Meconium

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Meconium
Meconium.jpg
Meconium from 12-hour-old newborn  –the baby's third bowel movement
Scale: 5 cm left to right.
Specialty Pediatrics

Meconium is the earliest stool of a mammalian infant resulting from defecation. Unlike later feces, meconium is composed of materials ingested during the time the infant spends in the uterus: intestinal epithelial cells, lanugo, mucus, amniotic fluid, bile, and water. Meconium, unlike later feces, is viscous and sticky like tar – its color usually being a very dark olive green and it is almost odorless. [1] When diluted in amniotic fluid, it may appear in various shades of green, brown, or yellow. It should be completely passed by the end of the first few days after birth, with the stools progressing toward yellow (digested milk).

Contents

Clinical significance

Meconium in amniotic fluid

Meconium is normally retained in the infant's bowel until after birth, but sometimes it is expelled into the amniotic fluid prior to birth or during labor and delivery. The stained amniotic fluid is recognized by medical staff as a possible sign of fetal distress. Some post-dates pregnancies (when they are more than 40 weeks pregnant) may also have meconium-stained amniotic fluid without fetal distress. Medical staff may aspirate the meconium from the nose and mouth of a newborn immediately after delivery in the event the baby shows signs of respiratory distress to decrease the risk of meconium aspiration syndrome, which can occur in meconium-stained amniotic fluid.

Most of the time that the amniotic fluid is stained with meconium, it will be homogeneously distributed throughout the fluid, making it brown. This indicates that the fetus passed the meconium some time ago such that sufficient mixing occurred as to establish the homogeneous mixture. Terminal meconium occurs when the fetus passes the meconium a short enough time before birth/cesarean section that the amniotic fluid remains clear, but individual clumps of meconium are in the fluid.

Failure to pass meconium

The failure to pass meconium is a symptom of several diseases including Hirschsprung's disease and cystic fibrosis.

The meconium sometimes becomes thickened and congested in the intestines, a condition known as meconium ileus. Meconium ileus is often the first sign of cystic fibrosis. [2] In cystic fibrosis, the meconium can form a bituminous black-green mechanical obstruction in a segment of the ileum. Beyond this, there may be a few separate grey-white globular pellets. Below this level, the bowel is a narrow and empty micro-colon. Above the level of the obstruction, there are several loops of hypertrophied bowel distended with fluid. No meconium is passed, and abdominal distension and vomiting appear soon after birth. About 20% of cases of cystic fibrosis present with meconium ileus, while approximately 20% of one series of cases of meconium ileus did not have cystic fibrosis. [3] The presence of meconium ileus is not related to the severity of the cystic fibrosis. [4] The obstruction can be relieved in a number of ways. [5]

Meconium ileus should be distinguished from meconium plug syndrome, in which a tenacious mass of mucus prevents the meconium from passing and there is no risk of intestinal perforation. Meconium ileus has a significant risk of intestinal perforation. In a barium enema, meconium plug syndrome shows a normal or dilated colon as compared to micro-colon in meconium ileus.

Testing meconium for drugs

Meconium can be tested for various drugs, to check for in utero exposure. Using meconium, a Canadian research group showed that by measuring a by-product of alcohol, fatty acid ethyl esters (FAEE), they could objectively detect excessive maternal alcohol consumption during pregnancy. [6]

In the US, the results of meconium testing may be used by child protective services and other law enforcement agencies if the capacity of the parents to look after their child is in question. [7] Meconium can also be analyzed to detect the tobacco use of mothers during their pregnancy, which is commonly under-reported. [8]

Sterility

The issue of whether meconium is sterile remains debated and is an area of ongoing research. Although some researchers have reported evidence of bacteria in meconium, [9] this has not been consistently confirmed. Other researchers have raised questions about whether these findings may be due to contamination after sample collection and that meconium is, in fact, sterile until after birth. [10] Further researchers have hypothesized that there may be bacteria in the womb, but these are a normal part of pregnancy and could have an important role in shaping the developing immune system and are not harmful to the baby. [11]

