You want to see a parent get excited, well, just bring up the topic of bedwetting with a mom of an eight year old bed wetter and stand back. Bedwetting creates a lot of stress in both the parents of the bed wetter and the bedwetting child themselves. When families first bring up this issue with their pediatricians, most parents fear that there is something wrong with their child. In most cases, this is simply not true. Parents also think that their child’s bedwetting emanates from something being wrong with their child’s urinary bladder. This is also not true in most cases so I thought that it would be useful, especially if you have a bed wetter in your house, to put some of these misconceptions to bed so to speak (pun intended) and getting a better understanding of the cause, natural history, and treatment options that are useful. If you have been wondering, why does my child wet the bed, you’ve come to the right place to get the answer. Stay tuned and I will answer that question for you.
How do Urinary Bladders Work?
Long time listeners of Portable Practical Pediatrics know I love to take my listeners to a place that I call “Science Drive” so we can talk numbers, chemistry, and various other scientific concepts you learned in science class. Refreshing you on a few scientific concepts will bring you an understanding of our topic today. So, hang with me for a few minutes while we go over some science concepts you need to understand to get an understanding of why your child is wetting the bed.
Concept #1-Your child’s kidneys filter wastes out their blood and continuously make urine 24/7 even though they only eliminate that urine about every three hours. Urine production is constant and predictable at the rate of aboutError! Hyperlink reference not valid. But urine elimination only happens every three hours, during the day. Nighttime is an entirely different beast. Let’s do some simple math; that means that a 19kg (42 pound) four year old makes about 285 ml (9.5 ounces) of urine if they sleep for 10 hours. Unfortunately, most 4 year olds only have 8-ounce bladders, not large enough to hold 9.5 ounces. You can see that this child and their parents have a problem, too much urine and too small a bladder to hold a night’s worth of urine. If this child doesn’t wake up and go to the bathroom before morning, the bed is likely to be wet by morning. It’s simple geometry; 9,5 ounces of urine to store in an eight ounce bladder. See the chart that I have created to check your child’s nighttime urine numbers and better understand what your child is up against. Some will have large enough bladders to hold a nights worth of urine but many will not and are destined to be budgeters unless they can wake and use the bathroom. Interestingly, during childhood, girls have larger bladders than boys. Could this be why fewer girls are budgeters than boys? Probably.
Age in years Volume of urine in 10 hours Calculated size of urinary bladder
4 5.6-11.3 ounces/night 8 ounce capacity
5 6.3-12.6 ounces/night 8.5 ounce capacity
6 7.3-14.6 ounces/night 9 ounce capacity
7 7.6- 15.3 ounces/night 9.5 ounce capacity
8 8.6- 17.3 ounces/night 10 ounce capacity
9 9.6-19.3 ounces/night 10.5 ounce capacity
Concept #2- There are two levels of control of your child’s bladder, at the spinal cord level where bladder emptying is an involuntary (meaning the child no control) and at the upper brain level (the consciously controlled part of the brain) where an awake child can run the show. Infants have no upper brain control of their bladders and their bladders empty reflexly every few hours due to their strong spinal cord reflex. Hence those diaper changes every 3-4 hours. Toddlers and school age children learn to control and suppress the bladder-emptying reflex while awake but cannot when they are asleep. Fortunately, most children begin to develop the skill of waking at night and using the bathroom if necessary between 7-10 years of age; some earlier and some later as you are well aware. As a child becomes older, they have two things going for them; they tend to sleep fewer hours at night than they did when they were very young (meaning less urine to store in their bladders) and they their urinary bladders are getting progressively larger. When they get a bladder large enough to hold a night’s worth of urine, especially if they can wake and use the bathroom before their spinal cord reflex takes over and empties their bladder early in the morning, their nocturnal enuresis or bedwetting days are over. Hallelujah.
Concept #3- Remember, your child is a living breathing constantly adjusting being not a simple machine. By that I mean your child’s bodily functions are in constant flux, changing and adapting to environmental stresses. It turns out that many of these environmental stresses affect your child’s rate of urine production as well as your child’s ability to wake and deal with a full bladder during sleep. Here are just a few situations to illustrate what I mean. We know that urine production can increase just before and during common illnesses in order to remove an increased amount of chemical wastes your sick child is producing during their sickness. If your child has consumed caffeine that are in things like sodas, tea, coffee, and chocolate, this will also increase their urine production since caffeine is a diuretic. It promotes urine production. Urine production also increases when your child simply has a lot to drink or has consumed foods that contain a lot of water. Additionally, we know that if your child is particularly anxious or overtired, their ability to wake up use the potty isn’t very good. All these situations make staying dry at night more difficult at times, even if they have been mostly dry in the past. Hopefully you now have a better understanding of why intermittently, your child may wet the bed.
