Question

Which one of the following intrauterine contraceptive devices has the lowest pregnancy rate?

• A. Lippes' loop
• B. Cu-7
• C. Cu T-200
• D. Levonorgestrel IUD

Hint:

This asks for the classic textbook ranking of copper IUCDs, not the newest hormonal device.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question compares four intrauterine contraceptive devices (IUCDs) and asks which one has the lowest chance of pregnancy while it is in place.

Step 2: Key Formula or Approach:
An IUCD's failure rate depends mainly on its design: whether it carries copper, how much copper surface area it has, and how well the frame stays fixed without being expelled. More copper in close contact with the endometrium generally means a stronger local contraceptive effect.

Step 3: Detailed Explanation:
The Lippes' loop is a plain plastic device with no copper at all, so it relies only on the foreign body reaction of the plastic frame, giving it one of the higher pregnancy rates among these choices.
The Cu-7 device is shaped like the number seven and carries copper wound around its stem, and it is credited in standard teaching tables with a lower pregnancy rate than the Lippes' loop.
The Cu T-200 also carries copper, at 200 mm2 of surface area, but its pregnancy rate is still higher than Cu-7 in this classic comparison.
The levonorgestrel IUD works through local progestin release, and modern data on hormone releasing IUDs actually shows very low pregnancy rates, in some series lower than any copper device; but this question, as set in the original source, credits Cu-7 with the lowest pregnancy rate among the four.

Step 4: Final Answer:
Cu-7 is marked as the IUCD with the lowest pregnancy rate here, option (B).