Table of Contents
Introduction:
There are several physical signs and milestones that must be checked soon after childbirth to ensure the proper physiological functioning of the just-born kid. One such indicator to be checked is the passage of meconium within one to two days of childbirth. There can be several reasons for the absence of meconium.
What Is Meconium?
Meconium is a sterile poop of the newborn infant that must be excreted from the child’s body within the first 24 to 48 hours of birth of the kid. The composition of the meconium is epithelial cells from the intestine, thin and fine hair (lanugo), mucus, water, a portion of the amniotic fluid, and a small quantity of bile. The presence of bile in the meconium gives it a tarry greenish-black appearance. The meconium is thick in consistency and contains materials that are ingested by the child in the mother’s womb.
What Is the Clinical Significance of Meconium?
The passage of meconium from the baby is considered the first sign to assess the gastrointestinal health of the newborn infant. Meconium passage within the stipulated timing indicates that the gastrointestinal tract is patent for the child, and there are no abnormalities involved. Sometimes, meconium can be passed by the baby even before birth along with amniotic fluid. This is referred to as meconium-stained amniotic fluid.
What Causes Meconium Absence?
The absence of meconium can occur due to several causes:
1. Delayed Passage:
The indicated timing for meconium passage is within the first two days of the child's birth. Sometimes, the baby can have a slow gastrointestinal transit time, which can delay the meconium passage. Some causes that can be attributed to this slow movement of meconium are difficulty in delivery, medicines taken during labor, and the mother's feeding practices.
2. Hirschsprung Disease:
Hirschsprung disease is a condition that is present at birth (congenital) and is considered a prominent cause of meconium absence. In this disease, there is absence of ganglion cells in some portions of the colon. The ganglion cells are responsible for the movement of stool materials in the intestine (peristaltic activity). Peristaltic activity is possible through the regulation of muscular activity in the colon. When the ganglion cells are responsible for muscular contraction and relaxation in the colon, the bowel segment can become completely contracted, causing a block in the colon. A block in the colon causes the stool to be unable to move forward..
Thus, children with a congenital disease like Hirschsprung disease cannot excrete meconium. Such infants will also have abdominal distension, bloating, and vomiting as clinical signs along with absence of meconium. These clinical manifestations can help in diagnosing Hirschsprung disease.
3. Cystic Fibrosis:
In kids who develop cystic fibrosis, the exocrine secretions become thick. The meconium also becomes thick and sticky, causing obstruction in the ileum of the small intestine. This condition is called meconium ileus. Meconium ileus initially causes intestinal obstruction, followed by inflammation when there is a rupture (leading to meconium peritonitis). Thus, the absence of meconium is considered the first sign to suspect cystic fibrosis in the child.
4. Meconium Plug Syndrome:
In this condition, the poop of the child becomes so thick that it forms a plug in the bowel. The formed meconium plug can obstruct the lower part of the intestine. Such a condition can cause delay or absence of meconium excretion. However, the presence of a meconium plug is not associated with cystic fibrosis, and it is generally managed through conservative methods only.
5. Anorectal Malformations:
Malformation or incomplete formation of the intestinal areas can cause the absence of meconium. Commonly seen among them are malformations in the anorectal areas, like imperforate anus, where the anus is not formed completely. Some children may also have more complex malformations like cloacal malformation that can cause further complications.
6. Intestinal Narrowing:
Intestinal narrowing or stenosis (complete obstruction) can occur due to atresia. This will cause obstruction in the pathway for passage of meconium congenitally. Such intestinal atresia or stenosis can be identified soon after the childbirth with clinical signs like bilious vomiting and distension of the abdomen.
How to Diagnose the Causative Factors for Meconium Absence?
- A clinical physical examination will clearly show some signs of underlying diseases in the baby, like bloating or distended abdomen, vomiting, or a palpable mass in the abdominal area. The perineal area will also be checked for anorectal malformations in the region.
- Since obstruction in the abdominal areas is the major cause of meconium absence, radiographic investigations focusing on the abdominal area will be performed. X-rays can reveal obstructed bowel and contrast studies (barium enema) will clearly indicate the presence of Hirschsprung disease or meconium plug syndrome in the babies.
- If Hirschsprung disease is considered an etiology for absent meconium, a rectal biopsy will be done. This is done to look for the presence of ganglion cells in the intestine. Absence of these cells confirms the diagnosis of Hirschsprung disease.
- If cystic fibrosis is suspected in the baby, genetic testing will be done. Sweat chloride tests will also be indicated to confirm the diagnosis.
How to Manage Absent Meconium?
The management of meconium absence depends on the underlying cause, and the following strategies are used accordingly.
- If there are no physical abnormalities and there is only a delay in meconium passage, proper feeding of the baby itself can help. Sometimes, a rectal examination or glycerin suppository may be employed to stimulate the meconium passage.
- In kids with Hirschsprung disease, the portion with absent ganglionic cells will be removed through a surgery called pull-through surgery. The defective portion is removed surgically, and the remaining portion of the healthy intestine will be tied to the anus to facilitate normal bowel action.
- For cystic fibrosis children, enemas or surgery will be performed to treat meconium ileus. However, such children also require long-term follow-up for respiratory symptoms and other nutritional aspects.
- Meconium plug syndrome does not usually require surgery. It is managed by rectal irrigations or enemas to remove the formed meconium plug.
- For anorectal malformations, atresia, or stenosis of the intestine, surgery will be the only choice to correct the malformation and restore intestinal function.
Conclusion:
Overall, there can be various causes for meconium absence in a newborn kid. Some causes may be due to physical abnormalities. However, sometimes an absent meconium can be a sign of underlying serious disorders, like Hirschsprung disease or cystic fibrosis, that require the children to be followed up and monitored for a long time.
