Intestinal obstruction in the neonate can be due to a wide variety of conditions with very varied pathology, associated conditions, treatment, and prognosis. However, the presenting features are very similar. Bile-stained green vomit is never normal in a neonate and implies the presence of an obstruction. The degree of abdominal distension varies with the level of obstruction. Ninety-five per cent of normal neonates pass meconium within 24 h of birth; failure to pass meconium at all or to stop after an initial defecation is abnormal. Pain is not usually a feature. Functional obstruction, as in Hirschsprung's disease, may also occur in septicaemia, premature babies with immature ganglion cells, in association with severe hypoglycaemia, or following hypotension and hypoxia. It is obviously important to avoid laparotomy in these babies.

Congenital aplasia, atresia, membranes, and webs of the pylorus are all very rare (0.5 per cent of all atresias). Embryologically they may reflect failure of recanalization, but this is uncertain. Polyhydramnios may be present. Complete obstruction presents with non-bile-stained vomiting and eventual metabolic alkalosis. Partial obstruction may not be detected until adult life.

Plain radiographs show a distended stomach, and a barium meal demonstrate a web. Following nasogastric decompression, gastric lavage, and correction of any metabolic abnormalities a laparotomy is needed to demonstrate the exact pathology.

Gastroduodenostomy is required for the treatment of aplasia, while atresia, membranes, and webs are all treated by a Heineke-Mikulicz pyloroplasty. Prompt diagnosis and treatment should ensure a good long-term prognosis.

Intrinsic obstruction of the duodenum may be complete or incomplete (with a ratio of 2: 1) and occurs in about 1 in 10000 live births.

The stomach and proximal duodenum are very hypertrophied and dilated, while the distal bowel is collapsed. The site of obstruction is most commonly in the second part of the duodenum, around the level of the ampulla of Vater. About 40 per cent of obstructions are preampullary, and 60 per cent postampullary. Less than 5 per cent are actually at the ampulla. The type of obstruction varies from a complete gap between the two ends, through connection with a fibrous cord, to apposition. A stenosis may be a short narrow segment or a perforate diaphragm, the small orifice of which may be central or eccentric. A thin diaphragm may stretch along the lumen like a ‘windsock’.

The biliary tree is usually normal. The common bile duct can terminate on or very close to the attachment of a diaphragm. Occasionally the terminal portion is bifid, with orifices in both parts of the atresia. This may be impossible to detect clinically unless there is a complete atresia with air in the distal bowel.

An annular pancreas is present in about 25 per cent of patients with duodenal atresia. It encircles the second part of the duodenum, which may be atretic or stenotic.

Between 30 and 40 days of gestation, the duodenal mucosa proliferates, occluding the lumen. Duodenal atresia is due to failure of recanalization (see ileal atresia). The embryological cause of annular pancreas is unclear, but it is probably related to failure of rotation of the ventral anlage.

At least 50 per cent of duodenal atresias and stenoses are associated with polyhydramnios, and at least 60 per cent of such pregnancies will be complicated or end prematurely. The hypertrophied, dilated stomach and duodenum are easy to see on early antenatal ultrasound scans.

Down's syndrome is present in 30 per cent of babies with duodenal atresia, and antenatal karyotyping is justifiable. Sixty-five per cent of both Down's and normal babies with duodenal atresia have at least one other abnormality, ranging from major cardiac defects through malrotation to biliary atresia and exomphalos. Oesophageal atresia is present in 10 per cent.

These are those due to a high gastrointestinal obstruction. Copious vomiting or regurgitation of feeds occur early, but this may be delayed if there is only a stenosis. If the obstruction is preampullary, the vomitus will not be bile-stained and diagnosis tends to be delayed. Postampullary obstruction produces classical bile-stained vomit. Some blood may be present, due to oesophagitis, and severe dehydration due to vomiting may develop. Jaundice is usually not due to anatomical abnormality but to biliary atresia or surgical trauma. Colic, distension, and constipation are not common features.

A large nasogastric tube needs to be passed urgently to empty the stomach and duodenum and prevent aspiration of vomit. Fluid replacement may be needed, depending on the degree of dehydration. The presence of major cardiac defects needs to be excluded. Surgery should only be considered when the baby is fit for theatre.

If 40 to 50 ml of air are blown down the nasogastric tube, a subsequent plain abdominal film should be diagnostic. In duodenal atresia, a classical ‘double bubble’ will be seen due to the massive dilatation of the first part of the duodenum, with air/fluid levels in the duodenum and stomach and no distal gas. Duodenal stenosis is characterized by the presence of air distally.

