Using B-mode ultrasound to monitor fetal health in swine is a game-changer for modern pig farming. By analyzing ultrasound images, farmers can quickly assess whether piglets are developing normally or facing issues like stillbirths or growth delays. This guide breaks down the visual clues in ultrasound images, helping you make informed decisions without needing advanced technical knowledge. Let’s dive into the basics.

Normal Fetal Ultrasound Features

1. Gestational Sac Shape

A healthy fetal sac in early pregnancy (around 25–30 days post-breeding) appears as a distinct, circular or oval dark area on the ultrasound screen . These “black circles” represent fluid-filled spaces around the embryos. By day 30, the sacs grow larger, and the edges remain smooth, indicating normal implantation and development. If multiple sacs are visible, each corresponds to a potential piglet .

2. Fetal Heartbeat

After 25–26 days of gestation, a rhythmic flickering within the sac—like a tiny blinking light—signals a fetal heartbeat. This is one of the most reliable signs of a viable pregnancy. A steady heart rate (typically 200–250 beats per minute) suggests the piglet is active and healthy .

3. Bone Development

By day 32, calcium deposits in developing bones create bright white spots or lines (strong echoes) on the ultrasound. These become clearer as pregnancy progresses: around day 45, the spine and ribs are visible, and by day 50, organ differentiation (like the liver and stomach) can be observed .

Identifying Abnormalities

1. Stillbirths

A collapsed sac with irregular edges or no heartbeat after day 25 often indicates a stillborn fetus. Another red flag is the absence of blood flow signals, which appear as color flashes in advanced ultrasound modes. If multiple sacs show no movement or structural details, immediate action is needed to prevent resource waste .

2. Growth Delays

Compare the size of the fetus to the expected growth timeline. For example, a 30-day-old fetus should have a sac diameter of 2–3 cm. If the sac or fetal structure appears smaller than average for its gestational age, it may signal underdevelopment. Regular scans every two weeks help track progress and catch discrepancies early .

BXL-S101 Pig ultrasound machine

Best Practices for Accurate Imaging

1. Timing Matters

The ideal window for pregnancy confirmation is 22–30 days post-breeding. Scanning too early (before day 18) may miss small sacs, while late-stage scans (after day 45) face challenges like overlapping fetal positions .

2. Image Clarity Tips

（1）Clean the sow’s skin thoroughly to avoid interference from dirt or hair.

（2）Apply ultrasound gel generously to improve contact between the probe and skin.

（3）Adjust the device’s frequency and contrast settings based on the sow’s body condition .

3. Avoid Misdiagnosis

（1）Empty uterus vs. early pregnancy: A true gestational sac has defined edges, while an empty uterus shows irregular, faint shadows near the bladder .

（2）Cysts vs. healthy sacs: Ovarian cysts appear as thick-walled, multi-chambered dark areas, unlike the smooth, single-chambered gestational sacs .

Why Consistency is Key

Regular scans every 14–21 days allow farmers to monitor trends and spot issues before they escalate. For instance, a sow with consistently small sacs over multiple scans likely needs intervention. Portable B-mode ultrasound devices, like those from BXL, offer high-resolution imaging for on-farm use, making frequent checks practical .

By mastering these ultrasound features and scanning techniques, farmers can optimize litter outcomes and reduce costs linked to undetected fetal issues. Remember: clear images and consistent timing are your best tools for ensuring healthy pregnancies.

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