Reference ranges and sources of variation for indices of pulsed Doppler flow velocity waveforms from the uteroplacental and fetal circulation

Dear Sir, We have read the letters by your correspondents Drs Helm and Smith and Dr Wong. We apologize to the Frenchworkers (Giroud et a/. 1956) for missing their paper recording their original observations on the role of Chlamydia in human abortions and for our error of nomenclature in referring to cases of premature labour and fetal loss as miscarriage. Your correspondents raise points about the specific identification of Chlamydia psittaci of ovine origin in the case described by Johnson et al. (1985). We can merely reiterate that this Chlamydia isolate was not identified as an ovine C. psittaci strain in the paper published by Johnson et al. (1985). Subsequently Herring et al. (1987) identified this isolate as an ovine C. psittaci strain on the basis of restriction endonuclease analysis of chlamydia1 DNA. This paper was published after our paper was in press and this should have been obvious to your correspondents. We are, incidentally, unaware that the isolate reported by Buxton (1986) was identified as an ovine C. psittaci strain as this was not referenced in Dr Herring’s paper. We suspect that part of this problem arises from repeat publications of isolates previously reported making it unclear as to the pedigree of different reports. May we take this opportunity of repeating that it was Dr Herring who kindly identified our isolate as an ovine strain by restriction endonuclease analysis. Drs Helm and Smith comment on the mode of transmission which might have occurred in our case. We pointed out that a worrying aspect of this case was that the woman had no contact with sheep and we postulated that infection may have arisen as a result of her husband introducing the organism into the household fromcontamination of his clothing. This was speculative and we refrained from speculating even further to explain how she might have acquired the infection mechanically (as suggested by Drs Helm and Smith) in the absence of any acceptable scientific evidence. Other portals of entry could equally be postulated, i.e. the mouth and nose. Finally, we emphasized that our patient acquired infection in the absence of clinical disease in the sheep and with no apparent contact and so it seems obvious that all sheep contact is a risk to a pregnant woman. We are pleased that DrsHelm and Smith concur with thisview and for the need for wider publicity to the medical profession. D. V. McGivern E. 0. Caul Acute Services Unit Castlp Hill Hospital Castle Road, Cottingham North Humberside HU165JO