During early pregnancy, the gestational sac appears round and evenly bordered du to the embryo and fluid inside. When the embryo is dead or nonviable, the sac becomes corrugated or irregular. Your irregular sac does suggest that the embryo is nonviable. In addition, you are having brown spotting. Brown spotting or discharge in pregnancy is also indicative that the child inside is not alive. So both your signs are suggestive of pregnancy continuing with an embryo that is not living - we call this as missed abortion. Your doctor has very rightly diagnosed the condition. In such condition it is always advisable to get the pregnancy terminated without loosing any time lest the complications are quite serious. Even before you go for termination, I would advice you to get your certain tests to evaluate the coagubility of the blood and the fibrinogen levels. In this condition, a complication called as disseminated intravascular coagulopathy is known (DIC) in which it is very difficult to controll the bleeding. I am sure your obstetrician will do the required investigations and do the termination of pregnancy.