Neonatal abdominal emergencies

1. NEONATAL ABDOMINAL
EMERGENCIES
BY: ANGELO N. NDWIGA AND ANNE E. ODARO
FACILITATOR: DR. P. MBURUGU

2. INTRODUCTION
There are numerous disorders that can present as
abdominal emergencies, ranging from a self-limiting
condition, such as gastroenteritis, to life-threatening
conditions such as perforated appendicitis and midgut
volvulus.
The presenting symptoms of an abdominal emergency in
childhood are mainly vomiting, abdominal distension,
abdominal pain and sometimes hotness of body.

3. CAUSES OF ABDOMINAL EMERGENCIES
NEONATES INFANTS AND TODDLERS 5-13 YEARS
Atresia or stenosis of GIT Gastroenteritis Appendicitis
Malrotation with volvulus Intissusception Mesenteric adenitis
Meconium ileus Mesenteric adenitis IBD
Meconium plug syndrome Bowel obstruction Bowel obstruction
Hirschsprung’s disease Renal pathology Renal pathology
NEC Malrotation Gynaecological disorders
Pyloric stenosis Appendicitis Abdominal malignancy
Abdominal malignancy Appendicitis
Metabolic disease Hepato-biliary pathology
Abscess
Hematological disorders

4. EMBRYOLOGY OF THE GIT
The gastrointestinal tract (GIT) arises initially during the process
of gastrulation from the endoderm of the trilaminar embryo
(week 3) and extends from the buccopharyngeal membrane to
the cloacal membrane. The tract and associated organs later
have contributions from all the germ cell layers.
During the 4th week three distinct regions (fore-, mid- and
hind-gut) extend the length of the embryo and will contribute
different components of the GIT. The large mid-gut is generated
by lateral embryonic folding which "pinches off" a pocket of the
yolk sac, the 2 compartments continue to communicate through
the vitelline duct.

6. FOREGUT
 The foregut gives rise to the esophagus, the trachea, lung buds, the stomach, and the
duodenum proximal to the entrance of the bile duct. In addition, the liver, pancreas, and
biliary apparatus develop as outgrowths of the endodermal epithelium of the upper part of
the duodenum.
 Since the upper part of the foregut is divided by the tracheoesophageal septum into the
esophagus posteriorly and the trachea and lung buds anteriorly, deviation of the septum
may result in abnormal openings between the trachea and esophagus.
 The epithelial liver cords and biliary system growing out into the septum transversum
differentiate into parenchyma.
 Hematopoietic cells (present in the liver in greater numbers before birth than afterward),
Kupffer cells, and connective tissue cells originate in the mesoderm.
 The pancreas develops from a ventral bud and a dorsal bud that later fuse to form the
definitive pancreas. Sometimes, the two parts surround the duodenum (annular pancreas),
causing constriction of the gut.

7. MIDGUT
 The midgut forms the primary intestinal loop, from which originates the distal
duodenum to the entrance of the bile duct. The loop continues to the junction of
the proximal two-thirds of the transverse colon with the distal third.
 At its apex, the primary loop remains temporarily in open connection with the yolk
sac through the vitelline duct. During the sixth week, the loop grows so rapidly that
it protrudes into the umbilical cord (physiological herniation). In the 10th week, it
returns into the abdominal cavity.
 While these processes are occurring, the midgut loop rotates 270°
counterclockwise.
 Common abnormalities at this stage of development include remnants of the
vitelline duct, failure of the midgut to return to the abdominal cavity, malrotation,
stenosis, and duplication of parts.

8. HINDGUT
 The hindgut gives rise to the region from the distal third of the transverse colon to the upper
part of the anal canal. The distal part of the anal canal originates from the ectoderm. The
hindgut enters the posterior region of the cloaca (future anorectal canal), and the allantois
enters the anterior region (future urogenital sinus).
 The urorectal septum divides the two regions and breakdown of the cloacal membrane
covering this area provides communication to the exterior for the anus and urogenital sinus.
The upper part of the anal canal is derived from endoderm of the hindgut. The lower
part (one-third) is derived from ectoderm around the proctodeum.
 Ectoderm, in the region of the proctodeum on the surface of part of the cloaca, proliferates
and invaginates to create the anal pit. Subsequently, degeneration of the cloacal membrane
establishes continuity between the upper and lower parts of the anal canal.
 Abnormalities in the size of the posterior region of the cloaca shift the entrance of the anus
anteriorly, causing rectovaginal and rectourethral fistulas and atresias.

