Pregnancy testing and ultrasound scanning
About two weeks after insemination, a pregnancy test is performed. Sometimes the patient may have some vaginal spotting or bleeding prior to the pregnancy test. She may think that her period has already started and decline having the pregnancy test. However, it is recommended that the pregnancy test is done as it is the only way to determine whether there is a pregnancy. In the happy event that this is positive, an ultrasound scan is arranged 3-4 weeks later, to check the number, location, size and viability of pregnancy .
The ultrasound scan can demonstrate that the pregnancy is normally located (intra uterine pregnancy), or abnormally located (ectopic pregnancy). If the patient has a positive pregnancy test but there are no signs of a pregnancy on the vaginal scan, this is called (pregnancy of unknown location). Blood tests to measure HCG and progesterone levels are recommended. Furthermore, a repeat scan after 7-10 days is necessary to make the diagnosis (RCOG Guidelines) .
The ultrasound scan can demonstrate that the pregnancy is viable (live) or non viable. If the scan shows a gestational sac that is less than 25 mm in diameter and with no obvious yolk sac or a fetus or the scan shows a fetus less than 7 mm in length and no obvious fetal heart beating, this is called (pregnancy of uncertain viability). A repeat scan after 7-10 days is necessary to make the diagnosis.
Dr Sur and colleagues from Nottingham University UK (2012), tracked the growth of 247 single and 264 twin embryos conceived through IVF treatment. For each embryo, they measured the crown-rump length (the distance from the top of the embryo's head to the bottom of its buttocks), during the first trimester using ultrasound scan. The pregnancy was then monitored until birth. They reported that 78% of single embryo pregnancies that miscarried were growth restricted, while 98% of single embryo pregnancies that did not miscarry were not growth restricted. This is in contrast to twin pregnancies, where 29% of pregnancies that miscarried were growth restricted and 98% of twin pregnancies that did not miscarry were not growth restricted. The study also found that twin embryos grew at the same rate as single embryo.