What Are Complications of Cerumen?

Patient Presentation
A 17-year-old male went to an urgent care center with a 12 hour history of right ear pain that was not improving. The pain woke him up from sleep and he was able to return to sleep after some acetaminophen. The pain still woke him a few more times during the night, and was described as a constant, dull pain that was not improving over the rest of the day. He denied any discharge from the ear, popping sounds or acute hearing loss. He denied any trauma or placing anything into the ear. He did say that maybe he felt some water in the right ear. He was on his second day of vacation in Florida and had been swimming in the ocean and a pool the day before, and had not been scuba diving. The past medical history showed some acute ear infections as a young child. The review of systems was negative.

The pertinent physical exam showed a healthy male in no acute distress with normal vital signs. His left ear had moderate cerumen in the external canal and a normal tympanic membrane. The right ear was totally occluded with wax. The right ear was irrigated with warm water which returned a large amount of pelleted amber colored cerumen. Most of the pain immediately improved after irrigation. The external canal had some erythema near the tympanic membrane, but the tympanic membrane itself was not reddened and there was no middle ear effusion present. The diagnosis of cerumen impaction causing pressure along with mild otitis externa was made. The patient was prescribed ofloxacin otic drops and given instructions to use the drops until there was no pain but for at least 48 hours. He was also give instructions about how to prevent cerumen accumulation. He did endorse that he had used cotton-tipped swabs to try to self-clean his ears over the past several months during this discussion and was told not to do this.

Discussion
Cerumen or ear wax is produced in the outer third of the external auditory canal. It contains exfoliated squamous epithelium along with waxy substances. It is controlled by autosomal alleles and has two main phenotypes – “wet” cerumen which is dominant and common in Caucasian and African populations, and “dry” cerumen which is recessive and found more often in Asian populations. Cerumen protects the external canal and has some antibacterial and antifungal properties including against strains of Staphylococcus aureus, Pseudomonas aeroginosis, and Candida albicans. Staphylococcus aureus and Pseudomonas aeroginosis are the most common causes of otitis externa.

The external auditory canal is a self cleaning mechanism which is assisted by jaw movement. It helps to trap dirt and keep out water. When this self cleaning system fails, cerumen accumulation and potential impaction can occur. Cerumen impaction is defined as “…accumulation that causes symptoms and prevents the needed assessment of the ear canal/tympanic membrane or audiovestibular system or both.” Cerumen impaction is common in children,the elderly and also in developmentally disabled populations.

Treatment is by use of cerumenolytics, aural irrigation or manual removal.

  • “Cerumenolytics work by hydrating the desquamated sheets of keratinocytes and by inducing keratinolysis causing disintegration of the cerumen.”
    A Cochrane Collaboration review found that cerumenolytics were better than no treatment for cerumen impaction but no particular product was recommended over another. A meta-analysis of two high quality trials found a statistical difference in favor of using triethanolamine polypeptide drops over saline though.
    Cerumenolytics usually need several treatments to be successful and should never be used if there is any suspicion that the tympanic membrane is perforated.

  • Aural irrigation with warm water or saline is often used. Sometimes it is used after a cerumenolytic. Problems can occur because of pain or irritation with the irrigations.
    Irrigation should not be attempted if there is any concern for tympanic membrane perforation.

  • Manual removal by curette, suction or other instrumentation is also used frequently. This requires a cooperative patient so as not to cause trauma.
    Studies have found that manual removal does not increase the risk of otitis externa.

Cerumen impaction can be prevented by not placing anything into the canal and also by various ceruminolytics.

Learning Point

Cerumen build up and even impaction usually do not cause problems but they can occur. The cerumen in this patient probably absorbed water while swimming and therefore he developed pain because of the expanded mass. A mild otitis externa also appeared to be developing and was treated.

Complications of cerumen can include conductive hearing loss, irritation, infection (otitis externa), itching, pain, ear fullness, tinnitus, dizziness, and vertigo, and has been associated with chronic cough.

An overview of otitis externa can be found here and complications of otitis media can be found here.

Questions for Further Discussion
1. What organisms cause otitis media?

