top of page
Recent Posts

Why an X-ray for Childhood Constipation Can Seem Like a Rorsach Test

By Steve Hodges, M.D.

how to get an accurate x-ray for childhood constipation

The other day I reviewed the abdominal x-ray of an 11-year-old boy with persistent bedwetting. The boy’s rectum was jam packed with stool, and the mass extended upward to his belly button like a column of poop.

I told his mom: “This is one of the more impacted x-rays I have seen in a while. The mass of poop in the rectum is significant.”

Yet the radiologist’s report on the x-ray, which was taken at a pediatrician’s office, found only a “moderate amount of stool in the colon.”

This kind of discrepancy happens all the time.

A radiologist will pronounce a child’s x-ray “normal” or the stool burden “moderate,” and on this basis, the pediatrician will tell the family that no treatment is warranted or perhaps all the child needs is a daily dose of Miralax. Meanwhile, the enuresis, whether bedwetting or daytime wetting, persists. Eventually, the family gets frustrated and lands in my clinic or joins our private Facebook support group. I get a look at the x-ray and find it’s not “normal” at all.

Naturally, parents want to know: How can two doctors come to such different conclusions about the same x-ray?

After all, an x-ray is not a Rorsach test! It’s a precise image of a child’s abdomen, and it shouldn’t mean different things to different people. But it does, for a couple of reasons.

For one thing, when presented with an abdominal x-ray of a child, radiologists tend to look for indications of a serious medical condition, such as an intestinal injury that would cause air to leak out of the intestine into the belly. That’s called “free air,” and it’s dangerous; if bacteria from stool leaks into the belly, you can get really sick. The radiologist who looked at the 11-year-old’s x-ray commented, “There is no free intraperitoneal air.”

But x-rays of kids with enuresis almost never show anything dangerous, so for our purposes, that kind of commentary is beside the point.

ER docs, by the way, also tend to be looking for serious conditions and miss the constipation. Some constipated children experience so much pain that they end up at the ER, and their constipation is overlooked or minimized.

The 11-year-old's mom, who happens to be an ER nurse, says: "Poop problems are the LAST thing an ER doctor looks for. ER doctors are just like the radiologists. They’re looking for something more serious, and poop is harmless to them. If poop is found, then Miralax and discharge home is the final word."

In addition, radiologists and ER docs aren’t necessarily trained on the significance of stool in specific areas of the colon. They may think it’s fine if there’s a moderate amount of stool anywhere in the colon. In reality, if there’s stool in the rectum — the very end of the colon — that’s not fine.

The rectum is not designed as a storage locker! When stool progresses into the rectum, via the conveyor belt that is the intestinal tract, the rectal nerves signal to the brain that it’s time to evacuate, and the child senses the urge to poop. But if the child ignores or overrides this signal by clenching, the exit door remains closed, and stool starts to pile up.

The rectum stretches to accommodate this stockpile. But eventually so much stool accumulates that the stretched rectum encroaches upon the nearby bladder. The bladder’s nerves become aggravated, triggering the bladder to periodically empty without warning. On x-rays, I often see the enlarged rectum squashing and even flattening the bladder.

And yet, the radiologist’s report comes back “normal.”

What’s more, when a child is severely backed up, as this 11-year-old was, stool not only accumulates in the rectum but backs up way into the colon. But radiologists rarely comment on the “column of stool” I observed. It’s just not something they’re taught to focus on.

Getting an accurate x-ray evaluation is important, because the film can offer proof of chronic and severe constipation — and proof that aggressive treatment (such as a the Modified O'Regan Protocol, aka M.O.P.) is warranted. By contrast, feeling a child’s belly, the diagnostic method many doctors use, is absolutely useless. A small, lean child can harbor an enormous mass of rectal stool that is simply not palpable.

I’ve worked with countless families who were told, emphatically, “Your child is not constipated — I feel nothing,” only to learn otherwise from an x-ray.

In addition to feeling a child’s abdomen, physicians also typically ask parents how often the child poops. If the answer is “every day,” this may reinforce the doctor’s conclusion that the child is not constipated and that no treatment is necessary. But a child’s pooping frequency, like the feel of a child’s belly, is also a flawed indicator of constipation.