Etymology

The Latin term meconium derives from Greek μηκώνιον, mēkōnion, a diminutive of μήκων, mēkōn 'poppy', in reference either to its tar-like appearance that may resemble some raw opium preparations or to Aristotle's belief that it induces sleep in the fetus. [12] [13] [14]

Other uses

Related Research Articles

<span class="mw-page-title-main">Meconium aspiration syndrome</span> Medical condition affecting newborn infants

Meconium aspiration syndrome (MAS) also known as neonatal aspiration of meconium is a medical condition affecting newborn infants. It describes the spectrum of disorders and pathophysiology of newborns born in meconium-stained amniotic fluid (MSAF) and have meconium within their lungs. Therefore, MAS has a wide range of severity depending on what conditions and complications develop after parturition. Furthermore, the pathophysiology of MAS is multifactorial and extremely complex which is why it is the leading cause of morbidity and mortality in term infants.

<span class="mw-page-title-main">Amniocentesis</span> Sampling of amniotic fluid done mainly to detect fetal chromosomal abnormalities

Amniocentesis is a medical procedure used primarily in the prenatal diagnosis of genetic conditions. It has other uses such as in the assessment of infection and fetal lung maturity. Prenatal diagnostic testing, which includes amniocentesis, is necessary to conclusively diagnose the majority of genetic disorders, with amniocentesis being the gold-standard procedure after 15 weeks' gestation.

Fetal distress, also known as non-reassuring fetal status, is a condition during pregnancy or labor in which the fetus shows signs of inadequate oxygenation. Due to its imprecision, the term "fetal distress" has fallen out of use in American obstetrics. The term "non-reassuring fetal status" has largely replaced it. It is characterized by changes in fetal movement, growth, heart rate, and presence of meconium stained fluid.

Potter sequence is the atypical physical appearance of a baby due to oligohydramnios experienced when in the uterus. It includes clubbed feet, pulmonary hypoplasia and cranial anomalies related to the oligohydramnios. Oligohydramnios is the decrease in amniotic fluid volume sufficient to cause deformations in morphogenesis of the baby.

Colic in horses is defined as abdominal pain, but it is a clinical symptom rather than a diagnosis. The term colic can encompass all forms of gastrointestinal conditions which cause pain as well as other causes of abdominal pain not involving the gastrointestinal tract. What makes it tricky is that different causes can manifest with similar signs of distress in the animal. Recognizing and understanding these signs is pivotal, as timely action can spell the difference between a brief moment of discomfort and a life-threatening situation. The most common forms of colic are gastrointestinal in nature and are most often related to colonic disturbance. There are a variety of different causes of colic, some of which can prove fatal without surgical intervention. Colic surgery is usually an expensive procedure as it is major abdominal surgery, often with intensive aftercare. Among domesticated horses, colic is the leading cause of premature death. The incidence of colic in the general horse population has been estimated between 4 and 10 percent over the course of the average lifespan. Clinical signs of colic generally require treatment by a veterinarian. The conditions that cause colic can become life-threatening in a short period of time.

<span class="mw-page-title-main">Volvulus</span> Twisting of part of the intestine, causing a bowel obstruction

A volvulus is when a loop of intestine twists around itself and the mesentery that supports it, resulting in a bowel obstruction. Symptoms include abdominal pain, abdominal bloating, vomiting, constipation, and bloody stool. Onset of symptoms may be rapid or more gradual. The mesentery may become so tightly twisted that blood flow to part of the intestine is cut off, resulting in ischemic bowel. In this situation there may be fever or significant pain when the abdomen is touched.

<span class="mw-page-title-main">Prelabor rupture of membranes</span> Medical condition

Prelabor rupture of membranes (PROM), previously known as premature rupture of membranes, is breakage of the amniotic sac before the onset of labor. Women usually experience a painless gush or a steady leakage of fluid from the vagina. Complications in the baby may include premature birth, cord compression, and infection. Complications in the mother may include placental abruption and postpartum endometritis.

