I was planned for an emergency cesarean,so they gave me iv (drips) and an injection in my hand ,and i decided to pray isha before the doctor could begin the operation.so while making wudhu i didnt wet a portion of my hand where they have stuck the needle for iv and on the spot where they injected.is my wudhu and salah valid or should i repeat my salah when i become pure ?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

The Wudhoo’ is not valid  by default if any of the body parts of Wudhoo’ are left unwashed. The evidence for this is that the Prophet, sallallaahu ‘alayhi wa sallam, saw a man praying with a spot the size of a Dirham (coin) on his foot which the water did not reach, so the Prophet, sallallaahu ‘alayhi wa sallam, ordered him to repeat the Wudhoo’ and the prayer. [Abu Dawood - Al-Albaani graded it Saheeh (sound)]

However, since you were unable to wash part of your hand, then there is a difference of opinion among the jurists regarding someone who is able to wash some but not all of the body parts of Wudhoo’. The Shaafi‘i and Hanbali Schools are of the view that such a person must wash whatever is possible and then perform Tayammum for what he could not wash. On Islamweb, we consider this view to be the strongest one.

Based on that, if you did not perform Tayammum for the body parts you were not able to wash, then your Wudhoo’ was not valid and you must repeat the prayer. Ibn Qudaamah said: “A wounded and an ailing person, if he can wash part of their body but not another part, then he is obliged to wash what he is able and then perform Tayammum for the remaining parts (i.e. which they could not wash). This is the view of ash-Shaafi‘i, but Abu Haneefah and Maalik said: If most of his body is sound, he should wash it, and he does not have to perform Tayammum, and if he is injured in most of his body, then he should perform Tayammum and he does not have to wash.” [End of quote]

Allaah Knows best.