Qualities of a Good Screening Test

1. The condition should be an important health problem and the condition screened for must have a high prevalence in the population.

2. There should be a latent stage of the disease. 3. There should also be effective treatment for the condition being screened. 4. Facilities for diagnosis and treatment should be available. 5. There should be a test or examination for the condition. 6. The test should be acceptable to the population and the total cost of finding a case should be economically balanced in

relation to medical expenditure as a whole. The potential benefits of early detection and treatment of a condition need to be weighed against many factors, including adverse side effects of the screening test, time and effort required (of both the patient and the health care system) to take the test, financial cost of the test, potential psychological and physical harm of false positive results (such as labeling and overtreatment), and adverse effects of the treatment.

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7. The natural history of the disease should be adequately understood. 8. There should be an agreed policy on whom to treat. 9. Case-finding should be a continuous process, not just a “once and for all” project.

10. An effective screening test should have very good sensitivity (identify most or all potential cases) and specificity (label incorrectly as few as possible as potential cases). Even a test with a sensitivity of 95% will lead to many false positives when the prevalence of the condition is very low.

United States Preventive Services Task Force Recommendations for Chlamydia Screening


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recommends screening for chlamydia infection in the following:

Grade Recommendation


All sexually active women age 24 and younger

Sexually active women age 25 and older who are at increased risk

Grade B recommendation

There is direct evidence that screening reduces complications of chlamydial infection in women who are at increased risk, with a moderate magnitude of benefit. Such complications include pelvic inflammatory disease, infertility, and premature delivery (among pregnant women).

The USPSTF advises against screening women age 25 and older if not at increased risk, regardless of pregnancy status. Only the above categories are found to have a high enough pretest probability to recommend screening. Women (pregnant or non-pregnant) in general are not recommended for chlamydial screening as the overall benefit of screening would be small, given the low prevalence of infection among women not at increased risk. Risk factors for chlamydial infection include a history of chlamydial or other sexually transmitted infection, new or multiple sexual partners, inconsistent condom use, and exchanging sex for money or drugs. Risk factors for pregnant women are the same as for nonpregnant women. The USPSTF states that there is “Insufficient” evidence for or against screening men. The CDC recommends consideration of screening for chlamydia in sexually active young men in settings with high prevalence or in men with high risk behaviors overall.

1. The CDC recommends consideration of screening for chlamydia in sexually active young men in settings with high prevalence or in men with high-risk behaviors overall.

2. The AAP recommends considering annual screening for chlamydia in sexually active males in settings with high prevalence rates, such as jail or juvenile correction facilities, national job training programs, STD clinics, high school clinics, and adolescent clinics (for patients who have a history of multiple partners), as well as routine annual screening for men who have sex with men.

There are several good sources for preventive screening recommendations. The Guidelines for Adolescent Preventive Services (GAPS) was developed by the AMA in 1993. Other recommendations include those from the American Academy of Pediatrics’ Bright Futures and the U.S. Preventive Services Task Force.

Adolescent Health Counseling and Screening: Preventing Sexually Transmitted Infection and Unintended Pregnancy

Counsel all sexually active adolescents regarding contraception. Options include: oral contraceptives, medroxyprogesterone (Depo-Provera) injections, long-acting reversible contraceptives such as implantable options and IUDs, as well as the vaginal ring (NuvaRing) Remind patients these options do not protect against sexually transmitted infections Discuss condoms and abstinence Discuss emergency contraception Recommend folic acid supplementation to prevent neural tube defects in the event of pregnancy

Preconception Counseling

It can be challenging to find the opportunity to discuss reproductive life planning. Whether it is walk-in / urgent care visits, sports pre-participation examinations, or adolescent well-child exams, it can be helpful to bring this topic up to allow for adequate counseling around pregnancy prevention or preconception planning, as appropriate. Preconception Health Care Checklist:


Folic acid supplement (400 mcg routine): The USPSTF recommends that all women “planning or capable of pregnancy” take a daily supplement containing 400 to 800 mcg of folic acid. The dose is increased for the following high-risk scenarios:

A. 1 mg in patients with diabetes or epilepsy B. 4 mg in patients who bore a child with a previous neural tube defect Carrier screening (ethnic background):

Sickle cell anemia Thalassemia Tay-Sachs disease

Carrier screening (family history): Cystic fibrosis Nonsyndromic hearing loss (connexin-26)

