310

PELVIMETRY IN OBSTETRICSBy H. CECIL BULL, M.R.C.P.

Pregnancy is by the laws of nature the universalexperience of women, parturition no disease, anatural act, tending to become less natural aswoman ascends the higher reaches of civilization.The native girl of Ceylon undertakes marriageearly while the bones are soft and the muscleshard, pregnancy follows and parturition is aninterlude in the working hours. With the economicstresses of western life marriage is later, mal-formations of the skeleton more frequent, par-turition less easv and regard for life keener. Evenso parturition for the majoritv of western women isa natural event taking place under the kindly eye ofan elder or semi-skilled female friend.To this in the past Medicine has stood in

benevolent and advisory capacity, willing to helpwhen required. Now, the policy is to round uppregnant women and bring them all under medicalcare in the early stages. In this antenatal periodshe is examined to determine her general healthand to forecast the probable course of labour. Itis an important decision to which the doctor isguided by clinical judgment and the customaryobstetric measurements, crude but accessory aidsto build up the clinical picture.The pelvis has a certain geometrical shape, so

has the foetal head ; the soft parts are malleable toa degree, expulsion being effected by muscularcontraction provided the passage is adequate.The important factors therefore in prognosis are-knowledge of the pelvic canal and clinicaljudgment.Now we have with X-rays accurate methods of

measuring the diameters of the pelvic canal and ofthe foetal head as well as of checking the moreobvious difficulties-multiple pregnancy, abnormalpresentation and lie, anencephalic monster, etc.Full advantage is not made of these methods.Radiologists the world over have worked andwritten about it and it is difficult at first sight tounderstand why X-ray pelvimetry is not used inevery doubtful case. Radiology calculatesmathematically, determining the diameters of thepelvic inlet, midplane and outlet, and with approxi-mate accuracy the posterior sagittal diameters of

midplane and outlet, the surface areas of brim andmidplane and the biparietal diameter of the foetalhead. Besides this we have the positive evidenceof presentation and position, extended legs inbreech presentations, deformities, etc.

In radiology, diameter measurements are be-tween bony points and therefore greater than factbecause they do not take account of soft tissues.Clinically or radiologically we can forecast anormal labour in a pelvis of ample dimensions, orthe impossible delivery when the pelvis is con-tracted. The important group is the intermediatewhere there may be doubt of a living child ordanger to the mother. Here, neither clinician norradiologist is certain; every art and craft ofmedicine should therefore be impressed to save alife or forestall a danger. Of old, ' trial labour '

was recommended on the argument that thesecond labour would be easier, provided themother survived. Now the pendulum swings,perhaps overswings, in the opposite direction andwhere there is doubt there is Caesarean section.The gap between normal and impossible is toowide, and one way to narrow the gap is to en-courage and develop a closer harmony betweenclinical and radiological investigations.

In the first place there should be a certainstandardization of radiological technique, an agree-ment to accept some methods and reject others.Secondly, it should be recognized that radiologyintroduces rigid mathematics whose value can onlybe appreciated in conjunction with clinicaljudgment.

If radiology be accepted as a real help in fore-casting the course of labour, we must integrate thefigures produced in terms of obstetrical difficulties.This has been done by Allen (I947) whose table isan excellent beginning, though wide in its limits.The following paragraphs are concerned firstly

with the radiological measurements of the pelvisand calculations therefrom; secondly, with thevarious types of pelvis and, finally, with thedeductions that can be made from these observa-tions and their relation to obstetrical difficulties.Radiology undertakes:-

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JUIy 1949 BULL: Pelvimetry in Obstetrics 311

1. Measurements(a) PELVIC INLET

Anteroposterior (conjugate).Transverse.Right oblique.Left oblique.Area.

The anteroposterior is the shortest distance be-tween the symphysis pubis and the sacrum. Inmost patients the point on the sacrum is theanatomical promontory, but where there issacralization of the last lumbar vertebra and insome other subjects, the first two pieces of thesacrum may be straight instead of curving back-wards from the promontory; the shortest dis-.tance is then to the second piece of the sacrum.

Transverse-the widest diameter of the brim.Right and left oblique-from each sacroiliac joint

to the opposite pubic ramus. These measure-ments show if there is asymmetry of the brim butare not otherwise useful in diagnosis.