<span class="mw-page-title-main">Respiratory disease</span> Disease of the respiratory system

Respiratory diseases, or lung diseases, are pathological conditions affecting the organs and tissues that make gas exchange difficult in air-breathing animals. They include conditions of the respiratory tract including the trachea, bronchi, bronchioles, alveoli, pleurae, pleural cavity, the nerves and muscles of respiration. Respiratory diseases range from mild and self-limiting, such as the common cold, influenza, and pharyngitis to life-threatening diseases such as bacterial pneumonia, pulmonary embolism, tuberculosis, acute asthma, lung cancer, and severe acute respiratory syndromes, such as COVID-19. Respiratory diseases can be classified in many different ways, including by the organ or tissue involved, by the type and pattern of associated signs and symptoms, or by the cause of the disease.

<span class="mw-page-title-main">Chorioamnionitis</span> Medical condition

Chorioamnionitis, also known as intra-amniotic infection (IAI), is inflammation of the fetal membranes, usually due to bacterial infection. In 2015, a National Institute of Child Health and Human Development Workshop expert panel recommended use of the term "triple I" to address the heterogeneity of this disorder. The term triple I refers to intrauterine infection or inflammation or both and is defined by strict diagnostic criteria, but this terminology has not been commonly adopted although the criteria are used.

<span class="mw-page-title-main">Distal intestinal obstruction syndrome</span> Medical condition

Distal intestinal obstruction syndrome (DIOS) involves obstruction of the distal part of the small intestines by thickened intestinal content and occurs in about 20% of mainly adult individuals with cystic fibrosis. DIOS was previously known as meconium ileus equivalent, a name which highlights its similarity to the intestinal obstruction seen in newborn infants with cystic fibrosis. DIOS tends to occur in older individuals with pancreatic insufficiency. Individuals with DIOS may be predisposed to bowel obstruction, though it is a separate entity than true constipation.

<span class="mw-page-title-main">Intestinal atresia</span> Medical condition

Intestinal atresia is any congenital malformation of the structure of the intestine that causes bowel obstruction. The malformation can be a narrowing (stenosis), absence or malrotation of a portion of the intestine. These defects can either occur in the small or large intestine.

<span class="mw-page-title-main">Duodenal atresia</span> Medical condition

Duodenal atresia is the congenital absence or complete closure of a portion of the lumen of the duodenum. It causes increased levels of amniotic fluid during pregnancy (polyhydramnios) and intestinal obstruction in newborn babies. Newborns present with bilious or non-bilous vomiting within the first 24 to 48 hours after birth, typically after their first oral feeding. Radiography shows a distended stomach and distended duodenum, which are separated by the pyloric valve, a finding described as the double-bubble sign.

Amnioinfusion is a method in which isotonic fluid is instilled into the uterine cavity.

Artificial rupture of membranes (AROM), also known as an amniotomy, is performed by a midwife or obstetrician and was once thought to be an effective means to induce or accelerate labor. The membranes can be ruptured using a specialized tool, such as an amnihook or amnicot, or they may be ruptured by the proceduralist's finger. The different techniques for artificial rupture of membranes have not been extensively compared in the literature. In one study comparing amnihook versus amnicot for artificial rupture of membranes, use of an amnicot was associated with fewer neonatal scalp lacerations.

Birth injury refers to damage or injury to the child before, during, or just after the birthing process. "Birth trauma" refers specifically to mechanical damage sustained during delivery.

Neonatal bowel obstruction (NBO) or neonatal intestinal obstruction is the most common surgical emergency in the neonatal period. It may occur due to a variety of conditions and has an excellent outcome based on timely diagnosis and appropriate intervention.

The initial acquisition of microbiota is the formation of an organism's microbiota immediately before and after birth. The microbiota are all the microorganisms including bacteria, archaea and fungi that colonize the organism. The microbiome is another term for microbiota or can refer to the collected genomes.

<span class="mw-page-title-main">Neonatal infection</span> Human disease

Neonatal infections are infections of the neonate (newborn) acquired during prenatal development or within the first four weeks of life. Neonatal infections may be contracted by mother to child transmission, in the birth canal during childbirth, or after birth. Neonatal infections may present soon after delivery, or take several weeks to show symptoms. Some neonatal infections such as HIV, hepatitis B, and malaria do not become apparent until much later. Signs and symptoms of infection may include respiratory distress, temperature instability, irritability, poor feeding, failure to thrive, persistent crying and skin rashes.

