From the Guidelines
The implantation hemorrhage seen on ultrasound in the left anterolateral position measuring 1.3 x 2.7 x 3.0 cm, which has grown from a previous measurement of 0.6 x 0.7 x 0.9 cm at 9 weeks, represents a subchorionic hematoma that should be monitored but is not necessarily cause for immediate concern. These hematomas occur when blood collects between the chorion (outer fetal membrane) and the uterine wall, and are relatively common in early pregnancy 1. The increasing size between 9 and 12 weeks warrants follow-up ultrasound monitoring, typically in 2-4 weeks, to ensure it resolves or doesn't continue growing significantly.
Key Considerations
- The growing size suggests active bleeding occurred between the two ultrasounds, but now that you're entering the second trimester, the risk of complications typically decreases as the placenta becomes more firmly established 1.
- The anterolateral position is generally less concerning than if it were located near the cervix.
- Patients should report any heavy bleeding, severe cramping, or other concerning symptoms immediately.
- Most subchorionic hematomas resolve spontaneously without intervention, particularly as pregnancy progresses beyond the first trimester.
Monitoring and Follow-up
- Follow-up ultrasound monitoring is recommended in 2-4 weeks to ensure the hematoma resolves or doesn't continue growing significantly.
- No specific medication is typically prescribed for subchorionic hematomas.
- The primary focus is on monitoring the size and position of the hematoma, as well as the overall health and well-being of the patient.
From the Research
Implantation Haemorrhage Significance
- Implantation haemorrhage seen on ultrasound can be a significant finding, especially in the context of early pregnancy complications 2.
- The presence of haemorrhage in the left antero lateral position measuring 1.3 x 2.7 x 3.0 cm, slightly larger than previous measurements, may indicate an abnormal implantation process 2.
- Abnormal implantation and placentation can lead to pregnancy-related complications, such as pre-eclampsia, preterm labour, and intrauterine growth restriction 2.
Ultrasound Findings and Management
- Ultrasound findings, including cervical length, distance between the internal cervical os and placenta, and placental edge thickness, can help individualize management of placental implantation abnormalities 3.
- In cases of first trimester bleeding, ultrasound can help distinguish between normal and abnormal early pregnancy, and guide management decisions 4.
- The presence of haemorrhage on ultrasound may require closer monitoring and potentially more aggressive management to prevent adverse pregnancy outcomes 3, 4.
Haemostatic System Changes in Pregnancy
- Pregnancy is associated with unique and profound changes in the hemostatic system, including an increased risk of bleeding during implantation and endovascular trophoblast invasion of the maternal spiral arteries 5.
- These changes can lead to an increased risk of venous thromboembolism and other haemostatic complications, highlighting the need for careful management and monitoring 5, 6.
- The diagnosis and management of haemostatic disorders, such as disseminated intravascular coagulation (DIC), require vigilance and knowledge of the physiologic changes during pregnancy 6.