Anterior and posterior sagittal-intersection ofthe transverse with the anteroposterior diameter,divides the latter into anterior and posteriorsagittal diameters. These are of interest only inthe 'android' pelvis of Caldwell and Moloy(1935)-

The brimn area is calculated from the formula ofNicholson (1938)

7rabArea-~~

4where a conjugate.

b transverse diameter of inlet.The error is least in the round pelvis but area

measurements are necessarily inaccurate in an.imperfect geometric figure. This being born inmind, they are useful in showing the combinedvalue of the two diameters.

(b) MIDPLANEThe midplane is the area bounded in front by

the .symphysis pubis, behind by the sacrum frompromontory to the last piece excluding the coccyx,and laterally by the ischium, pubis and sacro-sciatic ligaments. For linear measurements ofthis space we take:--

Anteroposterior-from lower edge of symphysisto the lower end of the last sacral segment.

Lateral-the distance between the ischial spines.Posterior sagittal-from the midpoint of the

above lateral (bispinous diameter) to the lower endof the last sacral segment.Midplane area. Calculation is made from the

anteroposterior and lateral diameters according tothe formula

7rab4

where a= anteroposterior diameter of mid-plane.

b = transverse (bispinous).

(C) OUTLETThe transverse diameter is the distance between

the ischial tuberosities.No full anteroposterior diameter can be measured

because the protrusion of the head through thesubpubic arch cannot be measured. The onlylinear measurement possible is the ischio-sacral,i.e. from the midpoint of the transverse diameterto the last piece of the sacrum.

(d) SUBPUBIC ANGLENicholson (1938) gives 750 as the ' critical

angle, meaning that anything less than 750 islikely to lead to obstetrical difficulty. This is in-accurate as will be shown later.

Because of the variable shape of the pelvis noabsolute standards of normal can be given, but thefollowing is a list of diameter measurements andarea calculations, being an average of routinecases.Inlet Average normal about

Conjugate I20 mm.Transverse I28 mm.Right oblique I17 mm.Left oblique II7 mm.Brim area I20 sq. cm.

MidplaneAnteroposterior I20 mm.Transverse (interspinous) I00 mm.Posterior sagittal 43 mm.Midplane area 98 sq. cm.

OutletTransverse (intertuberous) I20 mm.

Anteroposterior (ischiosacral) 8o mm.Subpubic angle-8o0.Perpendicular-62 mm.

2. ShapePelves are classified by the shape of the inlet,

by the .roportion of the conjugate to the trans-verse diameter.

(a) Round (mesatipellic), the transverse diameteris equal or nearly equal to the conjugate.

(b) Long oval (dolichopellic or anthropoid), thetransverse is smaller than the conjugate.

(c) Flat (platypellic), the transverse is greaterthan the conjugate.

This relationship is expressed by the brimindex:

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312 POST GRADUATE MEDICAL JOURNAL Yuly I949

ConjugateTransverse

Brim IndexPer Cent.

Round pelvis 85 to IOOLong oval pelvis over iooFlat pelvis under 85A fourth, the triangular shaped pelvic inlet

where the rami tend to narrow anteriorly, hasbeen named the 'android' pelvis by Caldwelland Moloy (I935). It may be regarded as amodified anthropoid shape but is imnportant be-cause it leads to obstetrical difficulties. In suchcases nothing is learnt from the brim index. Theanterior narrowing of the pelvis means there mustbe more space posteriorly if the head is to passthrough. For recognition of the android pelvis weuse the relation of the posterior sagittal diameterof the inlet to the conjugate expressed as apercentage:

Posterior sagittalConjugate

It is not established how low this ratio may beto come into the classification of android. Opinionranges between 24 and 40. The formula appliesonly to the android pelvis and is not an index forother pelvic types.

3. PlacentaThe placenta can often be identified in shaded

films as a soft tissue shadow on the anterior orposterior wall of the uterus (Fig. 2).

CommentaryTo the pelhic brim most attention has been given

in obstetrics and it is from the pelvic brim that theclassification of types is derived. Most importantof the measurements of the brim has been and isthe conjugate diameter. The minimum diameterof the foetal head at term is 98 mm. ; if eitherconjugate or transverse diameter is less, the headwill not easily pass through.The relationship of the transverse to the con-

jugate is the other important brim characteristicexpressed as a percentage in the brim index.The oblique diameters measured from the sacro-liac joints to pubic rami are equal in thesymmetrical pelvis.

