The 10-week pregnancy ultrasound, often called the dating scan, uses high-frequency sound waves to create images of the developing embryo and surrounding structures within the uterus. This examination confirms the existence of the pregnancy, provides early insights into fetal development, and establishes a baseline for the pregnancy’s progression.
The Standard Procedure at 10 Weeks
The 10-week scan can involve both external (transabdominal) and internal (transvaginal) methods. Clinicians usually begin with the transabdominal scan, moving a transducer across the lower abdomen to provide a broad view of the pelvic organs.
However, at 10 weeks, the uterus is low in the pelvis, and the embryo is small, measuring only about 30 millimeters. Because of this deep position, the external view may not provide the necessary detail for accurate measurements.
If the initial images are insufficient, the sonographer transitions to a transvaginal scan. This internal method places a specialized transducer closer to the uterus, offering a superior, higher-resolution image of the developing embryo. This proximity is necessary to obtain precise diagnostic data.
Key Information Gathered During the 10-Week Scan
The primary objective of the 10-week scan is to confirm a healthy, ongoing pregnancy. The first step involves confirming fetal viability by detecting and measuring the embryonic heart rate. A visible, rhythmic heartbeat at this stage is a reassuring sign of progression.
The scan is most frequently used to accurately date the pregnancy, which is accomplished by measuring the Crown-Rump Length (CRL). The CRL is the measurement from the top of the embryo’s head to its bottom, and it is the most reliable parameter for estimating gestational age during the first trimester. This measurement helps establish the estimated due date, which is especially helpful for individuals who are unsure of their last menstrual period.
Another function of the scan is to determine the location of the gestation, ensuring that the pregnancy has implanted correctly inside the uterine cavity. This step rules out the possibility of an ectopic pregnancy, where the embryo develops outside the uterus, which requires immediate medical attention.
The sonographer also checks for the presence of multiples, identifying whether there is a single embryo, twins, or higher-order gestations. Additionally, the scan provides an early assessment of the surrounding structures, including the ovaries and the gestational sac, to check for any abnormalities.
Preparing for the Ultrasound: Internal vs. External Requirements
Preparation for the 10-week scan differs depending on which type of procedure the provider anticipates performing. A transabdominal scan requires a full bladder, as the fluid helps push the uterus into a better position and serves as an acoustic window for the sound waves.
Conversely, if the provider is performing a transvaginal scan, the bladder should be empty, as a full bladder can interfere with the probe’s access and the resulting image quality. The internal procedure allows the transducer to bypass the abdominal wall entirely.
Because many providers plan to attempt the external scan first and then switch to the internal method if needed, patients are often advised to arrive with a moderately full bladder. The sonographer can then proceed with the transabdominal view and ask the patient to empty their bladder before performing the transvaginal scan if the initial images are not sufficient.