Understanding a Delayed HCG & Embryo Growth at 5w6d

Question
I just went to my doctor and I she saw an embryo, but it only measured 5w6days.I should be 7 weeks today. She did not see a heartbeat, but said that at 5w6d she would not expect to. She recommended a D&C. I want to wait another week and see what happens. She also said the gestational sac was not as round as it should be, more odd shaped. Is there any chance for this pregnancy?
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Followup To
Question -
I am 34 years old and I have a 2 year old son. My LMP was June 10, 2004. I had a blighted ovum in Feb 2004.  I have had 4 HCG test done and they do not look good. The results were 1)726  2)1288 3)1580 4)2300 . Each of the test were taken about 4 days apart. I had an ultrasound at 5w5days and they saw a gestational sac and a yolk sac but could not tell if there was an embryo. My OB says to stop taking progesterone because I am going to miscarry. My breast are becoming more sore by the day and I am very tired. No cramping or bleeding. Can a pregnancy still survive even if HCG scores do not double?
Answer -
Even though we usually prefer to have HCG results double every 48 hours, as long as they are rising and you are not having any vaginal bleeding, you may still have a perfectly normal preganncy. A sonogram performed prior to 6 weeks (from the first day of your last period) will only show an empty gestational sac and no fetus (embryo) or fetal heartbeat. After 6-7 weeks, we can see a fetus and a fetal heartbeat. I would sait one more weeks and repeat the sonogram. By then, you should see the fetus. It cannot hurt to continue the progesterone until you know for sure. Good Luck to you.

Answer
If a fetus was seen at 5 weeks 6 days, there definitely is hope for this pregnancy. Obviously, you were incorrect with your dates and you should not have a D&C at this time, but should repeat the sonogram in two weeks. Then, if the fetus does not have a heartbeat, it is not a viable pregnancy and you should have a D&C. HOwever, it is worth repeating the sonogram in 2 weeks unless you start to have heavy bleeding. There is no way to know if it is a normal 5-6 week pregnancy or if you really should be 7 weeks.