Overview

Definition

• Constipation Constipation Constipation is common and may be due to a variety of causes. Constipation is generally defined as bowel movement frequency < 3 times per week. Patients who are constipated often strain to pass hard stools. The condition is classified as primary (also known as idiopathic or functional constipation) or secondary, and as acute or chronic. Constipation is a relative term and depends on a number of factors including frequency, consistency, and difficulty in passage of stool:
  • A hard stool (consistency) passed every 3rd day (frequency) with “difficulty” requires management. 
  • A soft stool that is passed without difficulty every 2–3 days is not constipation.
• The Paris Consensus on Childhood Constipation Constipation Constipation is common and may be due to a variety of causes. Constipation is generally defined as bowel movement frequency < 3 times per week. Patients who are constipated often strain to pass hard stools. The condition is classified as primary (also known as idiopathic or functional constipation) or secondary, and as acute or chronic. Constipation Terminology (PACCT) definition:
  • A period of 8 weeks with at least 2 of the following symptoms: 
    • Defecation < 3/week 
    • Fecal incontinence 2 ⩲/week 
    • Passage of large stools that clog the toilet 
    • Palpable abdominal or rectal fecal mass 
    • Habit of withholding stool
    • Painful defecation

Epidemiology

• Constipation Constipation Constipation is common and may be due to a variety of causes. Constipation is generally defined as bowel movement frequency < 3 times per week. Patients who are constipated often strain to pass hard stools. The condition is classified as primary (also known as idiopathic or functional constipation) or secondary, and as acute or chronic. Constipation of all etiologies:
  • Affects 30% of children
  • Makes up approximately 4% of pediatrician visits
  • Most common in 2–4-year-old children
• Functional constipation:
  • Constitutes 95% of all cases of constipation
  • Most common in preschool-aged children

Etiology

• Functional constipation:
  • Meets clinical PACCT criteria for constipation with no underlying pathologic causes
• A minority (about 5%) may have constipation due to organic causes.

Table: Causes of constipation in children

Nonorganic (functional or retentive)	No underlying pathologic causes
Anatomic	Anal stenosis, atresia with fistula Imperforate anus Anteriorly displaced anus Intestinal stricture (post- necrotizing enterocolitis Necrotizing enterocolitis Necrotizing enterocolitis (NEC) is an intestinal inflammatory process that can lead to mucosal injury and necrosis. The condition is multifactorial, with underlying risk factors that include prematurity and formula feeding. The clinical presentation varies in severity from feeding intolerance, acute findings on abdominal exam, and systemic symptoms. Necrotizing Enterocolitis) Anal stricture
Abnormal musculature	Prune-belly syndrome Gastroschisis Gastroschisis Gastroschisis is a congenital abdominal wall defect characterized by the complete lack of closure of the abdominal musculature. A portion of intestine does not return to the abdominal cavity, thereby remaining in its early embryonic herniated state but with no coverings. Gastroschisis Down’s syndrome Muscular dystrophy
Intestinal nerve or muscle abnormalities	Hirschsprung’s disease Intestinal neuronal dysplasia Spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord lesions Tethered cord Autonomic neuropathy Spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord trauma Spina bifida Chagas disease Chagas disease Chagas disease is an infection caused by the American trypanosome Trypanosoma cruzi. This parasitic protozoan is transmitted in the feces of reduviid bugs in South and Central America. Acute infection may present with inflammation at the inoculation site (chagoma), fever, and lymphadenopathy. Untreated, chronic infection can progress to severe complications. Trypanosoma cruzi/Chagas disease
Metabolic disorders	Hypokalemia Hypokalemia Hypokalemia is defined as plasma potassium (K+) concentration < 3.5 mEq/L. Homeostatic mechanisms maintain plasma concentration between 3.5-5.2 mEq/L despite marked variation in dietary intake. Hypokalemia can be due to renal losses, GI losses, transcellular shifts, or poor dietary intake. Hypokalemia Hypercalcemia Hypercalcemia Hypercalcemia (serum calcium > 10.5 mg/dL) can result from various conditions, the majority of which are due to hyperparathyroidism and malignancy. Other causes include disorders leading to vitamin D elevation, granulomatous diseases, and the use of certain pharmacological agents. Symptoms vary depending on calcium levels and the onset of hypercalcemia. Hypercalcemia Hypothyroidism Hypothyroidism Hypothyroidism is a condition characterized by a deficiency of thyroid hormones. Iodine deficiency is the most common cause worldwide, but Hashimoto's disease (autoimmune thyroiditis) is the leading cause in non-iodine-deficient regions. Hypothyroidism Diabetes mellitus Diabetes mellitus Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus, diabetes insipidus Diabetes Insipidus Diabetes insipidus (DI) is a condition in which the kidneys are unable to concentrate urine. There are 2 subforms of DI: central DI (CDI) and nephrogenic DI (NDI). Both conditions result in the kidneys being unable to concentrate urine, leading to polyuria, nocturia, and polydipsia. Diabetes Insipidus Porphyria
Intestinal disorders	Celiac disease Celiac disease Celiac disease (also known as celiac sprue or gluten enteropathy) is an autoimmune reaction to gliadin, which is a component of gluten. Celiac disease is closely associated with HLA-DQ2 and HLA-DQ8. The immune response is localized to the proximal small intestine and causes the characteristic histologic findings of villous atrophy, crypt hyperplasia, and intraepithelial lymphocytosis. Celiac Disease Cow’s milk protein intolerance Cystic fibrosis Cystic fibrosis Cystic fibrosis is an autosomal recessive disorder caused by mutations in the gene CFTR. The mutations lead to dysfunction of chloride channels, which results in hyperviscous mucus and the accumulation of secretions. Common presentations include chronic respiratory infections, failure to thrive, and pancreatic insufficiency. Cystic Fibrosis (meconium ileus equivalent) Inflammatory bowel disease (stricture) Tumor Connective tissue Connective tissue Connective tissues originate from embryonic mesenchyme and are present throughout the body except inside the brain and spinal cord. The main function of connective tissues is to provide structural support to organs. Connective tissues consist of cells and an extracellular matrix. Connective Tissue disorders Systemic lupus erythematosus Systemic lupus erythematosus Systemic lupus erythematosus (SLE) is a chronic autoimmune, inflammatory condition that causes immune-complex deposition in organs, resulting in systemic manifestations. Women, particularly those of African American descent, are more commonly affected. Systemic Lupus Erythematosus Scleroderma Scleroderma Scleroderma (systemic sclerosis) is an autoimmune condition characterized by diffuse collagen deposition and fibrosis. The clinical presentation varies from limited skin involvement to diffuse involvement of internal organs. Scleroderma
Drugs	Anticholinergics Narcotics Methylphenidate Antidepressants Phenytoin Lead Vitamin D intoxication Chemotherapeutic agents
Psychiatric	Anorexia nervosa Anorexia Nervosa Anorexia nervosa is an eating disorder marked by self-imposed starvation and inappropriate dietary habits due to a morbid fear of weight gain and disturbed perception of body shape and weight. Patients have strikingly low BMI and diverse physiological and psychological complications. Anorexia Nervosa

