Ministry of Health
common to see abdominal distension with CPAP. Gas flow rates can be
high to maintain a CPAP pressure, and some gas will naturally take the path
of least resistance and enter the gastrointestinal tract.
Clinically, there is
distension of the abdomen without discolouration of the abdominal wall
and without tenderness. Feeds are often tolerated but gastric
aspirate residuals are not uncommon. The aspirates are usually
undigested milk, and bilious aspirates should make you think of other
causes. Occasionally the distension can be so great as to cause
Radiographically, there is
evidence of intestinal air, without features which would suggest other
more sinister processes (i.e. intramural gas, free air, thick-walled
Treatment is to
- ensure that a large-bore
intragastric tube is vented
allow time off CPAP if possible
- encourage the baby to pass
stool (using glycerine suppositories) if this is a problem
Perforation is not a diagnosis and does not indicate the underlying cause.
A lateral decubitus film with the left side down gives the best opportunity
to define air within the abdominal cavity. The radiograph must be
closely scrutinised for evidence of Necrotising Enterocolitis.
- "Spontaneous" intestinal
perforation (frequently in the terminal ileum)
Gastric or duodenal ulcer erosion and perforation
Association with postnatal steroid use
The use of indomethacin has
been postulated to increase the incidence of bowel perforation.
However, large randomised studies have not shown any increase in infants
treated with indomethacin.
The radiograph to the left
shows extensive intraperitoneal air - so much so that this supine film
clearly outlines air around the liver, the falciform ligament, and
provides an air-contrast film of the bowel wall. There is also air
in the scrotum (where there were inguinal herniae). The lower film
demonstrates the placement of an intraperitoneal drain.
There is debate about whether
an isolated perforation can be managed conversatively with peritoneal
drainage. This may be used as a temporary measure if the baby is
too ill to be considered for a laparotomy, or for some infants this may
be a definitive treatment. There are presently trials designed to
answer this question for both spontaneous perforations and perforated
Partial or complete duodenal obstruction may result from intrinsic causes or
external compression. Duodenal atresia results in complete
obstruction. Radiographs show a characteristic picture of a "double bubble",
with air filling a distended stomach and the blind-ended duodenum.
There is an association with
Partial obstruction may be caused
by an intraluminal web, duodenal stenosis, annular pancreas, or congenital
Duodenal obstruction may present
in utero with polyhydramnios. The antenatal ultrasound and plain
radiograph images are of an infant with duodenal atresia who underwent a
duodenoduodenostomy on the second day of life. The karyotype was
formation of normal bowel in the embryo involves a rotation of elongated
intestine into the abdominal cavity. The proximal small intestine
develops a C-shaped contour, with the duodenum fixing to the left of the
midline at the ligament of Treitz. The caecum undergoes
counter-clockwise rotation to end up in the right lower abdomen.
Incomplete rotation results in inadequate fixation of the intestinal
mesentery. Bands may be formed which cause incomplete intestinal
obstruction. If there is inadequate fixation of the small bowel, the
intestine can twist on the axis of the superior mesenteric artery.
The presentation may be
subtle (including intermittent episodes of vomiting in a baby otherwise
feeding normally) or more obvious with signs of bowel obstruction or
even life-threatening collapse. Episodes of
in infants should be taken seriously. There may be blood-stained
Plain films may be normal or
may show evidence of duodenal obstruction with a paucity of bowel gas
through the rest of the abdomen (see top image to left). Air-fluid
levels suggesting obstruction are not usual with malrotation. An
airless abdomen is a sign of severe problems and usually indicates
intestinal infarction. Upper intestinal contrast studies are
reliable in localising the ligament of Treitz. There may be a typical
corkscrew constriction of the third portion of the duodenum (see images
to the bottom left).
Treatment is surgical, with
correction of the malrotation of the colon and therefore prevention of a
midgut volvulus. If a volvulus is suspected, an emergency
laparotomy should be undertaken.
The bottom image shows the plain abdominal film of a preterm infant who
presented with acute abdominal distension and cardiorespiratory collapse at
a month of age. She had been well, with no problems with feed
tolerance, then presented acutely shocked and critically unwell. The
radiograph shows dilated bowel loops, without evidence of intramural gas or
Viscous meconium in the terminal ileum may cause intestinal obstruction.
It may be a manifestation of cystic fibrosis in approximately 10% of the CF
population. Therefore, any baby with meconium ileus requires further
investigation for CF.
Clinical presentation is
usually with abdominal distension and bilious vomiting. There are
often many gas-filled bowel loops, but without air-fluid levels.
Air-fluid levels are thought not to occur because the meconium does not
provide a good air-fluid interface. There may be a "soapy" mass in
the right lower quadrant. A contrast enema will show a microcolon
secondary to distal ileal obstruction. Calcification may be seen
on a plain radiograph if there has been meconium peritonitis.
Gastrograffin enemas may
relieve the obstruction, but surgery may also be required.
