SummaryA retrospective study of postoperative respiratory morbidity in 247 patients requiring renal transplantation between 1955 and 1973 showed that 7 patients required postoperative controlled ventilation for up to 6 days. The non‐depolarising relaxants tubocurarine and pancuronium were used in only 65 patients, but all 7 cases of respiratory failure occurred in this group. This suggests that the use of these drugs in anephric patients is potentially hazardous so far as postoperative respiratory insufficiency is concerned.

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We describe three cases of ovarian ectopic pregnancies with an intrauterine device (IUCD) in situ, and suggest that prostaglandins may have played a major part in this combination. The IUCD alters the ratio of the prostaglandins secreted, so that tubal peristalsis is reversed and the fertilised ovum is carried the opposite way. Case reportsThree multigravidae presented with varying degrees of abdominal pains. All of them had suffered from menstrual irregularity of recent duration, and all had had Lippes' loops inserted for over two years. X-ray films confirmed that the device was in position in each case. Laparotomy showed rightsided cystic ovarian swelling in one case and left-sided in the other two. The other ovary and both Fallopian tubes in each case were intact and uninvolved. Ovarian tissue was conserved in two cases, but the ovary had to be removed in one because of heavy, uncontrollable bleeding. The pathologist reported the histological features of pregnancy in the tissue excised. DiscussionOvarian pregnancy is very rare, a ratio of 0 7 ovarian per 100 ectopic pregnancies having been suggested.' Women who wear an IUCD appear to have higher incidence, a ratio of one ovarian to nine ectopic pregnancies having been reported.2 Our cases fulfil the diagnostic criteria formulated by Spieglberg.3 Very little is known about the mode of action of the IUCD. It has been claimed that it distorts and distends the uterine cavity and thereby impairs its tonicity, or that it causes a foreign body reaction with leucocytic infiltration resulting in an environmental hostility to the ovum or that the macrophages phagocytoze the sperms. This spermatotoxic or blastotoxic hypothesis cannot explain the high relative frequencies of both tubal and ovarian ectopic pregnancies in patients fitted with IUCDs. Lehfeldt et all suggested that the antifertility effect is maximal in the endometrium, weaker in the tubes, and absent beyond that-that is, about the ovary. This pattern, they thought, suggested direct enzymatic or chemical action, possibly by retrograde flow from the endometrium outwards.We suggest that perhaps the chemical action is due to a substance resembling prostaglandin, which is secreted abundantly from the endometrium causing contractions and preventing implantation. Prostaglandin is also secreted from the fallopian tubes but in lesser amounts. Nevertheless, it is not secreted from the non-contractile ovaries.Alternatively, possibly the IUCD alters the ratio of the amount of the prostaglandins secreted. Therefore, instead of the normal contraction of the proximal part of the tube and relaxation of the distal segments, causing a suction action which favours the entrance of the ovum from the abdominal cavity into the tube, and its retention in the oviduct until fertilisation,4 the reverse occurs and the reversed suction and peristaltic action of the tube (due to the effect of the altered ratio of prostaglandins) will carry the ovum the opposite way. This hypothesis could also explain the reported cases of peritoneal p...