Meconium Aspiration Syndrome

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Meconium aspiration syndrome (MAS) is the aspiration of stained amniotic fluid, which can occur before, during, or immediately after birth. Meconium is the first intestinal discharge from newborns, a viscous, dark-green substance composed of intestinal epithelial cells, lanugo, mucus, and intestinal secretions (eg, bile. Water is the major liquid constituent, comprising 85-95% of meconium; the remaining 5-15% of ingredients consists of solid constituents, primarily intestinal secretions, mucosal cells, and solid elements of swallowed amniotic fluid, such as proteins and lipids.

Meconium is sterile and does not contain bacteria, which is the primary factor that differentiates it from stool. Intrauterine distress can cause passage of meconium into the amniotic fluid. Factors that promote the passage in utero include placental insufficiency, maternal hypertension, preeclampsiaoligohydramnios, infection, acidosis, and maternal drug abuse, especially use of tobacco and cocaine.

As noted above, meconium-stained amniotic fluid may be aspirated before or during labor and delivery. Because meconium is rarely found in the amniotic fluid prior to 34 weeks’ gestation, meconium aspiration primarily affects infants born at term and postterm.

In utero meconium passage results from neural stimulation of a maturing gastrointestinal (GI) tract, usually due to fetal hypoxic stress. As the fetus approaches term, the GI tract matures, and vagal stimulation from head or spinal cord compression may cause peristalsis and relaxation of the rectal sphincter, leading to meconium passage.

The effects of meconium in amniotic fluid are well documented. [1] Meconium directly alters the amniotic fluid, reducing antibacterial activity and subsequently increasing the risk of perinatal bacterial infection. In addition, meconium is irritating to fetal skin, thus increasing the incidence of erythema toxicum. However, the most severe complication of meconium passage in utero is perinatal aspiration of stained amniotic fluid (before, during, or immediately after birth)—ie, meconium aspiration syndrome (MAS). Aspiration of meconium-stained amniotic fluid may occur if the fetus is in distress, leading to a gasping breathing pattern. This aspiration induces hypoxia via four major pulmonary effects: airway obstruction, surfactant dysfunction, chemical pneumonitis, and pulmonary hypertension. [1]

Complete obstruction of the airways by meconium results in atelectasis. Partial obstruction causes air trapping and hyperdistention of the alveoli, commonly termed the ball-valve effect. Hyperdistention of the alveoli occurs from airway expansion during inhalation and airway collapse around inspissated meconium in the airway, causing increased resistance during exhalation. The gas that is trapped (hyperinflating the lung) may rupture into the pleura (pneumothorax), mediastinum (pneumomediastinum), or pericardium (pneumopericardium).

Meconium deactivates surfactant and may also inhibit surfactant synthesis. [2, 3] Several constituents of meconium, especially the free fatty acids (eg, palmitic, stearic, oleic), have a higher minimal surface tension than surfactant and strip it from the alveolar surface, resulting in diffuse atelectasis. [4]

Enzymes, bile salts, and free fatty acids in meconium irritate the airways and parenchyma, causing a release of cytokines (including tumor necrosis factor (TNF-α, interleukin (IL)-1β, IL-6, IL-8, IL-13), which initiate a diffuse pneumonitis that may begin within a few hours of aspiration.

All of these pulmonary effects can produce a gross ventilation-perfusion (V/Q) mismatch.

To complicate matters further, many infants with meconium aspiration syndrome (MAS) have primary or secondary persistent pulmonary hypertension of the newborn (PPHN) as a result of chronic in utero stress and thickening of the pulmonary vessels. PPHN further contributes to the hypoxemia caused by meconium aspiration syndrome. [5]

Finally, although meconium is sterile, its presence in the air passages can predispose the infant to pulmonary infection.

