The nurse is calculating the estimated date of confinement (EDC) using Nagele’s rule for a client whose last menstrual period started on February 13th. Which date is most accurate?
A.
November 20
B.
November 27
C.
November 21
D.
November 14
The Correct Answer and Explanation is:
To calculate the Estimated Date of Confinement (EDC) using Nagele’s rule, you need to start from the client’s first day of their last menstrual period (LMP) and add 280 days, or 40 weeks, which is the typical duration of a pregnancy. Nagele’s rule is a standard method used to estimate the due date and is based on the assumption that the cycle length is 28 days with ovulation occurring approximately 14 days before the next period.
Here’s how you apply Nagele’s rule step-by-step:
- Identify the Start Date of the Last Menstrual Period (LMP): For this client, the LMP is February 13th.
- Add One Year to the Year of the LMP: This changes the year from 2024 to 2025.
- Subtract Three Months from the Month of the LMP: From February, subtracting three months brings you to November.
- Add Seven Days to the Day of the LMP: Adding seven days to February 13th results in February 20th. Since you are working with the new year and month (2025 and November), this gives you November 20th.
So, putting it all together:
- Starting date: February 13th
- Adding 280 days (or 40 weeks) lands on November 20th of the following year.
Therefore, the most accurate date for the Estimated Date of Confinement (EDC) is November 20.
Answer: A. November 20
Explanation:
Nagele’s rule is a widely used method for calculating the due date, assuming a standard 28-day cycle. By adding 280 days to the first day of the last menstrual period (LMP), you estimate the expected date of delivery. The calculations are straightforward but can be affected by variations in cycle length or ovulation timing. This method provides a general estimate and should be adjusted if the patient has irregular cycles or other factors that might affect the timing of ovulation.