Hypertrophic pyloric stenosis (HPS)
Hypertrophic pyloric stenosis is a narrowing of the lower portion of the stomach (pylorus) that leads
into the small intestine. It is actually an enlargement of the muscles in this
area of the stomach that contributes to the narrowing problem, and as a result
food does not move easily into the intestine for digestion.
Incidence
HPS is a disease of newborns with an incidence of 1 in 300 to 1 in 900 live
births. Infants with HPS generally present between the second or third week of
life to two months of age. Rare cases have been reported throughout childhood
and into adult life. It is most commonly found in Caucasians of northern
European descent. Throughout the world, HPS appears to be less common in
Africans, African Americans, and Asians. HPS is more common in infants with
blood types B and O.
What causes the condition?
Despite extensive clinical and laboratory research, the cause of pyloric
stenosis remains unknown. Although a genetic predisposition to HPS is suspected,
the exact mode of inheritance is unknown. Males are affected four times as often
as females, and first born males are at highest risk. Family history is
relevant. When parents (mother or father) have had HPS, it occurs in 5% to 20%
of their male children but in only 3% to 7% of their female children.
Signs and symptoms
Symptoms begin as mild vomiting that gradually worsens. With time, the emesis
becomes more frequent and forceful (often described as "projectile"). After
vomiting epidoses, infants can usually be quieted, but they are obviously
hungry. In a small number of cases, the vomitus will be brown or even bloody due
to irritation of the esophagus and/or stomach lining.
If not treated promptly, infants become dehydrated, lose weight, and fail to
thrive because of the uncorrected fluid losses and inadequate nutrition caused
by a nearly complete blockage of nutrients. Gastric secretions contain
significant quantities of potassium, hydrogen, and chloride.
When the surgeon examines the ill infant, one of the classical findings in
HPS is the presence of a nodule about the size of olive that the surgeon feels
while palpating the baby's upper abdomen. This olive-size nodule is in fact the
over-developed muscle that surrounds the opening of the channel emptying from
the stomach into the intestine.
Diagnosis
The enlarged muscle (the "olive") is felt by the surgeon on clinical exam in
about 75% to 90% of infants with HPS. If the "olive" cannot be felt or the
diagnosis is in doubt, an abdominal ultrasound is beneficial.
If for some reason, the ultrasound is not conclusive, another x-ray can be
done - an upper gastrointestinal study (UGI).
Treatment
Part of treatment is to give the dehydrated infant intravenous fluids to
rebalance the body's normal chemistry. Once this is done, an operation called a
pyloromyotomy is performed, a procedure to loosen the tight musculature that is
blocking the normal passageway from the stomach into the intestine. Most infants
can be operated upon within 24 hours of admission.
Postoperative care
Feeding is started 6 to 8 hours postoperatively. Most regimens begin with
sugar water followed by increasing concentrations and volumes of the child's
formula. Occasionally, infants will continue to have small amounts of vomiting
when feedings are resumed postoperatively. This vomiting is usually a simple
self-limited, postoperative problem.
Gradually, the amount of formula is increased every few hours. The infant is
discharged when intake by mouth is adequate to maintain hydration and meet
estimated nutritional needs. This typically occurs in 1 to 3 days.
The baby's incision should be kept clean and dry, and no tub baths should be
given for two days after surgery. Steri-strips (bandage-like tape) that are
placed over the incision should be left in place and then removed according to
the instructions of your pediatric surgeon. Typically, the steri-strips are left
in place for 7 to 10 days.
Outcomes
Infants tolerate pyloromyotomy very well. Recurrence of HPS is extremely
rare.