No abstract

Objective To compare assisted vaginal delivery by forceps with delivery by vacuum extractor, where a new vacuum extractor policy was employed which dictated the cup to be used in specific situations. Design Multicentre randomised controlled trial. Setting Four district general hospitals in the West Midlands. Subjects Six hundred‐seven women requiring assisted vaginal delivery, of whom 296 were allocated to vacuum extractor delivery and 311 to forceps. Main outcome measures Delivery success rate, maternal perineal and vaginal injuries, maternal anaesthetic requirements, neonatal scalp and facial injuries. Results Of the vacuum extractor group, 85% were delivered by the allocated instrument compared to 90% in the forceps group (odds ratio (OR) 0.64; 95% confidence intervals (CI) 0.4–1.04). However, more women in the vacuum extractor group were delivered vaginally (98%) than in the forceps group (96%). There were significantly fewer women with anal sphincter damage or upper vaginal extensions in the vacuum extractor group (11%vs 17%, OR 0.6; 95% CI, 0.38–0.97). There were significantly fewer women in the vacuum extractor group requiring epidural or spinal anaesthetics (25.4%vs 32.7%, OR 0.69; 95% CI 0.49–0.99) or general anaesthetics (1%vs 4%, OR 0.17; 95% CI 0.04–0.76). Although there were significantly more babies in the vacuum extractor group with cephalhaematomata (9%vs 3%, OR 3.3; 95% CI 1.4–7.4) there were fewer babies in the vacuum extractor group with other facial injuries. There were three babies in the forceps group with unexplained neonatal convulsions. Conclusions Assisted vaginal delivery using the new vacuum extractor policy is associated with significantly less maternal trauma than with forceps. Further studies are required to assess neonatal morbidity adequately.

The factors that determine progression of cervical intra-epithelial neoplasia (CIN) to squamous cell carcinoma (SCC) are unknown. Cigarette smoking is a risk factor, suggesting polymorphism at loci that encode carcinogen-metabolizing enzymes such as glutathione S-transferase (GSTT1, GSTM1) and cytochrome P450 (CYP2D6) may determine susceptibility to these cancers. We have studied the frequency of the null genotype at the theta class GSTT1 locus in women with low-grade CIN, high-grade CIN and SCC. The control group comprised women with normal cervical pathology suffering menorrhagia. We found the frequency of GSTT1 null in the control and case groups was not significantly different, though frequency distributions of combinations of the genotype with smoking in mutually exclusive groups in the high-grade CIN group and the other case groups were significantly different. Interactive effects of GSTT1 null with the GSTM1 null and CYP2D6 EM genotypes, and cigarette smoking were also studied by comparing the multinomial frequency distributions of these factors over mutually exclusive categories. These showed no significant differences between the controls and SCC or low-grade CIN. Frequency distributions in high-grade CIN, however, were significantly different to the controls, and both SCC and low-grade CIN; frequency distributions of GSTT1 null with smoking and CYP2D6 EM, individually and in combination, were significantly different. However, inspection of our data does not indicate that GSTT1 null is a major factor mediating risk. Thus, comparison of chi 2 values for the differences between frequency distributions in high-grade CIN and other groups shows that values for combinations of GSTT1 null with other factors are lower than those for equivalent combinations with smoking and CYP2D6 EM. Interestingly, the combination GSTT1 null/GSTM1 null did not appear to influence susceptibility to CIN or SCC.

No abstract

Hospital. Stoke-on-Trent. Staffordshire ST4 7QB, LK.Summan The factors that determine progression of cervical intraepithelial neoplasia (CIN) to squamous cell carcinoma (SCC) are unknown. Cigarette smoking is an independent risk factor for cervical neoplasia. suggesting that polymorphism at detoxicating enzyme loci such as cvtochrome P450 CYP2D6 and glutathione S-transferase GSTM I mav determine susceptibility to these cancers. We have studied the frequencies of genotypes at these loci in women suffering low-grade CIN. high-grade CIN and SCC. A non-cancer control group uas pros ided by women with normal cervical histology suffering menorrhagia. Comparison of the frequency distributions of the CYP'D6 PM. HET and EM genotypes (G-*A transition at intron 3 exon 4 and base pair deletion in exon 5) revealed no significant differences between the menorrhagia and SCC groups. Frequency distributions in the menorrhagia group. however, were significantlv different (P <0.04) from those in the lou-and high-grade CIN groups. Thus. the proportion of EM was significantly larger (P <0.03) and of HET generally lower. We found that the frequency of GSTMI null in the menorrhagia and case groups was not significantly different. Interactive effects of enzyme genotypes with cigarette smoking were studied bv comparing the multinomial frequency distributions of CYP2D6 EM GSTMI null smoking over mutuallv exclusive categories. These showed no significant differences between the menorrhagia group and SCC or low-grade CIN groups. The frequency distribution in high-grade CIN. however. was significantlv different to that in the menorrhagia group and in both SCC and low-grade CIN groups. This study has identified, for the first time. an inherited characteristic in women with high-grade CIN who appear to be at reduced risk of SCC. Thus. women with CYP2D6 EM who smoke have increased susceptibility to high-grade CIN but are less likelv to progress to SCC. possibly because they effectively detoxify an unidentified chemical involved in mediating disease progression.