Paediatric disorders
Hypertrophic
pyloric stenosis of infancy
Aetiology
The incidence of this condition is
approximately three cases per 1000 births. It is four times as common in males
as in females and the aetiology is unknown. It may be that the condition is
analogous to achalasia of the oesophagus in which there is a failure of the
pylorus to relax, leading to the muscular hypertrophy. In some cases there seems
to be a familial association. In such families the mother has suffered from the
condition in 50 per cent of cases, and 10 per cent of male siblings and 2 per
cent of female siblings are affected.
Pathology
The classical feature is that the musculature
of the pylorus and adjacent antrum is grossly hypertrophied, the hypertrophy
being maximum in the pylorus itself. The mucosa is compressed such that only a
probe can be inserted.
Clinical features
Characteristically it is a first-born male
child that is most commonly affected. The condition is most commonly seen at 4
weeks after birth ranging from the third week to, on rare occasions, the
seventh. Inexplicably, it is the time following birth that seems important and
not the child’s gestational age. A premature infant will also develop the
condition at about 4 weeks after birth. Vomiting is the presenting symptom
that after 2—3 days becomes forcible and projectile. The child vomits milk and
no bile is present. Immediately after vomiting the baby is usually hungry.
Weight loss is a striking feature and rapidly the infant becomes emaciated and
dehydrated. Diagnosis can usually be made with a test feed. This may produce
characteristic peristaltic waves that can be seen to pass across the upper
abdomen. At the same time, using a warm hand, the abdomen is palpated to detect
the lump (Fig. 51.10).
Imaging
Ultrasonography is the investigation of choice
as it can, without difficulty, detect the classical features in the pyloric
canal. Contrast radiology is not now necessary.
Differential diagnosis
The common conditions from which pyloric
stenosis must be differentiated are gastro-oesophageal reflux, feeding problems,
urinary tract infection and raised intracranial pressure. The condition cannot
normally be confused with duodenal atresia or intestinal obstruction because of
the absence of bile in the milk vomit.
Treatment
Following diagnosis the first concern is to
correct the metabolic abnormalities. Essentially this is the same situation
that pertains in adults with the patient being dehydrated, with low sodium,
chloride and potassium, and a metabolic alkalosis. The child should be
rehydrated with dextrose—saline and potassium (2.5 per cent dextrose plus 0.45
per cent sodium chloride plus 1 g of potassium chloride per 500 ml of fluid).
This will restore the infant’s clinical condition and electrolytes to normal.
Following this operation is required. Conservative treatment has little place in
the management of this condition as with appropriate surgical treatment recovery
is virtually 100 per cent.
Ramstedt’s operation
In preparing the child for operation it is
important that the stomach is emptied and washed out with saline, and that
hypothermia is avoided. To achieve this the patient is encased in cotton wool
allowing exposure of the upper abdomen. Operation is performed under general
anaesthesia, although it is possible to perform the procedure under a local anesthetic. The skin is opened through a transverse incision placed in the
upper abdomen over the right rectus sheath, which is opened in the same line.
The rectus muscle is then split along the line of its fibres and the posterior
rectus sheath opened in the line of the skin incision. The hypertrophied pylorus
is delivered and rotated so that its superior surface comes into view (Fig.
51.11). Thus, the least vascular portion
After
operation the nasogastric tube can be removed and feeding commenced on the
morning after operation. If the infant manages to feed without difficulty it can
be discharged early from hospital. If the mucosa is inadvertently opened it is
wise to delay feeding for 48 hours and to retain the child in hospital longer.
Complications of operation
Postoperative pyrexia is common and usually
treated with paracetomol elixir. Wound disruption is rare and is more liable to
occur in emaciated subjects. The incidence of wound infection is around 5
per cent, and 1 per cent will suffer wound disruption.
Duodenal
atresia
This occurs at the point of fusion between the
foregut and midgut, and therefore lies in the neighborhood of the ampulla of
Vater. There is a diaphragm, which is usually complete, across the duodenum at
this point (Fig. 51.12) and the condition is frequently accompanied by other
defects. The diagnosis is now made antenatally in most cases through the use of
ultrasound. This shows the characteristic appearance of a dilated stomach and first part
of the duodenum (double bubble). The child vomits from birth and the vomitus is
bile stained. The differential diagnosis includes high intestinal obstruction.
Occasionally, however, the diaphragm may be proximal to the ampulla and in these
circumstances the condition can be confused with pyloric stenosis, although in
pyloric stenosis vomiting does not start from birth. Treatment is by the
operation of the duodenoduodenostomy in which the dilated proximal duodenum is
anastomosed to the atrophic distal duodenum (Ladd). This disparity in luminal
size can produce delays in emptying and some surgeons have advocated the use of
a transanastomotic tube. However, this has been demonstrated to delay emptying
and is not now commonly used.