If the baby has Down's syndrome then the ethics of corrective surgery may need to be discussed with the parents.

All babies with duodenal atresia should be treated by duodenoduodenostomy following Kocher's manoeuvre of the duodenum. One layer of absorbable sutures is sufficient. An annular pancreas is left alone and an anterior duodenoduodenostomy created.

Diaphragms can be incised or excised superolaterally to avoid damage to the ampulla. The presence of windsock diaphragms and additional diaphragms must be excluded by passing a catheter proximally and distally through the duodenostomy. A grossly ectatic duodenum may function more quickly if it is tapered or plicated to a more normal size, but this is unproven.

Gastrostomies are not necessary if intravenous feeding is available. A soft silicone transanastomotic tube (a Silk tube) can be passed into the mid-jejeunum. Any other intra-abdominal pathology, such as malrotation, should be corrected.

The nasogastric tube must be aspirated regularly to avoid the possibility of aspiration pneumonia. After 24 h the transanastomotic tube can be used for replacement of nasogastric losses directly into the distal bowel and for feeding. Presence of the tube is unlikely to hasten feeding or bowel movements. The bowel may take 1 or 2 weeks to start to function normally, and if feeding via the transanastomotic tube is unsuccessful, intravenous feeding may be required.

Between 10 and 20 per cent of affected babies die due to their associated congenital abnormalities, including major cardiac problems, the reduced resistance of Down's syndrome babies to infection, or the complications of prematurity. Most of the rest become asymptomatic, though bile reflux into the stomach has been demonstrated in adults.

Atresia and stenosis of the bowel are less common distal to the duodenum than in the duodenum; estimates of the incidence vary widely from 1 in 1500 to 1 in 20 000 live births.

Atresia distal to the duodenum is not an early event, as it occurs after the production of bile (11th week). No single cause explains all cases: some are due to intussusception with necrosis, while others are caused by a vascular accident which may or may not be identifiable (such as volvulus). Multiple atresia appears to be due to hereditary maldevelopment of the bowel.

There are four main types. Type I has a diaphragm with continuity of the bowel wall. Type II has a gap between the two ends, (which may be connected by a fibrous cord), together with a mesenteric defect. Type III has multiple atresias. Type IV is ‘apple peel’ atresia with loss of the dorsal mesentery and a blood supply to the ileum from the middle colic artery. The proximal bowel is always dilated and hypertrophied and the distal bowel collapsed but containing meconium.

Antenatal ultrasound examination may show polyhydramnios or dilated bowel. Postnatally, the abdomen becomes very distended and bile-stained vomiting occurs early, especially in those with high obstruction. Meconium may be passed rectally. Stenoses commonly present after a delay of days to years, depending on the size and level of the stenosis.

Plain radiographs of the abdomen disclose hugely dilated bowel and a gas-free rectum (Fig. 1(a)) 2128. It is often possible to identify the level of obstruction preoperatively by the size, position, and number of bowel loops. Distal air is present in patients with stenosis and further contrast studies are required for accurate preoperative diagnosis.

A nasogastric tube needs to be passed to decompress the stomach and avoid aspiration pneumonia. Dehydration must be corrected preoperatively.

At laparotomy, the hugely dilated proximal bowel should be resected if possible, or tapered, to reduce postoperative ileus and to make the anastomosis easier (Fig. 1(b)) 2129. The initial 5 to 10 cm of distal bowel should also be resected if there is any question of a poor vascular supply. After cut back of the distal bowel to ensure two lumina of approximately the same size, a single layer end-to-back anastomosis with interrupted absorbable sutures is performed. Multiple atresias can often be excised, leaving only one anastomosis. In apple peel atresia the blood supply of the ileum is precarious and great care is required to ensure viability of the distal bowel. Second look laparotomy may be a wise precaution. Stenoses require excision and end-to-end anastomosis.

Postoperative ileus is reduced by excising the dilated proximal bowel, but it may still occur. Intravenous feeding may rarely be necessary. Lactose intolerance is common and a lactose-free milk containing medium chain triglycerides (such as pregestemil) should be tried initially.

The mortality rate of 100 per cent seen early this century has been replaced by a survival rate of over 85 per cent. Death is usually due to associated abnormalities.