2. What causes acute hearing loss? A differential diagnosis can be found here.

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for these topics: Ear Disorders and Ear Infections.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Dimmitt P. Cerumen removal products. J Pediatr Health Care. 2005 Sep-Oct;19(5):332-6.

Saloranta K, Westermarck T. Prevention of cerumen impaction by treatment of ear canal skin. A pilot randomized controlled study. Clin Otolaryngol. 2005 Apr;30(2):112-4.

Lum CL, Jeyanthi S, Prepageran N, Vadivelu J, Raman R. Antibacterial and antifungal properties of human cerumen.
J Laryngol Otol. 2009 Apr;123(4):375-8.

Burton MJ, Doree C. Ear drops for the removal of ear wax.
Cochrane Database Syst Rev. 2009 Jan 21;(1):CD004326.

Guidi JL, Wetmore RF, Sobol SE. Risk of otitis externa following manual cerumen removal. Ann Otol Rhinol Laryngol. 2014 Jul;123(7):482-4.

Soy FK, Ozbay C, Kulduk E, Dundar R, Yazıcı H, Sakarya EU. A new approach for cerumenolytic treatment in children: In vivo and in vitro study. Int J Pediatr Otorhinolaryngol. 2015 Jul;79(7):1096-100.

Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa Children’s Hospital

What is a Ganglion Cyst?

Patient Presentation
A 16-year-old male came to clinic with a 2 week history of a mass on the inside of his wrist. He had noticed it when he was keyboarding. He denied pain, irritation, redness, warmth or limitation of motion of the wrist. He also thought that it wasn’t getting larger but wasn’t going away. The past medical history and review of systems was non-contributory.

The pertinent physical exam showed a well-appearing male with normal vital signs and growth parameters. There was a ~10 mm round, mobile mass along the lateral, palmer aspect of the wrist. It was non-tender without changes in the overlying skin. He had complete range of motion that did not elicit tenderness. The mass transilluminated. The diagnosis of a ganglion cyst was made. The natural history of this potentially becoming larger or receding was discussed. Potential future options such as aspiration or surgery were also discussed but the family was told that they could often recur. The patient wanted to wait and watch.

Discussion

Lumps and bumps in the pediatric age group are most often benign. They can be from unwitnessed/unrecognized trauma (e.g. leg bruise, Osgood-Schlater disease, insect bites), normal pubertal changes (e.g. gynecomastia, testicular enlargement, acne) or normal variants (e.g. prominence of mastoid or occipital process). Some are often uncomplicated but need appropriate treatment (e.g. early abscess formation, inguinal hernia, dermoid cyst). Prominent lymph nodes are a very common reason for parents to come to the physician. Patients and families are often distressed by these masses and seek help because “they weren’t there before” or “they’re not going away.” They are often surprised to find out that the mass is benign or normal but are happily reassured.

Learning Point
Ganglion cysts (GC) are cystic masses that can overlying a tendon, ligament, joint and occasionally a bone. They are benign but because of size or location may need treatment. GC are not considered true cysts as they do not have an epithelial cell lining. The etiology is unclear but the walls are made up of smooth muscle cell variants and there is mucinous fluid within. They can be solitary or multilobulated. Often they are not palpable and are found secondary to evaluation for other problems. GC can occur anywhere in the appendicular skeleton but wrists are a very common location and are the most common cause of wrist soft tissue masses in the general population. The incidence in the pediatric population is not known. Adults have more lesions on the dorsal surface and adolescents have more on the palmar surface. They can occur at any age in the pediatric age group and are more common in adolescents. In the pediatric age group, females have them more than males.

GC usually has low morbidity with potential spontaneous resolution and unfortunately a relatively high recurrence rate after various interventions. Evaluation may including imaging with ultrasound or magnetic resonance imaging (MRI) and both have equal effectiveness but ultrasound is significantly more cost effective. In a study of pediatric patients who had MRI imaging of their wrist, ~ 1/3 had a GC. Many had pain (82.9%), swelling (20%) or a palpable mass (11.4%). Most also had other significant wrist abnormalities and it was difficult to ascertain if these wrist symptoms were due to GC or GC was an incidental finding.