Shortening of the posterior sagittal diameter ofthe inlet is a feature of the ' android ' pelvis.There is as yet no agreement as to how low th

Posterior sagittalindex x ioo may be to beConjugateclassified as android, figures from 24 to 36 aregiven by various workers. It is suggested byAllen (I947) that 40 per cent. should be regardedas the dividing line, ratios below this being android.

In other words the normal posterior sagittalmeasurement is 40 to 50 per cent. of the length ofthe conjugate and when we find it to be less than40 per cent. we are dealing with an android pelvis.The small inaccuracy due to the slightly differentplane levels of conjugate and transverse diametersis not significant.The brim area calculated from the conjugate

and transverse diameters is but another, not veryaccurate figure expressing plane area. It would beaccurate if the pelvic inlet were a circle; in-exactitude grows in proportion as it departstherefrom.

MidplaneOnce through the brim in a normal pelvis the

head has more room to move and can rotate sincethe backward curve of the sacrum gives a greateranteroposterior diameter. There are, however,some sacrums which do not curve backwards andsome, indeed, which come a little forward so thatthe anteroposterior diameter between symphysisand sacrum is less than between symphysis andpromontory. The narrower diameter is then re-garded as the true conjugate. The straight sacrumis usually associated with a congenital anomalv ofthe first piece; either the last lumbar vertebrais sacralized or the first piece of the sacrumresembles a lumbar vertebra (Fig. 3).

Diameters of the MidplaneThe anteroposterior diameter of the midplane

from the inner surface of the svmphysis to the lastpiece of the sacrum might be called the outlet ofthe midplane. It is the smallest anteroposteriorlength of the midplane and varies with the forwardcurve of the sacrum. It is one of the essentialdiameters, rarely measuring as little as ioo mm.in the female, but if it does there will be difficulty,especially if the interspinous is also ioo mm. Thisanteroposterior measurement disregards the coccyxon the assumption that it will dislocate backwardsif necessary.The interspinous, the diameter between the

ischial spines, is an essential diameter throughwhich the full width of the head must pass. Thereis no slipping in front or behind it, the fact ofnarrowing here also meaning that the body of theischia below come together and the whole lengthof descent will be a close fit of approximately thesame transverse width as that between the ischialspines. A measurement below go mm. thereforeis on the danger level. The transverse diameterof the outlet (intertuberous) is proportional to theinterspinous. It is uncommon to find it less thanIOO mm. but, if so, it is an index of trouble, notso much on its own account but as a warning thatthe whole passage through the midplane is narrow.

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uly 1949 BULL: Pelvimetry in Obstetrics 3[3

........

:Mii

*'k:

Fi lGp

FIG. I.-Normal proportions.

...... ..

. . . .....

FIG. 2.-Placenta on posterior wall of fundus.

~~~.

*:w-l~~-*Ia E

FIG. 3. Sacralization. Breech presentation. The variousmeasured di'ameters are shown. The patient had twonormal births previously but this was complicated byan ovarian cyst. Caesarean section.

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314 POST GRADUATE MEDICAL JOURNAL Yuly. 1949

FIG. 4. Subpubic angle.

,,~ ~ ~ ........,: ,....,,.A'I.0U t2 z2 0 0 0 0 1 1i1 c1g.uP .. . . .............'.".'..'o.......2g,. 15 .' .................;...

*klE........."...u~'XB V !;SK,:;?; z % & . S:'

...5e:

:.Ri2<ye§2~~.! ^,- -?9&?lps 11 EX ~S S,,:.N 2'6,.::..,;,1:2>:.2.g.......

FIC. 5.-Antero-poster;()r.

r^ rrro|:s. ::.

'. ... .S ......................,..;.....:..:.'.....

~~~~~...

