Blood Type / Blood Group Regex for Python

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching blood type / blood group, ported and verified for Python. Identity and credential patterns need both correctness and safety, since they're frequent targets for adversarial input. The snippet below is ready to drop into your Python project — whether you're validating in a Django view, a FastAPI endpoint, or a standalone data processing script.

Python Implementation

# Blood Type / Blood Group
# ReDoS-safe | RegexVault — Identity & PII > Biometric & Physical

import re

blood_type_blood_group_pattern = re.compile(r'^(A|B|AB|O)[+-]$')

def validate_blood_type_blood_group(value: str) -> bool:
    return bool(blood_type_blood_group_pattern.fullmatch(value))

# Example
print(validate_blood_type_blood_group("A+"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Identity & PII > Biometric & Physical category and carries a ReDoS-safe certification. That matters for Python developers because particularly important in Python web servers where CPU-bound regex operations can stall concurrent request handling. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

ABO blood groups: A, B, AB, O. Rh factor: + (positive) or - (negative). O- (O negative) is the universal donor for red blood cells. AB+ is the universal recipient. Blood type is health data classified as sensitive under GDPR Article 9.