Interventions include aspiration, puncture rupture, steroid injection, open or arthroscopic excision. In a prospective study of adults with GC, 70 months after reassurance or treatment, the GC often did not resolve (58%) and 39% had recurrence after intervention. Patients who had intervention were more satisfied overall than patients who were reassured though. Surgical complications were 7.7%. Treatment costs obviously increased with intervention because of radiology, pathology and surgery costs.

GC are sometimes called “bible bumps” because laypeople would take the largest book they had in the house (i.e. a bible or similar book) and smash the lesion to treat it. This form of treatment is NOT recommended.

Questions for Further Discussion
1. What are common benign and malignant bone masses in adolescents?
2. What are indications for referral for a mass to a surgeon?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Wrist and Hand Disorders

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Dias JJ, Dhukaram V, Kumar P. The natural history of untreated dorsal wrist ganglia and patient reported outcome 6 years after intervention. J Hand Surg Eur Vol. 2007 Oct;32(5):502-8.

Gant J, Ruff M, Janz BA. Wrist ganglions. J Hand Surg Am. 2011 Mar;36(3):510-2.

Bracken J, Bartlett M. Ganglion cysts in the paediatric wrist: magnetic resonance imaging findings. Pediatr Radiol. 2013 Dec;43(12):1622-8.

O’Valle F, Hernandez-Cortes P, Aneiros-Fernandez J, Caba-Molina M, Gomez-Morales M, Camara M, Paya JA, Aguilar D, del Moral RG, Aneiros J. Morphological and immunohistochemical evaluation of ganglion cysts. Cross-sectional study of 354 cases. Histol Histopathol. 2014 May;29(5):601-7.

Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa Children’s Hospital

What Causes Pelvic Pain?

Patient Presentation
A 15-year-old female came to the emergency room with abdominal pain for about 1 day. She describes the pain as at the lower right abdomen but said that it felt “even deeper” into her pelvis. The pain was constant and increasing in intensity without radiation. She had vomited twice after the pain began that was non-bilious and non-bloody. She was not eating but was trying to drink despite feeling quite nauseous. She denied any dysuria, but had a temperature of up to 102°F. She had had a normal bowel movement just before the pain began and had no history of constipation. During a private interview she confided that she had become sexually active with 1 male partner about 3 months ago and didn’t use condoms consistently or any other form of birth control. Her last intercourse was just before her normal period about 2 1/2 weeks previously and she had noticed increased vaginal discharge since around that time. She could not further describe the discharge. The past medical history was non-contributory. The family history was negative. The review of systems was negative for diarrhea and rashes, There were no previous surgeries.

The pertinent physical exam showed a cooperative adolescent in moderate pain. Her temperature was 101.7°F., pulse of 128, respiratory rate of 30 and had a normal blood pressure. HEENT, lungs and heart were non-contributory. Abdominal examination showed tenderness in the right lower quadrant especially near the pelvis with positive guarding and positive rebound tenderness. There was no abdominal rigidity. Her liver was non-tender and spleen was not palpable. She had no masses. There was no change with straight leg lifts or other skeletal maneuvers. Her external genital examination was negative. Her pelvic examination showed a yellow, slightly smelly vaginal discharge including some from the cervix. She had mild cervical motion tenderness without obvious masses or tenderness of the left ovaries or uterus. The right lower pelvic area was difficult to examine because of patient cooperation secondary to pain.

A working diagnosis of pelvic inflammatory disease versus appendicitis was considered. The laboratory evaluation showed a normal pregnancy test, liver function tests, amylase, lipase, electrolytes, BUN and creatinine. Her urinalysis had a specific gravity of 1.025, pH of 6 with negative nitrites and leukocyte esterase. Urine testing was positive for chlamydia, but negative for gonorrhea. An HIV performed later was negative. Her complete blood count had a normal hemoglobin, hematocrit and platelets. Her white blood cell count was 18.4 x 1000/mm2 with a 65% left shift. Her C-reactive protein was 2.5 mg/dl. The radiologic evaluation of an abdominal ultrasound was positive for an enlarged appendix. Over the next few hours the patient’s clinical course had her taken to the operating room where she had an uneventful appendectomy performed. The uterine structures appeared normal under direct visualization and palpation. She was discharged 48 hours after surgery because of post-op emesis. She was also treated for chlamydia, started on Depo-Provera® for contraception and was counseled about consistent use of condoms to prevent sexually transmitted infections. Treatment was arranged for her partner. Followup with adolescent medicine and surgery was arranged before discharge.

