What is Meconium Aspiration?
Meconium is a term for a newborn baby’s first poop. Sometimes, babies can pass this meconium while still in labor or during delivery, which can stain the amniotic fluid (the liquid that surrounds and protects the baby in the womb). This is called meconium-stained amniotic fluid (MSAF). Meconium aspiration syndrome (MAS) is a condition in newborns characterized by difficulties in breathing due to MSAF, especially when there are no other health reasons behind these breathing symptoms.
The symptoms of MAS can differ greatly among babies, with some babies experiencing mild distress, while others suffer from severe respiratory failure. It’s essential to note that MAS has been linked to more serious health conditions in newborns like persistent pulmonary hypertension of the newborn (PPHN) – a lung condition causing high blood pressure, and air leak syndromes – conditions where air leaks into spaces it shouldn’t be.
What Causes Meconium Aspiration?
MAS, or Meconium Aspiration Syndrome, happens when a baby inhales a mixture of meconium and amniotic fluid before, during, or just after birth. Meconium is the baby’s first stool, which is usually thicker and darker than normal infant stool as it’s made up of stuff the baby accumulates while in the womb, like skin cells, hair, and gut secretions. This mixture of meconium and amniotic fluid, referred to as MSAF (meconium-stained amniotic fluid), can sometimes be found but it doesn’t always mean the baby will get MAS.
Things like low oxygen levels or an infection can cause a baby to pass meconium while still in the womb. When this gets inhaled, it can block the baby’s airways, cause inflammation, and stop a substance called surfactant from working properly. Surfactant is a substance that keeps the small air sacs in the lungs from collapsing. When all this happens, the baby can have trouble breathing, which is also known as respiratory distress.
Risk Factors and Frequency for Meconium Aspiration
Meconium-stained amniotic fluid (MSAF) is more widely seen in babies born after their due dates. The chances of it occurring vary with the baby’s gestational age, which is the number of weeks the baby has been in the womb. Research has found MSAF in 5.1% of premature babies, 16.5% of babies born on time, and 27.1% of babies born late. However, it’s worth noting that just because a baby is born through meconium-stained amniotic fluid, it doesn’t automatically mean they will develop Meconium Aspiration Syndrome (MAS), as it only happens in 2% to 10% of such cases.
The frequency of MAS could also be influenced by how easily a mother can access health care, and it tends to be higher in places where babies are often born late. Conversely, in areas where early cesarean sections are more common, despite the risks they bring, the incidence of MAS is lower. In terms of ethnicity, one study found a higher rate of MSAF amongst Black patients.
Signs and Symptoms of Meconium Aspiration
Diagnosing Meconium Aspiration Syndrome (MAS), a newborn lung condition, requires considering various factors. The relevant elements in the baby’s history to identify include:
- Being born around or after the estimated date of delivery
- Unexplained difficulties in breathing shortly after birth
- Amniotic fluid (the fluid surrounding the baby in the womb) stained with meconium (the baby’s first stools)
Here is a list of physical signs that may indicate a baby has MAS:
- Indications that the baby is post-term, such as the presence of vernix (a white, waxy substance on the skin), peeling skin, or long fingernails
- Signs of breathing difficulties at birth, such as slow heart rate (bradycardia), low oxygen levels in the blood (hypoxemia), bluish discoloration of the skin (cyanosis), and rapid breathing (tachypnea)
- Baby appears weak or less active than expected (known as birth depression)
- The presence of meconium in the amniotic fluid, or evidence of meconium staining upon physical examination.
Testing for Meconium Aspiration
If your doctor thinks you might have MAS, or Meconium Aspiration Syndrome, your medical history and current symptoms will play a big role in making that diagnosis. This is very important because starting treatment early can be necessary to help with your breathing and heart function.
In evaluating you for MAS, your doctor might use several tools:
– A chest X-ray: At first, this X-ray might show some nonspecific findings, like streaky densities that appear on both sides of the chest. Later on, it could show over-inflation of the lungs, a flattening of the diaphragms (the muscle that helps you breathe), or atelectasis, which is the collapse or closure of a lung or part of it. A pneumothorax, which is air leaking into the space between your lung and chest wall, can also be seen.
– An Arterial Blood Gas (ABG) test: This is a blood test that measures the acidity (pH) and the levels of oxygen and carbon dioxide in the blood. It’s used to check how well your lungs can move oxygen into the blood and remove carbon dioxide from the blood. In severe cases of MAS, the ABG test will show low oxygen levels, high carbon dioxide levels, and more acidic blood. This can help your doctor decide if you need help breathing, like being put on a ventilator.
– Pulse oximetry: This test measures the amount of oxygen in your blood. It helps the doctor assess how well your body is getting oxygen, but it also can show whether there’s a difference in oxygen levels before and after the blood passes through your heart (which is called shunting).
