Cervical Cytology Screening
The American College of Obstetricians and Gynecologists released its revised guidelines concerning cervical cytology screening (Pap test) in December 2009. These reflect the balance between providing enough screening to reduce cervical cancer and avoiding unnecessary costs of overtesting and of treatment due to false-positive results. The guidelines are based on the best available information about human papillomavirus (HPV), cervical dysplasia, and cervical cancer in women of varying age groups.
HPV is a common, sexually transmitted organism that can cause abnormal cervical cell growth. In most women, the immune system overcomes the virus within one to two years, and cervical abnormalities that can lead to cancer do not develop. Dysplasia is most likely in women whose systems cannot vanquish the infection. Some strains of HPV are more virulent than others and have a higher risk of producing cancer.
According to the new guidelines, cervical screening is to begin at age 21 and be performed every two years for women aged 21 through 29. The guidelines do not advise screening in younger women even if they are sexually active because cervical cancer is rare in women aged 15 to19: less than two cases per 1 million. Even though cervical cancer is rare in this age group, dysplasia is not; but it usually clears on its own. The guidelines caution against unnecessary removal of the lesions in young women because excision for dysplasia appears to increase premature births. For women aged 30 or more, the guidelines recommend screening every three years if their last three tests have been negative for intraepithelial lesions and malignancies.
Any woman who has been treated for CIN2, CIN3, or cervical cancer should be screened annually for at least 20 years after treatment, as recurrent disease is possible. Yearly screening is also recommended for women who had a hysterectomy, with or without cervical removal, if they do not have a history of three consecutive negative screens. Dysplasia and/or cancer can arise at the vaginal cuff years after treatment in these high-risk women. Women with suppressed immune function (e.g., transplant recipients or women with HIV) and those who were exposed to diethylstilbestrol (DES) in utero also have a higher risk of developing cervical cancer. The guidelines recommend yearly screening for them as well.
"Postmenopausal women with multiple prior consecutive negative cervical cytology test results are at low risk for cervical cancer," according to the guidelines. Cervical cancer develops slowly and is unlikely to occur in low-risk women as they age. False-positive results, however, occur more frequently in this age group because of mucosal atrophy (dryness) in the cervical tissue. Upon reaching age 65 to 70, women do not need to be screened if they have a ten-year history of negative test results and are at low risk for cervical cancer.
Cervical screening is not 100% accurate. Errors in sampling, interpretation of the sample, and follow-up by practitioner can leave cervical cancer undetected. Nevertheless, the ACOG bulletin asserts that "secondary prevention, through a screening regimen of cervical cytology with or without concomitant HPV DNA testing remains the best approach to protecting women from cervical cancer." Testing has led to a significant decrease in cervical cancer among US women, dropping from 14.8 per 100,000 women in 1975 to 6.5 cases of cervical cancer per 100,000 in 2006.
Contrary to all the hoopla, the HPV vaccine will not have an effect on cervical cancer incidence for another 15 to 20 years – if ever. Even if the vaccine were 100% effective against HPV types 16 and 18, it does not address other virulent HPV strains that account for about 30% of all cases of cervical cancer. In addition, the vaccine is not as effective in women who have already been exposed to HPV types 16 and 18. Ninety percent of all HPV infections resolve without treatment within two years. Of the remaining 10%, half will produce cervical cancer. Less than half of the women who develop cancer will die from the disease, according to American Cancer Society estimates. The benefit/risk of universal vaccination is clouded by the vaccines' adverse effects. As of October 2009, the Vaccine Adverse Event Reporting System (VAERS) had received 15,037 reports of adverse reactions, including the development of Guillian-Barré syndrome, lupus, seizures, paralysis, blood clots, brain inflammation, and deaths, according to journalist Susan Brinkmann.
American College of Obstetricians and Gynecologists. ACOG Practice Bulletin: cervical cytology screening. Obstet Gynecol. December 2009;114(6):1409–1417.
Brinkmann S. Gardasil researcher drops a bombshell. The Bulletin. October 25, 2009. Available at: http://thebulletin.us/articles/2009/10/25/top_stories/doc4ac4b76d07e16766677720.txt. Accessed November 19, 2009.