Discussion
Appendicitis results from a closed loop obstruction of a blind-ending tubular structure arising from the cecum. It is a common cause of abdominal pain. It is the most frequent condition leading to emergent abdominal surgery in pediatrics. The combination of obstruction, edema, bacterial overgrowth, increased inflammatory process and increased intraluminal pressure leads to abdominal pain and possibly perforation. Appendicitis occurs in all age groups but is rare in neonates. The peak age is 6-10 years old.

Pelvic inflammatory disease (PID) is an inflammatory disease of the uterus, fallopian tubes and adjacent pelvic structures caused by ascending microorganisms from the vagina and cervix particularly Neisseria gonorrhea and Chlamydia trachomatis. Increased risks for PID includes early age at first intercourse, multiple sexual partners, intrauterine device insertion and tobacco smoking. The Centers for Disease Control’s Sexually Transmitted Disease Treatment Guidelines can be found here.

The causes of pelvic pain and abdominal pain necessarily overlap a great deal due to the proximity of anatomic structures as this case illustrates.

Acute pelvic pain is defined as 6 months of noncyclic pain that is at the umbilicus or lower.

Complete histories and good general physical examinations are important to guide the differential diagnosis. Pelvic examination may or may not be indicated. Laboratory testing especially to determine pregnancy status also helps guide diagnosis. General testing such as complete blood counts, C-reactive protein and Erythrocyte sedimentation rates can be helpful in addition to urine testing for sexually transmitted diseases. Imaging particularly by ultrasound is also important to narrow the diagnosis and determine treatment plans.

Learning Point
The differential diagnosis of pelvic pain includes:

  • Acute pelvic pain
    • Non-pregnant
      • Simple ovarian cysts
      • Ruptured or hemorrhagic ovarian cysts
      • Pelvic inflammatory disease
      • Endometritis
      • Pelvic abscesses – tubo-ovarian abscesses
      • Ovarian torsion
      • Intrauterine device malpositioned
    • Pregnant
      • Pregnancy
      • Corpus luteum cyst
      • Subchorionic hemorrhage
      • Spontaneous abortion
      • Ectopic pregnancy
    • Post partum
      • Retained products of conception
      • Endometritis
      • Ovarian vein thromphlebitis
      • Cesarian section
    • Other
      • Appendicitis
      • Adhesions
      • Malrotation
      • Musculoskeletal pain
      • Sickle cell anemia
      • Tumor
      • Renal stones
      • Urinary tract infection
  • Chronic pelvic pain
    • Genitourinary
      • Ovarian cysts
      • Endometriosis
      • Uterine outflow tract obstruction and congenital abnormalities – imperforate hymen
      • Pelvic inflammatory disease
    • Gastrointestinal
      • Constipation
      • Food sensitivity or intolerance – lactose intolerance
      • Gastroesophageal reflux
      • Inflammatory bowel disease
      • Irritable bowel syndrome
      • Meckel’s diverticulum
      • Pancreatitis – chronic, relapsing
      • Peptic ulcer disease
    • Neurologic / Psychologic
      • Abdominal epilepsy
      • Abdominal migraine
      • Abuse – physical and sexual
      • Factitious
      • Fibromyalgia
      • Nerve entrapment
      • Munchausen by proxy
      • Psychological stress, anxiety, depression
    • Musculoskeletal
      • Abdominal wall strain
      • Pelvic musculature strain
    • Renal
      • Cystitis
      • Hydronephrosis
      • Renal stones
    • Miscellaneous
      • Adhesions
      • Autoimmune diseases that may have dermatologic or mucous membrane symptoms
    • Inguinal hernia

Questions for Further Discussion
1. What are indications for referral to gynecology or surgery?
2. What are indications for a pelvic examination?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Topic

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Cicchiello LA, Hamper UM, Scoutt LM. Ultrasound evaluation of gynecologic causes of pelvic pain. Obstet Gynecol Clin North Am. 2011 Mar;38(1):85-114, viii.

