Dr. Nesochi comments on a painful medical procedure on Men’s Health.

It’s time to face your fears…

Pain is subjective—there’s no question about it.

But certain medical procedures have a reputation for being extra-unpleasant.

Still, each one could help pinpoint a tough diagnosis, improve your health, or possibly save your life.

Invasive surgeries and grisly injuries aside, here are 6 infamously uncomfortable medical procedures and why it’s worth facing your fears.

1) Arterial Blood Gas

You’re probably accustomed to the quick pinch of getting blood drawn from a vein, but an arterial blood gas—which taps the artery in your wrist to measures the blood’s acidity and oxygen levels—is about as uncomfortable as it sounds.

“Obtaining an ABG sample can be extremely painful for some patients…much more painful than a routine blood draw,” says Dr. Nesochi Okeke-Igbokwe, M.D., an internist at NYU’s Langone Medical Center.

However, it may be the best test to help your doctor diagnose conditions like kidney failure, heart failure, or lung disease.

2) Colonoscopy

Colonoscopies are performed to screen for colon cancer or identify the cause of gastrointestinal issues like pain, bleeding, or persistent constipation or diarrhea.

Most patients need pain meds and/or a mild sedative to deal with the wholly unpleasant exam, during which a camera-equipped scope is inserted through your rectum and threaded to your colon.

Many patients say the most painful part is actually the prep, when you chug a colon-clearing laxative with explosive results.

But don’t skip the exam—according to the National Cancer Institute, regular colonoscopies can reduce your risk of dying from colorectal cancers by up to 70 percent.

3) Root Canal

The pain from an abscessed tooth can be brutal, but patients may tough it out longer than necessary because they’re terrified of the treatment.

But a root canal is actually pretty simple. An endodontist removes the infected pulp of the tooth, then cleans and seals the area.

And while it’s not terribly enjoyable, it’s an effective way to stop the infection, save the tooth, and end your misery.

4) Bone Marrow Exam

If you get abnormal results from a blood test, your doctor may want to check your marrow (the spongy tissue in your bones) for blood disorders or certain types of cancer.

There are two common ways to do it: An aspiration, which samples the fluid in your bone marrow, and a biopsy, which samples the tissue.

Unfortunately, both involve a long, hollow needle being inserted into your hipbone.

Your doctor will likely use a local anesthetic, but patients may still experience sharp pain.

Fortunately, anyone who’s thinking about a bone marrow donor can usually opt for a more comfortable route.

While traditional marrow donation requires a process that’s similar to aspiration or biopsy, nowadays around 70 percent of donors can give peripheral blood stem cells instead (which isn’t much different from donating blood).

5) Vasectomy

You’re probably wincing just thinking about this procedure, which kicks off with a local anesthetic being injected into the scrotum.

Once the area is numb, the doctor makes a small puncture or incision, snips the tube that transfers sperm to the penis, and ties the loose ends.

Luckily, this procedure has gotten easier in recent years.

“Doing a vasectomy using the no-scalpel technique, which is virtually painless, helps alleviate a lot of this anxiety and discomfort,” says Philip Werthman, M.D., urologist and director of the Center for Male Reproductive Medicine and Vasectomy Reversal in Los Angeles.

6) Spinal Tap

This test—formally known as a lumbar puncture—is a nightmare for needle-phobic patients.

While the patient curls up in a fetal position to stretch the spine, a thin needle isinserted between two vertebrae to withdraw cerebrospinal fluid from the spinal canal.

By evaluating the fluid, doctors can check for serious infections and certain types of cancer cells.

The good news: A local anesthetic can numb the area, and for many patients, that initial sting is the worst part.

Learn more at Men’s Health