At the time of blood collection, the blood group of the donor and the recipient is checked and cross-matched. If not, the dangers that are likely to occur are:
- Blood cells will clump together and disintegrate.
- Hemoglobin will be excreted with urine.
- Accumulation of hemoglobin in kidney will cause uremia and kidney function will be disturbed.
- There will be outbreaks of jaundice.
- A patient may die after a variety of procedures.