A 2-day-old, term male was being seen in the newborn nursery. He was born to a G2P2 28-year-old female. There were no complications of pregnancy or vaginal delivery, after late second term prenatal care. He was breastfeeding well and had only lost 4% of his birthweight.
The pertinent physical exam showed a healthy male with weight of 3547 grams (75%), length of 50.5 cm (50%) and head circumference of 36.5 cm (75%).
He had some milia on his face, but was otherwise normal.
The diagnosis of a healthy male was made. Before rounding that day, his nurse informed the physicians that a meconium drug screen had been sent because the umbilical cord had been lost in transit to the laboratory. The physicians were surprised but upon further review, the mother’s chart noted that she had disclosed using marijuana as a teenager, and along with her later prenatal care, drug screening had been completed per hospital protocol. The patient’s clinical course showed he was discharged and at followup 2 days later was doing well. His weight was only 6% down from discharge and the mother was feeling well and supported by her family. The meconium drug screen laboratory evaluation eventually was normal.
During fetal life from approximately 12-13 weeks gestation, meconium accumulates in the small bowel and migrates to the large bowel and rectum by ~20 weeks gestation. Meconium is a combination of bile, mucous, desquamated intestinal cells, bowel secretions, dessicated swallowed amniotic fluid and lanugo. It is sterile before birth and once produced is odorless with a blackish green (sometimes brown or yellow) color, and tarry or sticky quality. Defecation does not occur during fetal life unless the fetus is significantly stressed. Normal meconium passage after birth occurs within 24-48 hours of life (more often within 24 hours). Delayed meconium passage begins an evaluation for anatomical obstruction (e.g. imperforate anus, colonic/rectal stenosis or atresia, mass effect, etc.), peristaltic problems (e.g. functional ileus, Hirschsprung disease) or intraluminal problems (e.g. cystic fibrosis) or other causes. Extreme prematurity also can have delayed passage of meconium as it is thought the normal intestinal musculature and/or innervation is also too immature to produce appropriate peristalsis and meconium movement. Imaging can be found here. Meconium’s tarry quality leads many parents commenting that they are happy once the stools transition and hygiene is easier to perform.
Meconium is normal and usually does not cause problems but they can be serious when they occur.
Meconium ileus is a neonatal intestinal obstruction problem caused by extremely thickened or inspissated meconium in the distal ileum. It is a very common first presentation of cystic fibrosis with ~20% of patient with cystic fibrosis present with it, but if it occurs almost 100% of patients have cystic fibrosis.. Complications of meconium ileus can include small bowel volvulus, bowel ischemia and/or necrosis, bowel perforation and possible meconium peritonitis and/or meconium pseudocyst formation. A broad differential diagnosis, where meconium ileus is only one possibility, or ileus and intestinal obstruction should to be considered and appropriately evaluated. Prenatal ultrasound can show meconium and meconium ileus appears as a hyperechoic bowel. Postnatally, plain radiographs show dilated loops of small bowel with or without air-fluid levels. Sometimes it may appear as “soap bubbles” when air mixes with the meconium. Contrast enemas will show a small or microcolon as the colon has not been used and therefore is not dilated to the normal expected size. Imaging can be found here and here. Management can include radiological and surgical procedures along with clinical management and support of the patient’s overall health. Distal intestinal obstruction syndrome is a fecal impaction in the distal ileum in patients with cystic fibrosis and is the child and adulthood equivalent of meconium ileus. It is common for patients with DIOS to have a history of meconium ileus. A review can be found here.
Meconium plug is caused by a functional colonic obstruction of retained meconium plugs with resultant small left colon often seen on radiographs. It is common in infants of diabetic mothers or mothers who received perinatal magnesium sulfate. Constrast enema shows multiple filling defects (the plugs) in the colon with a normal rectum. There may be a small left colon to the splenic flexure. Meconium passage is common after the procedure. Imaging can be found here.
Meconium aspiration syndrome (MAS) “is a clinical diagnosis what includes delivery through MSAF [meconium stained amniotic fluid] with respiratory distress with a characteristic appearance on chest radiograph and lack of an alternative diagnosis to explain respiratory distress.” Infants who are born through MSAF have been stressed and therefore are at risk for many problems including neonatal depression, birth asphyxia, respiratory distress, pand persistant pulmonary hypertension of the newborn. Infants born through MSAF are usually term or postterm and uncommon in premature infants unless there is prolonged rupture of membranes. In MAS, the meconium can cause chemical pneumonitis with surfactant dysfunction and inflammation and even physical airway obstruction. This can causes dead-space in the lungs, with resultant pulmonary vasoconstriction and pulmonary hypertension which causes right-to-left vascular shunting and resultant hypoxemia. Mitigation through use of infant suctioning at birth is standard but the exact procedure has changed overtime based on research studies. After delivery, respiratory support and/or mechanical ventilation may be necessary and ECMO (extra corporal membrane oxygenation) procedures sometimes are needed. ECMO treatment is less common in recent years as obstetrical intervention for the mother before becoming post-dates is more common. Imaging can be found here.
Drug testing can be completed using multiple body samples including urine (usual and preferred sample), saliva, sweat, hair and meconium. Meconium is the gold standard for detecting in utero drug exposure as it is non-invasive and has a large detection window including the second and third trimesters. Cons to meconium testing are that it can be contamined with urine, drugs given between birth and collection could be detected, there could be a limited sample and the sample needs more extensive extraction techniques to complete the testing.
Questions for Further Discussion
1. What are your hospital protocols for screening infants for potential maternal drug exposure?
2. What testing do you have available for drug testing at your institution?
3. What are some presentations for cystic fibrosis?
- Disease: Meconium | Childbirth
- Symptom/Presentation: Health Maintenance and Disease Prevention
- Age: Fetus and Mother | Newborn
To Learn More
To view pediatric review articles on this topic from the past year check PubMed.
Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.
Information prescriptions for patients can be found at MedlinePlus for this topic: Childbirth Problems
To view current news articles on this topic check Google News.
To view images related to this topic check Google Images.
To view videos related to this topic check YouTube Videos.
Jerdee T, Newman B, Rubesova E. Meconium in Perinatal Imaging: Associations and Clinical Significance. Seminars in Ultrasound, CT and MRI. 2015;36(2):161-177. doi:10.1053/j.sult.2015.01.007
Rawat M, Nangia S, Chandrasekharan P, Lakshminrusimha S. Approach to Infants Born Through Meconium Stained Amniotic Fluid: Evolution Based on Evidence? Amer J Perinatol. 2018;35(09):815-822. doi:10.1055/s-0037-1620269
Tamama K. Advances in drugs of abuse testing. Clin Chim Acta. 2021;514:40-47. doi:10.1016/j.cca.2020.12.010
Tobias J, Tillotson M, Maloney L, Fialkowski E. Meconium Ileus, Distal Intestinal Obstruction Syndrome, and Other Gastrointestinal Pathology in the Cystic Fibrosis Patient. Surgical Clinics of North America. 2022;102(5):873-882. doi:10.1016/j.suc.2022.07.016
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa