| Subject | Contents |
| Definition | test thisand this.... Meconium is the first feces (stool) of the newborn. It is thick, sticky, and greenish-black in color and may be seen in the amniotic fluid after 34 weeks gestation. Aspiration occurs when the newborn inhales the meconium mixed with amniotic fluid either in the uterus or just after delivery.
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| Alternative Names | Meconium aspiration syndrome (MAS) |
| Causes, incidence, and risk factors | Meconium staining of the amniotic fluid with possibility of aspiration occurs in approximately 5% to 10% of births. Aspiration typically occurs when the fetus is stressed during labor. The infant is often post term (more than 40 weeks gestation ). The condition is serious: meconium aspiration is a leading cause of severe illness and death in the newborn.
During labor, the infant may suffer a lack of oxygen. This can cause increased movement of the intestines ( peristalsis ) and relaxation of the anal sphincter, resulting in passage of meconium into the amniotic fluid surrounding the unborn baby. The amniotic fluid and meconium mix to form a green stained fluid of various thickness (viscosity). Meconium itself is thick, sticky and greenish-black in color and may be seen in the amniotic fluid after 34 weeks gestation. If the infant breathes while still in the uterus or while still covered by this fluid after birth, the meconium/amniotic fluid mixture can be inhaled into the lungs. The inhaled meconium can cause a partial or complete blockage of the airways, causing difficulty breathing and poor gas exchange in the lungs. In addition, the substance is irritating and causes inflammation in the airways and potentially, chemical pneumonia.
About one third of the infants with meconium aspiration will require some type of assisted breathing. Risk factors include maternal diabetes, maternal hypertension, difficult delivery, fetal distress and intra-uterine hypoxia (decreased oxygen to the infant while it is still in the uterus). |
| Symptoms | dark greenish staining or streaking of the amniotic fluid or the obvious presence of meconium in the amniotic fluid infant's skin stained greenish (occurs if meconium passed a long period before delivery) infant appears limp at birth bluish skin color in the infant (cyanosis) rapid breathing (tachypnea) labored breathing (the infant needs to work hard to breathe) absence of breathing ( apnea ) the infant may show signs of post-maturity ( weight loss , peeling skin) |
| Signs and tests | Before birth, the fetal monitor may show a slow heart rate (bradycardia). At birth, there is meconium in the amniotic fluid (dark staining or streaking). The infant may have a low Apgar score. PHYSICAL EXAMINATION OF THE INFANT: Direct visualization of the vocal cords for meconium staining with a laryngoscope in the delivery room is the most accurate evaluation for possible meconium aspiration. The diagnosis may be aided by listening to the infant's chest with a stethoscope ( auscultation ) and hearing abnormal breath sounds , especially coarse, crackly sounds. Tests performed on the infant may include: blood gas analysis showing low blood pH ( acidosis , an acidic condition of the blood), decreased pO2 and increased pC02 a chest X-ray showing patchy or streaky areas on lungs |
| Treatment | The newborn's mouth should be suctioned as soon as the head is delivered. Further intervention is necessary if there is thick meconium staining and fetal distress. A tube is placed in the infant's trachea and suction is applied as the endotracheal tube is withdrawn. This procedure is repeated until meconium is no longer seen in the suction contents. If there have been no signs of prenatal fetal distress, and the baby is a vigorous term-birth newborn, however, experts now recommend no deep suctioning of the trachea for fear of causing aspiration pneumonia. Occasionally, a saline solution is used to "wash" the airway of particularly thick meconium.
After delivery, the infant is observed carefully. The infant may be placed in the special care nursery or newborn intensive care unit. Other treatments may include chest physiotherapy (tapping on the chest to loosen secretions), antibiotics to treat infection, use of a radiant warmer to maintain body temperature and mechanical ventilation to keep the lungs inflated. |
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| Expectations (prognosis) | Respiratory distress generally subsides in 2 to 4 days, although rapid breathing may persist for days. Infants with severe aspiration that require mechanical ventilation have a more guarded outcome. Lack of oxygen in the uterus or from complications of meconium aspiration may lead to brain damage. The outcome depends on the degree of brain damage. Meconium aspiration rarely leads to permanent lung damage.
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| Complications | aspiration pneumoniapneumothorax ( collapsed lung ) persistent fetal circulation residual brain damage due to lack of oxygen persistent respiratory distress ( breathing difficulty ) lasting for several days |
| Calling your health care provider | If the baby is born outside of the hospital and exhibits any signs of distress, immediate emergency help should be sought. |
| Prevention | Risk factors should be identified as early as possible. If the mother's membranes ruptured (water broke) at home, she should tell the health care provider whether the fluid was clear or stained with a dark substance. Fetal monitoring is started to allow early recognition of fetal distress. Immediate intervention in the delivery room can sometimes help prevent aspiration . (See Treatment)
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