Pathophysiology

Functional constipation is the most common cause of constipation:  

• Causative psychologic vicious cycle 
• Dietary or environmental factors lead to hardened stool → more painful to pass.
• Bowel movements associated with pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain →  withhold defecation
• Chronic stool holding → accommodation by the rectum Rectum The rectum and anal canal are the most terminal parts of the lower GI tract/large intestine that form a functional unit and control defecation. Fecal continence is maintained by several important anatomic structures including rectal folds, anal valves, the sling-like puborectalis muscle, and internal and external anal sphincters. Rectum and Anal Canal and further hardening of stool
• Reduced sensitization to defecation reflex and less effective peristalsis
• Encopresis (inability to hold stool): 
  • Passage of proximal watery content around compacted stool 
  • May be mistaken for diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea
• May rarely cause urinary stasis
• Chronic severe constipation may have an emotional impact on the patient and family.

Clinical Presentation and Diagnosis

History and exam are performed to rule out any organic causes and reassure the provider that the symptoms in question are due to functional constipation.

History

Toileting patterns:

• Frequency, consistency, size of stools, pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, and association with bleeding are important defining and etiologic clues.
• Fecal incontinence or diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea may indicate encopresis.
• History of frequent urinary tract infections Urinary tract infections Urinary tract infections (UTIs) represent a wide spectrum of diseases, from self-limiting simple cystitis to severe pyelonephritis that can result in sepsis and death. Urinary tract infections are most commonly caused by Escherichia coli, but may also be caused by other bacteria and fungi. Urinary Tract Infections may indicate constipation-induced urinary stasis or vesicoureteral reflux Vesicoureteral Reflux Vesicoureteral reflux (VUR) is the retrograde flow of urine from the bladder into the upper urinary tract. Primary VUR often results from the incomplete closure of the ureterovesical junction, whereas secondary VUR is due to an anatomic or physiologic obstruction. Vesicoureteral Reflux.

Timing of onset of symptoms:

• Dietary transition
• Recent severe illness, dehydration, or diaper rash

Psychosocial stressors:

• Starting a new school
• Family changes (moving, birth of new sibling, or divorce)
• Toilet training

Behavioral cues:

• Squatting 
• Crossing ankles
• Stiffening the body
• Holding onto furniture

Cues pointing to organic etiologies:

