Can constipation cause bedwetting? — and how to tell if your child is constipated

Parents come to my clinic about bedwetting or daytime urinary incontinence, and in a considerable share of those visits, the underlying problem turns out to be in the bowel. That surprises people. Constipation and bladder problems look like two unrelated conditions, and are mainly treated by two separate specialists. But in children the two are so tightly linked that treating the constipation alone may resolve the urinary symptoms. On the other hand, missing the diagnosis and treatment of constipation can result in prolonged bladder symptoms or nonresponse to the prescribed treatment.

This article explains how the two are connected, how I check for constipation in clinic, and why the treatment order is important: constipation first, bladder second, bedwetting third.

A note on medications. Osmotic laxatives such as macrogol (PEG 3350) are the first-line pharmacological treatment for constipation. Nothing here is a substitute for your doctor’s judgment — but knowing which questions to ask makes the next appointment more productive.

Full article — 10-minute read

1. What “constipation” actually means

Parents often think of constipation as “not going often enough.” That is part of it, but not the whole picture. The internationally accepted definition — the Rome IV criteria — considers not only how often a child has a bowel movement, but also stool consistency, painful bowel movements, withholding, and fecal soiling.

In a child older than four, functional constipation is diagnosed when two or more of the following are present at least once a week for a minimum of one month:^2,6

• 2 or fewer bowel movements in the toilet per week
• At least 1 episode of fecal incontinence per week
• History of retentive posturing or excessive voluntary stool retention
• History of painful or hard bowel movements
• A large fecal mass in the rectum on examination
• Stools of large diameter that can obstruct the toilet

The criteria for children under four are similar. In toilet-trained children, fecal incontinence is also included as a criterion.² Most children — more than 90% — have functional constipation, meaning no organic cause is found on evaluation.²

Two things about this definition matter for parents:

Frequency alone is not enough to rule constipation out. A child who has a bowel movement daily can still be constipated if the stool is hard, painful, or leaves a sense of incomplete emptying. Conversely, a child who goes only every other day but passes a soft, formed stool without straining is probably fine.

Overflow soiling is a sign of constipation, not diarrhea. When the rectum is chronically loaded, small amounts of soft stool can leak around the impacted mass. Parents may mistake this for diarrhea, but the underlying problem is the opposite: retained stool needs to be cleared rather than bowel movements slowed down.²

2. How common is it?

Very. In a systematic review of general-population studies, the pooled prevalence of functional constipation in children was around 9.5%.³ It is more common in children under 4, where prevalence approaches 17.5%.² Boys and girls are affected roughly equally.

In children specifically referred for lower urinary tract symptoms, the numbers are also high. In my own clinical study of children with overactive bladder, about 10% had a diagnosis of, or were being treated for, constipation at the time of the workup.⁴ Constipation and bladder problems often occur together. When doctors specifically look for constipation in children with urinary symptoms, they find it more often than parents may expect.⁵

3. Why the bowel affects the bladder

The rectum sits directly behind the bladder. When it is chronically loaded:

• It compresses the bladder, reducing its functional capacity, so the child feels urgency at a lower volume.
• It triggers detrusor overactivity. This is the pattern the ICCS and pediatric gastroenterology societies now describe as bladder-bowel dysfunction (BBD) — one clinical entity, not two coincidental ones.⁵
• It changes pelvic-floor coordination, which can lead to incomplete emptying with residual urine, and post-void dribble, a small urine spot on the underwear after peeing.

The clinical fingerprint of BBD is urgency, frequency, daytime leaks or bedwetting combined with infrequent, hard, or painful stools — with the bladder symptoms often being the ones that bring the family to a doctor. The bowel side is missed unless someone specifically asks about it.

One of the strongest indications that the two are connected is that treating constipation can resolve urinary symptoms in many children — without bladder-directed treatment. In a classic series, daytime urinary incontinence resolved in about 89% of children with chronic constipation once the constipation was properly treated, and night-time incontinence in about 63%.¹ Subsequent reviews have consistently supported the same direction.⁵

The reverse is also true: standard bedwetting protocols work less well when there is unrecognized constipation running in the background.^1,5,7

4. How I check for constipation in clinic

The history is where most of the answer sits. For patients with bladder symptoms, I use standardized forms so that I don’t miss important questions. For bowel habits, I ask about:

Stool frequency. In practice, I think about it simply: once or twice a week is constipation. Three or four times a week is a grey zone worth investigating further. Five or six times a week, or daily, is generally fine — if the consistency is good.

Stool consistency, using the Bristol Stool Scale. Types 1 and 2 (separate hard lumps; a lumpy sausage) are the concerning end. Type 3 (a sausage with cracks on the surface) is borderline. Types 4 and 5 (smooth sausage, or soft blobs) are healthy. Types 6 and 7 (fluffy pieces, or entirely liquid) go the other direction — diarrhea. Consistency carries more information than frequency, which is why the Bristol Scale is in the BeDRY diary rather than a simple yes-or-no.

