Correct understanding of ultrasound results without fetal heart

The article was professionally consulted by Specialist Doctor I Le Hong Lien - Department of Obstetrics and Gynecology - Vinmec Central Park International General Hospital.

According to the normal development of the fetus, about 22 days after conception, the fetal heart begins to form quite clearly and has a beat. Thus, for the most part, the fetal heart develops before the mother realizes she is pregnant. Today, by modern ultrasound technology. Fetal heartbeat appears and can be observed from 6-7 weeks of pregnancy.
However, in some cases, the fetus at 8 -10 weeks can only hear the heartbeat and clearly see the fetal heart, the reason is due to the error in the calculation of gestational age.
The formation and development of the fetus is associated with the fetal heart formation process, so this is an important sign for fetal health exploration. Normally, the zygote moves down to the uterus and rapidly divides after being fertilized.
5 days after conception, the zygote develops into a small mass, called a blastocyst, which then travels to the uterus after about 2 days. Here, the embryo begins the implantation process by firmly attaching to the lining of the uterus. At this stage, the new embryo secretes HCG in the urine, which can be used to detect pregnancy. At this time, ultrasound still does not clearly show the embryo.
During the development of the fetus, the fetal heart is the part that begins to form quite early. The primordial cardiac duct formed from the mesenteric mesoderm begins to beat about 3 weeks after conception. The heart tube will continue to grow and bend, a septum will be formed, dividing the heart into 4 chambers. The heart will develop fully when the two exit lines separate.

Through real-time 2D imaging of the mother's uterus, ultrasound detects the fetal heart based on determining the heart's activity. Calculating gestational age according to the last menstrual cycle, this time falls between 5 weeks and 6 weeks of the fetus.
Can produce color Doppler signal of the beating blood flow in the fetal heart as well as the major vessels of the fetal body after 6 weeks of pregnancy. It is possible to hear with normal headphones the fetal heartbeat from the 20th week of pregnancy onwards. The fetus is very healthy and develops very well if the fetal heartbeat is getting bigger and bigger.
From the 6th week of pregnancy onwards, it is possible to detect the fetal heart through ultrasound based on the time and process of development and formation of the fetal heart. In some cases, it may be later, starting from the 8th week of pregnancy, the reason is because of miscalculation of menstrual period, gestational age.

6 weeks pregnant ultrasound, if the embryo results are complete, the fetal heart begins to appear, this is a good sign because the baby is developing very well.
However, mothers should not be too worried if they have not seen the fetal heart or heard the fetal heartbeat, the doctor will determine and explain the cause. At your next visit, if your baby is developing normally, you should see a clear heartbeat. However, if the fetus has grown, but the ultrasound does not show the fetal heart, the fetal heartbeat can not be heard, it can be due to some of the following reasons:
2.1 Miscarriage Most of the cases of ultrasound without fetal heart are caused by miscarriage if not due to error in gestational age calculation. Causes of miscarriage can be due to:
Spontaneous miscarriage: currently the cause of the fetal heartbeat has stopped suddenly, as a result, the mother's health is still very good despite the fact The baby is no longer there. Chromosomal abnormalities, damaged eggs, poor sperm or sperm quality, and abnormal cell division are responsible for 50% of spontaneous abortions. Maternal health: Miscarriage is more likely to happen if the mother has some of the following health conditions: Polycystic ovary syndrome, diabetes, blood clotting disorders, thyroid problems, immune disorders, any Usually in the uterus, cervical incompetence.

External effects: the cause of fetal cardiac arrest, miscarriage can also be due to unwanted effects from the external environment, including: Being bumped, abdominal trauma, sick mother, infection such as rubella, toxoplasmosis.... Mother smoked, drank alcohol, used stimulants, used drugs, infected with HIV/AIDS... Mother suffered from depression, stress for a long time Mother exposed in the environment toxic

