The urinary system is one of the most vital in the human body. It has 2 functions: to filter waste and excess water from our blood to form urine and to return salt and other important chemicals to the blood. It is of extreme importance to your health that the urinary system functions properly.
The urinary system consists of a pair of kidneys, 2 ureters, a bladder, a urinary sphincter muscle, and a urethra. The kidneys are made of special filtering tissue through which all of the body's blood passes several times a day. They strain the useful material from the blood and send excess water and waste material down 2 thin tubes (ureters) to the bladder. Each ureter has a flap of skin on the end of it which closes to prevent urine from flowing backwards up the ureters into the kidney.
Diagram of normal emptying bladder compared to an incompletely emptying bladder
The bladder is a muscle lined sac. The muscle, called the detrusor, remains relaxed creating a low-pressure reservoir for the urine until urination occurs. A 12-year old's bladder capacity is about 300-400 mL. A 3- or 4-year-old's is about half this. The outlet from the bladder is a small tube called the urethra. It is longer in boys than girls, because it passes through the penis. The urethra is surrounded by 2 small circular muscles called sphincters, which remain contracted until urination. One of these operates involuntarily, and the other voluntarily, ie. we can control it.
When the bladder is full sensory receptors tell the brain via the nerves in the spinal cord that the bladder needs emptying. When the person is ready to go to the toilet, the brain sends messages via the nerve pathways to the bladder muscle and sphincter. It coordinates the contracting of the bladder muscle with the relaxation of the sphincter muscle. This discharges urine from the body.
A person with spina bifida is usually born with an undamaged urinary system but with an interrupted nerve supply between it and the brain. This is called neurogenic or neuropathic bladder.
Nerve damage can result in impairment to either or both the bladder muscle and the urinary sphincters. The bladder muscle can be such that it cannot contract (ie it is always relaxed) or overactive and the sphincters (especially the voluntarily controlled one) uncontrollable and either too relaxed or too tight. It is rare for the bladder muscle to be flaccid and the sphincter muscle too tight.
There are basically 3 common scenarios.
1. A bladder with a muscle which cannot contract combined with a sphincter which is too relaxed. This is the most common situation for people with spina bifida.
2. An overactive bladder with a sphincter which is too relaxed. This also results in unpredictable discharge of urine and incomplete bladder empyting.
3. An overactive bladder with a sphincter which does not relax. This is a dangerous situation because when the bladder contracts, the urine cannot get past the tight sphincter and is forced through the small valves at the bottom of the ureters back up into the kidneys. As well as the damage that this high pressure can do to the urinary system, urine in the kidneys can cause serious kidney infections. Repeated infections substantially damage the kidneys and impair their filtering capabilities, leading to a reduced ability to filter wastes from the body.
It is very important for health that the bladder is completely emptied regularly. Urine that remains in the bladder provides an excellent breeding ground for bacteria, which thrive in warm, damp conditions.
The signs of a urinary tract infection are cloudy or discoloured urine, fever, chills and shakes, headache, fatigue, nausea, pain and an increased frequency and need to urinate.
A person with spina bifida who has paralysis in the lower extremities should monitor the appearance of their urine carefully since they may not be able to feel the first warning signs of a urinary tract infection, pain while urinating.
Urinary incontinence will usually affect those children who have the most serious type of spina bifida, myelomeningocele. It may also affect those children with the less serious types of spina bifida, spina bifida occulta and meningocele.
N.B. A combination of the above strategies is usually required to successfuly manage urinary continence.
The key to a healthy urinary system is frequent complete empyting
Clean intermittent catheterisation is the process in which the bladder is drained several times a day (usually every 4 hours during waking hours) with a catheter using a clean but non-sterile technique.
Clean intermittent catheterisation helps the urinary system by facilitating complete bladder emptying, reducing constant urinary leakage and protecting the kidneys from damage.
Training in independent clean intermittent catheterisation is usually started when a child is at kindergarten or preschool. Most children can be reasonably independent by 8 years of age.
Children should still see their urologist or paediatrician regularly to monitor kidney and bladder function.
The human body is designed to rid itself of waste products. If we do not rid ourselves of waste material we can become very ill. The organs which help our body cleanse itself of waste are part of the lower digestive system and are often called the ‘bowels’.
The bowel consists of the small intestine, the large intestine, the rectum, internal and external anal sphincters and the anal canal. The large intestine (the colon) stores the waste material in liquid form and moves it along towards the rectum by a series of waves and contractions known as peristalsis. While the faeces is in the colon, excess water is removed from it until it forms the consistency of a stool. The internal anal sphincter located below the rectum, opens automatically when it senses that there are faeces in the rectum. Nerves located in the anal canal send a message to the brain that a bowel movement is required. When it is convenient the brain tells the external sphincter to relax and the rectum and the stomach muscles to contract. The faeces is then discharged from the body. We usually learn to control this process between the ages of one and three.
The bowel system
Almost all people born with spina bifida have bowel problems. As with most of the conditions associated with spina bifida, bowel problems are a result of damaged nerves at the bottom of the spinal cord. Nerve damage generally affects 3 areas of the bowel:
In a normally operating bowel the external sphincter will contract when the rectum is full and hold the faeces in the anal canal. However, because there is little or no control over the external anal sphincter for a person with spina bifida, faeces can be discharged or flow from the body unexpectedly.
The interrupted nerve supply to the colon also means that the liquid faeces do not progress as quickly through the colon as it normally would. The longer time spent in the colon leads to more water than usual being extracted from the faeces, turning it into a very hard consistency and leading to constipation.
Even though a person is constipated, the liquid faeces moving into the top of the colon can work its way past the dry faecal mass and leak out. This 'overflow' diarrhoea makes it appear that the person is not constipated at all. This type of diarrhoea is common for people with spina bifida and when it happens, the person should be checked for constipation.
The overall aims of bowel management programs are:
The child with spina bifida will probably have some problem with continence and will need:
The system that is in place should always maintain the dignity of the child.
Bladder augmentation - A surgical procedure in which a section of the bowel is taken and sewn onto a surgically created opening in the bladder to increase its capacity.
Perineal urethrostomy - The creation of an opening for the urethra in the perineum for ease of catheterisation.
Artificial urinary sphincter - A surgical procedure in which a small fluid filled cuff is placed around the neck of the urethra. A pump is also inserted which when activated, releases the pressure of the cuff allowing urine to flow.
MACE (or ACE) - The creation of a stoma (opening) for easy access into the caecum or top of the large bowel in order to irrigate (wash out) the bowel. The appendix is often used as the duct between the opening and the bowel.
Megacolon - An overstretched piece of bowel resulting from the accumulation of too much dry hard faeces.
Last Reviewed: 03 December 2014