PREDICTION OF MATURITY IN FIRST TRIMESTER OF PREGNANCY BY ULTRASONIC MEASUREMENT OF FETAL CROWN-RUMP LENGTH by A. Kurjak, S. Cecuk,* and B. Breyer

ABSTRACT Three hundred ninety fetal crown-rump measurements by ultrasound echography were performed in order t o correlate the crown-rump length with gestational age between the sixth and fourteenth weeks of gestation. A blind trial in 58 patients showed a good correlation of ultrasonically determined age and menstrual age. A graph of normal values was designed and is currently being used in routine work.

Indexing Words Crown-rump Early Pregnancy

Gestational Age

Biometry Ultrasound

measurements would be offset by better insight into real growth (2, 3). Following essentially the It is well known that any method providing method of Robinson ( l ) , we performed 390 reliable information on fetal maturity, growth examinations in 220 women, all of whom had rate, and size which can be used to screen large normal menstrual cycles and knew the dates of numbers of patients will be an important factor their last menstruation. Normally the fetal echo in reduction of perinatal mortality and would first be identified and then enlarged t o an morbidity. approximately life-sized picture on the screen. It is a general rule that the earlier the fetus is Taking the exact scale factor into account, the measured the more accurate will be the maturity fetal length could then be measured on the prediction. Recently, Robinson from Glasgow screen or from a Polaroid photograph. Fetal life obtained the earliest measurements during the T.P. scan and by was confirmed by.making a embryonic period by measurement of the fetal showing the fetal heart movement. The apparacrown-rump length ( 1 ) . This is done by identifying the embryonic echo within the gestational tus used was a Diasonograph NE 4102. Nominal sac on the longtudinal scan to establish the posi- frequency was 2.5 MHz and nominal caliper tion of the embryonic long axis, enlarging the sound velocity was set t o 1600 M/sec. A full bladder was essential for this examinapicture t o life size and measuring the crowntion. In several patients whose bladders were not rump length on the scale. Using this method completely filled, we were unable to identify the Robinson has achieved extremely accurate prefetus, but second examinations taken with a full diction of maturity. Stimulated by the investigabladder were successful in all cases. tion of Robinson, we decided t o start our own 1 and 2 illustrate the rapid growth of Figures fetal crown-rump measurements. the fetus at this early stage of pregnancy. INTR 0D UCTION

MATERIALS AND METHODS

In deciding to measure crown-rump length as RESULTS opposed to measuring the area of the gestational Using the results of our measurements, we sac, we hoped that the problems in fetal echo designed a chart showing normal crown-rump From t h e University Gynaecological Hospital, Petrova 1 3 , length values which we use in routine examinaZagreb, Yugoslavia; *Khnicka bolnica “Dr. M. Stojanovic,” tions. The graph is reproduced in Figure 3. Vinogradska cesta. Zagreb. Yugoslavia. It can be seen that standard deviations are Received August 6 . 1 9 7 5 ; revision accepted December 5, 1975. smallest between eighth and eleventh weeks. We For reprints, contact: B. Breyer. University Gynaecological attribute the slightly higher measurement variHospital, Petrova 1 3 , Zagreb, Yugoslavia. VOLUME 4. NUMBER 2

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FIGURE 1. Fetal echo a t eight weeks and three days. C-R length

20 mm.

FIGURE 3. Normal graph used for fetal maturity assessment on the base of crown-rump length measurement.

reliable, it requires a good deal more practice and experience than cephalometry and is more dependent on the imaging properties of the diagnostic machine. If these factors are taken into account, we feel that the crown-rump length measurement is an acceptable routine technique for estimating fetal age. ACKNOWLEDGMENT

The cooperation of Dr. I. Olajos is kindly acknowledged. FIGURE 2. Fetal echo a t twelve weeks and one day. C-R length 50 mm.

REFERENCES

ability at the lower end of the scale t o identify errors. The increased margin of error at the upper end of the scale can be attributed to the higher incidence of biological variations in more mature fetuses and t o angulation (alignment) errors in routine work. To check these results, we performed a double-blind trial. Fifty-eight patients whose menstrual histories were known were examined. Their gestational ages as determined by ultrasound were compared with their menstrual ages (4, 5 ) . Good correlation was obtained, with a correlation factor of 0.958. DISCUSSION

The results of our investigation are summarized in Figure 3. This graph is now in regular use in our department. The results obtained with crown-rump length measurements match very well with the subsequent cephalometry . Although this technique has proved to be quite a4

1. Robinson HP: Sonar measurement of fetal crownrump length as means of assessing maturity in first trimester of pregnancy. Br Med J 4: 28,1973. 2. Hellman LM, Kobayashi M, Fillisti L, and Lavenhar M: Growth and development of the human fetus prior to the twentieth week of gestation. Am J Obstet Gynecol 103: 789,1969.

3. Jouppila P: Ultrasound in the diagnosis of early pregnancy and its complications. Acta Obstet Gynec Scand Suppl 15,1971. 4. Kurjak A, Drazancic A, Olajos I, Gorecan V, Latin V, Kuvacic I, Polak J: Ultrasonic biometry in intrauterine growth surveillance. Proceedings of the Symposium “Perinatal days 1974,” Zagreb, Yogoslavia, 1974. (in press) 5. Kurjak A, Cecuk S: Prediction of maturity in first trimester of pregnancy by ultrasonic measurement of fetal crown-rump length. Proceedings of the 2nd European Congress on Ultrasonics in Medicine, Munich, 12-16 May 1975. (to be published) JOURNAL O F CLINICAL ULTRASOUND

Prediction of maturity in first trimester of pregnancy by ultrasonic measurement of fetal crown-rump length.

PREDICTION OF MATURITY IN FIRST TRIMESTER OF PREGNANCY BY ULTRASONIC MEASUREMENT OF FETAL CROWN-RUMP LENGTH by A. Kurjak, S. Cecuk,* and B. Breyer AB...
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