NEONATAL INTESTINAL OBSTRUCTION

neonatal intestinal obstruction : Signs and Symptoms
1. Bilious vomiting is always abnormal.
2. Abdominal distention (scaphoid abdomen possible).
3. Delayed, scanty or no passage of meconium.
4. Polyhydramnios in mother.
5. Down's syndrome
6. Family history
a. Hirschsprung's disease
b. Diabetic mother
c. Jejunal atresia

Work-up (Logical approach)
1. While the infant is being studied, it must be kept in mind that the problem may be "non-surgical".
a. Sepsis of the newborn with associated ileus is the most important cause of non-surgical bilious
vomiting and abdominal distention.
b. Intracranial lesions
I. Hydrocephalus
ii. Subdural hemorrhage
c. Renal disease associated with uremia.
I. Renal agenesis
ii. Polycystic disease
iii. Other urinary tract anomalies which may be associated with severe hydronephrosis.

2. Plain roentgenograms of the abdomen.
a. Diagnostic in complete high intestinal obstruction-no gas in distal small bowel.
I. Double bubble in duodenal obstruction.
ii. Few gas filled loops beyond duodenum indicates jejunal atresia.
b. Many gas filled loops (requires 24 hours) indicates some form of low intestinal obstruction.
I. Ileal atresia
ii. Meconium ileus(an unfortunate misnomer)-obstruction of the distal small intestine by thick
undigested meconium.
iii. Meconium plug syndrome-obstruction of colon by a plug of meconium.
iv. Small left colon syndrome.
v. Hirschsprung's disease-congenital aganglionosis of colon starting with the rectum.
vi. Colonic atresia.
c. May be nonspecific in instances of malrotation of the intestines. This diagnosis must always be
considered in neonates with unexplained bilious vomiting.
d. Calcifications-at some time during fetal life meconium was (is) present in the abdomen.

3. Contrast enema will differentiate the various types of low intestinal obstruction.
a. Microcolon-complete obstruction of the small bowel.
b. Meconium plug syndrome-colon dilated proximal to an intraluminal mass.
c. Hirschsprung's disease-although it may appear to be diagnostic, not reliable in the newborn.
d. Small left colon syndrome-colon dilated to the splenic flexure, then becomes narrow.

4. Upper G.I.- the procedure of choice in diagnosing malrotation of the intestines. In the past a contrast enema was thought to be the diagnostic test of choice in instances of malrotation but the cecum and ascending colon can be in normal position in an infant or child with malrotation of the intestines.

5. Rectal biopsy- a pathologist competent in reading the slides is essential and should not be taken for granted.
a. Suction biopsy of the rectal mucosa and submucosa- best screening procedure to rule out
Hirschsprung's disease (ganglion cells are present in the submucosa), and is diagnostic in experienced hands.
b. Full thickness biopsy of the rectal wall may be necessary if the suction biopsy is non-diagnostic or
if the pathologist is unwilling or unable to make the diagnosis of aganglionosis on a suction biopsy specimen. This procedure is difficult in the small infant and has been replaced by the suction biopsy in most centers.
c. All newborns who have delayed passage of meconium associated with a suspicious contrast enema
should have a suction biopsy of the rectal mucosa and submucosa. With this technique, Hirschsprung's disease will be diagnosed early before it is complicated with enterocolitis. If delayed passage of meconium is "cured" by rectal stimulation(suppository, thermometer, or finger), it must be kept in mind that the diagnosis of Hirschsprung's disease is still a possibility. Whether or not a suction biopsy of the rectum is done before the infant goes home depends on the clinical setting but the safe course of action is to do the rectal biopsy before discharge. Parents may not call before the infant gets into trouble with enterocolitis.
d. Suction biopsy of the rectum is probably indicated in all cases of so called meconium plug syndrome
or small left colon syndrome. If the suction biopsy is not done, the infant must be observed for recurrent
gastrointestinal symptoms. A breast-fed infant who has Hirschsprung's disease can "get by" for a prolonged period of time.

6. Concluding comments:
The newborn suspected of having intestinal obstruction should be studied in a logical step by step
manner. It is important that it be definitely established that the infant has a surgical problem before surgery is performed. This is usually not difficult in instances of complete high small bowel obstruction or when plain films of the abdomen show calcification and/or a distal small bowel obstruction with the contrast enema showing a microcolon or a definite malrotation of the colon (cecum in upper mid-abdomen or left upper quadrant). When plain films are suggestive of a high small bowel obstruction but there is gas in the distal small bowel, an upper GI rather than a contrast enema should be performed. It is critically important that the diagnosis of malrotation of the intestines be always considered and ruled out in a neonate with bilious vomiting. Prompt recognition and treatment of malrotation of the intestines which is often associated with a midgut volvulus avoids the dire consequences of the problems associated with a massive small bowel resection.

Mistakes are frequently made when the contrast enema is interpreted as normal, meconium plug syndrome, small left colon syndrome or Hirschsprung's disease. In all of these clinical situations, a suction biopsy of the rectum is an excellent screening procedure. If ganglion cells are present, Hirschsprung's disease is ruled out and the infant probably has a non-surgical diagnosis. If ganglion cells are absent, the next step depends on the clinical picture and setting. If the pathologist is experienced and confident of the interpretation, the diagnosis of Hirschsprung's disease can be made with confidence. If there is any doubt about the absence of ganglion cells in the suction biopsy, a full thickness biopsy of the rectum (a difficult technical procedure requiring a general anesthetic) can be done to settle the issue. If Hirschsprung's disease is believed to be the problem, it must be diagnosed histologically before the infant is operated upon because at the time of surgery the site of obstruction may not be apparent and the abdomen may be closed because no obvious site of obstruction is found.
Hypothyroidism in the first two to three months of life can mimic Hirschsprung's disease in all aspects
except for a normal rectal biopsy.

Another important point to remember is that duodenal atresia is a different disease from jejunal or ileal
atresia in terms of their cause. Jejunal and ileal atresia occur as a result of a vascular accident in the small bowel mesentery during fetal life. Consequently, there is a relatively low incidence of other congenital anomalies except for cystic fibrosis. Duodenal atresia is a different disease in that there is a very high incidence of associated anomalies-- (Down's syndrome, imperforate anus, renal anomalies, congenital heart disease, etc.).

Malrotation of the intestines and Hirschsprungs disease must be ruled out before a newborn with
unexplained bilious vomiting and/or abdominal distention is sent home. It can be unsafe to rely on parents to observe their infant for problems resulting from the above conditions. If diagnosed late, malrotation of the intestines or Hirschsprungs disease can become life threatening or result in life long problems.