811

punishment, school uniform, prefect systems, and awhole lot more. From this the team built up a pic-ture of how particular practices correlated withpupil behaviour and examination success.The "good" school offers few surprises. It is a

place where discipline is firm but humane and aca-demic emphasis is strong and consistent; teachersturn up on time and work conscientiously; home-work is set and marked; there are likely to be pre-fects, school uniforms, and many of the trappingsof the traditional school (though not much corporalpunishment). There is ample praise and encourage-ment for success. Teachers are not out on a limb,but under the supervision and guidance of theirhead of department.To the layman outside the schools, all this may

sound sensible to the point of banality. The mostworrying thing, perhaps, is that RUTTER and his

colleagues had to devote 9 years to proving it. Notso: this is going to be a book which sets offresonances throughout the education service. Itreinforces the more conservative tendencies now atwork in British education, providing a reasonedbasis for a trend which is already present (andwhich will be reflected in the Department of Edu-cation and Science’s curriculum review to be pub-lished shortly, and by the Inspectorate’s secondaryschool survey later in the year. There are, -of

course, plenty of loose ends-including the statisti-cal arguments which usually linger over the use ofmultivariate analysis in this way. The actual testsand questionnaires need to be examined in detail tosee if the surrogates used to establish particularcharacteristics of schools can bear the weightattached to them. But the importance of this booklies less in the elegance of its research methods thanin the central point it is making-a point which ismore philosophical than statistical-namely, thatresponsibility for teaching and learning cannot beshifted from the individual pupil and teacher toexternal and impersonal forces. Genes and socialclass may be important, but the job_of the schoolsis to help people make the best of whatever handof cards they have been dealt.

MISSING THREADSA SUBSTANTIAL number of women fitted with an intra-

uterine contraceptive device (I.U.C.D.) are referred to

hospital gynaecological departments with the markerthreads missing. The incidence of this complication is

uncertain, but some of the causes are well recorded.Expulsion-rates vary, with device, from 2 to 20%, andabout 20% of patients are unaware of the expulsion.2Translocation occurs in 0.05 to 13 per 1000 insertions.l

Pregnancy may cause the threads to retract, owing touterine enlargement, and the pregnancy-rate with a cor-rectly positioned LU.C.D. is 1-4% of women in the firstyear after insertion, becoming lower in succeedingyears. In most cases of missing threads, the I.U.C.D. is in

1 Gentile, G. P., Siegler, A. M. Obstet. gynec. Surv. 1977, 32, 627.2 Tietze, C. and Lewit, S. Stud. Fam. Plann. 1970, 1, no. 55. p. 1.

the uterus without pregnancy. With the Lippes loop thethreads may become retracted in as many as 10% of in-sertions.4 The packaging of the ’Gravigard’ (copper 7)partly loaded with the thread looped alongside it mayparticularly predispose to thread retraction.I.5

At a family-planning clinic, investigations are usuallylimited to excluding pregnancy and ensuring that thethreads are not accessible within the cervical canal, byexploration of the canal with forceps or a cotton-wool-tipped swab. When pregnancy has been excluded, someworkers sound the uterus in the hope of locating thedevice, though the newer devices are not easily palpatedand the investigation may be inconclusive or franklymisleading. Specialist referral usually follows. Ultra-sound is the safest and most reliable investigation,3,6 6being greatly preferable to previous methods such asplain X-ray,’ hysterosalpingogram,8 fluoroscopy,9 hys-teroscopy,10 or the ‘Beolocator’.4 Ultrasound will alsodiagnose pregnancy within 4 weeks of conception. Ifultrasound fails to show the device within the uterus, a

plain abdomen X-ray will differentiate between expul-sion and translocation. If the l.u.c.D. is correctly pos-itioned and the patient is not pregnant, some workersadvise no further action,’ but most patients request re-placement or removal of the device. This may be spe-cially true of the group who regularly check that theycan feel the threads." Removal is commonly done undergeneral anaesthesia, which means a wait for hospitaladmission, the risks of anaesthesia, and considerableexpense. Evans 12 calculated that in the United States in1972 the hospital cost of this procedure averaged$240’8 and estimated that, if such admissions could beavoided, the saving in hospital costs would exceed halfa million dollars even if there were as few as 600 0001. U. C. D. S in use.

Outpatient procedures for removing LU.C.D.S with

missing threads have been applied with variable successand discomfort to the patient. These include hystero-scopy,to exploration of the uterine cavity with an endo-metrial biopsy curette8 or hook," or even insertion of asecond I:U.C.D. which when removed later may bringdown the thread of the first. I2 Guillebaud andKasonde 14 have reported a method for retrieving missingthreads with a 4 mm disposable vacuum aspiration cur-ette which they believed suitable for use by trained per-sonnel in the normal family-planning clinic milieu. Themethod may require local anxsthesia for cervical dila-tation, which limits its application outside hospital andmay explain why it has not been widely accepted.

This is the background to the work of Dr Husemeyerand Mr Gordon of Northwick Park Hospital, who on p.807 this week describe the use of a simple plastic devicefor the retrieval of missing threads. If their results areconfirmed by larger series, this instrument may provesuitable for clinic use (in women known not to be preg-nant), sparing many patients of anxiety and risk andhealth services of much money.

3. McArdle, C. R. Obstet. Gynec. 1977, 51, 330.4. Rosen, E. Am. J. Obstet, Gynec. 1965, 93, 896.5. Sparks, R. A. Br. Med. J. 1977, ii, 1351.6. Meire, H. B. Renton, P. ibid. 1977, i, 713.7. Frampton, J. ibid. p. 445.8. Ansari, A. H. Obstet. Gynec. 1974, 44, 727.9. Spence, M. R. ibid. 1975, 45, 693.

10. Siegler, A. M., Kemmann, E. ibid. 1975, 46, 604.11. Chamberlain, G. Br. med. J. 1978, i, 23712. Evans, G. T. Obstet. Gynec. 1974, 44, 155.13. Sapiro, A. G. ibid. 1977, 49, 238.14. Guillebaud, J., Kasonde, J. ibid. 1974, iv, 167.