Over the years, I have seen a few reasons doctors are more apt to misdiagnose a miscarriage. A growing, empty-looking gestational sac is probably the most common reason behind a misdiagnosed miscarriage. Measuring a week or two behind during the ultrasound causes many to be misdiagnosed as well. Women with high hCG levels and no baby is seen is another. These are all topics I have covered here on my blog.
Another fairly common reason a viable pregnancy is misdiagnosed as a miscarriage is because the hCG levels either plateau or drop.
Before I begin, let's just state the obvious. Yes, dropping hCG levels can be a sign of impending miscarriage but not always. Let's look at some examples of misdiagnosed miscarriages because of dropping or plateauing hCG levels.
The first group of women are usually very early in the pregnancy and their levels are still under 1,000. Mary's story (click on the links to read these stories) is a perfect example. Not only had she had IVF so doctors were certain of dating, her levels started off low and had very slow doubling times. Mary went through several weeks of being told her pregnancy was non-viable before finding the heartbeat. She went on to have a beautiful baby boy.
In this same group of women, we have InGodsTime story. The first hCG draw showed a level of 25.8. Three days later it had dropped to 24. The doctors told her to expect to start bleeding soon. They were wrong and she has a baby girl now to prove it :)
Why did these women have hCG levels that started off slow or even dropped? Over the years, we've seen on the site that dehydration seems to play a role. You need to stay hydrated but don't overdo the water either. Illness may also be a reason. Whatever the reason, we've had numerous stories of levels plateauing or dropping very early on and women went on to find their babies.
A caution though, slow-rising, declining or 'bouncing around' levels may indicate an ectopic pregnancy. For this reason, you need to stay closely monitored until a gestational sac is viewed.
The second group of women have levels that slow down after they reach 1,000. Let me just state first of all, this is normal. I have talked about typical levels on my The First Trimester and Non-Doubling hCG Levels page. Before they reach 1,200, they can double in two to three days and be in normal range. Between 1,200 and 6,000, they can double in three to four days and be normal. After 6,000 they typically slow down and we've seen a number of women whose hCG levels plateaued between about 30,000 and 50,000 and did not go any higher. This is normal.
Cherbear's story is a fairly typical one. Her hCG levels went up to the 70,000s, slowed and started dropping. Her doctor diagnosed a miscarriage. BelieveNPrayer has a similar story. Her levels went up to the 40,000s and started declining. Both women were misdiagnosed with a miscarriage.
The Misdiagnosed Miscarriage site has many more stories like these. What you need to take away from this blog post is that declining hCG levels do not necessarily mean a miscarriage. In fact, after the gestational sac is viewed, many doctors no longer take hCG levels because they can go up, stay the same or go down and be normal. The most important thing is to make sure they find the gestational sac and, after that point, watch the size of the gestational sac. Doesn't even matter if it measures a week or two behind. What you want to see is the sac growing from week to week. If your sac gets to be more than 25mm and no baby is seen then you likely have your answer.