Chronic Pelvic Pain and Osteopathic Treatment
Chronic pelvic pain (CPP) arises from multiple physical, functional, and psychological factors that are often hard to identify. Most women never receive a definitive diagnosis and are treated symptomatically with pain medication. While conventional medicine searches primarily for physical causes, Bettina Herbert, MD, lead physician at the Jefferson-Myrna Brind Center for Integrative Medicine's pain program (Philadelphia), encourages practitioners to consider functional and emotional factors as well. Herbert wrote a chapter on CPP for the new reference book Integrative Women's Health, edited by Victoria Maizes, MD, and Tieraona Low Dog, MD. Alternative Therapies in Health and Medicine published the chapter in its January/February 2010 issue.
Herbert has found osteopathic manipulative therapy very helpful for some women with CPP. She encourages practitioners to look for signs of abnormal tissue texture (such as muscle tension); asymmetry (e.g., one shoulder higher than the other); restricted motion; or tenderness in the muscle, fascia, ligaments, or tendons. Even seemingly unrelated somatic dysfunctions can produce chronic pelvic pain over time.
In her chapter, Herbert presents three cases. In the first, a 38-year-old woman developed severe dysmenorrhea, for the first time in her life. Lab results and imaging studies showed no abnormalities. A detailed patient history provided Herbert with a possible cause: a sprained ankle that had occurred 18 months earlier – ten months before dysmenorrhea arose. The traumatic force that produced the sprain was conducted up the femur to the pelvic floor muscles, pelvis, fascia, and circulatory and neural structures in the area's connective tissue and organs. Without correction, the trauma caused malalignment, eventually producing dysfunction and pelvic pain. After receiving six weeks of manipulative and viscerofascial treatments to realign the pelvic bowl and sacrum (three treatments per week), the woman no longer had dysmenorrhea.
In the second case, a woman developed mild low back pain during the 32nd week of pregnancy. At six months after delivery, she had severe back and pelvic pain as well as stress incontinence. Misalignment due to pregnancy is not uncommon. "In this case, nonphysiologic alignment affected the symphysis pubis – and therefore the pelvic bowl – was well as suspensory structures of the bladder," Herbert explains. Again, osteopathic manipulative treatment, along with a short course of acupuncture, corrected both the pain and stress incontinence.
The third case involving a 52-year-old woman is more complicated. This woman had been in two serious car accidents and had broken several vertebrae in the previous 30 years, resulting in severe back and right-leg pain. CT findings and somatic guarding of her pelvis indicated pelvic pain as well, but it took months of weekly treatment before she admitted to a pain "‘shooting from the right hip across to my left.'" With the woman's consent and after consultation with her psychologist, monthly somatoemotional release sessions (a body-centered therapy for uncovering and resolving trauma stored in the body) were added to her treatment. As her trust in her practitioners and in the process grew over months of treatment, the woman was gradually able to work though the severe emotional, sexual, and physical abuse that she had experienced as child, and made significant lifestyle changes. Her pain declined, reflected in pain medication changes. Instead of Kadian (morphine) 1800 mg/day and Valium 10 mg, three times daily, she controlled her ulcerative colitis and pain with herbs and 28 mg/day of buprenorphine (a semisynthetic opiate).
In treating chronic pelvic pain, Herbert encourages working with a multidisciplinary team that includes a mental health specialist. Posttraumatic stress disorder and abuse are common contributors to chronic pain. In addition to body-centered therapies, she has found mind-body therapies and nutritional changes helpful. Food intolerances and/or pro-inflammatory foods can contribute to pelvic pain. Most importantly, Herbert urges practitioners to deal with the patient's expectations, since it can take weeks or months before noticeable improvement occurs: "Patient education about time frames and recognizing incremental change can reduce frustration and increase self-observation skills."
Herbert B. Chronic Pelvic Pain. Alternative Therapies. Jan/Feb 2010;16(1):28–32.
Questions about Depo/Provera
Medroxyprogesterone acetate (MPA), a synthetic progestin, decreases vascular endothelium function in premenopausal women, according to an April 2008 study from the University of Oregon. MPA is used in Depo/Provera, an injectable, long-lasting contraceptive, and in Provera, a drug used to treat abnormal uterine bleeding, induce menstrual cycles, and relieve menopause symptoms. The synthetic progestin's effect on premenopausal women has not been fully investigated. This short-term study is among the first to show that MPA affects the cardiovascular system negatively in this age group.
