There are certain medical treatments that most of us would, at face value, consider ridiculous.

Screening women for prostate cancer, for example, would not make sense. Nor would an appendicitis screening for someone who has already had their appendix removed. There's exactly a zero percent chance than an appendix-less individual could develop an appendix-specific disease.

These types of treatments, to prevent diseases that could never occur, sound like the medicine doctors would always avoid. New data from the Centers for Disease Control, however, suggests it happens thousands of times each year.

The majority of women who have had complete hysterectomies had a pap smear within the past three years, the federal agency found. In the sample of 24,443 post-hysterectomy women over 30, 58.7 percent (or 13,481 women) had undergone the cervical cancer screening.

To review some basic biology: A complete hysterectomy involves the removal of the uterus and the cervix. A pap smear screens for cancer of...the cervix. As obstetrician David Chelmow tells Reuters, perhaps pointing out the obvious, "It's tough to get cervical cancer without a cervix."

To this end, three major professional organizations - the United States Preventive Services Task Force, the American Congress of Obstetricians and Gynecologists, and American Cancer Society - all recommend against cervical cancer screenings for posthysterectomy women over 30.

"The net benefits of screening some women, particularly women who have undergone hysterectomy...might be outweighed by the net harm (e.g., false-positive tests leading to needless patient anxiety and invasive procedures)," CDC analysts write. 

Yet the screenings still continue, for the majority of posthysterectomy women.

As to why doctors perform a procedure that offers no value - one that professional organizations recommend against - some say it has to do with the practice being entrenched. The cervical cancer death rate dropped by 70 percent between 1955 and 1992 as early detection and screening became more prevalent. Doctors have become accustomed to the the screening and old habits die hard.

There is, however, some evidence of change. The CDC data does show decline in pap smears among this population over the past decade from 73.3 percent in 2002 to 58.3 percent in 2010. 

Still, the agency isn't exactly celebrating the drop.

"Despite consistent guidelines by three national organizations recommending against routine screening for cervical cancer posthysterectomy," they note, "The proportion of women aged <30 years who have had a hysterectomy and recently have been screened declined only 15 percentage points."