9. INNERVATION
 The gastrointestinal tract has both intrinsic and extrinsic innervation.
a) The intrinsic innervation, the enteric plexus, is derived from neural crest cells
migrating into and along the wall of the gastrointestinal tract.
i. mainly vagal region neural crest - generating both neurons and glia.
b) The extrinsic innervation occurs by efferent and afferent nerves, from the
vagus and sympathetic chain and pelvic nerves.
i. Vagus - sensory and motor fibers project from oesophagus to small
intestine.
ii. Sympathetic and parasympathetic - lower oesophagus to large intestine.
iii. Pelvic nerves - large intestine, rectum.

10. MOLECULAR REGULATION
 Regional specification of the gut tube into different components occurs
during the time that the lateral body folds are bringing the two sides of the
tube together.
 Different regions of the gut tube are initiated by retinoic acid (RA) from the
pharynx to the colon. This RA causes transcription factors to be expressed in
different regions of the gut tube.
 Thus,
a) SOX2 specifies the esophagus and stomach;
b) PDX1 specifies the duodenum;
c) CDXC specifies the small intestine;
d) CDXA specifies the large intestine and rectum.

11.  The differentiation of the gut and its derivatives depends upon
reciprocal interactions between the gut endoderm (epithelium) and
its surrounding mesoderm (an epithelial-mesenchymal interaction).
 Hox genes in the mesoderm are induced by SHH secreted by gut
endoderm and regulate the craniocaudal organization of the gut and
its derivatives.
 Once the mesoderm is specified by this code, it instructs the
endoderm to form components of the mid- and hindgut regions,
such as the small intestine, caecum, colon, and cloaca

12. EMBRYOLOGICAL ANOMALIES
LUMEN ABNORMALITIES
There are several types of abnormalities that impact upon the continuity
of the gastrointestinal tract lumen.
 Atresia - interuption of the lumen (esophageal atresia, duodenal
atresia, extrahepatic biliary atresia, anorectal atresia)
 Stenosis - narrowing of the lumen (duodenal stenosis, pyloric
stenosis).
 Duplication - incomplete recanalization resulting in parallel lumens,
this is really a specialized form of stenosis.

13. Meckel's Diverticulum
 Meckel's diverticulum, a true congenital diverticulum, is a slight bulge in the small intestine
present at birth and a vestigial remnant of the omphalomesenteric duct (also called the vitelline
duct or yolk stalk).
 It is the most common malformation of the gastrointestinal tract and is present in approximately
2% of the population.
 The majority of people with a Meckel's diverticulum are asymptomatic (Silent Meckel's
diverticulum). Symptoms typically appear before the age of two years.
 The most common presenting symptom is painless rectal bleeding such as melaena-like black
offensive stools, followed by intestinal obstruction, volvulus and intussusception. Occasionally,
Meckel's diverticulitis may present with all the features of acute appendicitis. Also, severe pain in
the epigastric region is experienced by the patient along with bloating in the epigastric and
umbilical regions. At times, the symptoms are so painful that they may cause sleepless nights with
acute pain felt in the foregut region, specifically in the epigastric and umbilical regions.

14. Pathophysiology
 In Meckel's diverticulum, the proximal part of vitelline duct fails to regress and involute,
which remains as a remnant of variable length and location.
 The solitary diverticulum lies on the antimesenteric border of the ileum (opposite to the
mesenteric attachment) and extends into the umbilical cord of the embryo.
 The left and right vitelline arteries originate from the primitive dorsal aorta, and travel with
the vitelline duct.
 The right becomes the superior mesenteric artery that supplies a terminal branch to the
diverticulum, while the left involutes. Having its own blood supply, Meckel's diverticulum is
susceptible to obstruction or infection.

15. A memory aid is the rule of 2s:
 2% (of the population)
 2 feet (proximal to the ileocecal valve)
 2 inches (in length)
 2 types of common ectopic tissue (gastric and pancreatic)
 2 years is the most common age at clinical presentation
 2:1 male:female ratio

16. Diagnosis
 A technetium-99m scan (Meckel scan) detects gastric mucosa; since approximately
50% of symptomatic Meckel's diverticula have ectopic gastric or pancreatic cells
contained within them, this is displayed as a spot on the scan distant from the
stomach itself.
 Colonoscopy might be helpful to rule out other sources of bleeding but it is not
used as an identification tool.
 Angiography might identify brisk bleeding in patients with Meckel's diverticulum.
 Ultrasonography could demonstrate omphaloenteric duct remnants or cysts.
TREATMENT
Treatment is surgical, potentially with a laparoscopic resection.