Meconium ileus is the most common cause of neonatal intraluminal intestinal obstruction and is usually (75–80 per cent) due to cystic fibrosis. It occurs in about 1:10000 to 1:20000 live births. Cystic fibrosis occurs in about 1:2000 live births and is inherited as an autosomal recessive trait.

In cystic fibrosis, the pancreatic secretions are abnormally viscid and cause obstruction within the pancreas itself. This event causes abnormalities in the composition of meconium which becomes inspissated in the lower ileum, due to the absence of proteolytic enzymes. The obstructed ileum becomes filled with putty-like lumps of meconium and classically tapers from the grossly dilated empty proximal ileum to the collapsed ileum distal to the obstructing meconium. There is a microcolon (Fig. 2) 2130. Complications such as volvulus, perforation, and atresia occur in 30 to 50 per cent of patients. The liver, sweat glands, epididymis, and lungs are also affected.

The features of low intestinal obstruction are usually apparent on the first day of life, as bile-stained vomiting and marked abdominal distension. Meconium is not passed, though bile-stained vomiting in utero can mimic meconium-stained liquor. Palpable, distended loops of bowel with indentable meconium may be felt. Radiology shows distended ileal loops, but few fluid levels. An intraluminal ‘ground-glass’ appearance due to air and abnormal meconium may be present, especially in the right upper quadrant (Neuhauser's sign). Calcification is due to meconium peritonitis and a resulting inflammatory mass.

Gastrografin enemata refluxed into the terminal ileum will be successful in about 50 per cent of patients with uncomplicated obstruction (15–25 per cent overall). The combination of a high osmolality (1800 mOsmol/l) plus a wetting agent (Tween 80) can free the viscid meconium. The baby must be well hydrated and carefully monitored, and an operating theatre must be available immediately in case of failure or complications (especially perforation).

The classical treatment was a Bishop-Koop or vented ileostomy. However, these require a second operation to close the stoma. More recently, enterotomy and lavage using either gastrografin or acetylcysteine (Parvolex) which liquefies the meconium, have superseded ileostomy. All of the tenacious meconium is removed. Any twisted or ischaemic bowel has to be excised and any atresia treated as above with a primary anastomosis, avoiding the complications of stomata in the neonate. The colon is also flushed intraoperatively to exclude any distal obstruction. To prevent any postoperative meconium ileus equivalent, Pancrex is administered immediately postoperatively via the nasogastric tube.

Ninety per cent of babies survive the neonatal period, though their long-term prognosis will depend on the severity of their pulmonary disease. If cystic fibrosis is not the cause and long-segment Hirschsprung's disease has been excluded, the postoperative course should be uneventful with no long-term problems.

Some babies fail to pass meconium until a rectal examination or wash-out has stimulated the passage of a meconium plug. This consists of a clear mucous lower third (tip) with a green meconium upper two-thirds (body). The babies usually vomit and have distended abdomens. The plug may be formed by over-reabsorption of water from the meconium by a colon with immature motility. Oral feeds can be started immediately. Most of these babies have normal bowel function, but cystic fibrosis and Hirschsprung's disease should be excluded routinely.

Meconium peritonitis (Fig. 3) 2131 is a result of antenatal perforation from any cause (such as meconium ileus). An intense chemical peritonitis following the presence of the meconium may result in calcification, dense adhesions, or the formation of a pseudocyst. Postnatally, if the perforation is still present, bacterial peritonitis will ensue. Perforation, adhesion, obstruction, and pseudocysts all require surgical treatment.

Between 4 and 10 weeks of development, the intestines herniate into the umbilical cord. When they return to the abdomen, they usually rotate anticlockwise, the duodenum by 270° so that the duodenojejunal flexure lies to the left of the superior mesenteric artery and the caecum by 360° so that the transverse colon is anterior to the superior mesenteric artery, and the caecum is in the right iliac fossa. Complete failure of this complex process will result in the ‘universal mesentery’ present in patients with congenital diaphragmatic hernia or exomphalos, whilst partial failure results in ‘malrotation’. The most common result is a caecum lying very close to the duodenojejunal flexure, with abnormal adhesions binding them both to the posterior abdominal wall. The resulting midgut mesentery is abnormally narrow, allowing volvulus to occur.

Malrotation presents in two main ways. A baby with intermittent bile-stained vomiting and possible abdominal distension who has passed meconium normally is often referred late. Alternatively, volvulus occurs, the baby collapses, and may be moribund, severely acidotic, and hyponatraemic. There may be very little to feel abdominally in either case.