Factors that promote the passage of meconium in utero include the following:

Placental insufficiency

Maternal hypertension

Preeclampsia

Oligohydramnios

Maternal drug abuse, especially of tobacco and cocaine

Maternal infection/chorioamnionitis

Fetal hypoxia

In the industrialized world, meconium in the amniotic fluid can be detected in 8-25% of all births after 34 weeks’ gestation. Historically, approximately 10% of newborns born through meconium-stained amniotic fluid developed meconium aspiration syndrome (MAS). However, changes in obstetric and neonatal practices appear to be decreasing its incidence. [6]  MAS was the admission diagnosis for 1.8% of term neonates in one large retrospective study from 1997-2007. [1]

In developing countries with less availability of prenatal care and where home births are common, the incidence of MAS is thought to be higher and is associated with a greater mortality rate.

MAS is exclusively a disease of newborns, especially those delivered at or beyond the mother’s estimated due date. [1]  MAS affects both sexes equally.

A study of 499,096 singleton live births in London, England, reported the rates of meconium-stained amniotic fluid varied by ethnicity: It was 22.6% in the black population, 16.8% in south Asian groups, and 15.7% in the white population. [7] The study also demonstrated that meconium-stained amniotic fluid occurred more often in later-gestational-age pregnancies and in babies in the breech presentation.

Most infants with meconium aspiration syndrome (MAS) have complete recovery of pulmonary function; however, MAS infants have a slightly increased incidence of respiratory infections in the first year of life because the lungs are still in recovery. Severely affected infants have an increased risk of developing reactive airway disease (RAD) in the first 6 months of life. [8]

Children with MAS may develop chronic lung disease from intense pulmonary intervention.

Prenatal and intrapartum events that initiate the meconium passage may cause the infant to have long-term neurologic deficits, including central nervous system (CNS) damage, seizures, mental retardation, and cerebral palsy.

A large retrospective analysis demonstrated the overall mortality rate for MAS to be 1.2% in the United States.The mortality rate for MAS resulting from severe parenchymal pulmonary disease and pulmonary hypertension is as high as 20%. Other complications include air leak syndromes (eg, pneumothorax, pneumomediastinum, pneumopericardium), which occur in 10-30% of infants with MAS. The neurologic disabilities of survivors are not due primarily to the aspiration of meconium, but rather by in-utero pathophysiology, including chronic hypoxia and acidosis.

A large retrospective analysis demonstrated the overall mortality rate for MAS to be 1.2% in the United States. [1]  The mortality for MAS resulting from severe parenchymal pulmonary disease and pulmonary hypertension is as high as 20%. Other complications include air-leak syndromes (eg, pneumothorax, pneumomediastinum, pneumopericardium) and pulmonary interstitial emphysema, which occur in 10-30% of infants who have MAS. The neurologic disabilities of survivors are not due primarily to the aspiration of meconium, but rather owing to in utero pathophysiology, including chronic hypoxia and acidosis. [9]

Singh BS, Clark RH, Powers RJ, Spitzer AR. Meconium aspiration syndrome remains a significant problem in the NICU: outcomes and treatment patterns in term neonates admitted for intensive care during a ten-year period. J Perinatol. 2009 Jul. 29 (7):497-503. [Medline].

Janssen DJ, Carnielli VP, Cogo P, et al. Surfactant phosphatidylcholine metabolism in neonates with meconium aspiration syndrome. J Pediatr. 2006 Nov. 149 (5):634-9. [Medline].

Clark DA, Nieman GF, Thompson JE, Paskanik AM, Rokhar JE, Bredenberg CE. Surfactant displacement by meconium free fatty acids: an alternative explanation for atelectasis in meconium aspiration syndrome. J Pediatr. 1987 May. 110 (5):765-70. [Medline].

Terasaka D, Clark DA, Singh BN, Rokahr J. Free fatty acids of human meconium. Biol Neonate. 1986. 50 (1):16-20. [Medline].

Wiswell TE, Tuggle JM, Turner BS. Meconium aspiration syndrome: have we made a difference?. Pediatrics. 1990 May. 85 (5):715-21. [Medline].

Yoder BA, Kirsch EA, Barth WH, Gordon MC. Changing obstetric practices associated with decreasing incidence of meconium aspiration syndrome. Obstet Gynecol. 2002 May. 99 (5 pt 1):731-9. [Medline].

Balchin I, Whittaker JC, Lamont RF, Steer PJ. Maternal and fetal characteristics associated with meconium-stained amniotic fluid. Obstet Gynecol. 2011 Apr. 117 (4):828-35. [Medline].

