Should I hold my urine for a B-ultrasound during early pregnancy?

For an ultrasound examination during early pregnancy, urine retention is necessary. In the early stages of pregnancy, when urine is retained, the bladder is relatively full, allowing for a clear observation of the uterus, appendages, and embryo. If urine is not retained, the gas in the bladder may overlap with the gas in the uterus, leading to misdiagnosis or missed diagnosis. Therefore, urine retention is required for ultrasound examination during early pregnancy.

1. Is it necessary to retain urine for an ultrasound examination during early pregnancy?

Yes, urine retention is required for an ultrasound examination during early pregnancy. For gynecological or early pregnancy (less than 3 months) obstetric ultrasound examinations, it is necessary to retain urine fully. This is because from the front of the human body, the uterus and its appendages are located behind the bladder. Only when the bladder is full can the ultrasound waves pass through the "sound-transparent window" formed by the bladder to observe the uterus, appendages, and embryo behind it. If the bladder is not full, the gas in the bladder may overlap with the gas in the uterus, causing misdiagnosis or missed diagnosis.

2. How many times should an ultrasound examination be performed during the entire pregnancy?

The first ultrasound examination should be completed within 3 months, and the best time for the examination is the 8th week. Its main purpose is to determine the gestational age, confirm intrauterine pregnancy, and check the thickness of the nuchal translucency (only for 4D ultrasound). Research data shows that during this period, by checking the thickness of the nuchal translucency and combining with Down's syndrome screening, the detection rate of fetal Down's syndrome can reach over 80%. The second ultrasound examination is scheduled between 20-26 weeks. This period is for anomaly screening, usually using 3D or 4D ultrasound, which can detect most fetal malformations, such as facial, limb, brain, internal organ, and heart malformations. The third ultrasound examination is scheduled between 30-32 weeks, serving as a supplementary anomaly screening and checking the fetal growth and development, including assessing any growth restrictions, amniotic fluid, and umbilical cord conditions. The fourth and fifth ultrasound examinations are performed at weeks 37 and 39, respectively, both serving the same purpose of checking placental maturity and fetal growth and development, without involving fetal structural examination. During this period, if there is no umbilical cord around the neck, a black-and-white ultrasound is sufficient. However, if umbilical cord entanglement occurs, the doctor may recommend using color Doppler ultrasound to perform umbilical artery blood flow examination.