WEEK 7 OF GESTATION

• Gestational Sac = 22mm in length.
• Embryo = 9-15mm in length.
• Amnion, extraembryonic coelom and gestational sac are all well seen.

Normal video at 7 weeks of gestation.

ULTRASOUND

• Extraembryonic coelom predominates in early pregnancy. Mean volume doubles between 6-8 weeks and reaches a maximum of 5-6 ml at 9 weeks. It then starts to gradually decrease.

• Amniotic cavity is invisible until 7 weeks gestation. It is seen as an anechoic space adjacent to the fetal body. It expands rapidly and from 9 weeks onwards it begins to occupy most of the gestational sac volume.

7 weeks 1 day – amnion becoming visible as a separate structure.
7 weeks 5 days – Amnion and amniotic cavity now well visualized.

• Developing Placenta.

• Upper and lower limb buds can be visualized. Lower limbs project 90 degrees off the body.

• Heart
• ± 2mm.
• Three chambers.
• Rate = 112-136 bpm on M Mode.

• Central Nervous System.
• Morphology not well depicted despite the marked differentiation that has occurred.

· Developing spine.