Macfarlane PI, Heaf DP. Pulmonary function in children after neonatal meconium aspiration syndrome. Arch Dis Child. 1988 Apr. 63 (4):368-72. [Medline].

Ghidini A, Spong CY. Severe meconium aspiration syndrome is not caused by aspiration of meconium. Am J Obstet Gynecol. 2001 Oct. 185 (4):931-8. [Medline].

[Guideline] Wyckoff MH, Aziz K, Escobedo MB, et al. Part 13: Neonatal resuscitation: 2015 American Heart Association guidelines update for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2015 Nov 3. 132 (18 suppl 2):S543-60. [Medline].

American College of Obstetricians and Gynecologists. ACOG Committee opinion no. 689 summary: delivery of a newborn with meconium-stained amniotic fluid. Obstet Gynecol. 2017 Mar. 129 (3):593-4. [Medline].

Nangia S, Pal MM, Saili A, Gupta U. Effect of intrapartum oropharyngeal (IP-OP) suction on meconium aspiration syndrome (MAS) in developing country: A RCT. Resuscitation. 2015 Dec. 97:83-7. [Medline].

Boujenah J, Oliveira J, De La Hosseraye C, Benbara A, Tigaizin A, Bricou A, et al. Should fetal scalp blood sampling be performed in the case of meconium-stained amniotic fluid?. J Matern Fetal Neonatal Med. 2016 Dec. 29 (23):3875-8. [Medline].

Liu J, Cao HY, Fu W. Lung ultrasonography to diagnose meconium aspiration syndrome of the newborn. J Int Med Res. 2016 Nov 1. [Medline].

American College of Obstetricians and Gynecologists. ACOG Committee opinion no 579: definition of term pregnancy. Obstet Gynecol. 2013 Nov. 122 (5):1139-40. [Medline].

American College of Obstetricians and Gynecologists. ACOG Committee opinion no. 561: nonmedically indicated early-term deliveries. Obstet Gynecol. 2013 Apr. 121 (4):911-5. [Medline].

ACOG Committee Obstetric Practice. ACOG Committee opinion number 346, October 2006: amnioninfusion does not prevent meconium aspiration syndrome. Obstet Gynecol. 2006 Oct. 108 (4):1053. [Medline].

Velaphi S, Vidyasagar D. Intrapartum and postdelivery management of infants born to mothers with meconium-stained amniotic fluid: evidence-based recommendations. Clin Perinatol. 2006 Mar. 33 (1):29-42, v-vi. [Medline].

Hofmeyr GJ, Xu H. Amnioinfusion for meconium-stained liquor in labour. Cochrane Database Syst Rev. 2010 Jan 20. CD000014. [Medline].

Fraser WD, Hofmeyr J, Lede R, et al, for the Amnioinfusion Trial Group. Amnioinfusion for the prevention of the meconium aspiration syndrome. N Engl J Med. 2005 Sep 1. 353 (9):909-17. [Medline].

Committee on Obstetric Practice, American College of Obstetricians and Gynecologists. ACOG Committee opinion no. 379: management of delivery of a newborn with meconium-stained amniotic fluid. Obstet Gynecol. 2007 Sep. 110 (3):739. [Medline].

Vain NE, Szyld EG, Prudent LM, Wiswell TE, Aguilar AM, Vivas NI. Oropharyngeal and nasopharyngeal suctioning of meconium-stained neonates before delivery of their shoulders: multicentre, randomised controlled trial. Lancet. 2004 Aug 14-20. 364 (9434):597-602. [Medline].

Chettri S, Bhat BV, Adhisivam B. Current concepts in the management of meconium aspiration syndrome. Indian J Pediatr. 2016 Oct. 83 (10):1125-30. [Medline].

Wiswell TE, Knight GR, Finer NN, et al. A multicenter, randomized, controlled trial comparing Surfaxin (Lucinactant) lavage with standard care for treatment of meconium aspiration syndrome. Pediatrics. 2002 Jun. 109 (6):1081-7. [Medline].

