When Jesus was pierced, why did blood and water come out of His side?John 19:31-34 offers this unique account that occurred at the end of Jesus' crucifixion: "Since it was the day of Preparation, and so that the bodies would not remain on the cross on the Sabbath (for that Sabbath was a high day), the Jews asked Pilate that their legs might be broken and that they might be taken away. So the soldiers came and broke the legs of the first, and of the other who had been crucified with him. But when they came to Jesus and saw that he was already dead, they did not break his legs. But one of the soldiers pierced his side with a spear, and at once there came out blood and water." Why did blood and water come out of Jesus' side?
Crucifixion typically resulted in death through one of two ways. The first way was hypovolemic shock. The prolonged rapid heartbeat resulting from hypovolemic shock can cause fluid to gather in the area around the heart. This is called pericardial effusion.
The second way death often occurred during crucifixion was due to asphyxiation. This simply means the person is unable to breathe in enough oxygen to survive. Crucifixion victims typically had to pull their weight up with their hands or wrists that were nailed to the crossbeam along with pushing up with the feet or ankles that had another nail through them. Over time, the ability to push up to breathe would end and oxygen flow would be restricted. This asphyxiation can also result in the buildup of fluid around the heart.
In either case, the account of John is quite accurate. The Roman executioners saw that the other two crucifixion victims were still alive and broke their legs so they would no longer be able to push themselves up to breathe, resulting in death within minutes. In the case of Jesus, they saw He had become unconscious and likely was already dead. To confirm, a spear was shoved into His side, likely under His ribs, that ruptured the pericardial sack, resulting in a flow of both blood and water.
While this manner of death was a brutal end for Jesus, there was also prophetic significance to this event. John states in John 19:36-37, "For these things took place that the Scripture might be fulfilled: 'Not one of his bones will be broken.' And again another Scripture says, 'They will look on him whom they have pierced.'" The first reference is likely to Exodus 12:46. The second reference is from Zechariah 12:10. Both were written hundreds of years before this event.
In summary, there were both practical and prophetic reasons for the blood and water that flowed from the side of Jesus at His crucifixion. The pierced side confirmed His human death while also fulfilling the messianic prophecies mentioned by John.
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