bubble_chart Overview

The inhalation of a large amount of amniotic fluid by the fetus in utero or during childbirth is called massive amniotic fluid aspiration, also known as amniotic fluid aspiration syndrome. It generally refers to uncontaminated amniotic fluid, often causing transient dyspnea or cyanosis, with mild symptoms and a good prognosis. If an inflammatory reaction occurs in the lungs, it is referred to as amniotic fluid aspiration pneumonia.

bubble_chart Pathogenesis

Any factor causing fetal hypoxia during intrauterine life or delivery can stimulate the fetal respiratory center due to hypoxemia, leading to gasping respiration and aspiration of amniotic fluid into the respiratory tract. The aspirated amniotic fluid is quickly absorbed by the alveolar capillaries. The lipids and desquamated keratinized epithelial cells in the amniotic fluid can cause chemical and mechanical irritation in the alveoli, resulting in diffuse pneumonia and impairing gas diffusion function. Abnormal childbirth, intrauterine distress, and macrosomia are common predisposing factors for massive amniotic fluid aspiration.

bubble_chart Pathological Changes

There are hemorrhagic spots on the lung surface, poor lung aeration, and amniotic fluid in the trachea. Microscopic examination reveals keratinized epithelium in the alveolar and bronchial lumens. Mononuclear cell exudation may be present.

bubble_chart Clinical Manifestations

The fetus has a history of intrauterine distress or intrapartum distress, and after resuscitation, respiratory distress and cyanosis may occur. The severity of symptoms is related to the amount of amniotic fluid aspirated. If the amount is small, there may be no clinical symptoms or only shortness of breath. A large amount of amniotic fluid aspiration may also lead to intrauterine fetal death. Surviving infants may have fluid or foam discharged from the mouth, and coarse moist rales can be heard on lung auscultation.

On X-ray, those with a small amount of aspiration show only thickened lung markings, appearing as linear shadows, accompanied by mild or grade II lung qi swelling. Those with a larger amount of aspiration exhibit faint patchy shadows. In cases of massive aspiration, patchy shadows are widely distributed but are most prominent in the inner zones and bases of both lungs.

bubble_chart Treatment Measures

The main approach is symptomatic treatment, ensuring airway patency. For those showing signs of hypoxia, oxygen is administered via nasal cannula or headbox. Corticosteroid therapy can reduce pulmonary inflammation and prevent fibrosis, but it may increase the risk of infection. Additionally, corticosteroids cannot remove foreign bodies such as keratinized epithelial cells, so their use should be cautious. Antibiotics can be employed to prevent secondary infections.