Final answer:
In the case of mastoiditis, a nurse would likely observe a perforation of the tympanic membrane due to the accumulation of pus in the middle ear, as seen in otoscopic examination.
Step-by-step explanation:
A nurse reviewing the record of a client with mastoiditis would expect to note characteristic findings on an otoscopic examination. According to the provided information, mastoiditis involves the formation and accumulation of pus in the middle ear, which can lead to the bulging of the tympanic membrane. With chronic inflammation in severe cases, this can result in a perforation of the tympanic membrane. Therefore, among the options provided, the one that aligns with the documented characteristics of mastoiditis seen through an otoscope would be Option 2: Perforation of the tympanic membrane.