The study involved 14 women, aged 19 to 27, who were clear of health conditions that could affect results. Four of the women acted as controls. The other ten were given a gonadotropin-releasing hormone antagonist (GnRHa) for 10 days to suppress their innate estrogens and progesterone. On the fourth day of this treatment, the women were given 0.1 mg of estradiol. Three days later, 5 mg of MPA was added to the protocol. The researchers assessed changes in lipids, homocysteine, high-sensitivity C-reactive protein, endothelin-1, and endothelium-dependent vasodilation and endothelium-independent vasodilation of the brachial artery. This artery provides an accurate representation of the coronary arteries in general and is considered "a good predictor" of cardiovascular disease.
The Oregon researchers found that estradiol produced the beneficial effects of lowering endothelin-1 levels below the level caused by the hormone antagonist alone and increasing endothelium-dependent vasodilation. Endothelin-1, a peptide, mediates inflammation and constricts blood vessels. When the women began taking MPA, endothelin-1 levels increased (not significantly different from hormone antagonist level) and endothelium-dependent vasodilation decreased. No other measurements changed. The researchers were concerned that MPA appears to "[negate] the beneficial effects of estradiol on endothelium-dependent vasodilation in young women … [and] may counteract the effect of estradiol on endothelin-1." Longer and larger studies need to be conducted to determine whether these short-term effects increase the risk of cardiovascular disease in women using the contraceptive Depo-Provera.
Depo-Provera was first approved for use in the US as a treatment for endometriosis in 1967. FDA refused its sale as a contraceptive until 1992, saying that available contraceptive methods had fewer risks. Depo-Provera has the advantage of preventing conception (97% effective) with a single injection in a woman's upper arm or buttock every 12 weeks – a boon for populations such as intellectually disabled teens. Side effects include weight gain, bone loss, and delayed conception after stopping the drug. Bone loss and weight gain reverse when the drug is discontinued.
An October 26, 2009, report from ABC News (US) said that some women experience withdrawal symptoms after taking the contraceptive for two or more years. The possibility of withdrawal effects has not been studied and would be "complicated," according to Dr. Paul Kaplan, coauthor of the Oregon study. "Withdrawal" complaints from older women could be due to the approach of menopause. These complaints may also be the resurrection of a medical condition, "masked" by the contraceptive. The women's anecdotal reports may indeed highlight a valid concern, but tracking down withdrawal effects will not be as easy to substantiate as MPA's effect on vascular endothelium.
Barlow J. UO study raises questions on synthetic progestins [press release]. March 2008. Available at: http://pmr.uoregon.edu. Accessed January 19, 2010.
James SD. Women struggle to quit Depo-Provera. ABCNews.com. October 26, 2009. Available at: www.abcnews.go.com. Accessed October 27, 2009.
Meendering JR, Torgrimson BN, Miller NP, Kaplan PF, Minson CT. Estrogen, medroxyprogesterone acetate, endothelial function, and biomarkers of cardiovascular risk in young women [abstract]. Am J Physiol Heart Circ Physiol. April 2008;294(4):H1630–H1637.
Play and Child Development
Child-driven play is crucial for healthy development, according to an article by Kenneth R. Ginsburg, MD, for the American Academy of Pediatrics. It can also be a means of creating and maintaining strong parent–child bonds. Play offers children what no other activity can: the opportunity to explore their world at their own rate and in a way that lets them master their environment and discover their own interests. Without having to worry about adult approval or mandates to excel, children develop physical and cognitive skills, creativity, and emotional and interactive skills as they play with others. Many factors prevent children's access to the active play and free time enjoyed by earlier generations, including competition from passive activities like television, video games, and computers; less recess time in schools; fears about neighborhood safety that keep children indoors; more adult-organized activities; and more pressure to succeed – however that word is defined.
Unlike other interactions, child-directed play gives adults the opportunity to follow the child's lead and to experience the world from the child's point of view. Sharing a child's world through play forges strong emotional bonds. For many children, play is a form of communication, a vehicle by which they express their concerns, fears, and interests. For older children, spending time together "off the clock," without schedules to meet or tasks to finish, provides the same opportunity. "The interactions that occur through play [and downtime]," writes Ginsburg, "tell children that parents are fully paying attention to them and help to build enduring relationships.
AAP urges pediatricians to advocate for unscheduled, independent, and active play time for their young patients. So many messages from government, media, and marketers bludgeon parents with ways to prepare their children for future success. But the qualities that truly make a difference to an individual's ability to navigate an increasing complex world are confidence, resilience, and the ability to relate to others with compassion and honesty. Such qualities develop through interactions within a loving, secure environment.
