Human Fetus at 18 Weeks in the Womb (Caucasian Skin)

Description

At approximately 18 weeks of gestation the fetus lies in a flexed attitude within the amniotic cavity, the head turned in profile with smooth cranial contours, closed fused eyelids, a formed nose and lips, and the external ear visible at the temporal region. One upper limb is flexed at the elbow so that the hand rests near the vertex, while the opposite arm crosses the chest; the lower limbs are drawn up with knees flexed and feet crossed close to the trunk. The umbilical cord emerges from the anterior abdominal wall and loops toward the discoid placenta, whose chorionic surface and vascular tree are seen through the translucent amniotic sac membrane and the surrounding vascularized uterine wall. This gestational stage sits at the centre of the second-trimester anomaly scan window, when biometry such as biparietal diameter, head and abdominal circumference and femur length is measured, and when cardiac outflow tracts, spine, kidneys and limbs are systematically surveyed. Placental position and cord insertion, both depicted here, are documented at the same examination and underpin later decisions about delivery route. Fetal movements are established but not yet reliably perceived by the mother, and amniotic fluid volume around the fetus is sufficient for amniocentesis or targeted ultrasound-guided procedures when indicated. The rendering suits obstetric and midwifery teaching on second-trimester development, antenatal class handouts, ultrasound training resources that pair a realistic model with sonographic planes, and patient-facing material explaining what an 18-week scan assesses. As part of a week-by-week gestational series it also supports publishers, health apps and educational timelines that require visually consistent stages of intrauterine growth. Anatomical accuracy verified by SciePro's Medical Advisory Board.