In transabdominal scanning, a normal gestational sac can be consistently demonstrated when the beta hCG level is mega international units per milliliter (mIU/ml).

Explanation:

HCG (human chorionic gonadotropin) is the hormone produced during early pregnancy after implantation. Pregnancy kits are available to test the level of HCG in urine samples. In transabdominal scanning, beta HCG levels should be 1800 mIU/ml for a normal gestational sac. HCG level is very important to maintained to carry on the pregnancy. If it level drops it may leads to miscarriage.

So, the correct answer is 1800 mIU/ml.

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.