Meconium aspiration syndrome occurs in a small proportion of neonates whose respiratory system is contaminated by the meconium and its content. The exact pathogenesis remains unknown, but conditions that lead to fetal stress and intrauterine hypoxia seem to be the most important risk factors. Tachypnea, grunting, and respiratory insufficiency are the main manifestations of this syndrome. Because of the life-threatening risk, close monitoring for possible respiratory distress in the first few days of life is needed. Together with clinical assessment, the early use of imaging studies (either plain radiography or ultrasonography) is recommended in the workup.
The signs and symptoms of meconium aspiration syndrome stem from the introduction of meconium into the respiratory tree    . It is well known that intrauterine hypoxia (which can occur due to numerous disorders and events, examples being placental insufficiency, preeclampsia, maternal abuse of tobacco and drugs, as well as oligohydramnios) is the main facilitator for the induction of meconium passage . Under physiological circumstances, the meconium (composed of gastrointestinal content, bile acids, pancreatic juice, blood, lanugo, and cellular debris) is a sterile mix of substances before the fetus is expelled from the uterus  . In approximately 1 in 7 births, the amniotic fluid is stained with meconium, but it is still not understood why only 5-9% of neonates exposed to a meconium-stained amniotic fluid (MSAF) develop meconium aspiration syndrome  . As meconium invades the lungs, neonates suffer from decreased lung compliance, eventually leading to hypoxia and tachypnea    . Grunting is a particularly important sign that should immediately raise suspicion toward respiratory distress . In fact, supplemental oxygen is almost always necessary to sustain adequate oxygen saturation in patients with MAS .
Entire Body System
- Gastric Lavage
INTERVENTION: Gastric lavage in the labor room with normal saline at 10 mL per kg body weight (n=350) or no gastric lavage (n=350). Meconiumcrit was measured and expressed as ≤30% and >30%. [ncbi.nlm.nih.gov]
Role of gastric lavage in vigorous neonates born with meconium stained amniotic fluid. Indian J Pediatr. 2013;80:195–8. CrossRef PubMed Google Scholar 27. Deshmukh M, Balasubramanian H, Rao S, Patole S. [doi.org]
- Cyanotic Congenital Heart Disease
Four patients (23.5%) died of acute respiratory failure and two patients with MAS, and persistence of the fetal circulation required cardiac catheterization to exclude cyanotic congenital heart disease. [doi.org]
- Fever of Unknown Origin
Pregnancy induced hypertension in 3, fetal decelaration in 4, chorioamnionitis in 3, premature rupture of membranes in 3 maternal drug use in 6, sickle-cell disease in 4, fever of unknown origin in 3, and presence of prolapsed cord in 3. [doi.org]
- Vascular Disease
This approach will help you understand if the infant has heart disease, lung disease, or pulmonary vascular disease. [clinicaladvisor.com]
Pulmonary vascular disease in fatal meconium aspiration. J Pediatr 1984; 104 : 758–762. 7. Gregory GA, Gooding CA, Phibbs RH, Tooley WH. Meconium aspiration in infants—a prospective study. J Pediatr 1974; 85 : 848–852. 8. Ting P, Brady JP. [doi.org]
Meconium contains everything the fetus has ingested while in the womb, such as mucus, amniotic fluid, water, lanugo (that downy hair babies have) and intestinal epithelial cells. Meconium can be passed before birth into the amniotic fluid. [babymed.com]
Under physiological circumstances, the meconium (composed of gastrointestinal content, bile acids, pancreatic juice, blood, lanugo, and cellular debris) is a sterile mix of substances before the fetus is expelled from the uterus. [symptoma.com]
Meconium is a thick, black-green substance consisting of desquamated intestinal and skin cells, gastrointestinal mucin, lanugo hair, fatty material from the vernix caseosa, amniotic fluid, and intestinal secretions. [my.anconsultants.com]
Meconium is the first stool of an infant, composed of materials ingested during the time the infant spends in the uterus : intestinal epithelial cells, lanugo, mucus, amniotic fluid, bile, and water. [wikidoc.org]
+ Hemorrhagic disease of the newborn + Spontenous gastric perforation in a neonate Meconium aspiration syndrome (MAS) Introduction Meconium is the first intestinal discharge of newborn, viscous and dark green composed of intestinal epithelial cells, lanugo [atlases.muni.cz]
- Skin Atrophy
Other issues can arise, such as aggravation of diabetes mellitus, osteoporosis, skin atrophy and growth retardation in children. [en.wikipedia.org]
The diagnosis of meconium aspiration syndrome can be life-threatening without early treatment , which is why an immediate postnatal clinical assessment is of critical importance. Evaluation of neonates through Apgar scoring is one of the most important steps when it comes to this condition, followed by determination of oxygen saturation, particularly if signs of hypoxia are present. Meconium aspiration syndrome is much more likely to develop if a thick meconium present, if fetal distress is observed, or if the Apgar score is < 7 in the first 5 minutes after birth . For this reason, many authors advise that all neonates who are exposed to MSAF should be monitored for the first 24 hours in case respiratory distress develops . Additional steps that may be useful are imaging studies and arterial blood gas (ABG) analysis . Plain radiography can show overexpansion of the lungs with patchy infiltrates, whereas consolidation, atelectasis, and coalescing B-lines are typical signs observed on ultrasonography  . The convenient real-time imaging provided by the latter technique can be rapidly employed yielding reliable results, with no exposure of the patient to radiation. Ultrasonography is considered superior to X-rays, and should be performed whenever clinical suspicion of meconium aspiration syndrome exists .