Dargaville PA, Mills JF. Surfactant therapy for meconium aspiration syndrome: current status. Drugs. 2005. 65 (18):2569-91. [Medline].

Dargaville PA. Innovation in surfactant therapy I: surfactant lavage and surfactant administration by fluid bolus using minimally invasive techniques. Neonatology. 2012. 101 (4):326-36. [Medline].

El Shahed AI, Dargaville PA, Ohlsson A, Soll R. Surfactant for meconium aspiration syndrome in term and late preterm infants. Cochrane Database Syst Rev. 2014 Dec 14. CD002054. [Medline].

Collins MP, Lorenz JM, Jetton JR, Paneth N. 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. Curr Opin Pediatr. 1998 Jun. 10 (3):236-42. [Medline].

Ward M, Sinn J. Steroid therapy for meconium aspiration syndrome in newborn infants. Cochrane Database Syst Rev. 2003. CD003485. [Medline].

Sarkar S, Hussain N, Herson V. Fibrin glue for persistent pneumothorax in neonates. J Perinatol. 2003 Jan. 23 (1):82-4. [Medline].

El Shahed AI, Dargaville P, Ohlsson A, Soll RF. Surfactant for meconium aspiration syndrome in full term/near term infants. Cochrane Database Syst Rev. 2007 Jul 18. 2:CD002054. [Medline]. [Full Text].

[Guideline] American Heart Association, American Academy of Pediatrics. 2005 American Heart Association (AHA) guidelines for cardiopulmonary resuscitation (CPR) and emergency cardiovascular care (ECC) of pediatric and neonatal patients: neonatal resuscitation guidelines. Pediatrics. 2006 May. 117 (5):e1029-38. [Medline].

Cialone PR, Sherer DM, Ryan RM, Sinkin RA, Abramowicz JS. Amnioinfusion during labor complicated by particulate meconium-stained amniotic fluid decreases neonatal morbidity. Am J Obstet Gynecol. 1994 Mar. 170 (3):842-9. [Medline].

Dargaville PA, Copnell B, and the Australian and New Zealand Neonatal Network. 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. Surfactant and surfactant inhibitors in meconium aspiration syndrome. J Pediatr. 2001 Jan. 138 (1):113-5. [Medline].

Glantz JC, Woods JR. Significance of amniotic fluid meconium. In: Creasy RK, Resnick R, eds. Maternal-Fetal Medicine. 4th ed. Philadelphia, Pa: WB Saunders; 1999. 393-403.

Kattwinkel J, Niermeyer S, Denson SE, eds. Textbook of Neonatal Resuscitation. 4th ed. Chicago, Ill: American Academy of Pediatrics; 2000.

Kinsella JP. Meconium aspiration syndrome: is surfactant lavage the answer?. Am J Respir Crit Care Med. 2003 Aug 15. 168 (4):413-4. [Medline].

Korones SB, Bada-Ellzey HS. Meconium aspiration. Neonatal Decision Making (Clinical Decision Making). St Louis, Mo: Mosby-Year Book; 1993. 128-9.

Kugelman A, Gangitano E, Taschuk R, et al. Extracorporeal membrane oxygenation in infants with meconium aspiration syndrome: a decade of experience with venovenous ECMO. J Pediatr Surg. 2005 Jul. 40 (7):1082-9. [Medline].

Lo KW, Rogers M. A controlled trial of amnioinfusion: the prevention of meconium aspiration in labour. Aust N Z J Obstet Gynaecol. 1993 Feb. 33 (1):51-4. [Medline].

Ranzini AC, Chan L. Meconium and fetal-neonatal compromise. In: Spitzer AR, ed. Intensive Care of the Fetus and Neonate. St Louis, Mo: Mosby; 1996. 297-303.

Roberton NRC. Aspiration syndromes. In: Greenough A, Robertson NRC, Milner AD, eds. Neonatal Respiratory Disorders. London, UK: Arnold Publication; 1996. 313-33.

Soll RF, Dargaville P. Surfactant for meconium aspiration syndrome in full term infants. Cochrane Database Syst Rev. 2000. CD002054. [Medline].

