What should the nurse instruct a client prior to measuring their fundal height at 16 weeks of gestation?

Before measuring fundal height at 16 weeks of gestation, it is essential for the client to empty their bladder. A full bladder can interfere with accurate measurement, as it can displace the uterine position and lead to inconsistent results. By ensuring the bladder is empty, the nurse can obtain a more precise fundal height measurement, which is important for assessing the growth and development of the fetus.

The other options do not relate directly to the need for accurate fundal height measurement. Laying in a side-lying position may be comfortable, but it is not necessary for the procedure itself, and it can actually hinder the measurement process. Preparing for an intravenous catheter is unrelated to the measuring of fundal height and is not a standard procedure for this process. Advising the client not to eat or drink two hours after measuring has no relevance to the fundal height measurement and does not impact its accuracy. Therefore, instructing the client to empty their bladder is the most appropriate action prior to measuring fundal height.