A patient presents at 39 weeks gestation in active labor. During vaginal examination, ruptured membranes are noted, and the amniotic fluid is observed to be thick, dark black-green in color.
What is the most likely underlying cause for this finding?
Meconium composition and passage
• Meconium is sterile, thick, black-green, odorless material. Fetal defecation with meconium normally begins early in the first trimester, slows after 16 weeks gestation, and becomes infrequent by 20 weeks.
• At 39 weeks (term), meconium passage indicates the fetus passed stool in utero, most commonly due to fetal stress (hypoxia) from events like cord compression or uteroplacental insufficiency during labor.
Meconium composition and passage
• Meconium is sterile, thick, black-green, odorless material. Fetal defecation with meconium normally begins early in the first trimester, slows after 16 weeks gestation, and becomes infrequent by 20 weeks.
• At 39 weeks (term), meconium passage indicates the fetus passed stool in utero, most commonly due to fetal stress (hypoxia) from events like cord compression or uteroplacental insufficiency during labor.