Paediatric surgery

Published on 11/04/2015 by admin

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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.

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.

Atresia of the small bowel

This is more common in the ileum but is relatively rare. The cause may be due to a vascular accident in the mesenteric vessels late in fetal development. Features are of intestinal obstruction. Resection of the atresia and anastomosis is possible and the prognosis is good.

Meconium ileus

Tenacious viscid meconium found in 15% of infants with cystic fibrosis obstructs the distal ileum. The terminal small ileum is full of meconium but the colon is empty and appears underdeveloped. Prenatal investigations may reveal cystic fibrosis.

Plain X-ray confirms low small bowel obstruction. Cystic fibrosis is diagnosed by measuring the sodium levels in samples of infants’ sweat or one of the specific defect genes found on chromosome 7. Water-soluble barium enema may relieve the obstruction, acting as a cathartic. Fifty per cent of infants require surgery as the condition is often complicated by the presence of atresia, volvulus or perforation.

Hirschsprung’s disease

One in 5000 newborns has Hirschsprung’s disease. There is a failure of development of the myenteric plexus of ganglion cells controlling parasympathetic activity in the wall of the large bowel. The aganglionic segment is most usually in the distal sigmoid colon and rectum. A number of abnormal genes have been identified in families and patients with this disease. Most infants present with acute large bowel obstruction at birth or within a few days. Abdominal distension is common. Contrast enema demonstrates proximal dilatation of the ganglionic bowel with a relative narrowing of the aganglionic segment. The diagnosis is confirmed by rectal biopsy which demonstrates lack of ganglion cells in Meissner’s plexus.

The obstruction is relieved by stoma. Operative correction occurs a few months later to excise the aganglionic bowel and anastomose normally innervated colon or ileum to the anorectal junction.

Anorectal abnormalities

Examination of the infant’s perineum may reveal abnormalities of the anus which may be a skin-covered anus with a narrow anterior ectopic opening to the skin of the perineum or vulva which may be corrected surgically. Absence of the anal canal and distal rectum with or without fistula from the rectum to the urethra or vagina is managed initially with a colostomy. Corrective surgery is delayed until the infant is thriving.

Necrotising enterocolitis

This affects the small or large bowel, occurring in 1 in 1000 infants. The cause is unknown. It is more common in neonates born prematurely. Symptoms include features of sepsis and failure to absorb feeds. Abdominal distension progresses with erythema and tenderness of the abdominal wall or the passage of stool which contains blood. Abdominal X-rays demonstrate dilated loops of bowel. Intramural gas (pneumatosis intestinalis) is diagnostic. Free gas in the peritoneum indicates perforation.

Management

Feeding is stopped immediately. Antibiotics are instituted against aerobic and anaerobic bacteria. Resuscitation includes intravenous fluids. Ventilation may be required for respiratory failure. Intensive medical treatment is required prior to laparotomy where any gangrenous bowel is excised and either primary anastomosis or exteriorisation of the bowel is performed. Mortality is high (20%). Longer-term complications include short bowel syndrome or strictures.

Abdominal wall defects

The most common abnormalities of the abdominal wall, which are all rare, include:

• gastroschisis

• exstrophy of the bladder.

Exomphalos

This is a defect with the umbilical cord inserted into a transparent amniotic sac with the vessels spreading out (Fig. 17.2). The sac contains loops of bowel and sometimes liver. There may be associated congenital heart disease or chromosomal abnormalities and neonatal hypoglycaemia. Diagnosis is established by mid-trimester ultrasound scan. Management is primary closure or staged reduction to achieve delayed closure.

Figure 17.2 Exomphalos.

Gastroschisis

This is a defect to the right of a normally inserted umbilical cord, with exposure of herniated loops of intestine. The defect is covered with a sterile bag and early operation is recommended to repair the abdominal wall.

Bladder exstrophy

This is more common in boys. There is an anterior opening of the bladder and urethra with absence of tissue of the subumbilical anterior abdominal wall and separation of the pubic bones. Major reconstruction is required in a specialist centre.

Umbilical hernia

There is a higher incidence in Afro-Caribbean children and in patients with Down’s syndrome and hypothyroidism. The infant presents with a protrusion that inverts the umbilicus. There is an easily palpable defect of the umbilicus with sharp-edged defect through which usually little more than the omentum protrudes.

Most hernias close spontaneously before the age of 4 years. Persistent umbilical hernias are closed surgically after the first 3 years of life.

Other lesions at the umbilicus are shown in Table 17.2.

Table 17.2 Moist lesions at the umbilicus

Condition	Appearance	Management
Granuloma	Dull and irregular	Cauterisation or surface ligation after excluding an underlying, more serious lesion
Patent vitello-intestinal tract	Red, smooth and leaking digested milk	Specialised investigation and laparotomy for repair
Patent urachus	Leakage of urine	Urological investigation and repair

Abdominal tumours

These may be classified according to site (upper abdomen, loin, pelvis, right hypochondrium). The investigation of all abdominal tumours should include abdominal X-ray and ultrasound scan.