Usta IM, Mercer BM, Aswad NK, Sibai BM. The impact of a policy of amnioinfusion for meconium-stained amniotic fluid. Obstet Gynecol. 1995 Feb. 85 (2):237-41. [Medline].

Whitsett JA, Pryhuber GS, Rice WR, Warner BB, Wert SE. Acute respiratory disorders. In: Avery GB, Fletcher MA, MacDonald MG, eds. Neonatology: Pathophysiology and Management of the Newborn. 5th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 1999. 494-508.

Wiswell TE, Gannon CM, Jacob J, et al. Delivery room management of the apparently vigorous meconium-stained neonate: results of the multicenter, international collaborative trial. Pediatrics. 2000 Jan. 105 (1 pt 1):1-7. [Medline]. [Full Text].

Yeh TF. Core concepts: meconium aspiration syndrome: pathogenesis and current management. NeoReviews. Sep 2010. 11(9):e503-12. [Full Text].

Young TE, Mangum OB. Neofax: A Manual of Drugs Used in Neonatal Care. 11th ed. Bethesda, M: American Society of Health-System Pharmacists; 1998.

Boet A, Brat R, Aguilera SS, Tissieres P, De Luca D. Surfactant from neonatal to pediatric ICU: bench and bedside evidence. Minerva Anestesiol. 2014 Dec. 80 (12):1345-56. [Medline].

Hermansen CL, Mahajan A. Newborn respiratory distress. Am Fam Physician. 2015 Dec 1. 92 (11):994-1002. [Medline].

von Bahr V, Hultman J, Eksborg S, et al. Long-term survival and causes of late death in children treated with extracorporeal membrane oxygenation. Pediatr Crit Care Med. 2017 Mar. 18 (3):272-80. [Medline].

Gina M Geis, MD Attending Neonatologist, Associate Director, Neonatal-Perinatal Medicine Fellowship Program, Albany Medical Center; Assistant Professor, Department of Pediatrics, Albany Medical College

Gina M Geis, MD is a member of the following medical societies: American Academy of Pediatrics, American Society for Bioethics and Humanities, Capital District Pediatric Society

Disclosure: Nothing to disclose.

David A Clark, MD Professor and Martha Lepow Chairman of Pediatrics, Professor of Obstetrics and Gynecology, Albany Medical College; Director, Children’s Hospital at Albany Medical Center

David A Clark, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American College of Nutrition, American Forestry Association, American Pediatric Society, Capital District Pediatric Society, Christian Medical and Dental Associations, European Society for Paediatric Research, Eastern Society for Pediatric Research, Floyd W Denny Pediatric Alumni Society, Medical Society of the State of New York, New York Academy of Sciences, Society for Pediatric Research

Disclosure: Nothing to disclose.

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Brian S Carter, MD, FAAP Professor of Pediatrics, University of Missouri-Kansas City School of Medicine; Attending Physician, Division of Neonatology, Children’s Mercy Hospital and Clinics; Faculty, Children’s Mercy Bioethics Center

Brian S Carter, MD, FAAP is a member of the following medical societies: Alpha Omega Alpha, American Academy of Hospice and Palliative Medicine, American Academy of Pediatrics, American Pediatric Society, American Society for Bioethics and Humanities, American Society of Law, Medicine & Ethics, Society for Pediatric Research, National Hospice and Palliative Care Organization

Disclosure: Nothing to disclose.

Ted Rosenkrantz, MD Professor, Departments of Pediatrics and Obstetrics/Gynecology, Division of Neonatal-Perinatal Medicine, University of Connecticut School of Medicine

Ted Rosenkrantz, MD is a member of the following medical societies: American Academy of Pediatrics, American Pediatric Society, Eastern Society for Pediatric Research, American Medical Association, Connecticut State Medical Society, Society for Pediatric Research

Disclosure: Nothing to disclose.

Melinda B Clark, MD Associate Professor of Pediatrics, Department of Pediatrics, Albany Medical College

Melinda B Clark, MD is a member of the following medical societies: Alpha Omega Alpha, Academic Pediatric Association, American Academy of Pediatrics, Medical Society of the State of New York

Disclosure: Nothing to disclose.

Meconium Aspiration Syndrome

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