Radiological examination after putting 40 to 50 ml of air into the stomach may show the distended first and second parts of the duodenum, or may show the ileum lying on the right (Fig. 4) 2132. Often there is no specific feature. Contrast studies may be necessary to confirm the diagnosis: a contrast meal tends to produce more diagnostic results than an enema. Non-ionic contrast should be used because of the possibility of perforation. Ultrasound examination may demonstrate an abnormal relationship between the superior mesenteric artery and the portal vein.

Because of the risk of volvulus and subsequent midgut ischaemic necrosis, laparotomy should be performed as soon as possible after adequate urgent resuscitation and nasogastric decompression. Any volvulus will need to be unwound, usually in an anticlockwise direction. All abnormal adhesions between the caecum and the duodenum need to be divided (Ladd's procedure). By making the midgut mesentery as wide as possible, the completely freed caecum and colon can be placed on the left. A kink-free duodenum will lie on the right of the midline with the ileum. Inversion appendicectomy should be performed to avoid peritoneal contamination and the diagnostic difficulty of appendicitis with a left-sided caecum.

If there is massive necrosis, obviously dead bowel should be resected. All doubtfully viable bowel should be left in situ and both ends exteriorized. A second-look laparotomy the next day may show more recovery than had been expected. A primary anastomosis of viable bowel may be possible, avoiding the morbidity associated with ileostomies in neonates.

Provided that there are no major associated abnormalities and no resection is necessary, survival should approach 100 per cent. Massive intestinal loss (short bowel syndrome) and associated abnormalities account for most of the deaths in recent series.

Necrotizing enterocolitis is one of the most common single presentations on a surgical neonatal unit. It was almost unknown before the mid-1960s, but is now seen as increasingly intensive management of sick premature neonates means that more of these babies survive. Although premature babies are the predominant group with necrotizing enterocolitis (90 per cent), term babies who are otherwise well may develop the condition, especially following surgery either for gastrointestinal or completely unrelated conditions.

Necrotizing enterocolitis appears to be the final common pathway or end result of a wide variety of stresses in a susceptible baby. Usually these stresses are multiple, though a single cause may occasionally be identified. The risk of necrotizing enterocolitis is inversely proportional to birth weight and is often associated with episodes of hypoxia, hypothermia, hypotension, hyperviscosity, acidosis, or the presence of free oxygen radicals. Umbilical artery cannulae, exchange transfusion, hyperosmolar feeds, packed cell transfusion, or overdosage with calcium antagonists are also known risk factors. All of these could cause mesenteric ischaemia which will allow bacterial invasion of the mucosa and bowel wall leading to necrosis. This ischaemia may mimic the ‘dive reflex’ in seals when the blood is diverted away from the bowel during episodes of hypoxia.

Necrotizing enterocolitis can affect any part of the bowel, but the terminal ileum and caecum, distal colon, and entire colon are predominately affected. Macroscopically the bowel is dilated and friable, with areas of haemorrhage and necrosis. The mucosa is ulcerated and sloughed. Microscopically, there is a complete spectrum from coagulation necrosis of the mucosa, through ulceration and haemorrhage, to transmural necrosis which is histologically identical to Hirschsprung's enterocolitis. Healing is by epithelialization but fibrosis may cause stricture formation.

Most babies with necrotizing enterocolitis present with bilious vomiting, abdominal distension, colour change, bradycardia, apnoea, lethargy, or poor response to handling. Gross or occult blood in the stools is seen in 75 per cent of patients. Initially the abdomen is soft, but erythema and oedema of the anterior abdominal wall often coincide with a mass of inflamed bowel. Thrombocytopenia and neutropenia indicate disseminated intravascular coagulation and septicaemia, often associated with acidosis.

The classical diagnostic finding is pneumatosis intestinalis on plain abdominal radiographs. This event appears as linear gas shadows in the bowel wall which are most dramatic when the bowel is seen end on (Fig. 5) 2133. The presence of portal vein gas increases the mortality by 20 per cent, though the exact mechanism of this is unclear. Free intraperitoneal air implies perforation, except in the presence of pneumomediastinum. A persistent gas filled loop in a series of radiographs implies the presence of infarcted bowel.

The baby is aggressively resuscitated with plasma, blood transfusion if necessary, additional oxygen or ventilation, and, following blood cultures, antibiotics. Antibiotics active against a broad spectrum, including anaerobes, must be used: most centres use metronidazole, an aminoglycoside, (e.g. gentamicin), and a penicillin or third-generation cephalosporin.

