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premature amniorrhexisFrom: cstewart (cstewart@global.co.za)Tue Mar 26 06:09:48 1996
On 23 March, dahmd@ gate.net (Ashley Hill) wrote: > I would hesitate to perform an amniocentesis on a patient who is very > premature ... because I would be more worried about a false positive result. While we accept that one of the risks to the pregnancy resulting from PPROM is prematurity and the complications thereof, expectant management in order to prevent this lays the mother and fetus open to the risks of infectious morbidity and mortality. In balancing the one versus the other it is reasonable to try and prolong the pregnancy if the population-specific infection rate is low. However, it must be born in mind that the prolongation of the pregnancy is always at the potential expense of an increased sepsis rate. In order to make this increase in sepsis rate acceptable, every effort must be made to identify those patients with either clinical or subclinical infection timeously. The methods used in this regard have included clinical features ( temperature, tachycardia, fetal tachycardia which tend to be late signs), white cell counts and CRPs and amniocentesis. Whether an amniocentesis is regarded as positive or negative depends on the parameters measured. Gram stain for white cells or organisms certainly has a reasonable specificity though poor sensitivity. Culture yields somewhat better results. The tests which show the best correlation with infection are low amniotic fluid glucose and interleukin-6. IL-6 has sensitivity of 79% and specificity of 100% in predicting histologic chorioamnionitis; specificity of 79% in predicting significant neonatal morbidity (Yoon, Romero et al). Low amniotic fluid glucose also has specificity of 100%, though lower sensitivity (Greig). Thus false positives are not a problem though false negatives still are. If the aim of an amniocentesis is to detect infection with the realisation that this may result in morbidity to the mother, fetus or both, then it should be done at any gestational age. Avoiding it at < 28 weeks while doing it at 32 wks is just hiding one's head in the sand. If a positive result is obtained then the appropriate management should be undertaken; either antibiotics or induction. It appears from the literature that the majority of people would not continue conservative management in the face of a positive amnio. Any comments? Finally, recognising the problem of a negative amnio if done too early after the PPROM, there is certainly evidence to suggest that biophysical profile may have similar predictive value as amniotic fluid culture. This also has the advantage of easy repetition. 1.Yoon BH, Romero R et al.( 1995) Amniotic fluid Interleukin-6: a sensitive test for antenatal diagnosis of acute inflammatoy lesions of preterm placenta and prediction of perinatal morbidity. Am.J Obstet Gynaecol 172(3): 960-70 2. Greig PC, Ernest JM & Teot L. (1994). Low amniotic fluid glucose levels are a specific but not a sensitive marker for subclinical infections in patients in preterm labour with intacy membranes 3. Vintzeleos AM, Campbell WA et al (1985).The fetal biophysical profile in patients with PPROM. An early predictor of fetal infection. Am.J Obstet Gynaecol 152:510 Thanks Chantal Stewart Consultant Obstetrician & Gynaecologist University of Cape Town S.A.
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