With rising costs of medical tests and the discomfort caused by some of the more invasive ones, the notion of testing yourself for a variety of conditions may never seem more appealing.
A quick search of the Web can turn up a number of tests for serious conditions such as HIV as well as curiosity questions, like determining a baby's sex.
With waits to get into a doctor's office at days or weeks and some patients concerned about wasting their physician's time, these home screening tests offer hope to patients wanting to determine the legitimacy of concerns about their symptoms.
But are they worth it?
"In general the medical profession should be a little cautious with these tests because of the rate of false negative and false positives and the seriousness of the condition," said Dr. Alan Peaceman, a professor of maternal-fetal medicine at the Feinberg School of Medicine at Northwestern University.
For potentially harmful conditions, Peaceman expressed concerns that patients would get a negative result on a home test and not seek treatment for a genuine problem.
On the other hand, he said, the tests may help patients avoid a trip to the doctor's office when it is unnecessary -- an idea that can be useful with a condition that is less serious and will not result in complications because of a prolonged wait.
"Ninety percent is probably a very reasonable number in terms of false positives, false negatives," said Peaceman.
Because some of these tests are not approved by the FDA, the accuracy of any one test is unclear. Some companies list the results on their Web site, but patients should consult with their doctor before using any test to screen their conditions.
And with almost any home test there will be accuracy problems, so the consequences of an incorrect result need to be considered.
"It's only as good as how accurate it is and it's probably not 100 percent," said Peaceman.
Many parents want to discover the sex of their unborn child, and while the sonogram that is typically part of prenatal care can give that information about halfway through the pregnancy, some would like to know sooner.
In recent years, a number of tests, such as the Baby Gender Mentor and the IntelliGender Gender Detection Test, have come to the market. The test makers note, however, that their tests are not 100 percent accurate. (IntelliGender claims an accuracy rate of 82 percent in the real world on its Web site, with more accurate results in lab tests.)
But attempts to determine a child's sex early in pregnancy have had problems in the past. As has been noted by test makers, multiple births or a "vanishing twin" can complicate results.
And, as Peaceman said, the test isn't done for medical reasons.
"It's hard to recognize that as truly a medical test because you're not trying to identify something that needs treatment," said Peaceman. "You cannot justify it on the basis of filling a medical need. On the other hand, patients are often very curious."
So, while parents may want to learn the sex of their baby as soon as they think they can, the $30 test, like a horoscope, is for entertainment purposes only at this point.
"Really it was designed to bridge that curiousty gap between the 10-week mark and the 20-week sonogram," said Rebecca Griffin, co-founder of IntelliGender. "Don't paint the nursery pink, don't paint it blue based on the medical results."
ABC News spoke with doctors and an advocate for a recent article about allergies who indicated that an at-home allergy test was not worth the cost, even if its $50 price tag was much lower than the skin test a doctor would administer.
For this test, a person would prick their finger and mail their blood sample to a lab, which would test it for 10 of the most common allergens.
"I don't think there is much value personally, because you're just doing tests without taking a history," said Dr. Anne Miranowski, an allergist with The Pediatric Lung Center in Fairfax, Va. "We determine what tests are necessary based on a person's history. We don't indiscriminately test before we see the patient."
Among the problems doctors cited with the test were the higher reliability of skin tests over blood tests, the fact that allergies might not be a person's problem in the first place and the fact that the 10 allergens tested for might not be relevant to people who live in certain parts of the country.
And as allergy advocate Gina Clowes noted, the risk of a false negative on a food allergen could lead someone to try a food they were allergic to, with potentially fatal results.
"Allergic symptoms can run the gamut from annoying to life threatening," she said. "If you're having serious symptoms, for me or my children, only a real M.D. would do when diagnosing or treating them."
Urinary Tract Infection
With a test that is FDA approved, an at-home test for a urinary tract infection might be worthwhile.
As Peaceman, the professor of maternal-fetal medicine at Feinberg, notes, urinary tract infections have symptoms that would alert a patient, but the disease rarely causes serious illness.
"That and testing for vaginal infections ... those are actually probably good ideas, because frequently a patient will call the doctor and say I have symptoms of a urinary tract infection," said Peaceman. He said the doctor can then either prescribe a possibly unnecessary antibiotic or have the patient come in, which may take some time, followed by a test where results will take another two days to come back.
Ever put a flashlight behind a live chicken egg in elementary school? Through the shell, children can see growing blood vessels, tissues and bones in the center.
Now some women are trying something similar with their breasts at home to see their own blood vessels and tissues among fatty tissue.
Marketed as a visual aid to help women see changes, or darks spots in the breast, at least one British company is selling this as a breast transillumination device called Breastlight as an at-home aid in monthly breast exams.
Dr. D. David Dershaw, the director of Breast Imaging at Memorial Sloan-Kettering Cancer Center in New York City, said he has seen breast transillumination before.
"It's been around for decades and does not detect curable cancers," Dershaw wrote in an e-mail to ABCNews.com. "This is probably used to help women determine if something they feel should be of concern."
While breast transillumination has been the area of several clinical trials for doctors' use, medical experts have been debating the idea of a self-breast exam whether or not it's aided by a light.
"It's really a challenge. The American Cancer Society [ACS] has agonized with recommendations about breast self-examination in the past," said Dr. Patricia Hillard, professor of obstetrics and gynecology at Stanford University School of Medicine.
Massive campaigns championed self-breast exam in the 1980s and '90s, but once doctors began to question the practice and researchers compared the number of cancers caught at home to the huge uptick in false positives, costly testing and women's anxiety over "too many nothings" increased, Hillard said.
