A prenatal ultrasound is a non-invasive imaging technique that uses high-frequency sound waves to create images of the fetus, placenta, and uterus. This procedure is a routine part of monitoring the health and developmental progress of the pregnancy. An ultrasound provides medical providers with valuable information, such as confirming the presence of a fetal heartbeat, assessing the baby’s size and position, and checking the location of the placenta. The process is generally safe, painless, and does not involve any radiation.
Determining the Timing and Purpose of the Scan
The schedule for medically recommended ultrasounds follows the progression of the pregnancy, with distinct purposes for each scan. The initial or “dating” scan is typically performed in the first trimester, ideally between 7 and 12 weeks of gestation. This early scan establishes the most accurate estimated due date by measuring the fetus’s size, known as the crown-rump length, and confirms the number of fetuses.
The most comprehensive scan is the anatomy or mid-pregnancy scan, usually scheduled between 18 and 22 weeks. This detailed examination assesses the baby’s developing organs, structure, and growth, looking for anomalies in the brain, heart, spine, and limbs. The sonographer also evaluates the placenta’s position and the amount of amniotic fluid.
For pregnancies proceeding without complications, these two scans are often the only routine ones performed. Additional scans in the third trimester, such as growth or biophysical profile scans, are typically reserved for specific clinical indications. These later scans monitor the baby’s growth or check the fetus’s overall well-being in higher-risk situations.
Navigating the Scheduling and Referral Process
The process of scheduling a diagnostic ultrasound begins with the ordering provider, usually your obstetrician, midwife, or other prenatal care practitioner. Diagnostic ultrasounds require a formal order or prescription from a healthcare provider to establish medical necessity for the procedure. This order includes details about the specific type of exam required and the medical reason, which is then sent to your chosen imaging facility.
The referral process often involves your provider sending the order directly to a hospital’s radiology department or a specialized outpatient imaging center. Before booking, you should verify that the selected location is in-network with your health insurance plan to minimize out-of-pocket costs. For some insurance plans, a pre-authorization may be required in addition to the referral, a step that your provider’s office usually handles.
Once the referral and any necessary pre-authorization are confirmed, you can contact the imaging facility to book the appointment. When calling to schedule, be prepared to provide the referral number, your insurance card details, and a few preferred dates and times. Since the anatomy scan has a specific window for optimal imaging, it is advisable to schedule this appointment several weeks in advance to align with the 18-to-22-week gestational period. The imaging center will confirm the appointment and provide specific instructions for the day of the scan.
Essential Preparation for the Appointment
Between scheduling and the appointment date, there are specific actions you can take to ensure a successful scan. For early first-trimester ultrasounds, a full bladder is often required because the fluid helps transmit the sound waves and pushes the uterus into a better position for clear imaging. Generally, you will be instructed to empty your bladder about 90 minutes before the appointment, drink a specific amount of water, and refrain from urinating until after the scan.
For later scans, such as the second-trimester anatomy scan, a full bladder may not be necessary as the growing uterus provides a clearer window for imaging. However, you should always confirm the exact preparation instructions with the facility when you book the appointment, as requirements can vary. Wearing comfortable, loose-fitting clothing is recommended, with a two-piece outfit being the most practical choice.
A two-piece outfit allows the sonographer easy access to your abdomen. Bring your photo identification, insurance card, and any physical copy of the referral or order you may have been given. While the actual scanning time can vary, a routine ultrasound typically lasts between 30 and 60 minutes.