Blood group of donor and recipient is well checked during blood collection. If not, the dangers that are likely to occur are:
(i) Blood cells will coagulate and disintegrate.
(ii) Hemoglobin will be excreted in urine.
(iii) Accumulation of hemoglobin in kidney will cause uremia and disturbance of kidney function.
(iv)) Hepatitis-B and Hepatitis-C causes outbreaks of blood jaundice.
(v) Blood of intoxicated and AIDS patient causes AIDS disease.
(vi) Patient may have problems like asthma and allergies.
(vii) Patient may have iron overload.
(viii) The patient may die.