WhatsApp is one of those apps which practically every doctor uses routinely in India. Most doctors use it for personal reasons , and many have also started utilising it to connect with their patients as well. Unfortunately, they do it in a disorganized and haphazard fashion, which means they are not making the best possible use of this very versatile platform !
Here's one way of making sure that WhatsApp can be used effectively to help improve medical care.
The doctor needs a dedicated mobile just for his clinic, which is used exclusively for this purpose , so he doesn't get troubled at all odd hours because of patients contacting him. The moment the patient contacts the clinic , the receptionist adds the patient's mobile as a new WhatsApp contact, and starts a conversation with that patient .  For example, this can be used to send a google map to the patient, so they can find the clinic easily !
When the patient comes for the first appointment, she adds a photo of the patient, as well as her demographic details as well . After the consultation, she ( or the doctor himself, or even the patient) can then take a picture of the consultation summary, as well as the prescription. Patients can continue adding the results of their lab reports and scans to this conversation, once they have done these, so the doctor can review them as needed. This way, he can interpret the results far more intelligently, because he has the clinical context he needs.
The beauty of WhatsApp is that all these documents are encrypted and secure, so you don't have to worry about confidentiality . You can thus create a  chain of conversations, which seamlessly provides a timeline of the patient's medical history, which both doctors and patients can refer to as needed. Because it's documented, there's no risk of miscommunication  ! Even better, patients don't need to keep on calling the clinic for every minor problem . The doctor can create lots of templates, which he can attach to the conversation as needed, to make sure the patient knows exactly what they need to do. If required, the doctor can even create WhatsApp groups of patients with similar problems ( for example, all patients with  diabetes). Not only can he educate them all at one time by sharing educational tips, they can also interact with each other, and thus help one another during their journey .
This is much better than a phone call, because the signal to noise ratio is far better . Doctors can now communicate with their patients in their own local language. Even if patients are illiterate, it's possible to leave messages for them using audio !
This will also empower patients. The WhatsApp trail will actually be far better than just the ordinary medical record, because it allows patients to provide their inputs and interpretation, rather than being only a medical document which doctors often refuse to share with patients ! Patients can also share their medical reports , and get a second opinion from another doctor anywhere in the world.
The beauty is that there is no incremental cost or friction for using WhatsApp for improving doctor-patient communication ! Doctors and patients use WhatsApp all the time, so there is no training needed - and it's free ! Patients are delighted , because this is not an additional communication channel they can use connecting with their doctor when they need to - no matter where in th world they are !   WhatsApp offers a direct and free backup of all communication including images and videos to the google drive, so you need not worry about what to do in case the phone crashes or goes dead (and they do).

While it's not great for an emergency, let's not forget that 90% of interaction with a doctor is for routine medical problems.  And the asynchronous nature of communication which WhatsApp allows means  that when the doctor is unable to pick up the phone, patients can use this channel to ask a query and/or send a photograph and get a response by a doctor when he gets free !
And if doctors want, they can always charge for these conversations, so that it's an additional source of revenue for them !

Also, once Whatsapp wants to start generating revenue, they will add lots of additional features which will help doctors to connect more effectively with their patients .  And there's no reason why they couldn't do this for other professionals as well - such as lawyers !