Why a Follow-Up Scan May Be Suggested After an Early Dating Scan?

Early pregnancy is an exciting time, filled with anticipation and a bit of anxiety. One of the key moments in early pregnancy is the dating scan, usually performed around six to eight weeks. This scan helps determine the gestational age of the pregnancy, confirm the presence of a gestational sac, and sometimes detect the fetal heartbeat. However, there are instances where a follow-up scan is recommended a week or two later. Here’s why this might be the case.

Early Pregnancy Development Stages

Understanding the stages of early pregnancy development is crucial in interpreting dating scan results. In the initial weeks, pregnancy progresses through several distinct phases:

  • Gestational Sac Formation: Around the fourth to fifth week of pregnancy, a small fluid-filled sac, known as the gestational sac, forms within the uterus. This sac is often the first visible sign of pregnancy on an ultrasound.
  • Yolk Sac and Embryo Formation: By the fifth to sixth week, the yolk sac appears within the gestational sac. The yolk sac provides essential nutrients to the developing embryo.
  • Fetal Pole and Heartbeat Detection: Between the sixth and seventh week, the fetal pole (early form of the baby) becomes visible, and the heartbeat can usually be detected around this time.

Reasons for a Follow-Up Scan

Sometimes, during an early dating scan, only the gestational sac is visible without the embryo or a detectable heartbeat. This can be due to several reasons:

  1. Early Scan Timing: If the dating scan is performed too early, it may be too soon to see the embryo or hear the heartbeat. Since pregnancy development follows a timeline, an early scan might only show the gestational sac, especially if ovulation occurred later than expected.
  2. Variability in Development: Each pregnancy develops at its own pace. While some pregnancies show the fetal pole and heartbeat by the sixth week, others might not until the seventh or eighth week.
  3. Ensuring Viability: To confirm a normal, viable pregnancy, it is essential to see both the embryo and the heartbeat. If only the gestational sac is seen, a follow-up scan is crucial to ensure that the pregnancy is progressing normally.

What to Expect in a Follow-Up Scan?

A follow-up scan, typically scheduled one to two weeks after the initial dating scan, allows time for further development of the pregnancy. During this scan, healthcare providers look for:

  • Growth of the Gestational Sac: The sac should have grown since the last scan.
  • Presence of the Yolk Sac: This indicates the embryo is developing as expected.
  • Appearance of the Fetal Pole: The early form of the baby should now be visible.
  • Detection of Heartbeat: A strong and regular heartbeat confirms the viability of the pregnancy.

The Importance of Follow-Up Scans

Follow-up scans are essential for providing accurate information about the health and progression of the pregnancy. They help in:

  • Reducing Anxiety: Waiting to see the heartbeat can be stressful. A follow-up scan provides reassurance and reduces anxiety for expectant parents.
  • Ensuring Proper Care: Confirming the presence of the embryo and heartbeat helps healthcare providers offer the appropriate care and guidance needed for a healthy pregnancy.


In early pregnancy, it’s common to only see the gestational sac during the initial dating scan. To ensure the pregnancy is progressing normally, a follow-up scan is often recommended. This subsequent scan, performed after one or two weeks, allows for the detection of the fetal pole and heartbeat, providing critical information about the viability of the pregnancy. Understanding the reasons behind these follow-up scans can help expectant parents navigate this early stage with greater confidence and peace of mind.

Thank you for reading, and Dr. Srinivas Prasad R.H – Founder of Nisarga Diagnostics, Sanjay Nagar, Bangalore.

If you have any questions or need further information, please feel free to reach out to your healthcare provider.

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