What Causes Emesis in a Neonate?

Patient Presentation
A 35-day-old male came to clinic with projectile vomiting.
He began having emesis 5 days prior that increased in frequency and amount. On the third day of emesis, he was evaluated; the parents were told that it probably was a viral syndrome.
The emesis is non-bloody, non-bilious, with just breast milk in the vomitus. It occurs about 1- 1.5 hours after feeding.
His mother states that initially it would just dribble out of his mouth, but now comes up forcefully and will hit an object or floor located a couple feet away.
He seems hungry between feedings and is crying more.
He is sleepier over the past couple of days and has had a decreased number and volume of wet diapers.
He was having normal stools up until 1 day ago.
The past medical history revealed a healthy infant born at 39 weeks gestation with no complications. He was healthy at day 5 and 13 of life.
His newborn screening test was reported as normal.
The family history is positive for a cousin with mental retardation. No other genetic or metabolic disorders and no gastrointestinal or neurological problems.
The review of systems was negative including fever, diarrhea, rashes, sweating, color changes, etc.
The pertinent physical exam showed his weight to be 3.65 kg (down 240 grams from the previous clinic visit 2 days ago, 10-25% for age),
afebrile, with heart rate = 128 beats/minutes, respiratory rate = 45 breaths/minute. All other growth parameters are 25-50% for age with normal trends.
He was alert with tacky mucous membranes and a capillary refill of 2 seconds.
Anterior fontanelle was normal.
Abdomen was soft, non-tender with no hepatomegaly, but with a small fullness felt in the mid- to right upper quadrant when feeding.
Genitourinary examination found no hernias or other masses.
Neurological and extremity examination was normal.
The diagnosis of hypertrophic pyloric stenosis was made clinically.
The laboratory evaluation was performed to assess for a metabolic problem, which were slightly abnormal in the CO2, showed a sodium = 142 mEq/L, potassium = 5.1 mEq/L, chloride = 99 mEq/L, and CO2 = 34 mEq/L, blood urea nitrogen = 15 mg/dl and creatinine = 0.5 mg/dl on a heel-stick blood draw.
A complete blood count was normal.
The radiologic evaluation of an ultrasound of the abdomen confirmed the diagnosis of pyloric stenosis with a pyloric muscle length of 2.1 cm and width of 5.3 mm.
The patient’s clinical course over the evening was that he urinated after 2 normal saline fluid boluses were given and then he was given D5, 0.45 normal saline at a maintenance fluid rate.
He was not given anything by mouth and but did have some minor spitting up of oral secretions.
Repeated electrolytes the next morning were normal before he was taken to the operating room where he underwent a pyloromyotomy without complications.
He was discharged home on Day 3, and was doing well at follow-up 2 weeks later.

Figure 53 – Longitudinal (left) and transverse (right) images from an ultrasound of the pylorus demonstrate the pyloric muscle to be abnormally thickened and elongated. The pyloric muscle measures 5 mm thick and 21 mm in length and these measurements meet the criteria for the diagnosis of pyloric stenosis by ultrasound.

Hypertrophic pyloric stenosis is the hypertrophying of the pylorus muscle with subsequent stenosis of the pyloric chanel. It usually presents in the 3-12th week of life as forceful or projectile non-bilious emesis. It occurs ~ 2-5 patients/1000 live births, more often in males than females (4;1) and most often in first-born males (30%).
The infant often appears hungry after feeding, but with increased crying (because of hunger) or later lassitude (because of the problem not being recognized and appropriately treated).
It can cause failure to gain normal weight, weight loss, and metabolic abnormalities (classically a hypochloremic, hypokalemia metabolic alkalosis).
Classically a small abdominal mass about the size of an olive can be palpated at the mid- to right upper quadrant just lateral to the rectus abdominus muscle.

On ultrasound examination, a pyloric muscle thickness of > 4 mm is considered diagnostic. The length of the muscle is variable from 14-20 mm, and pyloric diameter may be between 10-14 mm.

The cause is unknown but may be linked to sleeping position, acidity of the stomach, and the drugs nitric oxide and erythromycin have been implicated.
Treatment is surgical with good results. Fatality from pyloric stenosis is < 1%.

