Placenta Previa Distance from Internal Os Classification

Classify placenta previa by placental edge distance from the internal cervical os on transvaginal ultrasound. Distance <20 mm with posterior low-lying placenta or complete previa requires cesarean. Guides delivery planning.

Weight
Height
Clinical Guidance

BMI is a screening measure of body size, not a direct measure of body fat. The standard WHO categories are underweight (<18.5), normal (18.5–24.9), overweight (25–29.9), and obese (≥30).

BMI can overestimate body fat in athletes with high muscle mass and underestimate it in older adults with low muscle mass. Interpret it alongside waist circumference and clinical context rather than as a standalone diagnosis.

⚕ Clinical Disclaimer: These calculators are for educational and reference purposes only. Always verify results with qualified clinical judgment and current clinical guidelines. Do not use as a sole basis for medical decisions.
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How It Works

Classify placenta previa by placental edge distance from the internal cervical os on transvaginal ultrasound. Distance <20 mm with posterior low-lying placenta or complete previa requires cesarean. Guides delivery planning

Each component has a specific meaning:

  • Internal cervical os on transvaginal ultrasound — The internal cervical os on transvaginal ultrasound recorded for the scenario being assessed.

Note: Interpret the placenta previa distance result against the thresholds and context described above.

How to Use

Enter the internal cervical os on transvaginal ultrasound for the scenario you are assessing. Classify placenta previa by placental edge distance from the internal cervical os on transvaginal ultrasound. Distance <20 mm with posterior low-lying placenta or complete previa requires cesarean. Guides delivery planning. Use the placenta previa distance result to inform your calculation.

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Frequently Asked Questions