Infantile Hypertrophic Pyloric Stenosis - Department of Surgery at ...

Infantile Hypertrophic Pyloric
Stenosis
Tresara C. Bell, MD
Kings County Medical Center
22 October, 2004

Pyloric Stenosis
• Infantile hypertrophic pyloric stenosis (IHPS) is a
condition that effects young infants.
• The pylorus becomes abnormally thickened and
manifests as obstruction to gastric emptying.
• Infants with IHPS are clinically normal at birth, and
subsequently develop nonbilious forceful
(“projectile”)) vomiting during the first few weeks of
postnatal life.
• Gastric outlet obstruction leads to emaciation and,
if left untreated, may result in death

Historical Perspective
• Despite its frequency, it was virtually unknown
prior to 1627, when a clinical description with
survival was described by Fabricious Hildanus.
• Over the next 2 centuries, only 7 additional cases
were described, some without pathologic proof
and of doubtful origin.
• Harald Hirschsprung presented 2 infant girls with
pathologically proved IHPS at the German
Pediatric Congress in 1887.
• A profusion of scientific interest was triggered, and
by 1910, 598 cases had been recognized. Even as
late as 1905, its existence was still occasionally
doubted.

Epidemiology
• The incidence of IHPS is approximately 2 to 5 per
1,000 births per year in most white populations.
• Less common in India, and among black and
Asian populations, with a frequency that is one-
third to one-fifth that in the white population.
• The male-to
to-female ratio is approximately 4:1.
• There is a famlilial link, but a hereditary
propensity to the development of IHPS is likely
polygenic with no single locus accounting for the
fivefold increase in the risk of first-degree
relatives.

Epidemiology
• Male and female children of affected fathers carry
a risk of 5% and 2% respectively, of developing
IHPS.
• Male and female children of affected mothers
carry a risk of 20% and 7%, respectively of
developing IHPS.
• Concordance in monozygotic twins is 0.25-0.44,
0.44,
and that in dizygotic twins is 0.05-0.10.
0.10.

IHPS Anatomy
• In IHPS the pyloric ring is no longer
a clearly defined separation
between the pyloric canal and
duodenum.
• Instead the muscle of the pyloric
antrum is hypertrophic (3 or more
mm), which separates the normal
antrum (1mm thickness) from the
duodenum.
• The lumen is filled with compressed
and redundant mucosa, which
obstructs the passage of gastric
contents.

IHPS Anatomy

Clinical Presentation
• Varies with length of symptoms.
• Recent onset of forceful nonbilious vomiting,
typically described as “projectile. projectile.”
• Frequency of vomiting is initially intermittent, but
will progress to follow all feedings.
• Emesis may become blood tinged with protracted
vomiting, likely related to gastritis.
• Since the child is unable to achieve adequate
nutrition, he or she exhibits a voracious appetite.

Clinical Presentation
• Starvation can exacerbate diminished hepatic
glucoronyl transferase activity, and indirect
hyperbilirubinemia may be seen in 1-2% 1
of
affected infants.
• Prolonged vomiting leads to the loss of large
quantities of gastric secretions rich in H + and Cl - .
• As a result of dehydration, the kidney attempts to
conserve Na + to maintain volume, by exchanging
them for K + and H + (paradoxical aciduria).
• The net result is a loss of H + and K + , which results
in hypokalemic, hypochloremic metabolic acidosis.

Etiology
• It has been found that, when compared to
controls, in IHPS specimens, the muscle layer is
deficient in:
– the quantity of nerve terminals
– markers for nerve-supporting cells
– peptide-containing nerve fibers
– nitric oxide synthase activity
– mRNA production for nitric oxide synthase
– Interstitial cells of Cajal
Ohshiro and Puri. . Pathogenesis of infantile hypertrophic pyloric
stenosis: : recent progress. Pediatr Surg Int (1998)13:243-252.
252.

Etiology
• IHPS specimens contain increases in:
– Insulin-like like growth factor
– platelet-derived growth factor
• It is postulated that this abnormal innervation of
the muscular layer leads to failure of relaxation of
the pyloric muscle, increased synthesis of growth
factors, and subsequent hypertrophy, hyperplasia,
and obstruction.
• There is an increased incidence of IHPS in infants
receiving erythromycin. The reason is unclear,
although a prokinetic effect on gastric muscle
contraction is postulated.

Etiology
• The hypergastrinemia hypothesis proposes
that an inherited increase in the number of
parietal cells initiates a cycle of increased
acid production, repeated pyloric
contraction, and delayed gastric emptying.
– Development of IHPS after initiation of feedings,
increased postprandial gastrin levels, markedly
increased gastric acid secretion in infants with
IHPS, and the induction of IHPS in puppies after
pentagastrin infusion support this hypothesis.

Diagnosis
• Initially suggested by the typical clinical
presentation.
• The mass is firm, mobile, approximately 2 cm,
best palpated from the left, located in the mid-
epigasrtrium beneath the liver edge.
• Palpation of the hard muscle mass or olive is
diagnostic in conjunction with a typical history.
• Diagnosis by palpation of olive only successful
49% of cases in recent years vs. 78% 30 years
ago.
• Palpation requires a calm infant with relaxed
abdominal musculature, which is difficult in these
hungry babies.
• Macadesi and Oates. Clinical diagnosis of pyloric stenosis: : a declining art. BMJ
1993;306:553-555.
555.

