Caesarean May Pose a Risk for the Next Birth

TIMES MEDICAL WRITER

Women who have a caesarean delivery during childbirth are significantly more likely to suffer uterine rupture during a subsequent vaginal delivery, a new study finds.

Uterine rupture is an uncommon but serious obstetrical condition that may result in hysterectomy, urologic injury or a need for blood transfusion for the mother. It may also lead to neurological impairment of the child.

Dr. Mona Lydon-Rochelle of the University of Washington and her colleagues studied the delivery records of 20,095 women who delivered a single live infant in Washington state from 1987 through 1996 and who also had a second single live birth in the same period.

Among women who had a previous caesarean, they reported in the July 5 issue of the New England Journal of Medicine, those who had a subsequent vaginal delivery with a spontaneous onset of labor were three times as likely to suffer uterine rupture as those who had not had a caesarean.

Women who had an induced onset of labor that did not involve drugs called prostaglandins were five times more likely to have uterine rupture; those whose induced were 15 times as likely to have a uterine rupture.

Nonetheless, the absolute risk of a rupture was low. Among the 20,095 women, only 91 had a uterine rupture during the second birth.

Report Cautions Against Mercury Thermometers

Both physicians and parents should stop using thermometers containing mercury, according to a new technical report from the American Academy of Pediatrics.

Mercury is a toxic element that can produce a broad range of effects on the central nervous system, kidneys, skin and lungs and possibly lead to death. Although the amount of mercury in a single thermometer is not sufficient to cause severe poisoning when swallowed, the report said, the effects can be much more serious if the mercury vaporizes after a thermometer is broken and is inhaled.

Patient Diagnosed With Vitamin D Overdose

Researchers from Boston University Medical Center have reported on a man they hospitalized for symptoms of high calcium levels but who subsequently was found to be suffering from vitamin D intoxication, which can be fatal. The man, 42, had been taking supplements containing vitamin D for two years before his admission, and blood tests showed that he had a level 10 times higher than the upper normal range, the doctors reported in the July 4 issue of the New England Journal of Medicine.

The supplements were manufactured by Prolongevity of Markham, Canada. Analysis of three separate bottles of the supplement showed they contained 26 to 430 times the amount of vitamin D listed on the bottle.

The journal editors sent the report to Prolongevity, which refused to reply. The researchers cautioned that supplements are not regulated and may not contain what manufacturers say they do.

Cannabinoids Compared With Codeine for Pain

Cannabinoids--the active substances in marijuana--are no more effective than codeine in providing pain relief, but they are the best method available for controlling the nausea associated with chemotherapy, according to two new studies. In both cases, however, the drug's side effects make them unlikely to be widely used.

Dr. Fiona Campbell of the Queen's Medical Centre in Nottingham, England, and her colleagues reviewed nine trials, including 200 patients, in which cannabinoid capsules or injections were compared with codeine. They reported in the July 7 issue of the British Medical Journal that all but one of the studies found no major difference in pain control between the two drugs.

The only area where the cannabinoids might be useful, they concluded, was in controlling chronic non-cancer pain.

Dr. Martin Tramer of University Hospital in Geneva and his colleagues reviewed 30 trials in which cannabinoids were compared with other drugs for controlling nausea and vomiting in chemotherapy patients. They reported in the same journal that the cannabinoids were more effective than each of the other drugs and seemed to be preferred by patients.

Both studies, however, found potentially serious side effects associated with cannabinoids. These included potentially beneficial ones such as euphoria, sedation or drowsiness. But they also included harmful effects such as dizziness, depression and hallucinations.

An Argument for Lower Doses for Epidurals

Epidurals are the most effective form of pain relief during childbirth, but their use impairs motor function in the mother--which interferes with her ability to push--and is associated with a greater degree of physician intervention in delivery.

But new techniques using lower doses of the painkilling agents are as effective at relieving pain and increase the rate of normal vaginal delivery, British doctors say.

Dr. Andrew H. Shennan and colleagues at St. Thomas' Hospital in London studied 1,054 women who requested epidurals during birth.

A third were given conventional epidurals; the others received either of two new techniques for using lower doses of drugs.

Pain control was equivalent in all groups, the team reported in the July 7 Lancet, but 43% of women receiving low doses had a normal vaginal delivery, compared with 35% given conventional epidurals.

Hearing Loss Reported Among Many Youngsters

An estimated 5.2 million American youngsters have some degree of hearing loss from such sources of noise as rock concerts, fireworks and lawn mowers, government research suggests.

In at least 250,000 of those young people, the problem may be moderate to profound.

The figures do not indicate what percentage have simply temporary, slightly muffled hearing or more severe, permanent damage.

But the researchers said the numbers are worrisome, and they urged the use of earplugs.

"Even when you have temporary damage for a few days such as muffled hearing, that can influence the child's ability to learn in the classroom," said Amanda Niskar, a nurse-epidemiologist at the federal Centers for Disease Control and Prevention, who led the study.

The findings, based on 5,249 participants in a nationally representative 1988-94 survey, appear in the journal Pediatrics' July issue.

Participants were given hearing tests in which researchers looked for noise-induced hearing threshold shifts, or NITS. When extrapolated to the rest of the nation, the findings indicate the presence of NITS in 12.5% of all Americans ages 6 to 19--or 5.2 million young people. That suggests at least a one-time exposure to excessive noise, Niskar said.

The findings also suggest that 4.9%--or 250,000 young people--have moderate to profound NITS. That suggests possibly permanent damage, Niskar said

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Medical writer Thomas H. Maugh II can be reached at thomas.maugh@latimes.com. Associated Press contributed to this report.

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