Ginsburg KR et al. The importance of play in promoting healthy child development and maintaining strong parent-child bonds. Pediatrics. January 2007;119(1):182–191. Available at: www.aap.org/pressroom/playFINAL.pdf. Accessed January 4, 2010.
Reflexology for PMS?
Reflexology, the practice of applying pressure to reflex points in the feet and hands, is based on the recognition that connective tissue literally connects every bit of the body to the rest. Stimulation or trauma to one area travels to other areas. In the 1920s, Dr. William Fitzgerald and colleague Dr. Joe Shelby Riley found that pressure on points in different "zones" of the body decreased pain and could improve organ function. Physical therapist Eunice D. Ingham built upon their work, popularizing a system that can be used by laypersons.
Ingham asserted that "reflexes on the feet were an exact mirror image of the organs of the body." (A diagram is available at www.reflexology-usa.net.) In her book Stories the Feet Have Told, Ingham explained that compression massage on tender reflexes in the feet improves circulation and relieves congestion around the nerves. Her experience with thousands of clients found that as tenderness disappeared, function of the corresponding organ improved. The American Reflexology Certification Board does not make such claims for modern reflexology. It says, "Reflexology is primarily a relaxation technique. … Reflexology gently nudges the body toward better functioning by improving lymphatic drainage and venous circulation, stimulation to the nerve pathways, and muscle relaxation, helping the body to balance itself."
Reflexology has been studied in hundreds of small clinical trials as a means of relieving various illnesses and chronic conditions. A list is available at www.reflexologyresearch.net/ResearchCatList.shtml. One of the most frequently cited studies investigated reflexology's ability to relieve premenstrual symptoms. In 1993, T. Oleson and W. Flocco randomly assigned 35 women with premenstrual syndrome to receive "placebo reflexology" or true reflexology (ear, hand, and foot). The participants monitored their symptoms daily, using a four-point scale to rate severity of 38 somatic and psychological indicators of PMS for six months: two months before receiving treatment, two months during which they had weekly 30-minute sessions with a trained reflexology practitioner, and two months after the weekly sessions ended. "Analysis of variance for repeated measures demonstrated a significantly greater decrease in premenstrual symptoms for the women given true reflexology treatment than for the women in the placebo group," according to the study abstract. I don't know if these results have been reproduced.
Reflexology is a complementary therapy that can be used with any medical treatment, according to the American Reflexology Certification Board. Professional reflexology practitioners need a minimum of 200 hours of study and documented practice of reflexology to qualify for national certification. State licensure requirements for professional reflexology practitioners vary from state to state.
American Reflexology Certification Board. The differences between Reflexology and massage. www.arcb.net/differences.htm. Accessed January 20, 2010.
American Reflexology Certification Board. Unique characteristics of Reflexology and massage. www.arcb.net/unique_characteristics.htm. Accessed January 20, 2010.
Byers D. History of reflexology. www.reflexology-usa.net/history.htm. Accessed February 4, 2010.
Oleson T, Flocco W. Randomized controlled study of premenstrual symptoms treated with ear, hand, and foot reflexology [abstract]. Obstet Gynecol. December 1993;82(6):906–911.
Zuger S. Best foot forward. Energy Times. May 2009;14–15
Statistics, Mammography, and Informed Choice
In November 2009, the US Preventive Services Task Force (USPSTF) updated its 2002 recommendations for mammography screening. The new guidelines recommend against universal screening for women aged 40–49. Instead, USPSTF encourages "individualized informed decision making" that takes into account a woman's medical history and specific benefits and harms for her age group. Earlier guidelines had recommended screening for breast cancer every one to two years for all women in this age group, but the risks incurred from unnecessary treatment for false-positive results outweigh the benefits. In addition, the new guidelines recommend biennial screening instead of yearly screening for women aged 50–69: "Models indicate that biennial screening for this group maintained about 80% of the benefit of annual screening while halving the number of false-positive results." Biennial screening was also recommended for women aged 70–74, but the benefits are lower because of this group's higher death rate from other causes.