The images to the left show a
preterm infant who presented with marked abdominal distension at 3 days
of life. The top two images show his initial films. Three is
marked dilation of bowel loops. No air is seen in the colon or
The lower two films showed
progression to perforation, with overt free air under the diaphragm and
a double air-contrast of bowel. There is also free air in the
scrotum, from tracking of air into the processus vaginalis. At
laparotomy, a meconium plug was found.
Bowel obstruction with perforation occurring in utero can lead to leakage of
meconium into the peritoneal cavity. The subsequent chemical
peritonitis can leave calcified areas that are visible on plain radiography.
Any cause of bowel obstruction (atresia, volvulus,
meconium ileus, and
Hirschsprung's disease) can lead to this appearance.
peritonitis occurs close to delivery, there may not be sufficient time to
develop calcification, although there may be a significant chemical
peritonitis. Ascites may also be present. Some infants will
require surgery for persistent bowel obstruction or for adhesions.
Hirschsprung's disease causes up to 85% of neonatal intestinal obstructions.
Commonly, it presents as a failure to pass meconium in the first 24-hours of
life. There may be progression of signs and symptoms, with vomiting and
abdominal distension over the next few days. In older children,
short-segment disease may present as persistent constipation; in some
children, it may present as an enterocolitis with diarrhoea and rectal
The underlying pathology is
an absence of ganglion cells in the mesenteric plexus of the colon.
There is essentially an obstruction at the point of aganglionosis as
peristalsis cannot progress beyond this point. The point where
aganglionosis begins is most commonly at the rectosigmoid junction but
can be seen in some cases as proximal as the small bowel. Up to 10% of
cases involve the entire colon. Some cases are complicated by
enterocolitis with progressive dilation of the colon, stasis of bowel
contents with bacterial overgrowth, and acute fluid loss into the
intestine with diarrhoea and dehydration. This can be severe enough to
cause anuria and even death. The diagnosis can be made by a rectal
biopsy showing a lack of ganglion cells in the myenteric plexus of the
Plain radiographs may show
dilated loops of small bowel with air fluid levels. Although a
transition zone (where the agangliosis starts) may be seen in older
children, it is not usually seen in neonates. The transition zone is
normal in calibre but the proximal bowel is dilated. If enterocolitis is
present, the colon will appear dilated and there may be pneumotosis.
Oesophagel atresia is a relatively
malformation with an incidence of approximately 1:3000 births. In its
most common form (about 87% of cases) there is a blind proximal pouch in the
upper oesophagus, and the distal portion of the oesophagus is connected to
the trachea via a fistula (tracheo-oesophageal fistula, or TOF). Rarer
combinations include blind pouches at the end of each oesophageal portion
(8%), no atresia but a fistula connecting the oesophagus to the trachea
("H"-type fistula, 4%), fistulae connecting each oesophageal portion to the
trachea, and a proximal fistula and distal pouch.
Antenatally, there may be
polyhydramnios detected. An ultrasound may confirm this, and the
stomach may appear small. Following the delivery, the baby may
have excessive secretions which pool in the proximal pouch. The
baby will choke, cough,
or regurgitate if fed. Abdominal distension is common if there is a
distal fistula, as air moves through the fistula into the stomach.
If the baby requires ventilation, this may be exacerbated by positive
pressure ventilation and cause further respiratory deterioration.
The initial diagnosis of a
proximal pouch is confirmed by an inability to place a gastric tube into
the stomach. The tube is seen in the upper oesophagus and the
pouch may be outlined by air. The presence of air in the abdomen
indicates the presence of a distal fistula. For distal pouches or H-type
fistulae, the diagnosis can be more difficult.
An image of the anatomical
findings at bronchoscopy is shown to the left.
Be aware that a traumatic
oesophageal perforation (commonly after a difficult intubation or other
instrumentation of the pharynx) can give a similar radiological
Other associated anomalies are common and
the baby should have an echocardiogram. The echo should also
identify which side the aortic arch is on, as this impacts on the
Oesophageal atresia with a distal fistula
with blind pouches
Proximal fistula with
distal blind pouch
Proximal and distal
Inguinal herniae are relatively common in premature infants. They are
most common in males, but are seen in females. Bilateral inguinal
herniae are uncommon in females and may raise suspicion of an
See also the
inguinal, scrotal and genital guideline.
Inguinal hernie arise from persistence of
a patent processus vaginalis (a projection of the peritoneum which
accompanies the testis as it descends into the scrotum). In
females, the projection of peritoneum accompanies the round ligament.
Hydrocoeles are commonly seen with inguinal herniae, but can be
isolated. There can be diagnostic confusion between an
incarcerated inguinal hernia and a hydrocoele.
Link to the
hernia surgical guideline to view a video
demonstrating how to reduce an inguinal hernia.
The radiograph to the left
demonstrates air contained within bowel which has herniated into the
left scrotum. There is no evidence of bowel obstruction.
Tuesday, 29 November 2011