All feeds are stopped for a minimum of 7 to 10 days, a nasogastric tube is passed to allow gastric decompression, and intravenous feeding is started. Regular clinical monitoring of the baby together with measurement of the haemoglobin, platelets, and blood gases allow correction of any abnormality. Hypovolaemia is readily detected using the toe-core temperature difference, which should be less than 3°C. If there are coagulation problems fresh frozen plasma should be used rather than simple plasma. Serial radiographs are costly and unnecessary. The best method for pain relief is opiate analgesia by continuous intravenous infusion.

The optimal time for operation is not in the acute period, though whether it is better to operate after stabilization for a few days or electively for complications arising during convalesence is not known. Pneumoperitoneum is no longer an absolute indication for surgery as silent perforations are frequently recognized. The desperately ill, but stable neonate can withstand the presence of much more intestinal necrosis than would be possible in an adult, but suffers the stress of laparotomy poorly. In a baby who is deteriorating despite maximal support, laparotomy is the only option. However, in a stable neonate, non-surgical management should be maintained to allow as much recovery as possible. Very low birth weight neonates with extensive disease may benefit from percutaneous drainage under local anaesthesia. Despite extensive clinical or radiological disease not all neonates with necrotizing enterocolitis require laparotomy, either acutely or at a later date.

At laparotomy, all necrotic bowel must be excised, but provided the two bowel ends are viable and bleed well, primary anastomosis is safe and avoids the morbidity associated with ileostomies in neonates. Multiple areas of necrosis may require multiple anastomoses. Delayed surgery following prolonged medical management, usually for colonic stricture, is safer than emergency laparotomy.

Postoperatively many babies seem to do better on a homogenized lactose-free milk formula such as pregestemil. If a stoma has been created, then the sodium loss from this may cause failure to thrive and additional supplementation is required (an additional 0.13 mmol sodium/ml ileostomy loss or 1 ml 8.4 per cent NaHCO&sub3;/3–4 hourly feed).

The mortality rate of 40 to 50 per cent in the 1960s has been reduced to 25 per cent with more aggressive medical support and the introduction of metronidazole. Between 10 and 30 per cent of survivors develop a colonic stricture, whether they were operatively or conservatively managed, so this must be looked for clinically. Short gut syndrome may result from extensive resection.

Although this condition can occur within the first week of life, the age of presentation is usually between 10 days and 10 weeks, with a peak at about 4 weeks, independent of gestational age. The condition should, therefore probably be called infantile rather than congenital hypertrophic pyloric stenosis.

More boys than girls are affected, in a ratio of 4:1. Over half the infants are first born. The incidence varies throughout the world, but infantile hypertrophic pyloric stenosis affects approximately 2 per 1000 live births in the United Kingdom.

The aetiology must be multifactorial. There is a strong familial element, with a 5 per cent incidence in children with affected mothers. There is a seasonal variation (more common in the winter) and a relation to social class. Many hypotheses have been put forward to explain the hypertrophy, but it is difficult to decide whether the factors are cause or effect. Increased stress causing a hormonal effect both in pregnancy and postnatally has been suggested, with gastrin as the possible hormone.

Immunocytochemical studies show a reduced number of nerve fibres containing vasoactive intestinal peptide and enkephalin, but the pyloric ganglia otherwise seem normal.

Macroscopically there is an olive-shaped tumour up to 2.5 cm in diameter which blends into the antral musculature. At the duodenal end, the pylorus bulges into the lumen like the cervix into the vagina, creating a circumferential fornix. The stomach is markedly dilated.

Microscopically there is marked hypertrophy of the circular muscle of the pylorus and some hypertrophy of the longitudinal muscle, together with marked mucosal oedema. There is lengthening of the pyloric canal.

Most babies with infantile hypertrophic pyloric stenosis feed normally initially and then gradually vomit with increasing frequency and force. The vomit is not bile-stained, consists of milk curds and mucus, and becomes projectile. Following a vomit, the baby will generally feed again greedily. Twenty per cent of patients have haematemesis due to oesophagitis. The production of free fatty acids in the stomach causes gastritis.

