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Elimination disorders: Clinical practice

Elimination disorders: Clinical practice


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USMLE® Step 1 style questions USMLE

1 questions

USMLE® Step 2 style questions USMLE

9 questions

An 8-year-old girl comes to the clinic because of monosymptomatic enuresis for the past 3 months. She has a 2 year history of ADHD that is currently well-managed with medication. A detailed patient history and physical examination, as well as a fluid intake, stool and voiding diary show no abnormalities. Urinalysis is unremarkable. The parent and child are referred for education and behavioral therapy. The enuresis decreases, but persists. Which of the following pharmacological therapies is most appropriate for treating this patient's disorder?


Content Reviewers:

Rishi Desai, MD, MPH

Elimination disorders involve the elimination of feces - encopresis - or urine -enuresis, and they usually occur in children who struggle with going to the bathroom.

Although it is not uncommon for them to have occasional "accidents", when these behaviors occur for longer than three months particularly in children older than 5 years, they might have an elimination disorder.

There are many predisposing factors, including genetics, psychological factors, delayed or lax toilet training, and psychosocial stress.

Enuresis has been associated with delays in the development of normal circadian rhythms of urine production, resulting in nocturnal polyuria, and with reduced functional bladder capacities and bladder hyperreactivity.

In encopresis, painful defecation can lead to constipation and a cycle of withholding behaviors that make encopresis more likely.

Constipation may develop for psychological reasons like anxiety about defecating, a more general pattern of anxiety, dehydration associated with a febrile illness, hypothyroidism, or medication side effect like anticonvulsants.

Once constipation has developed, it may be complicated by an anal fissure, painful defecation, and further fecal retention.

Although there are minimum age requirements for diagnosis, these are based on developmental age or ‘mental age’ and not solely on chronological age or ‘real age.’

Both encopresis and enuresis may be voluntary or involuntary, and although they typically occur separately, they might also co-occur.

Associated symptoms include low self-esteem, loss of appetite, abdominal pain, decreased interest in physical activity and withdrawal from friends and family as children often feel ashamed and end up avoiding situations that can lead to embarrassing accidents like at school or camps.

According to DSM-5, there are four elimination disorders including enuresis, encopresis, other specified elimination disorder, and unspecified elimination disorder.

So first, in enuresis, individuals repeatedly pee in their bed or on their clothes, and it’s either involuntary or intentional.

Second, the behavior is clinically significant either because it occurs at least twice a week for at least 3 consecutive months or because it causes significant distress or impairment.

Third, the individuals are at least five year old or the equivalent developmental level.

Lastly, the behavior shouldn’t be attributable to the physiological effects of a substance like diuretics, or to another medical condition such as diabetes which can associate polyuria due to the osmotic effects of glucose.

There are three types of enuresis.

The nocturnal-only subtype of enuresis, which is sometimes referred to as monosymptomatic enuresis, is the most common one and involves incontinence only during nighttime sleep, typically during the first few hours of the night.

The diurnal-only subtype occurs in the absence of nocturnal enuresis and may be referred to as urinary incontinence.

The nocturnal-and-diurnal subtype is a combination of the first two and is also known as nonmonosymptomatic enuresis.

Second is encopresis, and it requires repeated passage of feces into inappropriate places like in the clothes or on the floor, whether involuntary or intentional.

Second, at least one such event occurs each month for at least 3 months.

Third, the chronological age is at least 4 years or the equivalent developmental level.

And lastly, the behavior should not be attributable to the physiological effects of a substance like laxatives or another medical condition except if they cause constipation and not the passage of feces behavior.

Encopresis has two main subtypes.

First, in the ‘with constipation and overflow incontinence subtype,’ the feces are poorly formed, and leakage occurs mostly during the day and only rarely during sleep.

In the ‘without constipation and overflow incontinence subtype,’ feces usually have a normal form and consistency, and soiling is intermittent.

Other specified elimination disorder applies to presentations in which symptoms characteristic of an elimination disorder cause distress and impairment but do not meet the full criteria for any of them and the clinician chooses to communicate the specific reason they don’t.

If the clinician chooses not to specify the reason, then the diagnosis is unspecified elimination disorder.

Imaging and laboratory findings can provide additional information and help eliminate other disorders that present the same symptoms, but they are not routinely used for diagnosis.

In enuresis, gastrointestinal imaging like abdominal radiography can help assess bladder dysfunction, where the most common findings are radiopaque calculi.

Other urologic imaging like renal sonogram and voiding cystourethrogram is reserved for children who have significant daytime complaints, a history of UTI, and symptoms of structural urologic abnormalities.

Ultrasonography may be helpful in determining post-void residual volume and bladder wall thickness.

Urinalysis should be performed in all children with monosymptomatic enuresis to screen for diabetic ketoacidosis, diabetes insipidus, water intoxication, or occult.

Urine culture is not necessary unless indicated by the presence of white blood cells or nitrites on urinalysis.

In encopresis, tests such as barium enema and anorectal monography may be used to help exclude other medical conditions, like Hirschsprung's disease which is a developmental disorder characterized by the absence of ganglia in the distal colon, resulting in a functional obstruction.