17. INTESTINAL MALROTATION
Intestinal malrotation is a congenital anomaly of rotation of the midgut (embryologically, the
gut undergoes a complex rotation outside the abdomen). As a result:
 the small intestine is found predominantly on the right side of the abdomen
 the cecum is displaced (from its usual position in the right lower quadrant) into the
epigastrium - right hypochondrium
 the ligament of Treitz is displaced inferiorly and rightward
 fibrous bands (of Ladd) course over the vertical portion of the duodenum (DII), causing
intestinal obstruction.
 the small intestine has an unusually narrow base, and therefore the midgut is prone to
volvulus (a twisting that can obstruct the mesenteric blood vessels and cause intestinal
ischemia).

19. Symptoms and signs
 Patients (often infants) present acutely with midgut volvulus, manifested by bilious vomiting,
crampy abdominal pain, abdominal distention, and the passage of blood and mucus in their
stools. Patients with chronic, uncorrected malrotation can have recurrent abdominal pain and
vomiting.
 Malrotation can also be asymptomatic.
Complications
 Acute midgut volvulus
 Chronic midgut volvulus
 Acute duodenal obstruction
 Chronic duodenal obstruction
 Internal herniation
 Superior mesenteric artery syndrome

20. DIAGNOSIS
 Plain radiography may demonstrate signs of duodenal obstruction with
dilatation of the proximal duodenum and stomach but it is often non-
specific.
 Upper gastrointestinal series is the modality of choice for the evaluation of
malrotation as it will show an abnormal position of the duodeno-jejunal
flexure (ligament of Treitz).
 In cases of malrotation complicated with volvulus, it demonstrates a
corkscrew appearance of the distal duodenum and jejunum. In cases of
obstructing Ladd bands, it will reveal a duodenal obstruction.
 In equivocal cases, contrast enema, may be helpful by showing
the caecum at an abnormal location.

21. TREATMENT
Treatment is possible and these are the steps taken: Resuscitate the patient with fluids to
stabilize them before surgically
 correcting the malrotation (counterclockwise rotation of the bowel),
 cutting the fibrous bands over the duodenum,
 widening the mesenteric pedicle by separation of the duodenum and cecum.
With this condition the appendix is often on the wrong side of the body and therefore removed
as a precautionary measure during the surgical procedure.

22. INTESTINAL AGANGLIONOSIS
A condition caused by the lack of enteric nervous system (neural ganglia) in the intestinal tract
responsible for gastric motility (peristalsis).
Related conditions include:
 Hirschsprung's disease: is due to an arrest in neural cell ganglia, leading to absent
innervation of a segment distal bowel, and appears as a massively dilated segment of distal
bowel on contrast enema.
 aganglionic colon
 Megacolon
a) congenital aganglionic megacolon
b) congenital megacolon

23. GASTROSCHISIS
 Gastroschisis (omphalocele, paraomphalocele, laparoschisis, abdominoschisis, abdominal
hernia) is a congenital abdominal wall defect which results in herniation of fetal abdominal
viscera (intestines and/or organs) into the amniotic cavity. Incidence of gastroschisis has
been reported at 1.66/10,000, occuring more frequently in young mothers (less than 20 years
old).
 By definition, it is a body wall musculoskeletal defect, not a gastrointestinal tract defect,
which in turn impacts upon GIT development.

24. MOLECULAR ANOMALIES
The endoderm of the developing gastrointestinal tract is a source for patterning signals for both
within the tract and also for the surrounding organs and tissues.
 Sox2 - expressed in the anterior part of the primitive gut
 Cdx2 - expressed in the posterior part of the primitive gut
 GDNF - regulate migration of enteric neural crest cells
 endothelin - regulate migration of enteric neural crest cells

25. OTHER ANOMALIES
Common causes of intestinal obstruction in neonates
High intestinal obstruction Low intestinal obstruction
Malrotation and midgut volvulus Ileal atresia
Duodenal obstruction Meconium ileus
Duodenal atresia/stenosis Meconium plug syndrome
Duodenal web Hirschsprung’s disease
Annular pancreas Anorectal malformation
Jejunal atresia

26. DUODENAL OBSTRUCTION
 Duodenal obstruction is a congenital malformation due to a variety
of conditions which can be classified as either intrinsic or extrinsic
lesions.
 Intrinsic lesions, including duodenal atresia, stenosis and a web, are
believed to be due to failure of recanalisation of the bowel lumen.
 Failure of the embryonic pancreatic tissue to rotate around the
duodenum leads to the development of annular pancreas.
 Other causes of extrinsic compression of the duodenum are
peritoneal bands, a duplication cyst and a preduodenal portal vein.

