Technically, medical or laboratory errors could theoretically lead to misdiagnosis of pregnancy loss at any point in pregnancy—but this is extremely uncommon. Most doctors use established guidelines before diagnosing miscarriage. And when evaluated by these guidelines, laboratory and imaging results are generally considered reliable and accurate for diagnosing pregnancy loss. Now and then, however, miscarriage misdiagnosis does occur. When it does, the situation almost always involves a few specific situations. Knowing more about them can help ease your mind and inform your prenatal care going forward.
Date Confusion
In early pregnancy, the embryo grows larger every day. Being off even by a few days with the dating can make a difference in the measurements and, as a result, whether or not first-trimester ultrasound will detect a fetal heartbeat. Most doctors avoid the possibility of miscarriage misdiagnosis by ordering a follow-up ultrasound to check for continued development anytime there’s any uncertainty about dates in early pregnancy. When a pregnancy is viable, the gestational sac and embryo will be considerably larger after a week (the usual interval for a follow-up scan), but a nonviable pregnancy will show either no growth or minimal growth. The possibility of misdiagnosis of pregnancy loss from confusion about dates and ultrasound results is specific to early pregnancy. Ultrasound is increasingly reliable for diagnosing pregnancy loss as the pregnancy progresses. Once the gestational sac and baby have reached a significant size, ultrasound findings can definitively diagnose miscarriage.
Misdiagnosis Based on hCG Levels
Doctors consider slow-rising levels of the hormone human chorionic gonadotropin (hCG) in a pregnant person’s blood or urine to be a warning sign of possible ectopic pregnancy, although hCG levels occasionally rise slowly in viable pregnancies as well. If a diagnosis were made based solely on slow-rising hCG levels, there is a possibility that it could be incorrect. Falling hCG levels nearly always mean miscarriage, but very rarely can reflect a condition like heterotopic pregnancy. Heterotopic pregnancy is a pregnancy that involves two conceptions—one viable pregnancy in the uterus and one nonviable ectopic pregnancy. Another possibility for falling hCG levels in a viable pregnancy would be vanishing twin syndrome, a twin pregnancy in which one baby is miscarried while the other is viable. This condition is also rare when the person has not used assisted reproduction technologies and is a highly infrequent explanation of falling hCG levels. Remember also that hCG levels do not continue rising throughout pregnancy; in fact, hCG begins to decrease naturally later in pregnancy. Slow rising or falling hCG levels can be a normal finding toward the end of the first trimester. Levels of hCG start to rise more slowly by around the eighth week of pregnancy and begin to fall after reaching a peak, so don’t be alarmed as these levels start to drop. Falling or slower rising hCG after the first two or three months of pregnancy is not necessarily a sign of miscarriage.
A Word From Verywell
During pregnancy, it’s natural to feel fearful of miscarriage, and a miscarriage diagnosis can be heartbreaking. But it’s important to remember that as with all medical conditions, misdiagnosis is always a possibility. Before making decisions about your treatment, your doctor will order additional tests to make an accurate diagnosis. Throughout this emotional journey, don’t forget to care for your own physical and emotional well-being. Set aside time for self-care and lean on friends and loved ones for support.
