Objective: To review published data regarding the accuracy and effectiveness of three screening tests: mammography, prostate-specific antigen (PSA), and prenatal ultrasound.

Methods: Published evidence regarding the accuracy and effectiveness of the three tests was collected by computerized literature search and supplemented by manual review of relevant bibliographies.

Results: Screening mammograms lower breast cancer mortality by about 20%. Most data come from women aged 50–64 years; women aged 40–49 years may also benefit, but the absolute risk reduction is lower. Up to 1,500 to 2,500 women must undergo screening to prevent one death from breast cancer. Mammograms miss approximately 12% to 37% of cancers, generate false-positive results, and cause anxiety while abnormal results are evaluated. PSA screening can detect 80% to 85% of prostate cancers but has a high false-positive rate. There is little direct evidence that early detection reduces morbidity or mortality. Indirect evidence includes a trend toward earlier stage tumors and steadily declining mortality rates in geographic areas where PSA screening has become common. Potential harms include the morbidity associated with evaluating abnormal results, and complications from treatment (e.g., impotence, incontinence). The overall balance of benefits and harms remains uncertain in the absence of better evidence. Prenatal ultrasound may reduce perinatal mortality, primarily through elective abortions for congenital anomalies, but does not appear to lower live birth rates. Although ultrasound has no proven effect on neonatal morbidity, it provides more accurate estimates of gestational age that prevent unnecessary inductions for post-term pregnancy. Screening detects multiple gestations, congenital anomalies, and intrauterine growth retardation, but direct health benefits from having this knowledge are unproved. Ultrasound has both positive and negative psychological effects on parents. The scans do not appear to harm childhood development.

Conclusions: Even for the most established screening tests, the appropriateness of routine testing depends on subjective value judgments about the quality of supporting evidence and about the trade-offs between benefits and harms. Individuals, clinicians, policy makers, and governments must weigh the evidence in light of these values and the constraints imposed by available resources.

Objective. The aim of this study was to show the diagnostic possibilities of ultrasound in twin-to-twin transfusion syndrome (TTTS), to demonstrate its usefulness in cases of hemoglobin difference < 5 g/dL in neonates as well as in cases complicated by intrauterine death of one or both twins.

Study design. The study included 4 pairs of twins. In two cases 3 fetuses died in utero. In the other two the hemoglobin difference in newborn infants was < 5 g/dL. The ultrasound examination, evaluating the fetal anatomy and biometry, amniotic fluid volume, placentation, was performed. The special attention was paid to polyhydramnios/oligohydramnios, discordant fetal growth (fetal weight, abdominal circumference), the presence of fetal hydrops, ascites, pericardial effusion. Doppler blood flow velocimetry has been done in umbilical vessels, middle cerebral artery. The data was compared with normal reference values for singleton pregnancies. The waveforms from both uterine arteries were also evaluated to exclude placental insufficiency. Additionally the blood flow through the AV valves was measured to exclude or confirm its regurgitation. Postnatally the hemoglobin difference was evaluated if available and compared with sonographic findings.

Results. In all cases inter-twin difference in abdominal circumference was greater than 18 mm and inter-twin weight difference of more than 15%. We observed polyhydramnios/oligohydramnios in all twin pregnancies.

It has been found decreased PI in middle cerebral artery in larger fetus (recipient) in all our cases (comparing to single pregnancy). PI values for this vessel in smaller fetuses were within normal range (for single pregnancy). PI values in umbilical arteries of recipients were abnormal (increased PI or absent end-diastolic flow).

Comments. The sonographic criteria seem to be very useful in diagnosis of twin-to-twin transfusion syndrome, especially in cases where the measurement of hemoglobin level is impossible. Doppler blood flow velocimetry in fetal vessels helps to explain the changes in fetal hemodynamics in TTTS.