*::E-.efr s4.,::. ....:.:

s..-:r.°.l e:;: -:: .: .::: ~. .. :.:....-.:-.-.:;::-:. :-.. ::< :* -: . : : r ' :w':i -.:5 ~ ~ ..... ..........- t:':

~~~~~. .. ....... i''''l"'

y~. ...E

'... .'. .. :...

.. .....:: .:..: ::.:.:.-........... ....... :-

*. ... : '

- .... .: :: :: .. .: .:.:

.. .......

... ..i . ...: : : :

FIc. 6.-Laterl.11

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BULL: Pelvimetry in Obstetrics

Posterior Sagittal of MidplaneThe measurement from the midpoint of the

interspinous diameter to the last piece of thesacrum is an accessory help in determining theavailable space for the head in its final passage tothe outlet.The writer has not been able to appreciate the

value of the posterior sagittal measurement of themidplane. If the full anteroposterior diameter isadequate the posterior sagittal is of no con-sequence. If the anteroposterior is not adequatethe head will not pass. Similarly if the ischia cometogether and the transverse interspinous diameteris inadequate no power and no extra room behindthe spines will bring the head through.The bi-parietal diameter of the head at term

being 98 mm., any pelvic diameter of 98 mm. maycause difficulty, and when it is as small as 85 mm.passage of the head borders on the impossible.The most certain bar to progress is when the twodiameters, anteroposterior and lateral, of one planeare narrowed. Thus an anteroposterior and lateralof 95 mm. is a more likely stop than an antero-posterior of iIO and a transverse of 90 mm.OutletThis is the most difficult part of the pelvis to

reduce to terms of mathematics because of itspeculiar anatomical shape. The maximum trans-verse diameter of the outlet is the distance betweenthe ischial tuberosities and apart from gross de-formity is never a narrow diameter. This trans-verse diameter marks the division of the outletinto anterior and posterior triangles which lie indifferent planes. The anterior, subpubic trianglefaces forward, having sides formed by the ischio-pubic rami and base by the imaginarv transverseintertuberous diameter (Fig. 4). The posteriortriangle makes a wide angle with the anterior andfaces somewhat backwards. Its anterior boundaryis the intertuberous diarneter, the lateral walls thesacro-sciatic ligaments and the posterior limit thelast piece of the sacrum. The distance from themidpoint of the intertuberous diameter to the lastpiece of the sacrum is the anteroposterior or sagittaldiameter of this posterior area of the outlet, it isnot a measurement which has been employed inradiological pelvimetry and may be called theischiosacral diameter of the outlet.Too little attention has been paid in the past to

outlet measurements. Much has been written onthe size and shape of the inlet and we can forecastwith fair accuracy whether or not the head willpass through the brim. If our judgment is atfault there is still time to delivery by Caesareansection. Once through the inlet there is spaceenough for movement through the midplane, butdifficulty may begin in the last act, the passing of

the head through the outlet. It is no longerpossible to go back; it is late for Caesareansection, the head is moulding perhaps excessivelyand the child must be delivered soon; forcepsare necessary but increase the risk of damage tothe head and if force is used may result in atentorial tear.Such disasters and near-tragedies still happen.

They should be largely avoided if all the helpmodern science can give is correctly brought tobear. Because the head is capable of mouldingand the sacroiliac joints allow some backwardmovement of the sacrum, much is left to chance.Let us consider the matter mathematically fromthe limits of the fixed bony points to see whetherit is not possible to anticipate trouble. In sodoing the writer sees no reason for making allow-ance for moulding of the head. Moulding is anundesirable, however common, insult to the foetalhead and slight moulding is accepted only as acompensation for small errors of calculation. Inthe interests of the breed, extreme moulding andthe use of forceps to overcome mechanical dis-proportion should be discouraged.We have already noted that the transverse

diameter of the outlet is adequate. The difficultiesresolve themselves, therefore, into the measure-ment of the anteroposterior diameter and of theangle of the pubic arch. In default of obtaining alarge number of pelves correctly articulated andnot too dry for experimental test, the writer hasused a geometric figure, a ball of ioo mm. diameterand a variable subpubic angle and ischiosacrallength. The rami of the subpubic arch were keptconstant at IOO mm. (a little greater than theaverage normal) and two characteristic inter-tuberous diameters of 115 and I25 mm. were usedas base lines (Figs. 5 and 6). It may be that theresults can be expressed as a formula but they canbe understood and appreciated more easily asgraphs; no reason appears for believing that thefacts which emerge differ materially from those ofthe pelvis in life.