Diagnosis
• If the olive is not palpable in an infant who has a
clinical picture suggestive of IHPS, further studies
are warranted.
• Ultrasonography is used to measure the thickness
of the pyloric wall and the length of the pyloric
canal.
– normal wall thickness 4 mm
– normal length of the pyloric canal 14 mm
• Sensitivity and specificity as high as 100%
• Heller, et al. Application of new imaging modalities to the evaluation of
common pediatric conditions. J Pediatr 1999; 135(5): 632-639.
639.

• False-negative result
can occur if antrum is
measured.
• False-positive can
occur is pyloric spasm
is present.
• If ultrasound is not
diagnostic and IHPS
remains a concern,
the next test of choice
is an upper GI series.
Diagnosis

Diagnosis
• The canal is outlined by a
string of contrast material
coursing through spaces
between redundant
mucosa (“string(
sign”).
• Alternatively, there may be
several linear tracts of
contrast material separated
by intervening mucosa
(“double-track sign”).
• Mass impression on gastric
antrum (“shoulder sign”)
may be present.

Diagnosis
• Upper endoscopy is used in rare occasions when
other imaging modalities are inconclusive.
• Nasogastric aspirates after 3-43
4 hours of fasting.
– IHPS was present in 92% of patients with
nasogastric aspirate of 10ml or more.
– GER was diagnosed in 86% of patients with
nasogastric aspirates of less than 10ml.

Differential Diagnosis
• Gastroesophageal reflux, with or without hiatal
hernia. Differentiated by radiologic studies. Also
amount of vomitus is smaller, and the infant does
not usually lose weight.
• Adrenal insufficiency. Differentiated by absence of
metabolic acidosis, hyperkalemia, , and elevated
urinary sodium.
• Viral gastroenteritis. Unusual in infants less than 6
weeks of age. Associated with significant diarrhea
and sick contacts.

Treatment
• The preoperative treatment is directed toward
correcting the fluid, acid-base, and electrolyte
losses.
• Intravenous fluid therapy is begun with 0.45–0.9%
0.9%
saline, in 5–10% 5
dextrose, with the addition of
potassium chloride in concentrations of 30–
50mEq
mEq/L.
• Fluid therapy should be continued until the infant
is rehydrated and the serum bicarbonate
concentration is less than 30mEq/dL
mEq/dL, , which
implies that the alkalosis has been corrected.

Treatment
• Correction of the alkalosis is essential to prevent
postoperative apnea, which may be associated
with anesthesia
• Most infants can be rehydrated within 24 hours.
• Vomiting will usually stop once the stomach is
empty. Occasionally an infant will require
nasogastric suction.
• Once resuscitated the infant can undergo the
Fredet-Ramstedt
pylormyotomy, , which is the
procedure of choice.

Treatment
• If the mucosa is entered (usually on the duodenal
side), it can be primarily repaited and reinforced
with an omental patch.
• Large perforations are managed by closing the
pyloromyotomy, , rotating the pylorus 90°, , and
repeating the myotomy.
• Mortality and morbidity of less that 0.5%
• Post-operative operative complications:
– Wound infection
– Imcomplete myotomy, , treated by repeat
myotomy or endoscopic balloon dilation.

Treatment
• Diet can be resumed within 6 to 12 hours post-
operatively.
• Post-operative operative vomiting may occur in up to 50% of
infants. Thought to be secondary to edema of the
pylorus at the incision site.
• Most infants will tolerate full diet within 24 to 48
hours.

Treatment
• Laparoscopic pyloromyotomy is performed
primarily for improved cosmesis and shorter
operative time, with comparable length of stay and
morbidity.
• Decreased rate of duodenal perforation.
• Increased rate of incomplete myotomies and
incisional hernias, requiring re-operation
operation.
• Yagmurlu, , et al. Laparoscopic pyloromyotomy: : a
concurrent single institution series. J Pedatr Surg
2004;(39)3:292-296.
296.

Treatment
• Endoscopic balloon dilation has been used to
treat IHPS. The seromuscular ring was not reliably
disrupted to relieve the obstruction. Most patients
failed balloon dilation and were treated with
pyloromyotomy.
• Ogawa, et al. Successful endoscopic balloon dilatation for hypertrophic
pyloric stenosis. . J Pediatr Surg 1996; (31)12:1712-1714.
1714.
• Hayashi, et a. Balloon catheter dilation for hypertrophic pyloric
stenosis. . J Pediatr Surg 1990; (25)11:1119-1121.
1121.

Treatment
• Atropine sulfate has been used to treat IHPS with
some success, however infants may not tolerate
diet for at least 5 days.
• Surgery was necessary in 30% of the patients.
• Yamatata, , et al. Pyloromyotomy vs. atropine sulfate for infantile hypertrophic
pyloric stenosis. . J Pediatr Surg 2000; 35(2):338-41.