19. (Illustrated) Urinary tract disorders - Enuresis

Question 1

Daytime enuresis (1/2)

What is daytime enuresis?
What may it be caused by? (7)

Answer 1

This is a lack of bladder control during the day in a child old enough to be continent (over the age of 3–5 years). Nocturnal enuresis is also usually present. It may be caused by:

• Lack of attention to bladder sensation: a manifestation of a developmental or psychogenic problem, although it may occur in otherwise normal children who are too preoccupied with what they are doing to respond to the sensation of a full bladder.
• Detrusor instability (sudden, urgent urge to void induced by sudden bladder contractions).
• Bladder neck weakness.
• A neuropathic bladder (bladder is enlarged and fails to empty properly, irregular thick wall, and is associated with spina bifida and other neurological conditions).
• A UTI (rarely in the absence of other symptoms).
• Constipation.
• An ectopic ureter, causes constant dribbling and child is always damp.

Question 2

Daytime enuresis (2/2)

What is a neuropathic bladder?
Sensory loss in which dermatomes should be sought?
Girls who are dry at night but wet on getting up are likely to have…
What investigations can be performed?
Management

Answer 2

Examination may reveal evidence of a neuropathic
bladder, i.e. the bladder may be distended, there
may be abnormal perineal sensation and anal tone,
or abnormal leg reflexes and gait.

Sensory loss in the distribution of the S2, S3, and S4 dermatomes should be sought. A spinal lesion may be present.

Girls who are dry
at night but wet on getting up are likely to have pooling
of urine from an ectopic ureter opening into the vagina.

Investigations:

• A urine sample should be examined for microscopy, culture, and sensitivity. Other investigations are performed if indicated.
• An ultrasound may show bladder pathology, with incomplete bladder emptying or thickening of the bladder wall.
• Urodynamic studies may be required.
• An X-ray of the spine may reveal a vertebral anomaly.
• A MRI scan may be required to confirm or exclude a spinal defect such as tethering of the cord.

Management:

Affected children in whom a neurological cause has
been excluded may benefit from star charts, bladder
training, and pelvic floor exercises. Constipation should
be treated. A small portable alarm with a pad in the pants,
which is activated by urine, can be used when there is
lack of attention to bladder sensation. Anticholinergic
drugs, such as oxybutynin, to dampen down bladder
contractions, may be helpful if other measures fail.

Question 3

Secondary (onset) enuresis

The loss of previously achieved urinary continence may be due to:… (3)
Investigation should include:… (3)

Answer 3

The loss of previously achieved urinary continence may
be due to:

• Emotional upset, which is the most common cause.
• UTI.
• Polyuria from an osmotic diuresis in diabetes mellitus or a renal concentrating disorder, e.g. sickle cell disease or chronic kidney disease or very rarely diabetes insipidus, which can be central or nephrogenic.

Investigation should include:

• Testing a urine sample for infection, glycosuria, and proteinuria using a dipstick.
• Assessment of urinary concentrating ability by measuring the osmolality of an early morning urine sample. Rarely, a formal water deprivation test may be needed to exclude a urinary concentrating defect.
• Ultrasound of the renal tract.