– An Echocardiography (or an ECG) test: This uses sound waves to create a detailed image of your heart. It’s an important tool that can show your doctor how your heart is functioning. It can help them screen for PPHN (Persistent pulmonary hypertension in newborns) and right ventricular dysfunction (when the right side of your heart can’t pump blood to your lungs well enough). It also shows the structure of your heart and can show whether there’s a right to left shunting (when the blood bypasses the lungs and directly goes back to the body).
Blood and tracheal cultures are also typically taken. These are lab tests to check for infection in the blood or the trachea (windpipe). If you are in severe distress, doctors may start antibiotics right away to treat possible infections while waiting for the lab culture results.
Treatment Options for Meconium Aspiration
When babies are born with a condition called Meconium-Stained Amniotic Fluid (MSAF), they require normal newborn care while being closely watched for any signs of distress. Current guidelines from the American Heart Association, the International Liaison Committee on Resuscitation, and the American Academy of Pediatrics no longer advise routinely using a tube to suction the windpipe for infants with MSAF who are not active or show signs of distress. The doctors will keep a close eye on babies with MSAF for signs of Meconium Aspiration Syndrome (MAS).
Management of MAS mainly relies on extra support to the infant, but spotting it early and providing appropriate support can greatly improve the child’s health outcomes, leading to decreased sickness and death risk. This requires a team effort from multiple healthcare professionals, including the obstetrician who delivers the baby, the midwife, a neonatologist who specializes in newborn care, a respiratory therapist for breathing support, a nurse for overall care, a pediatric pulmonologist who specializes in child lung health, and a pediatric cardiologist who focuses on heart health in children.
Treatment options for MAS can include:
- Oxygen therapy: Infants with MAS often require extra oxygen to help them breathe better. The goal is to have an oxygen saturation level of more than 90%. Maintaining this level prevents tissue from not getting enough oxygen, improves oxygen levels in the body, and reduces potentially harmful narrowing of blood vessels in the lungs.
- Ventilatory support: If high oxygen levels don’t help, or if the baby’s body retains too much carbon dioxide or is showing increasing signs of distress, breathing assistance devices can be used to provide ventilation support. Oxygen monitoring and regular tests to check oxygen and carbon dioxide levels in the blood help doctors better manage the baby’s condition. In serious cases where other treatments have not worked, the baby might need a life-support machine, like Extracorporeal Membrane Oxygenation (ECMO), to help provide oxygen to the body.
- Surfactant: Surfactants are naturally occurring substances that help the lungs inflate and breath more easily. They are not typically administered to babies with MAS, though some studies suggest that they may be helpful in certain cases.
- Nitric oxide: Nitric oxide is a drug that helps to relax and widen blood vessels in the lungs, which is beneficial for treating lung hypertension and Persistent Pulmonary Hypertension of the Newborn (PPHN).
What else can Meconium Aspiration be?
The potential diagnoses for MAS, also known as Meconium Aspiration Syndrome, includes other conditions that could cause discomfort in a newborn:
- Respiratory distress syndrome: This is often found in babies born too early.
- Transient tachypnea of the newborn: This condition typically goes away on its own within 72 hours.
- Sepsis/infection/pneumonia: Infections should be checked in any newborn showing signs of distress.
- Congenital heart disease: This is usually identified using an ultrasound of the heart, also known as an echocardiogram.
What to expect with Meconium Aspiration
Based on a large review study conducted in the United States, the mortality rate for MAS, a neonatal lung disorder, is about 1.2%. This is lower than what has been reported in developing countries. However, the good news is that the majority of infants tend to recover with a favorable outlook.
Possible Complications When Diagnosed with Meconium Aspiration
Short-term complications:
- Persistent Pulmonary Hypertension of the Newborn (PPHN)
- Air leak syndromes
Long-term complications:
- Babies with Meconium Aspiration Syndrome (MAS) can potentially develop a condition where their airways are over-responsive, causing them to narrow and leading to difficulty in breathing.
- These babies are also at risk for problems with brain development which could be associated with long-lasting insertion of a breathing tube, reliance on a mechanical ventilator for breathing, and a long-term requirement for supplemental oxygen.
Preventing Meconium Aspiration
Meconium aspiration often impacts full-term or post-term babies who are born with amniotic fluid (water surrounding the baby in the womb) colored by meconium (baby’s first poop). It happens in fewer than 10% of babies who are born with this meconium-stained amniotic fluid. This condition is a notable reason behind serious breathing issues in newborns and should be detected and treated early on. Your doctor will aim to exclude other potential health issues, such as infections that newborns can get. As parents, you should know that the treatment often involves admitting the infanct into the neonatal intensive care unit (a special hospital department for sick newborns), and the method is primarily supportive, focusing on easing symptoms and enhancing recovery. The good news is that most babies recover well with prompt diagnosis and treatment.