2.2 Fetal arrhythmias Fetal arrhythmias are quite rare cases, this condition usually occurs at a certain point in time, but cannot last during the whole pregnancy. Fetal arrhythmias are temporary, and are usually benign, however, in some cases, the fetus can be fatal.
Fetal heart rate is usually higher than normal, about 120-160 beats/minute. Your baby's heart rate may increase rapidly, slow down, or stop suddenly if there is a fetal heart disorder.
2.3 Ultrasound equipment is not guaranteed Important factors to help you hear your baby's heartbeat accurately and clearly include modern ultrasound equipment and a good stethoscope. However, you can mistakenly think that there is no fetal heart or there is a problem with the fetus if there is a device failure. It may be because the device is not sensitive enough for you to hear when the baby's heartbeat is still very weak, especially at 6-8 weeks of pregnancy.
2.4 Calculating wrong gestational age Because of the wrong calculation of gestational age, many cases of 7-week ultrasound have no fetal heart rate. Because the fetus is still small at this time, the gestational age can be 1 to 2 weeks different because the mother and the doctor calculate the gestational age based on the date of ovulation.
2.5 Due to the type of ultrasound Ultrasound results can be influenced by the type of ultrasound that the pregnant woman chooses. When the fetus is still small, the pulse is not clear, performing an abdominal ultrasound is often less sensitive, making it difficult to determine the fetal heart rate. Transducer ultrasound will give more accurate results because the probe is closer to the uterus.

The mother should not be too worried if the ultrasound does not have a fetal heart rate at 6-7 weeks because the high probability is due to the time of late fertilization, irregular menstruation, so the gestational age is not calculated accurately. At this time, the ultrasound may not detect the fetal heart and hear the fetal heartbeat because most likely your fetus is developing at 4-5 weeks of pregnancy.
In some cases, the embryo develops more slowly than usual, so you can only see the fetal heart at 8-10 weeks. Your doctor will perform an exam to determine if you have any abnormalities and assess the condition of your baby. Normally, you will be assigned an examination and ultrasound examination after about 1-2 weeks if no abnormalities are detected.
If there is no fetal heartbeat at 7 weeks pregnant due to objective factors, gestational age is wrongly calculated or the fetus is growing slowly, it is recommended to check the mother's HCG to see if the fetus is still there or not. Mother should wait 1 week after the ultrasound again if the pregnancy HCG is normal to see if the fetus has a fetal heart or rhythm. Avoid affecting the health as well as the fetus, the mother should not be too worried.
In the case of 7 weeks pregnant ultrasound, there is no fetal heart or fetal heart failure accompanied by some abnormal symptoms such as severe lower abdominal pain, vaginal bleeding, no feeling of morning sickness.. .need to notify the doctor immediately to check the fetal status.

In order to have a healthy pregnancy and a well-developed fetal heart, mothers should not be too worried and can do a few things:
Mothers need to limit alcohol use Prevent birth defects by taking supplements Folic acid during this period Mothers do not smoke, and at the same time limit exposure to cigarette smoke because they can cause birth defects in the fetus. Mothers need to keep blood sugar stable, especially mothers with diabetes. Pregnant women need to be supplemented with adequate nutrients, a variety of foods and reasonable rest. HCG should be checked urgently if after 12 weeks of pregnancy there is still no fetal heart rate to determine if you are really pregnant. pregnancy or not or if there is a problem with the pregnancy. In case you have a miscarriage, the doctor will apply a safe and appropriate method of abortion to avoid endangering the mother. Family, relatives, and friends need to be by your side to encourage your mother if in the worst case , ultrasound does not have fetal heart due to miscarriage because this is a huge and painful loss. The most important thing for the mother now is to overcome this great pain and restore her health. It is recommended to wait at least 3 months to get pregnant again after a miscarriage, you need to take time to rest and recuperate. Vinmec International General Hospital offers a Package Maternity Care Program for pregnant women right away. from the beginning of pregnancy from the first months with a full range of antenatal check-ups, periodical 3D and 4D ultrasounds and routine tests to ensure that the mother is always healthy and the fetus develops comprehensively. Pregnant women will no longer be alone when entering labor because having a loved one to help them during childbirth always brings peace of mind and happiness.
Specialist I Le Hong Lien is an obstetrician-gynecologist at Vinmec Central Park International Hospital since November 2016. Doctor Lien has over 10 years of experience as a radiologist in the Department of Ultrasound at the leading hospital in the field of obstetrics and gynecology in the South - Tu Du Hospital.