International clinics in Hanoi offer the highest quality care but also cost more. Local hospitals are not quite up to the standards of Thailand, Hong Kong, or Singapore, but they are decent and often employ doctors who have been trained overseas, typically in France.
Temperatures in Hanoi can get extremely hot, with average daytime temperatures in late spring and summer exceeding 100 degrees—drink plenty of water and use common sense to avoid dehydration and heat stroke. Sunscreen is also highly recommended. Dengue fever and malaria are real risks in Vietnam; if not taking a prophylaxis, make sure to use mosquito repellent.