For experimental purposes the foetal head maybe looked upon as a circle of ioo mm. diameterwhich is approximately the biparietal or minimumessential diameter of the uncompressed head. Inorder that the head may pass through the outletthe anteroposterior and lateral diameters musteach measure not less than ioo mm. The antero-posterior diameter consists of the ischiosacraldiameter plus the distance the head can pushthrough the pubic arch above the tuberosities. Ifwe imagine for a moment that the pubic arch isfilled in by a rigid membrane then the antero-posterior diameter is easy to measure; it is theischiosacral diameter and must be ioo mm. longif the head is to pass. But the ischiosacral diameter

YulY I 949 315

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3I6 POST GRADUATE MEDICAL JOURNAL July 1949

is usually less than ioo mm.; in fact, it averages8o mm. The additional length is obtained by thehead passing partway through the pubic arch assoon as the divergence of the rami allows, and bybackward rocking of the sacrum. A mistaken con-ception of the geometrics of the pubic arch hascrept into the literature. It is written that a wideangle of the pubic arch makes for ease in deliveryand that difficulties may be expected when thearch is narrow. The converse is the geometrictruth; the narrower the angle the easier for thehead to come forward.The anteroposterior measurement of the outlet

cannot be assessed as a simple figure since, asnoted above, it consists of two parts-the ischio-sacral from the midpoint of the intertuberousdiameter Ito the last piece of the sacrum, and theindefinite space the head may occupy by pushingforward through the subpubic arch. This antero-posterioi ' space ' of the outlet is best resolved intwo graphs using the intertuberous diameter as abase line and taking note of the perpendicularmeasurement from the subpubic angle to the baseline, the ' ischiosacral ' from the base line to thesacrum, and the subpubic angle. The graphs(Figs. 7 and 8) demonstrate that the lengths desir-

DegreesSubpubic Angle

7o.

70o 7sTOMillimetres

FIG. 7.-Jschiosacral diameterGraph A.

Perpendicular to Base lineMillimetres

lpp

70 \_\_l

6o

;7' 79 rg o 7

MillimetresFIG. 8.-Ischiosacral diameter.

Graph B.

able to secure an easy passage are the perpendicularof the subpubic angle and the base line. Theangle which the rami make as they come togetheris of secondary importance and since individualrami do not vary greatly in length the narrower thesubpubic angle the greater will be the ease ofpassage, given an adequate base line width. Thenecessary length required of the ischiosacraldiameter is shown on the graphs and need onlybe a large one when the subpubic angle is wide,the perpendicular short and the base line narrow.It must be added, however, that this ischiosacraldiameter which is measured in the still subject isby no means a fixed diameter during parturition.It is a diameter which is increased in length by thebackward movement of the sacrum, an increasewhich varies with the age of the patient and themobility at the sacroiliac joints.

Graph A shows that a biparietal diameter ofIOO mm. requires an ischiosacral measurement of89 mm. when the subpubic angle is go9, whereas8z mm. is sufficient for an angle of 700, the baseline berng I 5 mm. in each case. As the base lineincreases, the need for length in the ischiosacralline decreases, but the decrease is proportional tothe subpubic angle (or perpendicular bisector ofthe base) and the graphs are straight lines(Graph B).

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J7uly 1949 BULL: Pelvimetry in Obstetrics . 317

It will be seen that the important linear measure-ments of the outlet are the transverse (inter-tuberous) diameter and the perpendicular to itfrom the subpubic angle. Knowing these measure-ments we can postulate the length of the ischio-sacral diameter necessary for the head to passthrough.We progress so far by reducing labour to a

geometric figure and one feels that it expresses abasic truth correcting some of the minor errors.It does not follow in practice, however, that rigidmeasurements constitute a bar to natural delivery.We find that the ischiosacral diameter can fallshort of the desired length by anything up to I5mm. without obstructing delivery. This is heldto be due chiefly to the backward rocking of thesacrum which results from loosening of the sacro-iliac joints during pregnancy and which is atpresent immeasurable and likely to be variable indifferent subjects.

This is one of the problems in which radiologyextends help to the limits of its ability and invitesthe cooperation of clinical obstetrics to assess itsvalue. The argument cannot be accepted thatpractice bears no relation to theory merely becausenature can make an extra effort to overcomedifficulties. There is a point beyond which noeffort will be successful and we should be able tomake better forecasts of whether or no it is possibleto deliver naturally without injury to mother orchild.