<span class="mw-page-title-main">Placental microbiome</span>

The placental microbiome is the nonpathogenic, commensal bacteria claimed to be present in a healthy human placenta and is distinct from bacteria that cause infection and preterm birth in chorioamnionitis. Until recently, the healthy placenta was considered to be a sterile organ but now genera and species have been identified that reside in the basal layer.

<span class="mw-page-title-main">Uterine microbiome</span>

The uterine microbiome is the commensal, nonpathogenic, bacteria, viruses, yeasts/fungi present in a healthy uterus, amniotic fluid and endometrium and the specific environment which they inhabit. It has been only recently confirmed that the uterus and its tissues are not sterile. Due to improved 16S rRNA gene sequencing techniques, detection of bacteria that are present in low numbers is possible. Using this procedure that allows the detection of bacteria that cannot be cultured outside the body, studies of microbiota present in the uterus are expected to increase.

References

  1. ↑ Persis Mary Hamilton, Basic Pediatric Nursing (Maryland Heights MO: Mosby, 1991), 82. ISBN   978-0801658693
  2. ↑ Hutchinson JH (1975). Practical Paediatric Problems (4th ed.). London: Lloyd-Luke. p.  314. ISBN   0-85324-114-7.
  3. ↑ Hekmatnia A. "Meconium Ileus".[ permanent dead link ]
  4. ↑ Jones PG (1976). Clinical Paediatric Surgery (2nd ed.). Oxford: Blackwell. pp. 74–75. ISBN   0-632-00089-9.
  5. ↑ Irish M (29 December 2015). Minkes RK (ed.). "Surgical Aspects of Cystic Fibrosis and Meconium Ileus".
  6. ↑ Chan D, Knie B, Boskovic R, Koren G. Placental handling of fatty acid ethyl esters: perfusion and subcellular studies. J Pharmacol ExpTher 2004; 310: 75-82.
  7. ↑ G.B. v. Dearborn County Div. of Family and Children, 754 N.E.2d 1027 (Ind.Ct.App., 2001).
  8. ↑ Braun JM, Daniels JL, Poole C, Olshan AF, Hornung R, Bernert JT, et al. (August 2010). "A prospective cohort study of biomarkers of prenatal tobacco smoke exposure: the correlation between serum and meconium and their association with infant birth weight". Environmental Health: A Global Access Science Source. 9 (1): 53. Bibcode:2010EnvHe...9...53B. doi: 10.1186/1476-069X-9-53 . PMC   2944243 . PMID   20799929.
  9. ↑ Jiménez E, Marín ML, Martín R, Odriozola JM, Olivares M, Xaus J, Fernández L, Rodríguez JM (April 2008). "Is meconium from healthy newborns actually sterile?". Research in Microbiology. 159 (3): 187–93. doi: 10.1016/j.resmic.2007.12.007 . PMID   18281199.
  10. ↑ Perez-Muñoz ME, Arrieta MC, Ramer-Tait AE, Walter J (April 2017). "A critical assessment of the 'sterile womb' and 'in utero colonization' hypotheses: implications for research on the pioneer infant microbiome". Microbiome. 5 (1): 48. doi: 10.1186/s40168-017-0268-4 . PMC   5410102 . PMID   28454555.
  11. ↑ Willyard C (January 2018). "Could baby's first bacteria take root before birth?". Nature. 553 (7688): 264–266. Bibcode:2018Natur.553..264W. doi: 10.1038/d41586-018-00664-8 . PMID   29345664.
  12. ↑ O'Dochartaigh S. "HON Mother & Child Glossary, Meconium". www.hon.ch. Archived from the original on 1 May 2021. Retrieved 17 April 2018.
  13. ↑ μηκώνιον . Liddell, Henry George ; Scott, Robert ; A Greek–English Lexicon at the Perseus Project.
  14. ↑ "meconium". Online Etymology Dictionary .
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