Youngster M, Laufer MR, Divasta AD. Endometriosis for the primary care physician. Curr Opin Pediatr. 2013 Aug;25(4):454-62.

Powell J. The approach to chronic pelvic pain in the adolescent. Obstet Gynecol Clin North Am. 2014 Sep;41(3):343-55.

Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa Children’s Hospital

What Causes Vomiting?

Patient Presentation
A 4-year-old female came to clinic with a history of increasing rhinorrhea, coughing for 10 days, emesis and poor sleep. Her mother said that the rhinorrhea was clear but was in copious amounts and the cough was described as “phlegmy.” The patient had used her albuterol inhaler without much relief. The emesis was non-bilous, non-bloody and “looked like the cold coming out her nose.” Her mother noted that she frequently would gag. The mother stated that she would lie down, then after a while would start coughing forcefully and then she would have emesis. This was occurring at night and was bothering both the child’s and mother’s sleep. She did not have emesis at other times. The mother thought that the rhinorrhea and cough had started after exposure to other ill children at daycare. The family had pet fishes but no other animals in the home. The past medical history revealed a child with mild intermittent asthma and atopic dermatitis that was well-controlled with intermittent albuterol and lubricants. The family history was positive for asthma, seasonal allergic rhinitis and atopic dermatitis. There was no history of gastrointestinal diseases. The review of systems was negative for fever, chills, constipation, and nausea, but was positive for dry skin.

The pertinent physical exam showed a tired appearing female who was appropriately responsive. Vital signs were normal with growth parameters in the 10-25% for age. HEENT showed dark circles under her eyes with atopic pleats. Her conjunctiva showed mild erythema with some cobblestoning. Her nose was boggy with copious clear rhinorrhea. Pharynx and ears were normal. Her lungs had no wheezing and her skin examination showed general xerosis without acute inflammation. The diagnosis of a probable upper respiratory infection starting the rhinorrhea and cough, but with components of allergic rhinitis was made.. The mother was counseled that the emesis was because of an appropriate gag reflex because of the post-nasal drip. The patient was started on cetirizine to help with the allergic rhinitis, and counseled. The physician also counseled about decreasing exposure to environmental allergens particularly as it appeared that the child and family all had environmental allergies.

Discussion
Regurgitation is a passive expulsion of ingested material out of the mouth. It is a normal part of digestion for ruminants such as cows and camels. Nausea is an unpleasant abdominal perception that the person may describe as feeling ill to the stomach, or feeling like he/she is going to vomit. Anorexia is frequently observed. Nausea is usually associated with decreased stomach activity and motility in the small intestine. Parasympathetic activity may be increased causing pale skin, sweating, hypersalivation and possible vasovagal syndrome (hypotension and bradycardia). Retching or dry heaves is when there are spasmodic respiratory movements against a closed glottis. This often occurs just before emesis.

Emesis, vomiting or vomition is when stomach (sometimes small intestine also) contents are propelled up the esophagus and out the mouth.
It is composed of three basic parts:

  • A deep breath is taken, the glottis closed to prevent aspiration into the lungs, while the larynx is raised which helps to open the upper esophageal sphincter. There is a decrease in respiration.
    The soft palate also closes to try to protect the posterior nares. The pylorus also contracts.

  • The diaphragm contracts downward sharply which creates negative thoracic pressures. This also assists the opening of the lower esophageal sphincter and the esophagus itself.
  • As the diaphragm contracts, the abdominal wall muscles vigorously contract which increases the intragastric pressure. As the pylorus is closed, the path of least resistance is through the relatively open esophagus.

A differential diagnosis of bilious emesis in a neonate can be found here.
A differential diagnosis emesis in a neonate can be found here.
A differential diagnosis of hematemesis can be found here.