Signs of stool retention. Painful defecation, straining, blood on the paper or on the stool, stools of large diameter that block the toilet, or soiling of underwear (overflow, not diarrhea).

Ultrasound, when I have access. Transabdominal ultrasound of the rectum allows me to measure the transverse rectal diameter behind the bladder. A diameter greater than 3 cm is associated with rectal loading and correlates well with clinical constipation.⁸ It is a useful non-invasive marker in a child whose history is unclear. In the clinical study I ran on children with overactive bladder, we used exactly this method — Bristol type 1–2, or a transverse rectal diameter > 3 cm on ultrasound, alongside Rome IV — to identify constipation and treat it before including the child in the analysis.⁴ Ultrasound can also be useful during follow-up, as I can objectively see whether rectal dilatation decreases with treatment.

I use these three or four inputs together — history, Bristol, and (when available) ultrasound — to decide whether constipation is present. Rome IV is the formal definition. The clinical checks above are how I actually work through it in an outpatient visit.

5. The treatment order — constipation first, bladder second, bedwetting third

This is the single most important practical point of this article. In a child who has all three problems — constipation, a small or overactive bladder, and bedwetting — the order in which they are treated can be just as important as the treatment chosen for each problem.

Treat the constipation first. Osmotic laxatives — most commonly macrogol (polyethylene glycol 3350) — are the pharmacological first line.^2,9 Alongside medication, have the child sit on the toilet after breakfast and dinner and try to pass stool: this uses the gastro-colic reflex and builds the habit. Adequate fluid intake and correct toilet posture round out the non-pharmacological side. In long-standing cases, laxative treatment is usually needed for months, not weeks.

Then treat the bladder. Once the bowel is soft and moving regularly, reassess the bladder. Standard urotherapy — scheduled voids before urgency, adequate fluid distribution across the day, avoidance of provocative drinks late in the day, and correct toilet posture — is the first step.¹⁰ If daytime symptoms persist, an anticholinergic or a β3-agonist may be added under a specialist’s guidance. Percutaneous or transcutaneous tibial nerve stimulation is another option.

Then treat the bedwetting. Once the bowel is clear and daytime bladder control is stable, the remaining bedwetting is often driven by nocturnal polyuria — high overnight urine production relative to bladder capacity. This is where a bladder diary such as BeDRY becomes important. Objective measurement of bladder capacity and nighttime urine production helps guide rational treatment of bedwetting — matching the treatment to the underlying pattern. Desmopressin taken about an hour before bed, or an enuresis alarm, are the two standard first-line options. Details are in my previous article: Ten reasons bedwetting treatment isn’t working.

Step 1

Constipation

→

Treat first

Osmotic laxative (macrogol / PEG 3350), adequate fluids, toileting after meals to use the gastro-colic reflex, correct posture. Give it months, not weeks.

↓

Step 2

Small or overactive bladder

→

Treat second

Standard urotherapy — scheduled voids before urgency, fluid distribution, correct posture. If persistent: anticholinergic or β3-agonist; neurostimulation for resistant cases.

↓

Step 3

Bedwetting (nocturnal polyuria)

→

Treat third

Desmopressin (about 1 hour before bed) or an enuresis alarm.

Starting desmopressin while a child’s rectum remains chronically loaded is a common reason for treatment failure.

See how BeDRY worked for a 5-year-old boy with bedwetting →

6. What a bladder and stool diary shows

Almost every question in this article — how often is the child really passing stool, what does the stool look like, is the bladder capacity actually small, is night-time urine production high, are there daytime leaks the parents haven’t mentioned — is answered by keeping a properly kept bladder and stool diary.

Two days and three nights of bladder tracking. Seven days of stool tracking. This provides a reliable picture of bladder and bowel habits.

The BeDRY digital diary makes this easier:

• Log urination volumes and times, drinks, leaks, and stools in a few taps.
• The Bristol Stool Scale is built in — pick the picture that looks most like your child’s stool. No medical vocabulary required.
• An automatic Summary shows expected vs. measured bladder capacity, night-time urine output, urination counts, drinking pattern (including the crucial fluid distribution across the day), and the Overactivity Index — a metric calculated from the diary that flags signs of an overactive bladder without invasive testing.⁴
• Share the Summary directly with your doctor from the app. No printing required.

The diary is free. It is often the fastest way to see whether constipation, a small bladder, or high night-time urine production — or some combination — is driving the picture your family is seeing.

7. BeDRY’s Bladder Habit Builder

Bladder Habit Builder uses the diary findings to provide practical guidance for building healthier bladder and bowel habits. For a family dealing with bladder and bowel symptoms together, the Coach provides step-by-step guidance on:

• Fluid intake and timing. How much your child should drink per day (calculated from body weight), how to spread it across the day, and which drinks to avoid late in the afternoon.
• Regular voiding schedule. How often to visit the toilet during waking hours, to prevent urgency and leaks before they happen.
• Toilet posture for voiding and defecation. Coach includes short step-by-step video guidance for each posture.
• Bowel routines. Sitting on the toilet after meals to use the gastro-colic reflex — timing, duration, and how to make it a habit rather than a fight.

