Here is some essential vocabulary for medicine-related situations

Medical English (illnesses, symptoms, procedures, etc.)

to be in pain or distress;

I've got a dull ache in my stomach.

analysis of urine;

I need to take a blood test and urinalysis.

special sound waves used in such processes as examining organs inside the body;

They'll use ultrasound to monitor the baby.

an examination of a part of the body by taking and studying an X-ray photograph;

She had an X-ray to see if any of her ribs were broken.

a system for producing electronic pictures of the organs inside a person's body, using radio waves and a strong magnetic field:

He needs to get an MRI after this horrible car accident.

a medical test that involves using X-rays to create a three-dimensional image of the inside of the body; 

The doctor arranged for me to have a CAT scan.

a medical examination of the colon (= the lower part of the tube that takes solid waste out of your body) using a flexible colonoscope:

The doctor send me the appointment to do a colonoscopy.

the removal of living tissue from the body for diagnostic examination:

When my father has his follow-up with his doctor, he'll learn the results of the biopsy and discover whether or not he has a serious disease.

mild, not cancerous:

When the doctor said my tumor was benign, I was so happy.

cancerous;

The pathologist's report said the tumor was malignant.

an anti-inflammatory drug is one that is used to reduce pain and swelling;

They would've just given him a nonsteroidal anti-inflammatory unless he was allergic to aspirin.

a measure of body weight relative to height;

Adults who have a BMI of 30 or higher are defined as obese.

low blood pressure;

He has a low-grade fever, slight cough postural hypotension, and he's dehydrated.

high blood pressure:

He's being treated for hypertension.

seen and sent home the same day:

My doctor scheduled outpatient surgery right away.

person who enters a health care setting for a stay ranging from 24 hours to many years:

She'd been an inpatient on one of the Medical wards for a week now; I understood the prognosis wasn't good.

the temporary, partial, or complete disappearance of the symptoms of a disease without having achieved a cure:

My dad's cancer went into remission when the oncologist said that his large tumor had almost disappeared.

a condition marked by severe pain in the chest, often also spreading to the shoulders, arms, and neck, caused by an inadequate blood supply to the heart:

He has recently been diagnosed with angina.

a thick yellowish or greenish opaque liquid produced in infected tissue, consisting of dead white blood cells and bacteria with tissue debris and serum:

Pus oozed from the cat's injured ear.

a red, painful, and often swollen area in or on a part of your body:

Aspirin reduces pain and inflammation.