I have many severely constipated patients who poop every single day. But they don’t fully empty, and complete emptying is what matters most. When you see rectal stool on an x-ray, well, there’s your evidence that the child isn’t fully evacuating.

I x-ray my enuresis patients as a matter of routine, but in almost all cases, I don’t need the x-ray to tell me the child is constipated. Virtually all kids with daytime and/or nighttime wetting are chronically clogged, and if you ask families the right questions, you can easily deduce this without an x-ray.

For example, rather than focus on how often a child poops, I ask: How large are your child’s stools? Extremely large, formed stools are the number-one indicator of constipation. In the case of the 11-year-old, XXXL stools were part of his history. In fact, the boy’s mom described toilet-clogging stools “the size of a Pringles can.” The child also had a long history of skid marks, poop accidents, and daytime pee accidents — all listed on our 12 Signs a Child is Constipated infographic. Despite the radiologist’s tepid report, it was obvious this kid was seriously clogged.

Yet even in clear cases like this, I order x-rays, in part because the films help families understand why the child is having accidents. Many parents have been told their child wets the bed because he’s a “deep sleeper” or has an “underdeveloped bladder” or is stressed or anxious — all kinds of explanations that don’t hold water. An x-ray shows that the rectum is enlarged and encroaching upon the child's bladder. For many parents, seeing the x-ray is a real "aha" moment.

An x-ray is also helpful to establish a baseline for later comparison. Often a child will start on M.O.P., the enema-based regimen I use to resolve enuresis, and after a month or two of daily enemas, the parents will come back and say, “She’s still wetting. Constipation must not be the cause.”

We’ll do another x-ray, and sure enough, the kid is still monumentally clogged. All this means is that the child needs a more aggressive type of enema to clean out the rectum so it can shrink back to size and stop aggravating the bladder.

Another reason I x-ray patients is to rule out the rare medical conditions that can cause enuresis. Every once in a blue moon I will come across a child whose wetting is unrelated to a clogged rectum or whose rectal stool masses are caused by a congenital abnormality or disease.

For example, I recently saw a 4-year-old patient who was having frequent pee accidents, a red flag for constipation. Yet an x-ray showed the child’s rectum was free of stool, and his rectal diameter was normal.

An ultrasound revealed the culprit: posterior urethral valves, extra membranes that develop in utero and block the flow of urine through the urethra, causing accidents and eventually, if not repaired surgically, bladder and kidney damage.

This disorder occurs in 1 out of 8,000 births, always in boys. It’s almost always picked up on prenatal ultrasounds, but some cases slip by. I’ve seen the condition present at a late age just twice in my career.

I’ve also seen two cases of tethered cord syndrome, a rare condition in which the spinal cord is stuck to the spinal canal, causing faulty communication between the brain and bowels. With these two patients, ages 4 and 13, constipation was present and played a role in enuresis, but the fix was surgical.

Cases like these are a good reminder that you don’t want to jump to conclusions. But the old medical adage “When you hear hoof beats, look for horses, not zebras,” holds true for enuresis. Probably 99% of the time, the hoof beats indicate constipation that has no underlying medical cause.

What can you as a parent do to ensure an accurate x-ray reading? Here are some tips:

• Ask in advance for a measurement of rectal diameter.

To take a measurement, the radiologist must measure the rectum at its widest point and then compare that measurement, in centimeters, to the scale for that x-ray. Make sure the measurement is taken by the center performing the x-ray. I’m often asked to review x-rays that were taken elsewhere without a scale, but I can’t assess the rectal diameter under those circumstances.

• Ask in advance for a comment on how much poop is in the rectum specifically.

Radiologists don’t always comment on stool burden in the rectum, so they may miss it. It is stool in the rectum, not elsewhere, that aggravates the bladder.

• Rather than rely on the radiologist’s report, have your doctor personally read your child’s x-ray.

Don’t assume she will comment on rectal poop specifically, so ask!

• Use your phone to take a photo of your x-ray when you are in the exam room.

It can be very difficult to get a copy of your x-ray once you leave the office, and the x-ray may be in a format that you can’t even open. If you have a .jpg from your phone, you’ll find it easier to get a second opinion if necessary.

bottom of page