Table of Pelvimetry ValuesA table of values wherein to check results and

read off the chances of easy or difficult deliverywould be a helpful summary. Such a table is noteasily compiled ; the diameters are too intimatelyrelated. The accompanying table (Fig. 9) is anaverage of normal cases wherein the diametershave been sufficient for natural birth, and with itare shown measurements theoretically inadequatefor the passage of a foetal head at term.

Allen gives a guide to prognosis which is avaluable lead in this direction but suffers from thesame disadvantages. His upper limits in which

vaginal delivery is certain are above those of theusual normal.The foetus makes full use of the available space

between the bony points and for most women it isa close fit, however adequate. The interspinous isan important diameter and it is interesting to notethat the average measurement does not allow muchover the minimum. It is not a diameter thatvaries greatlv and, of course, the head can passeven when it is less than go mm., but mustinevitably be compressed in passage.The least informative in this table are the outlet

measurements since they are more interdependentthan any of the others.

ConclusionRadiology endeavours to give all the help it can

by pelvimetry in obstetrics. The best line ofapproach has not yet been reached a-nd the writerhas outlined within his own knowledge theaccepted measurements and calculations of theinlet and midplane. There is less unanimity aboutoutlet measurements and in these he has writtenhis own views and how those views have beenreached. They are offered for criticism byradiologists and obstetricians in the hope that bytheir experience they will modify or amplify thefindings of the geometrics of the pelvic outlet.The difficulty often mentioned in this article is

to link up the known with the unknown, that is torelate fixed diameters to variables. The con-clusions here expressed are based on the law thatan object of certain size will not pass through achannel smaller than itself. Radiological pel-vimetry must take its stand here and propoundthe theoretical view of obstetrics according to thecalculations of its own science. It only confusesthe issue if we begin to make allowance for thevariable and immeasurable factors such as mould-ing of the head and movement of the sacrum at thesacroiliac joints. Such factors lie in the realm ofthe obstetrician.

It is the purpose of radiology to supply allpossible information to the clinician in such manneras may be most useful to him. There are many

FIG. 9

INLET MID-PLANE OUTLET

Inter- -Ischio-

Conj. Trans. Area A.P. Spi. Area Trans. Perp. sacral

Average measurements. Natural de- 120 128 I20 120 100 98 120 75 8olivery should be possible mm. mm. sq. cm. mm. mm. sq. cm. mm. mm. mm.

Natural delivery theoretically im- 95 95 78 95 95 78 95 55 70possible mm. mm. sq. cm. mm. mm. sq. cm. mm. mm. mm.

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3I8 POST GRADUATIE MEDICAL JOURNAL JulY 1949

factors in obstetrics besides mathematics, andjudgment will be made oi the case as a whole,pelvimetry forming a small but important part ofthe evidence.

It is to be hoped that if radiological pelvimetrycan be standardized and put into general use, acloser correlation may be achieved and a moreaccurate forecast of difficulties obtained by a studyof pelvimetric results.

AcknowledgmentsApart from the books and articles of which a

few only are mentioned I am grateful for thiefacilities given me in the examination of pelves by

Dr. Joseph of the Department of Anatomy of theUniversity of London, Dr. Delmas of the Institutde M&d1cin of Paris and Dr. Horin, AssistantObstetrician to the Maternity Hospital, PortRoyal, Paris.

BIBLIOGRAPHY

ALLEN, E. P. (1947), Brit. .7. Rad., 20, 45, IoS, I64, 20S.CALDWELL MOLOY, and D'ESOPO (193s), Am. Y. Obst. and

GYn., 30,793NICHOLSON, C. (1938), Obst. and Gyn., BEit. Emp., 45, 950.PIZON, PIERRE (1948) 'Radiodiagnostic Obstetrical, I'Ex-

pansion Scientifique Francais.'REECE, L. N. (193S), Proc. Roy. Soc. Med., 489.WILLIAMS, E. R., and PHILLIPS, L. G. (Ir946),.Y. Obst. and

Gyn., Brit. Emp.

SIR JAMES YOUNG SIMPSON

Sir James Young Simpson (i8i8-I870) was born and educated in Edinburgh. His greatability and fascinating personality resulted in his appointment to the chair of Obstetrics inI840. Following his introduction of ether to midwifery he experimented in other less un-pleasant agents until in I847 he published the results offive cases anaesthetized with chloro-form. His advocacy of the use of anaesthesia in childbirth involved him in prolonged andbitter controversies, which were only ended in i853 when Queen Victoria herself receivedchloroform at the birth of Prince Leopold. His great inventive powers led to the introductionof the long obstetric forcep, uterine sounds, sponge tents and the use of dilation of the cervixuteri as a diagnostic measure.

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