B-ultrasound shows little urine retention and no fetal heartbeat

An ultrasound examination is performed around seven weeks of pregnancy, during which the fetal heartbeat can be seen. The pregnant woman must hold back her urine before the examination so that the fetal heart rate can be seen clearly. If the urine is insufficient, the doctor will ask the pregnant woman to drink more water and wait for a while. When the urine is sufficient, the examination can be repeated. If the urine is sufficient and no fetal heartbeat is detected, the fertilized egg may have stopped developing. Let us now take a closer look at why we need to hold our urine when doing an ultrasound.

In acoustics, audible sounds are called sound waves, while inaudible sounds with a frequency above 20,000 Hz are called ultrasonic waves. What we usually call B-ultrasound refers to type B ultrasound. Its basic method is to transmit ultrasound into the human body, receive and record ultrasound signals reflected from the interfaces of various organs and tissues in the body, and then obtain information based on the characteristics of these signals to diagnose the disease.

Ultrasound has excellent penetration into water, but very poor penetration into gas, with almost all of it being reflected back. From the anatomical point of view, the uterus and appendages are located in the pelvic cavity, with the bladder in front, the rectum behind, and the intestines surrounding them. If the bladder is not full, there is a lot of gas in front of the uterine appendages deep in the pelvic cavity. Ultrasound cannot easily pass through the gas, so the doctor cannot see the uterus and appendages behind the bladder on the fluorescent screen. All he can see are the reflected waves of the gas and the echoes of the intestinal tract.

When the bladder is full, the surrounding gas is expelled, and the ultrasound passes through the urine stored in the bladder, and a clear image of the uterus and its appendages is displayed on the fluorescent screen. It can be seen that a full bladder can sometimes be a good helper for doctors. Therefore, during an ultrasound examination, you must hold your urine before doing an ultrasound examination of the uterus and its appendages, but you do not need to hold your urine when using a vaginal probe.