In the end, Hillard said the ACS was moved by the many anecdotes of lives saved by the exam.
"Almost all of us have had patients who felt their own lumps, came in and it was worrisome to us [doctors], and it turned out that they had a cancer," said Hillard. "Breast self-exam is too valuable to disregard."
Given that debate, Hillard said there's just too little information to make a recommendation about the at-home breast transillumination.
"There just aren't data to conclude this is a good thing to do, and so therefore most don't recommend it," said Hillard. "Whether this too would lead to more testing and greater anxiety, we have no idea."
But representatives from Breastlight insist that their test is not meant to act as a diagnosis tool and that studies haven't shown a mad rush to doctors for more testing.
"We would never say that this is a replacement or better than mammography," said Kate Freeman, a spokeswoman for Breastlight. "This is just another measure to reassure women, really."
Freeman said in a user study of 1,200 women in the United Kingdom, only 1.3 percent of women found something that then motivated them to consult with their doctor.
As of now, Breastlight is available in Canada, and is in the approval process by the U.S Food and Drug Administration.
Home HIV Test
The mailed-in HIV test is at once one of the most popular and most contested at-home medical tests around.
Current popular models run for $60, and come with instructions to collect blood, a return envelope and then retrieve anonymous results through codes. Most models are FDA approved and claim 99 percent accuracy.
But many doctors feel ambivalent about the tests.
"Here's the deal: We should be HIV testing almost everybody -- the current recommendation for CDC is the vast majority of people should be offered HIV testing," said Dr. Elizabeth Steiner, of the Oregon Health and Sciences University in Portland.
"But some people don't get it because they think they're going to be grilled by the clinician about the behaviors and why they want the HIV testing," she said. "This has the potential to reduce that barrier."
Steiner insists most doctors do not ask questions about why a patient wants an HIV test, and while she hopes at-home HIV testing would inspire people to feel comfortable about the test and then come in to the doctor's office, she worries about those who test positive and stay at home.
According to Steiner, patients can miss essential information about HIV treatment and the six-month window of uncertainty after a possible exposure to HIV and possibility for a false negative.
"We know that people can be infected with HIV and not be antibody positive for up to six months," said Steiner.
"There's general screening and confirmatory screening that you're supposed to do if the test comes back positive," she said.
"So, I think they're a mixed blessing. I think at-home HIV tests have some real advantages," said Steiner. "But just as people have misconceptions about how we're going to interact with them when they come in for testing they may also have misconceptions about what the results mean."
Home Colorectal Disease Symptom Test
It's no wonder why some people would want to do their own at-home colorectal disease symptom test rather than giving a stool sample to a doctor. Home colorectal tests to detect blood in the stool are one of the Top 20 sellers on Amazon.com and can go for as little as $5.50.
Dr. Patricia Clancy, a family physician in Concord, N.H., said most of her patients wanting a colorectal test are trying to avoid the dreaded colonoscopy.
"If it's the same technology that we use when we test for blood in the stools, then I could see this as mildly helpful, only if the person then goes off to the doctor if it's positive," said Clancy. "The test is not as good as a colonoscopy, but some patients won't get them any way."
However, Dr. Steiner sees less use for the at-home tests.
"Blood in the stool can be an indication for colon cancer," said Steiner. "But you could have blood in the stool because you have colon cancer, because you have hemorrhoids; you could have it because you took aspirin, because you eat a lot of iron and because you ate red meat."
Without a doctor's knowledge of a host of other symptoms, warning signs and the meaning of your medical history, Steiner said she saw little point in doing this test at home.
"I will bet you dollars to donuts that those kits don't come with all that information," said Steiner.
Home Anemia Test
Anemia can have telltale signs of its own -- pale complexion, dizziness, fatigue -- and if a person can stomach pricking their own finger, then they can find out whether their anemic with much greater accuracy.
Mail order kits can run from $29.99 and up on Amazon.com and often are sold alongside iron supplements.
But primary care physicians say this test may not make sense for any patients.
"I'm a little puzzled as to why someone would have it. The reasons you could be anemic is a list as long as your arm," said Steiner. Someone may be anemic from a cancer, iron deficiency or leukemia, Steiner said.
In which case, the doctor would treat the underlying condition, not the symptom of anemia.
"If you already know that your anemic from your doctor, then the doctor doesn't want you to be at-home testing, they want you to be in their office," she said.
"The overall challenge is this: Interpreting the results of the test is as important as getting the test," she said.
That doesn't mean Steiner is against all at-home tests.
"Home blood pressure monitory makes a lot of sense, glucose monitoring makes sense," she said. "This doesn't make any sense at all you're not going to be checking it every day."
Test for pH Level
Much like a potential urinary tract infection, testing the pH of vaginal secretions may have some benefit.
"This one is based on a little bit of science," said Clancy, the family doctor in Concord, N.H. "Women think yeast is the only kind of infection that there is and there are many more."
Clancy and many women know that burning, itching, uncomfortable symptoms in the vaginal area could be a sign of infection -- either yeast or bacterial. While women can buy over-the-counter fungicides for yeast infections, only a doctor can prescribe antibiotics for a bacterial infection.
"For the woman who thinks she has a yeast infection and she has a high pH, she likely doesn't," said Hillard, the ob/gyn professor from Stanford.
"But the pH doesn't give an indication that it might be a [sexually transmitted infection], and that's a huge caveat," she said.
Overall, Hillard said she could see usefulness in pH testing and a test round of over-the-counter yeast infection medication. But if someone is at risk for an STI, she recommends heading into the doctor's office anyways.