Screen for infectious diseases, treat, immunize, counsel

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HIV Syphilis Hepatitis B immunization Preconception immunizations (rubella, varicella) Toxoplasmosis—avoid cat litter, garden soil, raw meat Cytomegalovirus, parvovirus B19 (fifth disease)—frequent hand washing, universal precautions for child care and health care

Environmental toxins

Occupational exposures: material safety data sheets from employer Household chemicals: avoid paint thinners and strippers, other solvents, pesticides Smoking cessation: bupropion (Zyban), nicotine patches (Nicoderm) Screen for alcoholism and use of illegal drugs

Medical assessment

Diabetes: optimize control, folic acid, 1 mg per day, off ACE-inhibitors Hypertension: avoid ACE inhibitors, angiotensin II receptor antagonists, thiazide diuretics Epilepsy: optimize control; folic acid, 1 mg per day DVT: switch from warfarin (Coumadin) to heparin Depression/anxiety: avoid benzodiazepines


Recommend regular moderate exercise Avoid hyperthermia (hot tubs, overheating) Caution against obesity and being underweight Screen for domestic violence Assess risk of nutritional deficiencies (vegan, pica, milk intolerance, calcium or iron deficiency) Avoid overuse of Vitamin A (recommendations are to 750 mcg (2500 IU per day) with daily upper intake limit of 3,000 mcg (10,000 IU)) Avoid overuse of Vitamin D (recommendations are 600 IU per day, tolerable upper intake is 4000 IU) Caffeine (limit to the equivalent of two cups of coffee or six glasses of soda per day) Note: The sugar intake in six glasses of soda is not recommended.

Signs and Symptoms of Pregnancy

Amenorrhea with fatigue, nausea, and/or vomiting as well as breast changes, including tenderness, are the classic presentations of pregnancy.

Urinary frequency can also occur. Although urinary frequency can be a normal symptom of pregnancy, the possibility of a UTI in a pregnant woman should also be considered. Softening of the cervix is known as Goodell’s sign, while softening of the uterus is known as Hegar’s sign. The bluish-purple hue in the cervix and vaginal walls is known as Chadwick’s sign and is caused by hyperemia. Enlargement of the uterus can be detected by an experienced examiner as early as 8 weeks on bimanual exam. Around 12 weeks, the uterine fundus can be palpated above the symphysis pubis. Between 20 to 36 weeks of gestation, the uterine enlargement, measured in centimeters, approximates gestational age and will become a routinely elicited physical exam finding. Fetal heart tones are typically elicited by hand-held Doppler between 10-12 weeks gestation. Fetal movement or “quickening” is detected by the mother around 18-20 weeks of gestation. Unfortunately, the menstrual history is not an entirely reliable indicator of pregnancy. Only 68% of pregnant adolescents report having missed a menses. Conversely, not every adolescent who misses a menses is pregnant because anovulatory cycles are normal in the early postmenarcheal years. Bleeding can occur in early pregnancy around the time of the missed menses as a result of an invasion of the trophoblast into the decidua (implantation bleed). Some adolescents mistake this bleeding for a menses, leading to a delay in diagnosis of pregnancy and potential misdating of the pregnancy. We should also remember that young women who have not yet menstruated, but are sexually active, may be at risk for pregnancy because ovulation can occasionally occur before the first menstrual period.

Reproductive Choice Counseling

Continue the pregnancy… …and raise the child. …and create an adoption plan.

Terminate the pregnancy… …medically …surgically Abortion restrictions in the U.S. vary state to state, as shown here: [https://www.guttmacher.org/state-policy/explore/overview-abortion-laws

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Calculating Estimated Gestational Age

Calculating the estimated gestational age (EGA) based on the last normal menstrual period (LNMP). Calculating the EGA in this manner is not only convenient but ubiquitous in clinical practice. Keep in mind, however, that the actual embryonic age (e.g., the age of the fetus since the date of conception) will typically be approximately two weeks less than the clinically calculated EGA based upon the LNMP. The other calculation used in clinical practice—which patients care a great deal about—is the estimated due date. Calculating the estimated due date (EDD—sometimes referred to as the estimated date of confinement or EDC) from the last menstrual period is a relatively simple process that can be done with an obstetric “wheel”, with an electronic calculator (e.g., http://www.mdcalc.com/pregnancy-due-dates-calculator ) or using Naegele’s Rule. Naegele’s Rule is commonly described as starting with the first day of the last normal menstrual period, then: