Article

Obstetric ultrasound: pregnancy phases

Patient guide on early pregnancy ultrasound, first and second trimester morphology, Doppler, preparation, safety, and exam limitations.

What an obstetric ultrasound does

Obstetric ultrasound uses sound waves to produce images of the embryo or fetus, uterus, ovaries, and pregnancy-related structures. It does not use ionizing radiation and is one of the central tools of prenatal care.

The exam changes according to the pregnancy phase. An early pregnancy ultrasound does not answer exactly the same questions as a second-trimester morphological scan, a growth scan, or an obstetric Doppler.

Most common phases

Tabela: Phase | What it usually evaluates | Point of attention

Terms that appear in the report

Tabela: Term | How to understand it

Safety and proper use

Before the exam

Bring the medical request, ID, prenatal card, LMP (Last Menstrual Period), EDD (Estimated Date of Delivery) if available, lab tests, and reports or images from previous ultrasounds. Arriving with this information avoids date confusion and makes interpretation easier.

• Obstetric ultrasound preparation
• Gestational calculator and EDD
• Medical course on early transvaginal pregnancy
• Ultrasound Academy

Frequently asked questions

Sources and next steps

The sources below support the explanation of phases, purpose, safety, Doppler, and documentation. The technical page shows how these same points become a structured medical report.

• Technical page for physicians: obstetric ultrasound in the report
• Physicians area
• Patients area
• Ultrasound sources
• Editorial policy
• Official contact

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