双顶径（Biparietal Diameter，简称BPD）是胎儿头部两侧顶骨之间的更大横向距离，作为产前超声检查的关键指标之一，主要用于评估胎儿生长发育状况、估算孕周及监测头盆对称性，其测量值随孕周增加而增长，正常范围因妊娠阶段而异，异常值可能提示胎儿发育迟缓、畸形或妊娠风险（如巨大儿），临床中常联合头围、股骨长等参数综合判断胎儿健康，尤其在孕中期（20周左右）对预产期校准和发育筛查具有重要意义，BPD的标准化测量需严格遵循超声切面规范，确保数据的准确性。
The biparietal diameter (BPD), often abbreviated in medical reports, is a critical measurement in prenatal ultrasound examinations. As one of the primary indicators of fetal growth, BPD helps healthcare providers assess the baby's development, estimate gestational age, and identify potential abnormalities.
What Is Biparietal Diameter (BPD)?
BPD refers to the distance between the two parietal bones of the fetal skull, measured during an ultrasound. This metric, typically recorded in millimeters, is most commonly used between weeks 12 and 28 of pregnancy. Alongside other measurements like head circumference (HC) and femur length (FL), BPD provides valuable insights into fetal health.
Why Is BPD Important?
- Gestational Age Estimation – BPD is highly correlated with fetal age, especially in the second trimester. Accurate dating helps monitor growth milestones and plan delivery.
- Growth Monitoring – Deviations from expected BPD values may indicate intrauterine growth restriction (IUGR) or macrosomia (excessive fetal size).
- Detection of Abnormalities – Abnormal BPD measurements can signal conditions like hydrocephalus (excess fluid in the brain) or microcephaly (underdeveloped skull).
Factors Affecting BPD Measurements
- Fetal Position – Optimal measurement requires a transverse view of the fetal head.
- Genetic Variations – Some ethnic groups may have naturally ***aller or larger head sizes.
- Pathological Conditions – Skull malformations or chromosomal disorders can alter BPD.
BPD in Clinical Practice
Doctors compare BPD with standardized growth charts to ensure the fetus is developing appropriately. If discrepancies arise, further tests (e.g., amniocentesis or Doppler ultrasound) may be recommended.
Conclusion
Biparietal diameter (BPD) remains a cornerstone of prenatal care, offering a non-invasive way to track fetal well-being. While it is just one component of a comprehensive ultrasound, its role in detecting potential complications makes it indispensable in modern obstetrics.
For expectant parents, understanding BPD can demystify ultrasound reports and provide reassurance about their baby’s progress. Always consult a healthcare provider for personalized interpretations of fetal measurements.
Note: BPD should not be confused with "biparietal diameter" in other medical contexts, such as bipolar disorder (also abbreviated BPD).