Most babies have lost weight by the time of presentation, either due to dehydration or to loss of subcutaneous fat. The absence of weight loss puts the diagnosis in doubt. It is crucial to examine the baby in the correct position to maximize the chance of the correct diagnosis. The baby should have a test feed from the mother's left breast or be held in the left arm. Milk is better than dextrose. The mother and baby should be seated between the window and the examiner, who sits on the baby's left side. The entire abdomen is exposed and the legs supported to relax the abdominal muscles. Talcum powder on the abdomen allows the fingers to move around more easily. Visible peristalsis of the hypertrophied stomach may be seen through the anterior abdominal wall coursing from the left towards the midline (Fig. 6(a)) 2134.

The examiner, using his left hand, attempts to feel the pylorus, or pyloric ‘tumour’, by trapping it against the vertebrae, either round the edge of the right rectus muscle or through the linea alba. It has been likened to ‘feeling a walnut through a blanket’. Projectile vomiting, weight loss, and a palpable pylorus make the diagnosis certain.

If the initial test feed is negative, it should be repeated 4 to 6 h later. If still negative, a more experienced clinician needs to repeat it again. If there is still doubt then a barium meal should be diagnostic. Ultrasound examination has superseded the ‘test feed’ and barium meal in some units.

Because of the obstruction at the pylorus, these babies produce the classical metabolic picture of hydrogen and chloride ion loss. This hypochloraemic metabolic alkalosis with dehydration is complicated by the renal response, which involves potassium excretion in exchange for hydrogen ions. These babies must therefore be resuscitated with at least 0.5 N saline solution (0.45 per cent NaCl) plus 2 g of potassium chloride per 500 ml bag initially to avoid profound hypokalaemia and failure to correct the alkalosis. Only when the baby is electrolytically normal (bicarbonate less than 30 mmol/l) should the child be taken to theatre. The stomach should be lavaged to ensure that all the milk curds are washed out.

Infantile hypertrophic pyloric stenosis is probably the only condition for which all the surgeons in the world use the same operation: Ramstedt's pyloromyotomy. Through a right upper transverse rectus-cutting incision, the greater curve of the stomach is delivered, followed by the pylorus. The pylorus is rotated so that the relatively avascular superior part (Fig. 6(c)) 2136 is uppermost and the serosa is incised from near the pyloroduodenal junction at least 2 cm on to the antrum. The muscle fibres are split by spreading them using an artery clip or a purpose-made spreader proceeding proximally until the fibres appear to tear tangentially. The mucosa bulges up into the defect. Distally, the muscle fibres are split almost to the pyloroduodenal junction, though a 100 per cent split of the tumour is not necessary, as a 95 per cent split works just as well. Because of the duodenal fornix, perforation is easy, but is simply oversewn with an omental buttress. Air (40–50 ml) is syringed down the nasogastric tube by the anaesthetist and squeezed through into the duodenum. Any leak is obvious. Haemostasis if usually unnecessary. Careful closure in a well-resuscitated baby should ensure that the incidence of dehiscence is minimal, though wound infection still occurs (5–10 per cent).

Feeds are withheld for 24 h postoperatively or until the following morning, when full feeds are restarted. There is no need for complex feeding regimens.

There should be no mortality, though wound dehiscence and infection still occur.

Intussusception is the most common cause of intestinal obstruction in infants aged 6 to 18 months.

Intussusceptions are most common in the terminal ileum and can only occur in the presence of a mobile ‘partly malrotated’ caecum and terminal ileum. When a lead point exists in the bowel wall, peristalsis causes that part of the bowel to invaginate and progress along the lumen, through the ileocaecal valve and along the colon. Although most intussusceptions only reach the transverse colon, if there is sufficient mobility they may present at the anus. Lead points may be an inflamed Peyer's patch, a Meckel's diverticulum, or a polyp (e.g. in Peutz-Jegher syndrome). Obstruction occurs due to oedema of the intussuscepted bowel, which may become ischaemic and necrotic.

Infants with intussusception present classically with intermittent attacks of intestinal colic lasting a few minutes, characterized by a high pitched scream, pallor, curling up their knees, and vomiting. The vomit is usually bile stained. Between bouts of colic the infant is quiet, listless, and anorexic. There may be a history of recent immunization or a viral illness. Rectal bleeding (redcurrant-jelly stool) (Fig. 7(a)) 2137 is said to be a late sign, but this is by no means always the case.

Examination between bouts of colic often reveals a soft abdomen which is remarkably non-tender. A sausage-shaped mass in the right upper quadrant or epigastrium is palpable in about 30 per cent of cases. Rectal examination may reveal the apex of the intussusception or blood on the glove. Bowel perforation is a rare event but leads to widespread peritonism.