27.  The presenting symptoms and signs include vomiting, which is
usually bilious, abdominal distension and in severe cases
dehydration.
 Neonates with duodenal atresia present acutely within the first few
hours of life, whereas infants with internal or external duodenal
stenosis present at a variable time depending on the severity of the
obstruction.
 Approximately 25% of patients with duodenal atresia have Down’s
syndrome (Dalla Vecchia et al. 1998).
 Other associations include malrotation, other intestinal atresia,
congenital heart disease, biliary anomalies and Vater syndrome
(vertebral, anorectal, cardiac, tracheo-oesophageal fistula and radial
and renal dysplasia) spectrum (Bailey et al. 1993).

28.  In cases of complete duodenal obstruction, abdominal radiographs
typically demonstrate a distended stomach and duodenal cap with
air–fluid levels – the “double-bubble sign” – and gasless distal bowel
unless a bifid hepatopancreatic duct is present (Kassner et al. 1972)
which allows air to bypass the site of atresia; this latter is extremely
rare.
 In cases of partially obstructing lesions, the double-bubble sign may
or may not present and air is usually visible in the distal bowel.
 Ultrasound can demonstrate the double-bubble sign and allows
visualisation of the rare causes of duodenal obstruction such as a
duplication cyst and preduodenal portal vein.

29. Complete obstruction of the duodenum may be identified
on antenatal ultrasound as fluid-filled bubbles complicated
by polyhydramnios (Lawrence et al. 2000).
A contrast study is unnecessary in the presence of the
classical double-bubble sign and gasless distal bowel;
however, if the radiographic features are not typical, a
contrast study is required to exclude malrotation.

30. MECONIUM ILEUS
 Accounts for approximately 20% of neonatal intestinal obstruction
and results primarily from accumulation of a sticky and inspissated
intraluminal meconium in the terminal ileum. Although it can rarely
occur in otherwise normal neonates (Fakhoury et al. 1992), the
majority of patients with this condition have cystic fibrosis.
 Most patients are usually normal at birth but soon present clinically
with bilious vomiting, abdominal distension and delayed passage of
meconium. Some patients present at birth with an abdominal mass
due to intrauterine volvulus caused by inspissated meconium.

31.  The diagnosis of MI may be suspected on the abdominal radiograph
which may demonstrate multiple dilated loops of bowel with few or
no air–fluid levels, soap bubble appearance in the right lower
quadrant due to mixed gas and inspissated meconium. These
findings are non-specific and can be seen in other conditions such as
ileal atresia and Hirschsprung’s disease (Carty and Brereton 1983).
 At contrast enema a microcolon and multiple intraluminal filling
defects representing inspissated meconium at the point of
obstruction in the terminal ileum are seen

32.  Half of neonates with MI present with uncomplicated intestinal
obstruction (Agrons et al. 1996).
 In such cases, the obstruction can usually be relieved non-surgically
by refluxing water-soluble contrast medium into the proximally
dilated ileum.
 The fluid and electrolyte status of the patient must be closely
monitored if hypertonic water soluble contrast media are used.
Though the reported success of enema relieving MI is up to 60% (Kao
and Franken 1995; Docherty et al. 1992).

33. MECONIUM PLUG SYNDROME
Meconium plug syndrome, also known as functional
immaturity of the large bowel or small left colon syndrome,
is the most common cause of functional large bowel
obstruction in neonates.
Risk factors associated with this condition include
prematurity, neonatal hypoglycaemia, maternal diabetes
and mothers who received magnesium sulphate for
eclampsia (Krasna et al. 1996; Davis and Campbell 1975).

34. Clinical presentation is with delayed passage of
meconium, vomiting and abdominal distension,
although these patients are generally not critically
ill.
Physiological passage of the first meconium stool
may be delayed in tiny premature infants and this is
usually not a cause of concern unless vomiting or
abdominal distension develops.

35. Diffusing dilated loops of bowel and paucity of gas in the
rectum are usually demonstrated on abdominal
radiographs.
Contrast enema studies show multiple filling defects due to
retention of meconium within a relatively normal calibre
large bowel “meconium plug syndrome”.
A transitional zone from slightly dilated ascending and
transverse colon to a narrowed descending colon at the
splenic flexure “small left colon syndrome” may be seen.

36. In contrast to Hirschsprung’s disease, the calibre of
the rectum is normal and the obstruction is usually
relieved by contrast enema. Rectal biopsy,however,
is indicated if the obstruction remains unresolved
following the enema or the diagnosis of
Hirschsprung’s disease is suspected radiologically
(Berdon et al. 1977).

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