What is a key characteristic of uterine contractions as monitored by external methods compared to IUPC?

The key characteristic of uterine contractions as monitored by external methods, compared to intrauterine pressure catheter (IUPC), is that external monitoring tends to provide less information on resting tone.

External methods detect contractions by measuring changes in abdominal pressure via a tocotransducer placed on the maternal abdomen. While this method is useful for assessing the frequency and duration of contractions, it lacks the ability to provide quantitative data about the intensity of those contractions or the resting tone of the uterus. In contrast, IUPC offers a direct measurement of intrauterine pressure, allowing for a more detailed assessment of both contraction intensity and resting tone.

Therefore, the limitation of external monitoring in terms of providing comprehensive data about resting tone is a significant characteristic that distinguishes it from IUPC methods. This difference is essential in clinical practice, as understanding resting tone can inform providers about uterine well-being and possible complications during labor.