Defining the Issue
Doctors don’t start using the term bedwetting until a child is at least 5 years of age since nocturnal bedwetting (also called enuresis) before this age is extremely common and considered normal. If the child has never had a six-month period of night dryness and is above the age of five years, doctors call their bedwetting primary nocturnal enuresis (enuresis meaning urinating). If a child over the age of five years has achieved a period of dryness at night for at least 6 months and then begins wetting again, urologist term their condition secondary nocturnal enuresis. It’s important to note that with secondary enuresis, an underlying medical cause of the nighttime wetting is more likely than in primary enuresis. And finally, a child with urinary accidents during the day is termed as suffering from daytime enuresis. Ok, so now you know the lingo but how common is bedwetting. I just told you that we don’t even start using the term nocturnal bedwetting or enuresis until a child reaches their 5th birthday since this situation is so common in the under 5 year olds as to be considered normal. Here are the percentages of children who bed wet broken down by age:
Age Percentage regularly wetting the bed
5 year of age 25%
12 years 8%
13 and older 3%
Adult army recruits 1%
You can see that the older a child gets, the better the chance they have of having outgrown bedwetting but there are a small percentage of adults who still bed wet.
Does my child need to the pediatrician?
If you have a child who regularly wets the bed and they have reached school age, you probably should discuss this with your child’s pediatrician, especially if they are over the age of six years. While uncommon, there are a number of medical conditions that can manifest as bedwetting. Expect that after your child’s pediatrician takes a good history focused on discovering significant health problems, they will likely check your child’s urine looking for signs of a urinary infection or diabetes. They will also do a physical exam with particular attention noting signs of a spinal cord problem. Remember, part of the control mechanism of your child’s urinary bladder involves the child’s their lower spinal cord. Your child’s doctor will be paying close attention to signs of problems in your child’s lower body such as birthmarks located over their lower spine, stiffness in their legs, toe walking, poor coordination of their legs, or altered muscle reflexes. The chances are that nothing will be found but these things need to be checked. If your child’s urine and examination are normal, their pediatrician will simply reassure you that your child will “outgrow this problem” which they almost always do. Remember, in most children, bedwetting is not a disease, but rather a storage problem along with a developmental immaturity.
What Treatments are available for bedwetting?
Parents who have children who bed wet often feel that their child needs “treatment” for this condition. The truth is that doing nothing other than making sure that their bedwetting is not a sign of a bigger physical problem is all that is necessary for most kids. Time will cure their wetting at night. But if your child is getting frustrated and the wetting is limiting their sleeping at friends homes or going to camp, here are some things you can try to help them:
–Providing them with pull-ups that they can discretely use at night. I don’t believe that using these slows down a child’s ability to learn to stay dry at night and their use is definitely good news for whoever is doing the laundry in the house!
–Setting up a reward system to encourage dryness. Stickers, stars and the like can really motivate some children to make extra effort to stay dry.
–Limiting fluids after 6 pm and getting your child up before you go to bed and encouraging them to urinate is helpful in some cases.
–Some physicians advocate trying a food elimination diet thinking tat some foods irritate a child’s bladder. I have not found this to be very helpful.
–Some physicians also believe that doing bladder stretching exercises can be helpful but I have to say, I am not a big fan of these either but if you want to learn more about how to do bladder exercises, check out this link. Bladder exercise link.
-Making sure that your child is not constipated can help bed wetters since bladder function and capacity and colon health are closely related. These organs are next-door neighbors in your child’s tummy and the size of one affects the other. Remember how often you had to go to the bathroom when you were in late pregnancy. Whether its a large distended uterus or a colon packed with poop pushing on a the urinary bladder, the result can be the same; a urinary bladder with less capacity to store urine.
–Some parents advocate purchasing your little bed wetter a bedwetting alarm system that can train them to wake up the moment the bedwetting begins. There are a number of these systems available and the manufacturers claim they work after a few months of use in about 70% of children. My experience tells me otherwise however but in some children, they can be very helpful.
–And finally, there are a number of medications that are used to prevent bedwetting, the safest and probably most effective of which is something called DDAVP. It comes as a nasal spray or as a tablet and is used in the evening on nights that the family chooses. It is only available by prescription. Chronic daily use of DDAVP is not often done used but rather, the enuretic child uses the DDAVP for camp, sleepovers, or vacations that include travel. Its great for intermittent use. In my experience DDAVP works well, is safe, and well tolerated.
So here is what I want you to remember about bedwetting in children:
–While possible, rarely is bedwetting a sign of a serious physical disorder.
–If your child is 7 years or older and still wets regularly or if they have stopped wetting and then restarted after 6 months of being dry, a visit to their pediatrician is warranted to make sure the wetting isn’t a sign of illness.
–The true cause of bedwetting emanates from the child’s inability to hold a nights worth of urine and their inability to awake during sleep to use the bathroom.
–Treatment of bedwetting is usually not necessary since time and maturation usually resolve the bedwetting problem.
–If a child and their family do want treatment, bedwetting alarm systems and a medication called DDAVP are safe options to try.
Well that wraps up this edition of Portable Practical Pediatrics. If you enjoy exploring topics about child health, by all means subscribe to this podcast at www.docsmo.com and consider writing a short review on iTunes or at the DocSmo.com Facebook page. By doing so, you are helping other parents to find my blog and podcast. This is your pedcast host, Dr. Paul Smolen, reminding you that if your child frequently wakes up wet, there is no reason to fret. Until next time.
Edited by Dr. Monica Miller. Thanks Monica.