push through pain. For the full list of cautions and the situations where pressing on yourself is not appropriate, read the full safety guide before you begin.

Questions People Ask

Where is the Pangguangshu (BL28) pressure point? Pangguangshu (BL28) lies on the sacrum, the flat triangular bone at the base of the spine, about two finger-widths out from its centre ridge and level with the second sacral hole. In practice that is a little below the two dimples above the buttocks, between each dimple and the middle. In Vietnamese it is called Bàng Quang Du.

How do I press a point at the base of my spine I cannot reach? Very few people can press their own sacrum well with their hands, and that is normal. Stand with your back to a wall and lean on a tennis ball placed over the spot. Two tennis balls tied in a sock sit on both sides of the centre ridge at once. A stick with a rounded end, reached around the hip, also works.

Can Pangguangshu (BL28) help me stop waking at night to pass water? In this tradition it is commonly used when the bladder wakes you in the night, and many people like it as part of a bedtime routine. It is not a cure for a weak or overactive bladder. Press it in the daytime and before bed, not in the middle of the night. If you get up more than twice a night, or the urge is new, mention it to your doctor.

Why is it called a bladder point? In this tradition each organ has a matching point on the back, and this one belongs to the bladder. The name reflects old ideas about energy in the lower body, not the bladder you see on a scan. Pressing here does not test or change how your bladder works.

How long should I press Pangguangshu? One to three minutes on each side. Keep the first sessions to about a minute, then add a little as the days go on, up to three. Once or twice a day is enough. Work both sides, even if only one side aches.

Can I press Pangguangshu while pregnant? No. If you are pregnant, skip this one. Points over the sacrum carry a traditional caution in pregnancy. Ask your midwife or doctor about safe ways to ease pain at the base of the back.

Other Points in This Library

Each of these sits within reach of the same hand. They are often worked in the same sitting.

This page shares general information about a traditional practice. It is not medical advice and does not replace what your doctor has given you. If you are pregnant, managing a health condition, or unsure whether this applies to you, check with your doctor first.

The whole inner edge of the foot, laid out on one page with photographs, is in The Foot Map — the free book. For every point in this library, see the full pressure point index.

(Point shown: BL28 · Pangguangshu · Bladder Transport Point · Bàng Quang Du.)