Childhood tumours are summarised in Table 17.3.

Table 17.3 Causes of childhood tumours

Site	Tumour
Upper abdomen crossing midline	Neuroblastoma Ganglioneuroma Lymphoma
Loin	Wilms’ tumour (the commonest cause of a solid renal mass in a child)
Pelvis	Urogenital cysts Neuroblastoma arising from pelvic sympathetic ganglia Presacral teratomas Ovarian cysts
Right upper quadrant	Hepatic haemangioma and hepatoblastoma

Upper abdominal tumours

The commonest tumour is a highly malignant neuroblastoma arising from the adrenal medulla or sympathetic ganglia. These are irregular and cross the midline and spread to lymph nodes, bone marrow, liver and skin. Most tumours are advanced at presentation. Nearly all neuroblastomas produce catecholamines which are metabolised to vanillylmandelic acid (VMA) and homovanillic acid (HVA). Diagnosis is confirmed by measuring urinary catecholamines. CT scan and MRI scan establish the stage of the disease. Treatment includes chemotherapy, surgery and sometimes radiotherapy. Most patients are incurable.

Loin tumours

Tumours arising in the loin are usually of renal origin. These include hydronephrosis, polycystic disease and non-functioning multicystic kidney. The Wilms’ tumour is the most common cause of a solid renal mass. This is a malignant nephroblastoma spreading to lymph nodes and via the renal vein to the inferior vena cava and lungs. They are occasionally bilateral. The commonest presentation is a palpable mass in a child of preschool age. Pain indicates haemorrhage or rupture. CT scan stages the disease. Treatment is by radical excision followed by chemotherapy and occasionally radiotherapy. Eighty per cent of patients are cured.

Masses arising from the pelvis

These include urogenital cyst or neoplasia, neuroblastoma, presacral teratomas and ovarian cysts. Urogenital cysts and neoplasms include rhabdomyosarcoma arising from the genitourinary tract. Treatment includes chemotherapy, surgery and radiotherapy. The condition may be cured. Ovarian cysts may be massive with calcification in older girls and are treated by surgical excision. Right upper quadrant tumours include haemangiomas and hepatoblastomas. Presacral teratomas contain elements of the three germ cell layers. The sacrococcygeal region is the commonest site in newborns. Chemotherapy and surgical excision are treatments of choice.

Pyloric stenosis

Hypertrophy of the pyloric circular muscles affects 2–3 per 1000 infants in Europe. The male/female ratio is 5 : 1. The disorder develops in the first 6 weeks of life. The cause is unknown.

Clinical features

Forceful projectile vomiting develops between the ages of 2 and 6 weeks. The vomit is not bile-stained. There may be signs of weight loss and dehydration. The diagnosis is confirmed by a test feed. The examiner sits to the child’s left and palpates the right hypochondrium where the hypertrophied and contracted pyloric pseudotumour is felt as a hard swelling of 2 × 1 cm when the abdomen relaxes. Visible peristalsis from the stomach may occur. If there is clinical uncertainty, imaging with ultrasound may confirm the diagnosis. Complications include metabolic alkalosis with a raised serum bicarbonate and low serum chloride concentration. This is corrected with normal saline with added potassium chloride.

Treatment

Pyloromyotomy (Ramstedt’s procedure) is carried out under general anaesthetic and the pyloric muscle is cut longitudinally down to the gastric mucosa. Postoperatively the infant can be re-established on full feeds within 48 hours. The prognosis is good.

Intussusception

This is an invagination of a segment of bowel into an adjacent segment. The common sites are terminal ileum invaginating into the transverse colon. Two per 1000 infants are affected between the ages of 3 and 12 months. The ratio of boys to girls is 2 : 1.

Hyperplasia of a Peyer’s patch due to infection by a virus is a common cause. The enlarged lymphoid tissue acts as a fixed eccentrically placed bolus in the lumen. The gut is invaginated as it tries to pass the ‘lump’ distally. The bowel can become strangulated, in which case there are signs of circulatory disturbance. There may be a history of preceding gastroenteritis or upper respiratory tract infection. There may have been a change in diet before the child presents with severe, colicky pain characterised by flexing the hips and facial pallor. Vomiting occurs and, within 24 hours, the passage of rectal blood.

On examination, the infant may be pyrexial and may be collapsed if strangulation has occurred. A sausage-shaped mass may be palpable in the epigastrium or right hypochondrium. Rectal examination confirms rectal bleeding. Many patients may present atypically. Plain abdominal X-rays suggest the diagnosis by the presence of a soft tissue shadow in the region of the transverse colon with empty distal bowel. Intestinal obstruction with a dilated loop of small bowel implies an established obstruction. Ultrasound examination may be helpful.

