What are the symptoms and implications of meconium aspiration syndrome (MAS) in a newborn, particularly if delivered via cesarean section (C-section)?

From the Guidelines

Meconium aspiration syndrome (MAS) is a serious respiratory condition that occurs when a newborn inhales a mixture of meconium and amniotic fluid into the lungs, and its symptoms include respiratory distress, cyanosis, and low Apgar scores, requiring prompt recognition and treatment to prevent complications. The symptoms of MAS include:

• Respiratory distress with rapid, labored breathing
• Cyanosis (bluish skin coloration)
• Low Apgar scores
• Barrel-shaped chest
• Grunting sounds while breathing
• Limpness or poor muscle tone
• Meconium-stained amniotic fluid, which appears greenish or yellowish rather than clear MAS can occur regardless of delivery method, including cesarean section (C-section), and treatment typically includes suctioning the airways immediately after birth, oxygen therapy, mechanical ventilation if needed, antibiotics to prevent infection, and in severe cases, extracorporeal membrane oxygenation (ECMO) 1. The condition occurs because meconium is thick and sticky, causing airway obstruction, chemical inflammation in the lungs, and inactivation of surfactant, which helps keep air sacs open, as noted in studies on surfactant replacement therapy for respiratory distress in preterm and term neonates 1. The most effective treatment approach for MAS is to prioritize ventilation over intubation and tracheal suctioning, especially in non-vigorous infants born through meconium-stained amniotic fluid, as delayed ventilation can worsen outcomes 1. In terms of morbidity, mortality, and quality of life, it is essential to prioritize prompt recognition and treatment of MAS to prevent complications such as pneumonia, persistent pulmonary hypertension, or chronic lung disease, and to improve outcomes for affected newborns 1.

From the Research

Definition and Symptoms of Meconium Aspiration Syndrome

Meconium aspiration syndrome (MAS) is a clinical condition characterized by respiratory distress in neonates born through meconium-stained amniotic fluid (MSAF) 2, 3, 4, 5, 6. The symptoms of MAS include:

• Respiratory distress
• Poor lung compliance
• Hypoxemia
• Radiographic findings of hyperinflation and patchy opacifications

Pathophysiology of Meconium Aspiration Syndrome

The pathophysiology of MAS is multifactorial and includes:

• Acute airway obstruction
• Surfactant dysfunction or inactivation
• Chemical pneumonitis with release of vasoconstrictive and inflammatory mediators
• Persistent pulmonary hypertension of newborn (PPHN) 3, 4

Management of Meconium Aspiration Syndrome

The management of MAS includes:

• Supplemental oxygen as the mainstay of therapy
• Intubation and mechanical ventilation for around one-third of infants
• High-frequency ventilation for infants with refractory hypoxemia and/or gas trapping
• Inhaled nitric oxide for infants with pulmonary hypertension
• Surfactant administration and lung lavage in selected cases 3, 4

Meconium Aspiration Syndrome and C-Section

There is no specific information in the provided studies about the relationship between meconium aspiration syndrome and C-section. However, it is known that MAS can occur in any delivery, regardless of the method, as long as the baby is born through meconium-stained amniotic fluid 2, 5, 6.

Treatment and Prognosis

The treatment and prognosis of MAS have improved significantly over the years, with advances in obstetric practices and perinatal care 2, 6. However, long-term morbidity among survivors remains a major concern, and the most appropriate approach to management is still a matter of debate 2, 6.