Paediatric surgery

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17 Paediatric surgery

General principles of paediatric surgery

Newborns and infants present with uncommon surgical disorders, peculiar to their age group. These patients need to be referred to expert centres that are experienced in their special needs. Specialist anaesthetic skills are crucial, sometimes more so than the surgery.

Priorities in care for an infant being transferred to a regional centre include:

• temperature control

• nasogastric intubation

• airway protection

• cardiovascular monitoring

• appropriate intravenous fluids (Table 17.1)

Table 17.1 Maintenance fluid requirements in the first week of life

Day Fluid (mL/kg/24 h)
1, 2 60
3, 4 90
5, 6 120
>7 150

Hypothermia may be controlled by the use of an incubator and warming mattress in the operating theatre and anaesthetic room. The extremities may be wrapped in aluminium foil and the infant nursed in warm cotton wool, exposing only the operating field.

Infection is a constant risk for newborns who need to undergo surgical procedures and broad-spectrum antibiotics, for example benzylpenicillin, metronidazole and aminoglycosides, are given intravenously at the start of all operations. Prolonged antibiotics may be required, particularly for bowel operations, and oral nystatin is given to reduce colonisation by yeasts.

Prenatal ultrasound scanning can identify major anatomical abnormalities, for example anterior abdominal wall defects, diaphragmatic hernia, duodenal atresia and hydronephrosis. Prenatal diagnosis allows the planning of post-delivery care of the baby in a hospital that is equipped to provide specialist services.

The spectrum of disorders seen in mid-pregnancy may be different from that seen in newborns because ultrasound-detected anomalies may be multiple and result in stillbirth. Fetal chromosomes can be checked, echo-cardiograms performed and scans done for detailed anomaly detection before a prediction of the findings at birth and the prognosis is reached and management planned.

Respiratory distress

Oesophageal atresia and tracheo-oesophageal fistula

One in 4000 babies has an oesophageal anomaly, most usually a mid-oesophageal atresia with a distal tracheo-oesophageal fistula (Fig. 17.1). Half the infants with oesophageal abnormalities have associated problems, including cardiovascular, renal and skeletal defects.

image

Figure 17.1 Common variant of oesophageal atresia and tracheo-oesophageal fistula.

Clinical features

In the common form with a blind upper oesophagus, the newborn is able to swallow amniotic fluid via the trachea and the fistula into the stomach but many of the pregnancies are complicated by polyhydramnios. The infant has excessive pharyngeal mucus at birth and, if fed by mouth, a cyanotic episode suggests aspiration into the respiratory tract.

Management

Feeding should be avoided where there is a suspicion of oesophageal atresia. Diagnosis is achieved by the passage of a small nasogastric tube which stops in the midoesophagus. Radiography shows the tube in the proximity of the first or second thoracic body and gas in the stomach confirms the presence of a distal tracheo-oesophageal fistula.

The upper airway is kept clear with suction and hydration is maintained with intravenous fluids. The fistulous opening on the posterior wall of the trachea is repaired via a right thoracotomy and the oesophageal anastomosis is constructed. Staged surgery is sometimes necessary if the gap is too wide to permit primary anastomosis. The outlook is excellent but dysphagia and respiratory complications may continue into adult life.

Diaphragmatic hernia

Diaphragmatic hernia occurs in 1 in 2000 live births, most commonly through a left posterior lateral defect. Agenesis of the hemi-diaphragm can occur, which is more severe. Intestine, stomach and spleen may be found in the pleural cavity and the lung is severely hypoplastic. There is severe respiratory distress and circulatory disability at birth. Diagnosis is confirmed by plain X-ray, which demonstrates lack of small bowel gas in the abdomen with loops of intestine in the pleural cavity and displacement of the mediastinum. Management includes resuscitation, positive pressure ventilation and a nasogastric tube to collapse the stomach. Face-mask assisted respiration is contraindicated. Infants with severe pulmonary hypertension require inotropic support, and intravenous colloids may be required to expand the circulating blood volume. Operative repair is carried out when the neonate is in a stable condition. The contents of the hernia are reduced from the thorax and the diaphragmatic defect repaired. There is a high mortality rate, related to bilateral pulmonary hypoplasia, but the majority of long-term survivors have no long-term problems.

Upper airway obstruction

This may be caused by:

• cystic hygroma: a fluid-filled collection in the neck which may extend to the mediastinum or axilla

• a small jaw (micrognathia), where a hypoplastic mandible causes obstruction of the pharynx by prolapse of the tongue associated with cleft palate. This is the Pierre Robin syndrome

• choanal atresia: a bony membranous obstruction to the nasal passages at the junction of the hard and soft palates. This diagnosis is confirmed by the inability to pass a nasal tube into the pharynx.

Neonatal intestinal obstruction

General clinical features of neonatal intestinal obstruction

The history includes details of maternal illness, for example diabetes mellitus, and medication during pregnancy. A history of intestinal obstruction, Hirschsprung’s disease or cystic fibrosis in relatives may be relevant. There is bile-stained vomiting (Box 17.1), failure to pass meconium or stools that change to the characteristic neonatal output, and abdominal distension.

Box 17.1 Bile-stained vomiting

Bile-stained vomiting in a neonate is always a sign of a serious intestinal abnormality and requires emergency specialist paediatric surgical referral.

On examination, a note is made of dysmorphic features, for example Down’s syndrome, which is often associated with bowel abnormalities. In the abdomen, dilated loops of bowel may be visible in distal obstruction with bulky, palpable meconium suggestive of meconium ileus. Site and size of the anus should be recorded and the rectum examined. If blood is found, this may be indicative of bowel ischaemia.

Plain abdominal X-rays confirm the presence of dilated loops of bowel and give an idea whether the obstruction is proximal or distal. Free gas means that intestinal perforation has occurred. The presence of small bubbles or intramural gas indicates gangrenous bowel.

Causes of neonatal intestinal obstruction

Duodenal atresia

This is the commonest cause of proximal intestinal obstruction. One-third of the infants have Down’s syndrome. The duodenum may be completely obstructed by a short segment of atresia. Partial obstruction may be caused by stenosis or incomplete web situated in the second part of the duodenum at the level of the ampulla of Vater.

Clinical features

Vomiting occurs in the first day of life and is bile-stained. Abdominal X-ray shows the double bubble appearance. The duodenal abnormalities may be corrected surgically.

Volvulus

Volvulus occurs due to mid-gut malrotation and the base of the small bowel mesentery is narrow. The duodenal-jejunal junction is to the right or in the midline and the caecum is mobile on a mesentery and lies close to the midline. Volvulus occurs in the first 4 weeks of life with bile-stained vomiting without distension. Signs of abdominal tenderness and rectal bleeding indicate intestinal ischaemia. Prompt surgical relief is required.

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