Hyperventilation to induce hypocapnia and compensate for metabolic acidosis is no longer a primary therapy for pulmonary hypertension, because hypocarbia often results in decreased cerebral perfusion (partial pressure of carbon dioxide [PaCO 2 ] 28 Jet [emedicine.medscape.com]
Hypocapnia and other ventilation-related risk factors for cerebral palsy in low birth weight infants. Pediatr Res. 2001 Dec. 50 (6):712-9. [Medline]. Abman SH, Kinsella JP. Inhaled nitric oxide therapy for pulmonary disease in pediatrics. [emedicine.com]
The presence of meconium was associated with severe asphyxia and carried a bad prognosis with an increased risk of developing hypoxia (58.3 %), need of mechanical ventilatory support (43.1 %), respiratory and/or metabolic acidosis (30.6 %), pulmonary [ncbi.nlm.nih.gov]
Any problem that stressed the newborn and caused meconium passage can affect prognosis. [merckmanuals.com]
Deliver before 42 weeks Close monitoring of high risk babies and mom What is the prognosis for MAS? Mild cases: resolve in 2-4 days Severe cases: Permanent airway damage Chronic lung disease If severity of hypoxia: Cerebral palsy [quizlet.com]
Etiology Risk factors (not always found) placental insufficiency maternal hypertension and preeclampsia oligohydramnion, maternal drug abuse Aspiration of meconium induces hypoxia via airway obstruction surfactant dysfunction chemical pneumonitis pulmonary [atlases.muni.cz]
The most common etiology of neonatal respiratory distress is transient tachypnea of the newborn; this is triggered by excessive lung fluid, and symptoms usually resolve spontaneously. [aafp.org]
One-third of cases • Depending on the extent of hypoxemia, echocardiography should be performed to ascertain: the degree to which the right-to-left shunting is contributing to the infant's overall hypoxemia and to exclude congenital heart disease as the etiology [slideshare.net]
One study suggests that fetal pancreatic digestive enzymes may play a part in causing the lung damage seen in MAS. [ 2 ] Epidemiology The figure quoted for infants born with meconium-stained liquor in the industrialised world is 8-25% of births after [patient.info]
The epidemiology of meconium aspiration syndrome: incidence, risk factors, therapies, and outcome. Pediatrics. 2006 May. 117 (5):1712-21. [Medline]. Dargaville PA, South M, McDougall PN. [emedicine.com]
Developmental Epidemiology Network Investigators. Pediatr Res 1999; 46: 566–75. 42. Mittendorf R, Montag AG, MacMillan W, et al. [jpatholtm.org]
(Epidemiology of respiratory failure in the newborn.) RCT on the role of inhaled nitric oxide and HFOV in MAS. (Cochrane review on amnioinfusion.) Copyright © 2017, 2013 Decision Support in Medicine, LLC. All rights reserved. [clinicaladvisor.com]
The concepts of pathophysiology and management of meconium stained amniotic fluid (MSAF) and meconium aspiration syndrome have undergone tremendous change in recent years. [ncbi.nlm.nih.gov]
The present review highlights the challenges in understanding the complex pathophysiology and optimal management approach to MAS. Potential future therapies and drugs in trial are also discussed briefly. [dovepress.com]
To provide an overview of the advances in our knowledge concerning the obstetric approaches to the prevention of MAS. [ncbi.nlm.nih.gov]
Prevention of MAS Prevention of MAS is paramount. Obstetricians should closely monitor fetal status in an attempt to identify fetal distress. [emedicine.medscape.com]
It functions to lower surface tension (to allow for lung expansion during inspiration), stabilise alveoli at the end of expiration (to prevent alveolar collapse) and prevents lung oedema. [en.wikipedia.org]
- Swarnam K, Soraisham AS, Sivanandan S. Advances in the Management of Meconium Aspiration Syndrome. Int J Pediatr. 2012;2012:359571.
- Dargaville PA. Respiratory Support in Meconium Aspiration Syndrome: A Practical Guide. Int J Pediatr. 2012;2012:965159.
- Lee J, Romero R, Lee KA, et al. Meconium aspiration syndrome: a role for fetal systemic inflammation. Am J Obstet Gynecol. 2016;214(3):366.e1-9.
- Piastra M, Yousef N, Brat R, Manzoni P, Mokhtari M, De Luca D. Lung ultrasound findings in meconium aspiration syndrome. Early Hum Dev. 2014;90 Suppl 2:S41-43.
- Lindenskov PH, Castellheim A, Saugstad OD, Mollnes TE. Meconium aspiration syndrome: possible pathophysiological mechanisms and future potential therapies. Neonatology. 2015;107(3):225-2s30.
- Liu WF, Harrington T. Delivery room risk factors for meconium aspiration syndrome. Am J Perinatol. 2002;19(7):367-378.