Learning Point
The causes of emesis are often broken down by age and also by history of being bilious or non-bilious. Bilious emesis should be considere always abnormal as it indicates ileus or obstruction distal to the common bile duct insertion into the duodenum.
Depending on the cause and its severity, emesis may be non-bilious especially early on in the illness course and later turn bilious.
Parents and health care providers alike may have problems accurately identifying bilious emesis and therefore the history may be inaccurate, so all causes of emesis should be considered in neonates and infants.

Common causes of emesis in children under 1 year include:

(Those with an * often present with true bilious emesis.)

  • Normal variation, i.e. “spitting up”
  • Overfeeding
  • Gastroesophageal reflux, severe
  • Gastrointestinal obstruction
    • Achalasia
    • *Annular pancreas
    • *Gastric/intestinal atresia/stenosis/duplications
    • Incarcerated hernia
    • *Intermittent malrotation/volvulus
    • *Intestinal or viscous organ perforation with peritonitis
    • Intussception
    • Imperforate anus
    • Hirschsprung disease
    • *Meconium plug and ileus
    • Pseudoobstruction syndrome
    • Pyloric stenosis
  • Drug overdose
    • Aspirin
    • Iron
    • Lead
    • Theophylline
    • Digoxin
  • Foreign body – esophageal, lactobezoar
  • Infections
    • Gastroenteritis
    • Meningitis
    • Necrotizing enterocolitis
    • Sepsis
    • Urinary tract infection
    • Otitis media
    • Pertussis
  • Metabolic
    • Inborn errors of metabolism
      • Aminoacidemia
      • Congenital adrenal hyperplasia
      • Galactosemia
      • Hypercalcemia
      • Organic acidemia
      • Urea cycle defects
    • Diabetic ketoacidosis
  • Neurologic
    • Hydrocephalus
    • Kernicterus
    • Mass lesion
  • Renal
    • Obstruction
    • Uremia
  • Rumination

Questions for Further Discussion
1. Explain the physiology behind the hypochloremia, hypokalemia metabolic alkalosis seen in pyloric stenosis?
2. What are the indications for an upper gastrointestinal radiographic series in a child who is vomiting?
3. What are the indications for an abdominal ultrasound radiographic examination in a child who is vomiting?
4. When in the evaluation process should a pediatric surgeon be consulted?

Related Cases

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

Information prescriptions for patients can be found at MedlinePlus for this topic: Pyloric Stenosis.

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

To view images related to this topic check Google Images.

Fleisher GR, Ludwig S. Synopsis of Pediatric Emergency Medicine. Williams and Wilkins. Baltimore, MD. 1996:266-71.

Rudolph CD, et.al. Rudolph’s Pediatrics. 21st edit. McGraw-Hill, New York, NY. 2003:1351-54.

Walker GM, Neilson A, Young D, Raine PA. Colour of bile vomiting in intestinal obstruction in the newborn: questionnaire study.
BMJ. 2006 Jun 10;332(7554):1363.

MacMahon B. The continuing enigma of pyloric stenosis of infancy: a review.
Epidemiology. 2006 Mar;17(2):195-201.

ACGME Competencies Highlighted by Case

  • Patient Care
    1. When interacting with patients and their families, the health care professional communicates effectively and demonstrates caring and respectful behaviors.
    2. Essential and accurate information about the patients’ is gathered.
    3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
    4. Patient management plans are developed and carried out.
    5. Patients and their families are counseled and educated.
    7. All medical and invasive procedures considered essential for the area of practice are competently performed.
    8. Health care services aimed at preventing health problems or maintaining health are provided.
    9. Patient-focused care is provided by working with health care professionals, including those from other disciplines.

  • Medical Knowledge
    10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
    11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.

  • Practice Based Learning and Improvement
    13. Information about other populations of patients, especially the larger population from which this patient is drawn, is obtained and used.
    14. Knowledge of study designs and statistical methods to appraisal clinical studies and other information on diagnostic and therapeutic effectiveness is applied.

  • Systems Based Practice

    24. Cost-effective health care and resource allocation that does not compromise quality of care is practiced.

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

    November 12, 2007