MECONIUM ASPIRATION SYNDROME : Causes, Diagnosis

INTRODUCTION :-

• Meconium Aspiration Syndrome (MAS) is one of the most common causes of severe respiratory failure in infants born at term/ post-term gestation.
• ‘Meconium’ is the first stool of an infant, composed of materials ingested during the period of gestation.
• It is normally stored in the infant’s intestines until after birth,
• but sometimes (often in response to fetal distress and hypoxia) it is expelled into the amniotic fluid prior to birth, or during labor.
• If the baby then inhales the meconium, MAS may occur.
• Meconium is present in the amniotic fluid in approximately 10-15% of all term deliveries, but MAS occurs in fewer than 1/3rd of these infants.

Meconium aspiration syndrome (MAS) is a respiratory distress in a newborn who has breathed (aspirated) meconium into the lungs before or around the time of birth.

Causes of MAS :-

• Hypoxia in distressed baby
• Meconium Stained Liquor
• Uterine Infections
• Difficulty during labour process

RISK FACTORS :-

• Gestational Hypertension
• Gestational DM
• Maternal heavy cigarette smoking
• Maternal chronic respiratory or cardiovascular disease
• Post date pregnancy/Post maturity
• Pre-eclampsia/eclampsia
• Oligohydromnions
• IUGR
• Abnormal fetal HR pattern

Pathophysiology :-

Sign and symptoms :

• Meconium stained skin, nails and umbilical cord
• Signs of respiratory distress develop usually within the 1st hour of birth:
• Tachypnoea,
• Intercostal retractions,
• Coarse bronchial sounds,
• Expiratory grunting, and/or
• Cyanosis.
• Chest may be overinflated/ barrel shaped, with a protruding sternum (due to obstructive emphysema).

Diagnosis :-

Chest Radiograph: Hyperinflated lung and flatten diaphragm.

• B/L diffuse grossly irregular patchy infiltrates
• Pneumothorax and pneumomediastinum
• Small pleural effusion
• No air bronchogram

ABG in first hour of birth: Often reveals evidences of perinatal asphyxia- Hypoxemia and

• Some degree of metabolic acidosis.

Management :-

1. Prenatal management: Key management lies in prevention during prenatal period.
2. Identification of high risk pregnancies and close monitoring.
3. Pregnancy that continue past due date, induction as early as 41 weeks may help prevent meconium aspiration.
4. If there is sign of fetal distress corrective measure should be undertaken or infant should be delivered in timely manner.

Goals :

• Increased oxygenation while minimizing the barotrauma (may lead to air leak).
• Prevent pulmonary hypertension.
• Successful transition from intrauterine to extrauterine life with a drop in pulmonary arterial resistance and an increase in pulmonary blood flow.