Congenital Hypertrpphic Pyloric Stenosis

7/31/2019 Congenital Hypertrpphic Pyloric Stenosis

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Dr. Rajneesh Varshney


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Congenital pyloric stenosis -

Infantile hypertrophic pyloric stenosis (IHPS) is

a condition that effects young infants.

The pylorus becomes abnormally thickened

and manifests as obstruction to gastricemptying.

Infants with IHPS are clinically normal at birth,

and subsequently develop nonbilious forceful

(projectile) vomiting during the first fewweeks of postnatal life.

Gastric outlet obstruction leads to emaciation

and, if left untreated, may result in death


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Historical Perspective

Despite its frequency, it was virtually unknownprior to 1627, when a clinical description withsurvival was described by Fabricious Hildanus.

Over the next 2 centuries, only 7 additional

cases were described, some withoutpathologic proof and of doubtful origin.

Harald Hirschsprung presented 2 infant girlswith pathologically proved IHPS at the GermanPediatric 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 stilloccasionally doubted.


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Epidemiology

The incidence of IHPS is approximately 2 to 5per 1,000 births per year in most whitepopulations.

Less common in India, and among black and

Asian populations, with a frequency that is onethird to one-fifth that in the white population.

The male-to-female ratio is approximately 4:1.

There is a famlilial link, but a hereditarypropensity to the development of IHPS is likely

polygenic with no single locus accounting forthe fivefold increase in the risk of first-degreerelatives.


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Male and female children of affected

fathers carry a risk of 5% and 2%

respectively, of developing IHPS.

Male and female children of affectedmothers carry a risk of 20% and 7%,

respectively of developing IHPS.

Concordance in monozygotic twins is0.25-0.44, and that in dizygotic twins is

0.05-0.10.


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Anatomy

In IHPS the pyloric ring is no longer aclearly defined separation between thepyloric canal and duodenum.

Instead the muscle of the pyloric antrumis hypertrophic (3 or more mm), whichseparates the normal antrum (1mmthickness) from the duodenum.

The lumen is filled with compressed andredundant mucosa, which obstructs thepassage of gastric contents.


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Clinical features -

Varies with length of symptoms.

Recent onset of forceful nonbilious vomiting,

typically described as 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 adequatenutrition, he or she exhibits a voracious

appetite.


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Starvation can exacerbate diminished hepaticglucoronyl transferase activity, and indirecthyperbilirubinemia may be seen in 1-2% ofaffected infants.

Prolonged vomiting leads to the loss of largequantities of gastric secretions rich in H+ and Cl-

As a result of dehydration, the kidney attemptsto conserve Na+ to maintain volume, by

exchanging them for K+ and H+ (paradoxicalaciduria).

The net result is a loss of H+ and K+, whichresults in hypokalemic, hypochloremic metabolicacidosis.


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Palpable lump of hypertrophied pylorus,

better felt from left side, as a mobile,

smooth, firm mass, move with

respiration, with impaired resonance onpercussion. It is most important clinical

feature (95%).


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In premature infants -

Visible gastric peristalsis & mass is

better seen & felt.

Vomiting is regurgitant.

Anorexia is common.


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Diagnosis -

Clinical examination.

Barium meal shows obstruction.

USG abdomen


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Diagnosis

Initially suggested by the typical clinicalpresentation.

The mass is firm, mobile, approximately 2 cm,best palpated from the left, located in the

midepigasrtrium 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 successful49% of cases.

Palpation requires a calm infant with relaxedabdominal musculature, which is difficult inthese hungry babies.


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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 thethickness 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%


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The canal is outlined by a string ofcontrast material coursing throughspaces between redundant mucosa

(string sign).Alternatively, there may be several linear

tracts of contrast material separated byintervening mucosa (double-track

sign). Mass impression on gastric antrum

(shoulder sign) may be present.


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Upper endoscopy is used in rare

occasions when other imaging

modalities are inconclusive.


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Differential diagnosis -

Duodenal atresia (Bilious vomiting

present).

High intestinal obstruction (eg. Volvulus

neonatorum)

Intracranial haemorrhage.


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Treatment -

The preoperative treatment is directed toward

correcting the fluid, acid-base, and electrolyte

losses.

Intravenous fluid therapy is begun with 0.450.9% saline, in 510% dextrose, with the

addition of potassium chloride in

concentrations of 30 50mEq/L.

Fluid therapy should be continued until theinfant is rehydrated and the serum bicarbonate

concentration is less than 30mEq/dL, which

implies that the alkalosis has been corrected.


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Correction of the alkalosis is essential toprevent postoperative apnea, which may beassociated with anesthesia

Most infants can be rehydrated within 24

hours. Vomiting will usually stop once the stomach is

empty. Occasionally an infant will requirenasogastric suction.

Once resuscitated the infant can undergo theFredet-Ramstedt pylormyotomy, which is theprocedure of choice.


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If the mucosa is entered (usually on theduodenal side), it can be primarily repaitedand reinforced with an omental patch.

Large perforations are managed by closing the

pyloromyotomy, rotating the pylorus 90, andrepeating the myotomy.

Mortality and morbidity of less that 0.5%

Post-operative complications:

Wound infection

Imcomplete myotomy, treated by repeatmyotomy or endoscopic balloon dilation.


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Diet can be resumed within 6 to 12

hours postoperatively.

Post-operative vomiting may occur in up

to 50% of infants. Thought to besecondary to edema of the pylorus at

the incision site.

Most infants will tolerate full diet within24 to 48 hours.


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Laparoscopic pyloromyotomy is

performed primarily for improved

cosmesis and shorter operative time,

with comparable length of stay andmorbidity.

Decreased rate of duodenal perforation.

Increased rate of incomplete myotomiesand incisional hernias, requiring re-

operation.


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Endoscopic balloon dilation has been

used to treat IHPS. The seromuscular

ring was not reliably disrupted to relieve

the obstruction. Most patients failedballoon dilation and were treated with

pyloromyotomy.


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Medical treatment -

Not advisable as cure is not guaranteed.

Atropine methyl nitrate orally is tried to

relax the pylorus muscle.

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Congenital Hypertrpphic Pyloric Stenosis