Hi Angelababy,
The SEA deletion is a deletion of both alpha genes on one chromosome. The combination of two sets of these genes when both parents are carriers is the most common cause of alpha thal major, or hydrops fetalis, in which the fetus does not survive pregnancy, unless it is detected very early and is determined to be a mutation that can be helped by in utero transfusions. It is not common for this solution to be used to save a fetus. Without knowing what has been found in your husband, it is not possible to say for certain what the possible outcomes of this pregnancy may be. If he is a one gene alpha carrier, the worst outcome is HbH disease. If he is an SEA carrier, like yourself, hydrops fetalis is a possible outcome. Because of this, you should absolutely get the CVS test done, as a thal major fetus can potentially threaten the life of the mother, and often early delivery is the best course to follow for the mother. If the fetus is alpha major, there is far more than a 1% chance of premature delivery, and intervention is often necessary.
Without knowing your husband's deletion, I cannot tell you if there is a chance of HbH (25% if he is a single gene deleted carrier). If he has the SEA deletion, he cannot pass just one deletion on to offspring. It would either be two alpha genes deleted or none. If the doctor knows the deletion your husband carries, he would be more informed and able to tell you if HbH is one of the possible outcomes. If the doctor does not yet know your husband's carrier status, he is simply giving you the known odds when both parents are carriers. There are several types of DNA tests used to diagnose alpha thal and depending on the test and the deletions, the results can be variable and not 100% accurate. I cannot advise on the legal issues but my feeling is that it would be useless to sue, as there is probably a known margin of undetected deletions. Alpha thal testing is difficult and the experience of the tech running the tests can be a factor in the outcome of the test.
Has the pregnancy been normal? Does the fetus seem to have a normal activity level? Has an ultrasound been done and was anything unusual noted about bone development, especially in the skull? It's not much to go on, but if nothing unusual has been noted so far, it is a positive but not conclusive sign. CVS is essential at this point. No mother should take the chance and risk her own health and life when hydrops fetalis is a possible outcome.