Some doctors and patients protested the changes, saying that mammography saves lives. Such protests stem from a "lack of understanding about the basics of health statistics" and "an emotional need for certainty," explain Gerd Gigerenzer, PhD, coauthor of the article "Knowing Your Chances." Gigerenzer directs the Max Planck Institute for Human Development and the Harding Center for Risk Literacy in Berlin. A large part of the confusion stems from media's and researchers' habitual use of relative risk, instead of absolute risk, to report research results. Relative risk usually evokes bigger numbers and sounds more impressive than absolute risk. A treatment that reduces the death rate from two people to one person in 10,000 (absolute risk) has a relative risk reduction of 50%. Fifty percent risk reduction sounds far more impressive than one fewer death among 10,000 people. A treatment that reduces the absolute risk of dying from 200 in a 1000 to 100 in a 1000 also has a relative risk of 50%; but in this case, the effect is more significant. Absolute risk gives a more accurate picture of the number of people affected by a course of action. "Reporting relative risks," Gigerenzer and colleagues explain, "can create unrealistic hopes as well as undue anxiety." Looking for absolute risk of mortality in a specific population over a set period of time provides the most accurate statistical way to assess the benefits of screening for a disease. The benefit must also be compared with the harm caused by inaccurate or inconclusive results – which is what USPSTF did to get its new mammography recommendations.
When the benefits of mammography are translated into absolute risk, the procedure's benefits seem less impressive: "Mammography reduces the risk of a woman in her 50s dying from breast cancer from about five to four in 1,000 over some 13 years." The reason that USPSTF has backed away from annual mammography, however, lies in the fact that 9 of every 10 women who test positive do not have cancer. Yet, these false-positives lead to further testing, unnecessary procedures (and complications), and anxiety. Gigerenzer and colleagues explain the risks another way: "Ten out of every 1,000 women have breast cancer. Of these 10 women with breast cancer, nine test positive. Of the 990 women without cancer, about 89 nonetheless test positive." Real numbers like these help doctors and patients make informed choices.
No matter how wondrous a medical test or procedure or how accurate the statistics, nothing is for certain. The authors state, "no unequivocal answers or absolute cures exist. Risk is unavoidable; it comes with all action or inaction." Yet human beings want certainty. The media sells its news, and the medical industry has built its power on the belief that medicine is able to cure far more that it can. Patients cannot begin to make informed decisions or take control of their health and their lives until they come to terms with the reality of uncertainty. They need to understand that accurate statistics give us pictures of risk and benefit, but those numbers can never guarantee specific outcomes for an individual.
For more information on this topic, see "Helping Doctors and Patients Make Sense of Health Statistics," an article from the Association for Psychological Science at www.psychologicalscience.org (click on "Journals," "PSPI Home," then "View the list of issues").
Gigerenzer G, Gaissmaier W, Kurz-Milcke E, Schwartz LM, Woloshin S. Knowing your chances. Scientific American Mind. April/May 2009;44–51.
Rebar RW. Altered approach to mammographic screening for breast cancer. Journal Watch General Medicine. December 31, 2009.
DVD Offers Massage Lesson
Massage does more than relax tired and overworked muscles. It also increases circulation, decreases stress, improves energy levels, and enhances sleep. Kathy Gruver, a licensed and certified medical massage therapist, had several clients tell her that they wanted to pass the benefits of massage on to family members and friends, but they didn't know how to give an effective massage without wearing themselves out. In her informative, well-organized, and relaxing DVD Therapeutic Massage at Home, Gruver teaches laypersons how to give a massage that eases tension and muscular knots in the back and neck. The DVD also works as a wonderful introduction to massage.
Massage is more than simply rubbing muscles or applying pressure to knots. As Gruver explains, massage uses a variety of different strokes and hand positions on various parts of the back and neck. Both the giver and the receiver need to be comfortable. Since not everyone has a massage table, Gruver demonstrates how the at-home masseur can use good body mechanics with the subject lying on a bed or the floor. Safety is another consideration. Certain parts of the neck, for example, should not be massaged. Also, massage should not be performed over open wounds, inflamed areas, sores, bruises, broken bone, or sites of recent surgery. People with diabetes or high blood pressure need to check with their doctors, because massage can lower blood pressure and blood sugar. Gruver also tells viewers to check with their doctors before being massaged if they are pregnant or have cancer.
Most of this 50-minute DVD demonstrates how to do a relaxing back and neck massage. The quality of the film is excellent; the music relaxing; the visuals clear; and the information concise, practical, and appropriate for a layperson. If you want to bring massage into your life on a regular basis, this DVD is a fine investment at $24.99 plus tax. It can be obtained at http://healingcirclemassage.com/instructional_dvd or by calling 805-680-1984.