A supine plain abdominal radiograph should reveal absence of the caecal gas shadow from the right iliac fossa. A soft tissue mass may be obvious. The apex of the intussusception may be visible in the transverse colon, outlined by the distal gas. Erect films demonstrate fluid levels in the obstructed bowel, though these are not useful prognostically. Any free gas due to perforation is best demonstrated on an erect chest radiograph. If there has been excessive vomiting, serum urea and electrolyte levels should be measured.

All infants with intussusception need resuscitation prior to treatment. A minimum of 10 ml/kg of plasma should be given routinely; even clinically ‘well’ infants may well need as much as 30 to 40 ml/kg eventually. All patients with intussusception have considerable ‘third space’ losses due to oedema of the bowel wall, fluid loss into the ileal lumen, and peritoneal exudation.

Reduction by enema should be attempted in all except very dehydrated and sick infants, in whom bowel necrosis has already occurred, or in those with free intraperitoneal air. A long (more than 48 h) history of intussusception is not a contraindication to enema reduction. The exact period of obstruction is difficult to define and, in a well baby, enema reduction may well be successful despite a ‘long’ history. Intussusception into the rectum implies extensive bowel mobility and an easy enema reduction, not the reverse.

Premedication with Omnopon (papaveretum) 0.2 mg/kg and scopolamine 0.004 mg/kg intramuscularly 1 h prior to the enema is helpful as Omnopon inhibits the desire to defecate and scopolamine is a smooth muscle relaxant. Traditionally, hydrostatic reduction using barium sulphate has been used, with up to a 75 per cent success rate. Air insufflation has been used extensively by Chinese surgeons and has the advantage that should perforation occur, there is no soiling of the peritoneum with barium. The apex of the intussusception can usually be identified and watched as it reduces. Free reflux of barium or air into the terminal ileum defines a successful reduction. Failure of reflux may be due to an incomplete reduction or an oedematous ileocaecal value; clinical observation is mandatory. If the infant is well, relaxed, and is no longer having bouts of colic, then the intussusception has been reduced. If there is still clinical evidence of intussusception then a further enema, 4 to 6 h later, when the oedema of the bowel has reduced, has a high success rate. It is important to avoid performing an unnecessary laparotomy for a reduced intussusception.

If there is evidence of necrosis, or if the intussusception is irreducible, laparotomy is performed through a right iliac fossa muscle-splitting incision, just below the level of the umbilicus (Fig. 7(b)) 2138. Reduction is achieved by gently squeezing the mass to reduce the oedema rather than by pulling on the ileum, which will cause tearing. Any necrotic bowel, Meckel's diverticulum, or polyp will needs to be resected. If possible, an appendicectomy should also be performed as this will encourage fixation of the caecum in the right iliac fossa and avoid any future confusion as to the reason for the abdominal scar.

Ileoileal intussusception requires laparotomy and resection of the offending polyp, the usual pathology, together with the minimum amount of normal ileum.

There is a 5 to 10 per cent recurrence rate following either enema reduction or laparotomy without resection. A repeat enema should be performed, but at the third recurrence, laparotomy is justified. In children over 3 years old, enlarged Peyer's patches are rare and laparotomy is more likely to be required.

Ten per cent of babies pass meconium at birth and a further 85 per cent pass meconium within the first 24 h. After that, breast-fed babies usually pass more motions than bottle-fed babies, though the absolute frequency is very variable. Normality for adults is between 3 stools per day and once every 3 days.

Constipation may present at birth due to conditions such as anal stenosis and Hirschsprung's disease, but it more commonly arises after 2 years of age. The most common cause is an anal fissure. A hard motion tears the anal verge, causing pain and spasm. The child holds on because it knows that defecation will be painful, and so a further hard motion is formed which eventually passes with more tearing, pain, and spasm in a vicious circle. A distended colon peristalses poorly and increases bowel transit time. The rectum is always full and soiling may occur. Behavioural changes, agression, and moodiness are common and are due to absorption of toxins from the colon. Even after the fissure has healed the abnormal bowel habit remains.

Early aggressive treatment of fissure in children with stool softeners, such as lactulose (in an adequate dose, of up to 20 ml three times daily) and local anaesthetic ointments such as lignocaine 5 per cent is often successful. A vigorous anal stretch under general anaesthetic which disrupts the pecten bands and abolishes the spasm may also allow healing.