• Hirschsprung’s disease:
  • Passage of meconium (1st bowel movement) delayed for more than 24 hours
  • Constipation Constipation Constipation is common and may be due to a variety of causes. Constipation is generally defined as bowel movement frequency < 3 times per week. Patients who are constipated often strain to pass hard stools. The condition is classified as primary (also known as idiopathic or functional constipation) or secondary, and as acute or chronic. Constipation during early months after birth
• Lead poisoning:
  • Pica Pica Pica is an eating disorder characterized by a desire or recurrent compulsion to eat substances that are nonnutritive and not food. These compulsions and ingested substances are inappropriate for age or culture. Pica
  • Developmental delay
  • Living in older home or home with lead-based paint
• Dietary intolerances (e.g., milk protein intolerance, celiac disease):
  • Recent transition from breastfeeding Breastfeeding Breastfeeding is often the primary source of nutrition for the newborn. During pregnancy, hormonal stimulation causes the number and size of mammary glands in the breast to significantly increase. After delivery, prolactin stimulates milk production, while oxytocin stimulates milk expulsion through the lactiferous ducts, where it is sucked out through the nipple by the infant. Breastfeeding to solid food
  • Transition from breast milk to cow milk–based formula
  • Intermittent blood noted in stool

Physical examination

General:

• Growth charts should be reviewed to ascertain appropriate growth: Failure to thrive Failure to Thrive Failure to thrive (FTT), or faltering growth, describes suboptimal weight gain and growth in children. The majority of cases are due to inadequate caloric intake; however, genetic, infectious, and oncological etiologies are also common. Failure to Thrive suggests organic causes of constipation. 
• Dysmorphia and other cues to syndromes should be noted:
  • Down’s syndrome
  • Prune belly syndrome
• Prenatal history suggestive of Hirschsprung’s disease should be reviewed.

Abdominal exam:

• Palpation of left lower quadrant may reveal stool mass.
• Auscultation may reveal hyperactive bowel sounds.

Rectal exam:

• Anal abnormalities may suggest an underlying pathology:
  • Abnormal position of the anus suggests anal atresia.
  • Presence of perineal or sacral dimples or hair tufts suggests spina bifida or a tethered cord.
  • Anal fissures or fistulas
  • Hemorrhoids Hemorrhoids Hemorrhoids are normal vascular cushions in the anal canal composed of dilated vascular tissue, smooth muscle, and connective tissue. They do not cause issues unless they are enlarged, inflamed, thrombosed, or prolapsed. Patients often present with rectal bleeding of bright red blood, or they may have pain, perianal pruritus, or a palpable mass. Hemorrhoids should be noted on inspection.
• Failure to elicit an anal wink (transient contraction) by stroking the perianal skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin may indicate sensory or motor nerve abnormalities:
  • Spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord lesions
  • Tethered cord
  • Autonomic neuropathy
  • Spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord trauma
  • Spina bifida
  • Chagas disease Chagas disease Chagas disease is an infection caused by the American trypanosome Trypanosoma cruzi. This parasitic protozoan is transmitted in the feces of reduviid bugs in South and Central America. Acute infection may present with inflammation at the inoculation site (chagoma), fever, and lymphadenopathy. Untreated, chronic infection can progress to severe complications. Trypanosoma cruzi/Chagas disease
• Digital rectal examination: 
  • Large, firm stool mass in the rectum Rectum The rectum and anal canal are the most terminal parts of the lower GI tract/large intestine that form a functional unit and control defecation. Fecal continence is maintained by several important anatomic structures including rectal folds, anal valves, the sling-like puborectalis muscle, and internal and external anal sphincters. Rectum and Anal Canal in many patients with functional constipation
  • Small, empty rectum Rectum The rectum and anal canal are the most terminal parts of the lower GI tract/large intestine that form a functional unit and control defecation. Fecal continence is maintained by several important anatomic structures including rectal folds, anal valves, the sling-like puborectalis muscle, and internal and external anal sphincters. Rectum and Anal Canal in Hirschsprung’s disease
  • A gush of liquid stool may occur following a digital rectal exam in patients with Hirschsprung’s disease. 

Neurologic exam: 

• Absent cremasteric reflex (pulling up of the ipsilateral testicle while stroking the thigh Thigh The thigh is the region of the lower limb found between the hip and the knee joint. There is a single bone in the thigh called the femur, which is surrounded by large muscles grouped into 3 fascial compartments. Thigh in boys) 
• Abnormal tone of the lower extremity: muscular dystrophy 

Diagnosis

In an otherwise healthy child, functional constipation is diagnosed clinically. Laboratory examination should be directed by cues suggesting other pathologic causes:

• Laboratory testing: not indicated unless an organic cause is suspected
• Abdominal radiographs: 
  • Not performed routinely
  • In special circumstances, radiographs may show a burden of a stool mass, especially when overflow diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea is suspected or physical examination is refused.
• Single-contrast enema (not air-contrast enema) with abdominal radiographs: 
  • May assist in the diagnosis of Hirschsprung’s disease 
  • Transitional zone from a narrow (aganglionic) distal segment to a distended (ganglionic) proximal segment is consistent with the diagnosis.
• Anorectal manometry: 
  • A rectal balloon is inserted and inflated to measure rectal pressure.
  • Can be helpful in diagnosing neurologic causes of constipation 
• Rectal biopsy: Absent ganglionic cells in the affected colon Colon The large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal. Colon, Cecum, and Appendix confirms a diagnosis of Hirschsprung’s disease.