Ultrasound in Pregnancy
Routine ultrasound screening during pregnancy has become the norm in Western countries, but its benefits and risks have not yet been conclusively determined. A 2010 Cochrane systematic review found evidence that using Doppler ultrasound to monitor the fetus during high-risk pregnancies "may reduce caesarean sections and the number of babies who die." The review used data from 18 studies of varying quality with a total of 10,000 women with high-risk pregnancies (e.g., women with hypertension or diabetes, those carrying growth-restricted babies, or those who had previously miscarried). The review's authors suggest that the use of ultrasound may have helped practitioners choose treatments that improved outcome. The conclusions of this review are not definitive. Lead researcher Zarko Alfirevic (University of Liverpool, UK) would like "a higher quality, multi-centre trial of Doppler ultrasound than we have so far seen." Although ultrasound screens may have benefits in high-risk pregnancies, I was unable to find definitive evidence that ultrasound screening, which has been used for over 30 years, makes any difference in the outcome of normal pregnancies.
The question of ultrasound's benefit is important because the screening may have risks to the developing fetus. Preliminary research showed that stress proteins, not caused by heat (which is a possible effect of ultrasound energy), arose in chick embryos exposed to ultrasound, according to a statement by FDA Center for Devices and Radiological Health. In a 2006 study, neurons failed to migrate to their appropriate position in the cerebral cortex in mice exposed to high doses of ultrasound while in utero. Applying the results of this study to human babies has been criticized because mice skulls are not as thick as humans'. Also, the mice in this study, conducted by Pasko Rakic, MD, and colleagues, were exposed to far longer and higher doses than a human fetus would receive. We don't know at what point, if at all, a dose can affect an infant's brain and central nervous system. Studies have shown a correlation between increased ultrasound exposure and delayed speech in children. The incidence of restricted fetal growth also increases as ultrasound exposure increases. (A 2004 Lancet study shows that growth and development among children who had multiple prenatal ultrasound scans are comparable with that of children who received only one scan by 1 year and up to 8 years of age.) The evidence is strong enough that the FDA and medical associations have taken a stand against "keepsake" ultrasound photos and videos.
Does an ultrasound lack risk simply because a health-care practitioner is the person performing it? During the 1930s, X-rays were used "to diagnose pregnancy and to measure the growth and normality of the fetus," writes Marsden Wagner. A 1937 standard textbook reassured readers that X-ray examination posed no danger to the fetus "… if the examination is carried out by a competent radiologist or radiographer." Years later, research showed that these routine examinations were causing childhood cancer.
Accuracy of prenatal ultrasound screenings is another factor. Accuracy depends upon the quality of the equipment and the skill of the person using it. Even then, results are not always correct. As with any test, false-positive results (during which a baby is wrongly diagnosed as having a problem) and false-negative results (the baby has a problem not found with ultrasound) are possible. As Zarko Alfirevic says, it is not the screening itself that determines outcome. The deciding factor is how practitioners intervene. It's exciting to see pictures of the growing baby in the womb, but is it necessary – especially during normal pregnancies?
Alfirevic A, Stampalija T, Gyte GML. Fetal and umbilical Doppler ultrasound in high-risk pregnancies. Cochrane Database of Systematic Reviews. 2010;1. Art. CD007529. DOI: 10.1002/14651858. CD007529.pub2.
FDA Center for Devices and Radiological Health. Ultrasound bioeffects: effects on embryonic development and cardiac function. Available at: www.obgyn.net/ultrasound/ultrasound.asp?page=/fm/news_articles/fda_
ultrasoundequip0304#embryo. (One link, two lines) Accessed January 28, 2010.
Newnham JP, Doherty DA, Kendall GE, Zubrick SR, Landau LL, Stanley FJ. Effects of repeated prenatal ultrasound examinations on childhood outcome up to 8 years of age: follow-up of a randomized controlled trial. Lancet. December 4, 2004:364(9450):2038-2044.
Smith M. Ultrasound affects development of murine brains. MedPage Today. August 8, 2006. Available at: www.medpagetoday.com. Accessed January 28, 2010.
Wagner M. Ultrasound: more harm than good? Midwifery Today. Summer 1999. Available at: www.midwiferytoday.com/articles/ultrasoundwagner.asp. Accessed January 27, 2010.
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