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Re: 'signs of infection'From: Mats Bergstrom (matsb@cor.sos.sll.se)Fri Jan 10 20:09:06 1997
On Fri, 10 Jan 1997 rbraun@indyunix.iupui.edu wrote:
> steroids and wait for "signs of infection" before we deliver. Signs of Basically I agree, but: I was part of a workgroup studying the literature on this subject a few years ago. There isn't any widely accepted definition of chorioamnionitis in pregnancy. Fetal tachycardia is stressed by many authors, but this can sometimes be secondary to maternal fever of unrelated causes (epidural, labor). Uterine tenderness is a basic criterium in some studies (I guess they studied only really bad cases). WBC, as in most kinds of infection, is not very reliable. CRP might be better. Counting bacteria in an amniocentesis sample could be the most accurate test, leukocyte esterase activity in amniotic fluid is probably less accurate. The uncertainty of all these diagnostic signs is evident in studies which compare them to post delivery examinations of the afterbirth and to neonatal morbidity. Fever is a relative phenomenon, not so much in a PPROM without contractions but certainlly in labor; much the following discussion is a bit removed from the origins of this thread but could be of related interest: Cohlstein (1875) discovered that the pregnant uterus is warmer than the vagina, postulating fetal heat production. Galabin (1886) and Hirst (1888) pointed to maternal temperature rise during normal labor associated with elevated FHR. Adamsons and Towell (1965) were the first to publish in modern times on thermal hemostasis in the fetus and newborn, establishing the phenomenon of fetal heat loss across the placenta. Walker and Wood (1969, 1970) studied the relation between fetal temperature and FHR, a slight rise in the former causing a more pronounced rise in the latter. They found that the rectal temperature of the newborn is 1 degree F above that of the mother. Marx and Loew (1975) measured a reversible elevation of maternal tympanic temperature during a labor contraction, <0.2 degrees C. The cumulative mean rise in maternal temperature during the labor phase was 1.46 degrees C in primipara, 0.51 in multipara. Abrams (1978) experimented on sheep and made the theoretical calculation that if the umbilicus was completely shut off (but the fetus would continue it's heat production unresisted) the fetal temperature would rise 0.57 degrees C per minute. Several studies have shown a significant elevation of maternal temperature caused by epidural anesthesia. Goodlin and Chapin (Am J Obstet Gynecol 1982) found a close relationship of the temperature of the posterior fornix and the fetal temperature. They postulated that placental failure causes fetal fever, and that this in turn is one of the causes for fetal tachycardia seen with placental insufficiency, and concluded: "The clinical implications of this study may be that temperature recordings are relatively uninterpretable in many pregnant women during labor."
-- Mats Bergstrom, MD Ob Gyn South Hospital Stockholm
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