Established constipation requires plenty of time and a full explanation to a family which is often completely fixated on the child's bowel habit. Suppositories, such as bisacodyl, or microenemata are more successful in keeping the rectum empty than are oral laxatives, and allow the colon to resume a more normal calibre. Regular rectal emptying allows the re-establishment of rectal sensation, the abolition of soiling, and the promotion of a regular bowel habit. Family interactions should improve once the parents can be convinced that they can control their child's bowels, and improvement is seen.

If meconium is not passed within 48 h of birth, or if there is no obvious history of a fissure, the diagnosis of Hirschsprung's disease needs to be excluded.

The reasons for rectal bleeding in a child vary with age and are usually diagnosable on history and examination. General causes such as haemorrhagic disease of the newborn are rare. Children rarely present with massive severe rectal bleeding. Brisk bright red bleeding is usually due to bleeding from an ulcer opposite a Meckel's diverticulum. Chronic, undiagnosed rectal bleeding despite a series of negative investigations has a 50 per cent chance of diagnosis at laparotomy.

Crohn's disease and ulcerative colitis are more common in adults than in children and are covered in detail elsewhere. Anyone treating children with inflammatory bowel disease needs to remember the psychological stresses which occur within the family of a child with a severe, chronic illness which may affect growth.

Ulcerative colitis is rare before the early teens and usually presents with diarrhoea, abdominal pain, and mucus and blood per rectum. Toxic megacolon is very rare (<2 per cent), weight loss and fever are common (80 per cent), and arthritis is unusual (10 per cent). An endoscopic examination under general anaesthetic allows a biopsy sample to be obtained for histological confirmation. An early barium enema is often normal. Treatment ranges from salazopyrine for mild cases through rectal steroids to systemic prednisone (1–2 mg/kg. day). Severe ulcerative colitis requires admission to hospital, maximal fluid support, antibiotics active against anaerobes, such as metronidazole, and intravenous hydrocortisone. Intravenous feeding is not helpful in inducing remission or predicting a need for colectomy. Regular endoscopic review is required for carcinoma surveillance. Colectomy is curative, but the psychological effect of a permanent ileostomy is variable. Continent intra-abdominal pouches are still improving, through the risk of a major complication is still formidable. Early diagnosis and treatment is associated with improved growth and general health. Chronic symptoms are present in 60 to 70 per cent of patients. Pancolitis is more likely to result in carcinoma, but the risk is not related to age of diagnosis. Although the chance of carcinoma is probably less than was originally thought, total colectomy is still performed in about 25 per cent of children with ulcerative colitis.

Fifteen per cent of patients with Crohn's disease present before the age of 15. The symptoms may mimic those of ulcerative colitis, or may be more subtle, with failure to thrive, anorexia, malabsorption, fistula formation, or perianal disease. Weight loss and fever are common, but arthritis is uncommon (15 per cent). The ESR and C-reactive protein level are usually raised (90 per cent) and a small bowel meal may be diagnostic. Infectious diseases, including yersinosis, must be excluded. The treatment of Crohn's disease has not been so well studied in children as in adults. Prednisone is probably better than salazopyrine but has a greater effect on growth potential. Because of their oncological risk, 6-mercaptopurine and azathioprine are reserved for use in steroid-dependent children with severe disease. Intravenous feeding has a major role in decreasing symptoms, inducing remission, closing fistulae, improving postoperative growth, and in the treatment of simple growth failure. At least 70 per cent of patients will require surgery within 7 years of diagnosis, usually for obstruction, fistulae, or growth failure. To improve the chance of normal growth, operation should be undertaken earlier than is usual in adults, though only the minimum surgery should be performed (minimal resection and primary anastomosis). Fifty per cent of children think that their quality of life is worse than that of their peers. Although eventual operation is likely, the mortality from the disease is low.

Clayden GS. Is constipation in childhood a neurodevelopmental abnormality? In Miller PJ, ed. Disorders of Gastrointestinal Motility in Childhood. Chichester: John Wiley & Sons Ltd, 1988: 111–21.

Kirschner BS. Inflammatory bowel disease in children. Pediatr Clin N Am 1988; 35: 189–206.

Lister J, Irving IM, eds. Neonatal Surgery 3rd edn. London: Butterworth & Co Ltd, 1990.

Sweeney JL, Sparnon AL. Neonatal intestinal obstruction. Br J Hosp Med 1989; 255–8.

Welch KJ, et al. Pediatric Surgery 4th edn, (volumes 1 and 2). Chicago: Year Book Medical Publishers Inc., 1986.