Final answer:
The nurse would suspect that the client has an incisional nick in the bladder.
Step-by-step explanation:
The nurse would suspect that the client has an incisional nick in the bladder as the cause of the bloody urine in the indwelling catheter collection bag. In a client with an abruptio placenta who has had an emergency cesarean birth, the bladder may be inadvertently nicked during the surgical procedure. This can result in blood entering the bladder and subsequently appearing in the urine drainage bag connected to the indwelling catheter.