Learning Point
The differential diagnosis of emesis include:

  • Normal variation, i.e. “spitting up”
  • Feeding problems
    • Overfeeding or force feeding
    • Incorrect feeding – delay in giving solid foods and food aversion
    • Refeeding syndrome
  • Excessive crying
  • Gastroesophageal reflux, severe
  • Gastrointestinal obstruction
    • Achalasia
    • Annular pancreas
    • Diaphragmatic hernia
    • Gastric/intestinal atresia/stenosis/duplications
    • Incarcerated hernia
    • Intestinal or viscous organ perforation with peritonitis
    • Intussception
    • Imperforate anus
    • Hirschsprung disease
    • Malrotation/volvulus
    • Meconium plug and ileus
    • Organomegaly
    • Pseudoobstruction syndrome
    • Pyloric stenosis
    • Superior mesenteric artery syndrome
    • Tumor
    • Tracheoesophageal fistula
    • Vascular rings
  • Gastroenterology, other
    • Constipation/encopresis
    • Celiac disease
    • Foreign body – esophageal, lactobezoar
    • Nutrient intolerance – lactose intolerance
    • Sensitive gag reflex
    • Swallowed blood – epistaxis and maternal
  • Allergy/Respiratory
    • Allergies
    • Cystic fibrosis
    • Asthma
  • Drug overdose
    • Aspirin
    • Iron
    • Lead
    • Theophylline
    • Digoxin
  • Genitourinary
    • Inguinal hernia
    • Testicular or ovarian torsion
    • Pelvic inflammatory disease
    • Pregnancy
  • Infections
    • Appendicitis
    • Cholecystitis
    • Encephalitis, meningitis, brain abscess
    • Gastroenteritis
    • Hepatitis
    • Necrotizing enterocolitis
    • Otitis media
    • Pancreatitis
    • Peptic ulcer disease
    • Pertussis
    • Perihepatitis
    • Peritonitis
    • Sepsis
    • Urinary tract infection
  • Metabolic
    • Diabetic ketoacidosis
    • Hyperammoninemia
    • Inborn errors of metabolism
      • Aminoacidemia
      • Congenital adrenal hyperplasia
      • Galactosemia
      • Hypercalcemia
      • Organic acidemia
      • Urea cycle defects
    • Reye’s syndrome
  • Neurologic
    • Cerebral edema
    • Cyclic vomiting
    • Familial dysautonomia
    • Head trauma
    • Hydrocephalus
    • Intracranial bleeding
    • Kernicterus
    • Mass lesion
    • Migraine
    • Seizures
    • Vestibular disorders – motion sickness
  • Psychological/Psychiatric
    • Attention seeking
    • Strong emotions – anxiety, fear
    • Intentional – bulimia
    • Munchausen by proxy
    • Neglect – rumination
    • Psychogenic
  • Renal
    • Obstruction
    • Uremia
  • Surgery and Trauma
    • Post-anesthesia
    • Non-accidental trauma

Questions for Further Discussion
1. How is bilious emesis defined?
2. What are “red flags” for potential serious causes of emesis?
3. What are the most common causes of emesis at different ages?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Nausea and Vomiting.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Sheldon SH, Levy HB. Pediatric Differential Diagnosis. Second Edition. Raven Press: New York. 1985:167-174.

R. Bowen. Physiology of Vomiting. Available from the Internet at http://www.vivo.colostate.edu/hbooks/pathphys/digestion/stomach/vomiting.html (rev. 4/10/96, cited 3/1/16).

Di Lorenzo C, Gastroesophageal Reflux in Pediatrics a Primary Care Approach. Berkowitz C. edit. W.B. Saunders Company, Philadelphia PA. 1996:334-339.

Rudolph CD, et.al. Rudolph’s Pediatrics. 21st edit. McGraw-Hill, New York, NY. 2003:1351-1354.

Colosini DM. Nausea and Vomiting in Infants and Children. Merck Manual. Available from the Internet at http://www.merckmanuals.com/professional/pediatrics/symptoms-in-infants-and-children/nausea-and-vomiting-in-infants-and-children (rev. 8/2013, cited 3/1/16).

Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa Children’s Hospital