The safety of obstetric ultrasonography: concern for the fetus

Article Abstract:

Ultrasound is an easily performed, noninvasive diagnostic technique that uses high-frequency sound to visualize internal structures. Fetal ultrasound is performed on almost half of all pregnant women in the US. Ultrasound can detect abnormalities in the structure of the fetus. The effect ultrasound has on the fetus is of great concern. Studies examining the effect of ultrasound on animals and plants have uncovered limited adverse effects, which are difficult to extrapolate to humans. High-intensity ultrasound used experimentally or for treatment can alter structure and function of tissue. However, these levels are not used during routine diagnostic evaluations. Ultrasound produces biological effects by increasing temperature and by producing microscopic gas-filled bubbles that grow in sound fields (cavitation). It is unlikely that a temperature rise of less than one degree centigrade could cause tissue damage, since humans have normal daily fluctuations in temperature and even greater temperature rises during fever states. Furthermore, it is not known if cavitation occurs in human tissue. Cultured cells exposed to diagnostic-quality ultrasound grew and divided normally but exhibited changes in the behavior of the cells's surface. One study found that cells exposed to ultrasound underwent changes in the chromosomes but did not experience an increase in chromosomal abnormalities. When the same test was repeated under different experimental conditions, the results were not reproduced. All the epidemiological studies examining the effect of ultrasound on fetal development have failed to demonstrate any consistent adverse effects. The current ultrasound intensities for diagnostic evaluations do not appear to impose any ill biological effects on patients, fetuses or ultrasound technicians. The benefits of careful ultrasonography surely outweigh the risks, if any. (Consumer Summary produced by Reliance Medical Information, Inc.)

Evaluation, Complications and side effects, Fetus, Prenatal ultrasonography, Ultrasonics in obstetrics

---

Indomethacin treatment for polyhydramnios and subsequent infantile nephrogenic diabetes insipidus

Article Abstract:

An increase in fluid surrounding the fetus, a condition known as polyhydramnios, is associated with some chromosomal abnormalities. Amniotic fluid is produced by the cells located in the fetal membrane. The fluid balance is maintained by the fetus when it swallows the fluid and excretes it as urine. A case is discussed of a 33-year-old woman who developed abdominal swelling during her 26th week of pregnancy. All the patient's prenatal examinations were normal, with the exception of a lower-than-normal level of alpha-fetoprotein, indicating possible fetal abnormalities. Fetal ultrasonography was normal and amniocentesis was performed. Chromosomal analysis detected one extra chromosome in most of the fetal cells. The patient was given 25 milligrams of indomethacin, a drug used to decrease the amount of amniotic fluid during pregnancy, every four hours. When serial ultrasound was performed, a decrease in urine output was noted. Indomethacin was continued until spontaneous labor began at 36 weeks of pregnancy. A structurally normal female infant was born. At six months of age, however, the infant was hospitalized for failure to thrive, a condition of halted growth and development because of poor feeding. The infant had a fever of 101 degrees F. and became dehydrated. Blood and urine analysis indicated that she had diabetes insipidus, a condition caused by a defect in the kidneys that prevents the tubules from responding to the hormone that regulates body fluids. A diagnosis of congenital nephrogenic diabetes insipidus (diabetes insipidus caused by a defective kidney as opposed to inadequate hormone production) was confirmed. Congenital nephrogenic diabetes insipidus should be suspected in cases of polyhydramnios. The infant remains on indomethacin therapy to control fluid and electrolyte imbalance. (Consumer Summary produced by Reliance Medical Information, Inc.)

Case studies, Diabetes insipidus

---

Maternal indomethacin therapy in the treatment of polyhydramnios

Article Abstract:

An increased volume of fluid surrounding the fetus is associated with a poor pregnancy outcome. An amniotic fluid volume of greater than 1.5 to 2.0 liters, a condition termed polyhydramnios, is found in pregnancies complicated by fetal abnormalities or diabetes. Symptoms include pain, abdominal tenderness, uterine contractions and breathing difficulties. Reduction of excess amniotic fluid may be necessary in severe cases. Amniotic fluid that is removed by amniocentesis can be replaced within 48 hours, so it would be useful to have an alternative therapy for reducing amniotic fluid. Indomethacin is a prostaglandin synthetase inhibitor commonly used to treat swelling. It is commonly given to newborns order to promote closure of the ductus arteriosus, a communication between the aorta and the pulmonary artery. One of the side effects of the drug is reduced urine production. Since most of the amniotic fluid is produced during pregnancy by fetal urine, 15 patients with polyhydramnios were studied to see if indomethacin could effectively reduce amniotic fluid volume. Women were given oral or rectal suppositories of indomethacin (2.0 to 2.2 milligrams per kilogram of body weight per day) up to the 35th week of pregnancy or for a maximum of four weeks. Fluid reduction was the greatest in the first week, followed by a gradual decrease in subsequent weeks. All the patients completed at least 38 weeks of pregnancy with an average birth weight of 7.8 pounds (3,543 grams). No adverse effects of indomethacin therapy were seen at follow-up. How indomethacin reduces amniotic fluid is not understood. Premature closure of the ductus arteriosus is a potential complication of therapy, so close surveillance is required. (Consumer Summary produced by Reliance Medical Information, Inc.)

Measurement, Amniotic fluid

Similar abstracts:

• Abstracts: The role of ultrasonography and amniocentesis in the evaluation of pregnancies at risk for neural tube defects
• Abstracts: Transvaginal ultrasonographic detection of congenital anomalies in the first trimester. Ultrasonographic criteria for the prenatal diagnosis of placental chorionicity in twin gestations
• Abstracts: The current role of sonography in the detection of Down's syndrome. The transverse cerebellar diameter cannot be used to assess gestational age in the small for gestational age fetus
• Abstracts: Transvaginal ultrasonographic detection of congenital anomalies in the first trimester. part 2 Embryoscopy: description and utility of a new technique
• Abstracts: The pathology of heart and heart and lung transplantation - an update. Management of cytomegalovirus antibody negative patients undergoing heart transplantation

This website is not affiliated with document authors or copyright owners. This page is provided for informational purposes only. Unintentional errors are possible.