Pediatric emergency medicine trisk 115

other signs of infection, a subarachnoid hemorrhage may be the cause. Common
avoidable errors in the evaluation and management of children with coma are
listed in Table 17.6 .
TABLE 17.6
COMMON ERRORS IN THE EVALUATION AND MANAGEMENT OF
CHILDREN WITH COMA
Assuming no head trauma has taken place if no such history is given
Neglecting to secure the airway before imaging studies are performed
Hyperventilating intubated patients to a Pco2 well below 35 mm Hg
Not sedating patients once they are paralyzed and intubated
Believing that a toxic ingestion has not occurred because the “tox screen” is
negative
Suggested Readings and Key References
Ashwal S. In: Swaiman KF, ed. Disorders of Consciousness in Children.
Pediatric Neurology: Principles & Practice . 6th ed. Elsevier; 2018:e1741–
e1773.
Moler FW, Silverstein FS, Holubkov R, et al. Therapeutic hypothermia after inhospital cardiac arrest in children. N Engl J Med 2017;376(4):318–329.
Richards JR, Smith NE, Moulin AK. Unintentional cannabis ingestion in
children: a systematic review. J Pediatr 2017;190:142–152.


CHAPTER 18 ■ CONSTIPATION
SARANYA SRINIVASAN, JAIME L. VELASCO MASSON

INTRODUCTION
Constipation is one of the most common complaints in the pediatric emergency
department, accounting for 3% of primary care visits. There are many causes of
constipation ( Table 18.1 ), some rare and some very common ( Table 18.2 ).
Most constipation in children is functional, meaning that no underlying medical
disease can be identified. Occasionally, the presentation of constipation is
atypical, with chief complaints that superficially seem unrelated to the

gastrointestinal tract ( Table 18.3 ). Although relatively rare, some causes of
constipation are potentially life-threatening and need to be recognized promptly
by the emergency physician ( Table 18.4 ). In addition, constipation may produce
symptoms that mimic other serious illnesses such as appendicitis.

DEFINITION
Although constipation most commonly is defined as decreased stool frequency,
the definition is not simple. The stooling pattern of children changes based on
age, diet, and other factors and there exist a variety of “normal” stooling patterns.
Average stooling frequency in healthy infants is approximately four stools per
day during the first week of life, decreasing to 1.7 stools per day by 2 years of
age, and approaching the adult frequency of 1.2 stools per day by 4 years of age.
Nevertheless, normal infants can range from seven stools per day to one stool per
week. It is normal for older children to defecate every 2 to 3 days.
It is easier to define constipation as a problem with defecation. This may
encompass infrequent stooling, passage of large and/or hard stools associated
with pain, incomplete evacuation of rectal contents, involuntary soiling
(encopresis), or the inability to pass stool.

PHYSIOLOGY
The passage of food from mouth to anus is a complex process that relies on input
from intrinsic nerves, extrinsic nerves, and hormones. The colon is specifically
designed to transport fecal material and balance water and electrolytes contained
in the feces. When colonic function is normal, the fecal bolus arrives in the
rectum formed but soft enough to easily pass through the anus. Normal defecation
requires the coordination of the autonomic and somatic nervous systems and
normal anatomy of the anorectal region. The internal anal sphincter is a smooth


muscle, innervated by the autonomic nervous system and contracted at baseline.

It relaxes involuntarily in response to the arrival of a fecal bolus in the rectum,
allowing stool to descend into the portion of the anus innervated by somatic
nerves. At this point, the external anal sphincter, striated muscle under voluntary
control, tightens until the appropriate time for fecal passage. Before defecation,
squatting or sitting straightens the angle between the rectum and anal canal,
allowing easier passage. Voluntary relaxation of the external anal sphincter and
increasing intra-abdominal pressure via Valsalva allow passage of the feces.

EVALUATION AND DECISION
The evaluation of the child presumed to have constipation should begin with a
thorough history and physical examination. Special attention should be paid to the
age of the patient, duration of symptoms, timing of first meconium passage after
birth, changes in frequency and consistency of stool, stool incontinence, pain with
defecation, rectal bleeding, presence of abdominal distention, and/or palpable
feces. A rectal examination to assess anal position, sphincter tone, widening of
the rectal vault, and presence of hard stool is also helpful. Signs and symptoms
concerning for more serious underlying pathology include onset of constipation in
the first month of life, delayed meconium passage >48 hours, ribbon-like stools,
blood in the stool without an anal fissure, failure to thrive, bilious emesis, fever,
severe abdominal distention, an abnormally positioned/appearing anus, or an
abnormal neurologic examination.
A complaint of constipation is not adequate to make the diagnosis. A decrease
in stool frequency or the appearance of straining is often interpreted as
constipation. The physician should be aware of the grunting baby syndrome, or
infant dyschezia, in which an infant grunts, turns red, strains, and may cry while
passing a soft stool. This is the result of poor coordination between the Valsalva
maneuver and relaxation of the voluntary sphincter muscles. Examination reveals
the absence of palpable stool in the rectum or abdomen. Complaints of
constipation not supported by history or physical examination are called
pseudoconstipation ( Fig. 18.1 ).

Acute Constipation
Constipation is not a disease; it is a symptom of a problem. Constipation is acute
when it has occurred for less than 1 month in duration. The patient’s age and the
duration of the constipation are important in determining the cause and
significance of the problem.
The infant younger than 6 months of age with acute constipation is particularly
concerning. Potential causes include dehydration, malnutrition, infant botulism,


and anorectal malformations. Constipation is often the first presenting sign in
infant botulism. A recent viral illness accompanied by dehydration from
vomiting, diarrhea, fever, and increased respiratory rate can precipitate acute
constipation in an infant. Paralytic ileus or decreased intake after gastroenteritis
may slow transit through the colon, leading to hard stools. Dietary protein allergy
(i.e., cow’s milk protein allergy) may also present with constipation. Anal fissures
and/or diaper rash after a bout of diarrhea may precipitate painful defecation,
resulting in stool retention.