Morphological Progression of Chorionic Membrane Development in Monochorionic and Dichorionic Twins: A Sonographic Assessment

Background: The zygote of twins implants themselves separately and on different spots in the uterine endometrium. However, the growth of fetal membranes may be collective or singly. There is little data from sonographic view of assessment on the exact progression at different stages of gestation. More so, the realistic evidences from radiographic assessment of the compartmentalization of chorion membrane in the developing monochorionic and dichorionic twins are not sufficiently available, hence, the call to ascertain the exact progression of the chorion membrane through ultrasound scanning in gestational subjects. Aim: This present study examined the structural progression of embryonic growth pattern of chorionic membrane in monochorionic and dichorionic twins. Materials and Methods: The study utilized transabdominal ultrasound to periodically assess the progression of chorion membrane and advancement in compartmentalization of monochorionic and dichorionic twins as pregnancy proceeds. Results: The monochorionic membrane showed an enclosure that progresses to be more distinct and thickened around the two embryos with a unique T-shaped point of insertion in latter development. The partitioning of dichorionic membrane progresses to be less thickened and with a distinct lambda (λ) sign which is a wedge-shaped protrusion into the inter-twin space. Conclusion: Assessment showed that the growth pattern of chorion membrane varied with different parameters observed as early as in the first trimester. Hence during early gestational stage, a twin can be said to be monochorionic or dichorionic with key anatomical landmarks monitored. The growth progression could be used to project abnormality and on time treatment would be offered to improve perinatal outcome.