Management

A contrast barium enema may be therapeutic by reducing the intussusceptive bowel. Otherwise, laparotomy is required after resuscitation. The intussusception is delivered and reduced by manual pressure. Resection is necessary for irreducible intussusceptions or if gangrenous bowel is discovered after reduction. Recurrence may occur in up to 5% of patients.

The inguinal region and male genitalia

Undescended testes

At the age of 1 year, 1.5% of boys have an undescended testis, most often palpable in the groin – superficial inguinal pouch. However, the testis may lie in the inguinal canal, the abdominal cavity or be absent. It is more common in premature births. Most undescended testes at birth will descend during the first few months of life.

Examination

The cremasteric reflex can be strong in the child, who must therefore be examined in a warm, reassuring atmosphere. The index finger of the left hand passes downwards and immediately over the inguinal canal and may guide the testis towards the scrotum. The infant may be examined in the squatting position, thereby controlling the cremasteric reflex, and the testis may be palpable or persuaded to reach the bottom of the scrotum.

A normal retractile testis does not require intervention but the child should be followed up until the testis drops. An impalpable testis requires laparoscopy to identify the site of the testis, either in the inguinal canal or in the abdomen. If the testicular vessels and the vas are seen to end short of the internal ring, the testis is absent. Once the site has been decided, a surgical decision is made on treatment.

Complications of an undescended testis include reduced fertility, torsion, inguinal hernia and increased risk of malignant change in adult life. Early operation abolishes these risks. If done before the age of 4 years, normal fertility may be achieved by scrotal placement of the testis from the superficial inguinal pouch. The increased risk of malignancy is not altered by orchidopexy. Orchidectomy should be considered for a school-aged boy with a unilateral intraabdominal testis when the contralateral testis is of normal size and position. Orchidopexy should be performed between the ages of 15 months and 4 years. The testis and spermatic cord are dissected free from any hernia and a herniotomy is done. The testis can be mobilised to reach the lower scrotum by being placed in a pouch between scrotal skin and external spermatic fascia (Datos pouch).

Indirect inguinal hernias

This is more common in boys and usually presents in the first year of life. It is more common in premature babies. Irreducibility is common and may result in intestinal obstruction and testicular infarction. The symptoms are usually noticed by the mother who notices a lump in the groin which disappears when the child is at rest. Strangulation may occur, causing pain and distress and features of intestinal obstruction. The swelling is visible and palpable in the medial part of the inguinal region and extends down into the ipsilateral scrotum or labium.

Management

A reducible inguinal hernia is an indication for early elective herniotomy through a small skin crease incision overlying the site of the internal inguinal ring. The hernia sac is isolated and transfixed. Herniorrhaphy is not indicated in this age group. An irreducible inguinal hernia requires analgesia and sedation followed by gentle compression of the lump (taxis), which achieves safe reduction in 90% of patients. Herniotomy is carried out 1–2 days later. A persistent, tender irreducible hernia requires emergency operation.

Hydrocele

The processus vaginalis is usually patent. Hydroceles are common in the first year of life and may resolve spontaneously. Symptoms include the mother reporting an increase in the size of one half of the scrotum. Swelling may fluctuate and transilluminate. If the hydrocele is persistent after the age of 2, an elective operation is recommended to ligate the patent processus vaginalis at the internal inguinal ring. This is similar to a herniotomy.

Torsion of the testis

The prepuce

Circumcision

Removal of the prepuce has been a religious rite for thousands of years. There is no medical indication for this operation, apart from phimosis or a previous episode of paraphimosis.

Phimosis is usually a result of trauma or infection and the flow of urine from the external meatus is obstructed. Marked ballooning occurs on micturition and the tissue around the preputial meatus is white, fibrotic and thickened. The foreskin cannot be retracted.

In paraphimosis the prepuce, which is usually fibrotic, is retracted and trapped in the coronal sulcus of the penile shaft, causing oedema of the glans. If this occurs, oedema is reduced by firm compression and manual reduction is usually possible, sometimes under anaesthetic.

Balanitis is recurrent sub-preputial inflammation with a wide variety of organisms, usually due to lack of cleanliness. Fibrosis may ensue.

Circumcision is usually performed under general anaesthetic and bipolar diathermy is used for haemostasis to prevent testicular vessel thrombosis or corpora cavernosa damage. Absorbable sutures are used and the glans is protected postoperatively by the application of soft paraffin dressing.

Complications of circumcision include bleeding and infection, meatal ulceration and stenosis and, more rarely, a urethral fistula. Removal of too much penile skin leaves the shaft covered by scrotal and abdominal wall skin which may cause sexual problems later in life. Recurrent phimosis can occur if too little inner preputial skin is excised.

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