Coach is not a substitute for medical treatment. It is the daily-habits side of the plan — the part that sits between doctor visits and does most of the actual work at home.

8. When to see a doctor

Book a pediatric or gastroenterology visit if any of the following apply:

• Painful bowel movements, blood on the stool or paper, or overflow soiling of underwear.
• Stools that block the toilet, or that a parent describes as unusually large.
• Long-standing constipation that has not responded to dietary measures and normal fluid intake.
• Bedwetting or daytime leaks in a child whose bowel history sounds concerning — either the parent already suspects constipation, or answers to the questions in Section 4 point that way.
• Alarm signs at any age: failure to thrive; delayed passage of first meconium after birth; symptoms present from the first weeks of life; a very narrow, ribbon-like stool; fever with abdominal distension. These need pediatric evaluation to rule out organic causes such as Hirschsprung disease.²

Bring the BeDRY bladder and stool diary to the appointment. It shortens the consultation and sharpens the plan.

In short — the order I teach my fellows to work through

1. Ask about the stool — frequency, Bristol type, pain, straining, soiling. Frequency alone is not enough.
2. If constipation is present, treat it first. Osmotic laxative (macrogol), adequate fluids, toileting after meals to use the gastro-colic reflex, correct posture. Give it months, not weeks.
3. Reassess the bladder once the bowel is soft and regular. Many urinary symptoms resolve at this point on their own.
4. Standard urotherapy for remaining daytime bladder symptoms — schedule, fluid distribution, posture.
5. Desmopressin or bedwetting alarm for remaining night-time symptoms, once the daytime picture is clean.
6. Keep a bladder and stool diary at the start, and again after each stage of treatment, to see what has actually changed.

Bladder and bowel together — in practice

Urgency and daytime leaks in a 9-year-old girl

Dry until she was seven, then urgency several times a day and leaks she hides with pads at school. Her stool was Bristol type 3 and she went regularly — the diary made both sides visible at once.

See how BeDRY worked through this case

References

1. Loening-Baucke V. Urinary incontinence and urinary tract infection and their resolution with treatment of chronic constipation of childhood. Pediatrics. 1997;100(2 Pt 1):228–232. doi:10.1542/peds.100.2.228
2. Močić Pavić A, Jadrešin O, Despot R, et al. Postupnik za dijagnozu i liječenje kronične opstipacije u djece — Smjernice Hrvatskog društva za pedijatrijsku gastroenterologiju, hepatologiju i prehranu Hrvatskog liječničkog zbora. Liječ Vjesn. 2022;144(Suppl 1):83–88. doi:10.26800/LV-144-supl1-12
3. Koppen IJN, Vriesman MH, Saps M, et al. Prevalence of Functional Defecation Disorders in Children: A Systematic Review and Meta-Analysis. J Pediatr. 2018;198:121–130.e6. doi:10.1016/j.jpeds.2018.02.029
4. Abdović S, Ćuk M, Bahtijarević Z, et al. Overactivity index: A noninvasive and objective outcome measure in overactive bladder in children. J Pediatr Urol. 2022;18(3):352.e1–352.e7. doi:10.1016/j.jpurol.2022.03.012
5. Burgers RE, Mugie SM, Chase J, et al. Management of functional constipation in children with lower urinary tract symptoms: report from the Standardization Committee of the International Children’s Continence Society. J Urol. 2013;190(1):29–36. doi:10.1016/j.juro.2013.01.001
6. Hyams JS, Di Lorenzo C, Saps M, et al. Functional Disorders: Children and Adolescents. Gastroenterology. 2016;150(6):1456–1468.e2. doi:10.1053/j.gastro.2016.02.015
7. Nevéus T, Fonseca E, Franco I, et al. Management and treatment of nocturnal enuresis — an updated standardization document from the International Children’s Continence Society. J Pediatr Urol. 2020;16(1):10–19. doi:10.1016/j.jpurol.2019.12.020
8. Joensson IM, Siggaard C, Rittig S, et al. Transabdominal ultrasound of rectum as a diagnostic tool in childhood constipation. J Urol. 2008;179(5):1997–2002. doi:10.1016/j.juro.2008.01.055
9. Tabbers MM, DiLorenzo C, Berger MY, et al. Evaluation and treatment of functional constipation in infants and children: evidence-based recommendations from ESPGHAN and NASPGHAN. J Pediatr Gastroenterol Nutr. 2014;58(2):258–274. doi:10.1097/MPG.0000000000000266
10. Nieuwhof-Leppink AJ, Hussong J, Chase J, et al. Definitions, indications and practice of urotherapy in children and adolescents: a standardization document of the International Children’s Continence Society (ICCS). J Pediatr Urol. 2021;17(2):172–181. doi:10.1016/j.jpurol.2020.11.006