1975, British Journal of Radiology, 48, 638-645
Urinary tract dilatation in pregnancy A. Schulman, M.B., M.R.C.P., F.R.C.R.* and H. Herlinger, M.D., D.M.R.D., D.C.H., D.T.M. and H.f Departments of Radiodiagnosis, Leeds (St. James's) University Hospital and the University of Leeds (Received October, 1974 and in revised form January, 1975)
ABSTRACT
Two radiologists individually studied 220 intravenous urograms done during pregnancy in patients with apparently normal urinary tracts, and an observer-agreement technique was used to obtain the results. The few cases seen in early pregnancy show that dilatation of the urinary tract is uncommon, or at least mild, before mid term. Shortly thereafter, however, dilatation appears abruptly and remains virtually unchanged both in incidence and degree until full term. After mid term, the right side is dilated in about three-quarters of cases and the left side in about one-third. In only 10 per cent was the left side fuller than the right; in 86 per cent, the right side was the fuller. Severe dilatation is infrequent, especially on the left. The dilatation never extends into the pelvis. The abdominal ureters are displaced outwards in a minority of cases, more often on the left. Little or no association was found between the dilatation and fetal position, maternal gravidity or urinary infection. These statistically derived conclusions should provide a firmer basis for what constitutes the limits of normality in the intravenous urogram during pregnancy.
To investigate possible acute or serious urinary tract disease during pregnancy, it is occasionally necessary to perform an intravenous urogram during that pregnancy. It is well known that urinary tract dilatation frequently occurs as a normal accompaniment to pregnancy, particularly on the right side. However, to be able to make a confident distinction between normality and abnormality in pregnancy urography, it is essential to have a much more exact knowledge of the full range of normal appearances in this examination. This is especially so as generally only a single film is available because of the risks of radiation to the developing fetus. Early authors (quoted by Opitz, 1905) stated that the dilatation extends down to the pelvic brim and not below, and that the right-sided predominance is due to a greater kinking of the right ureter as it crosses the iliac vessels at the brim. The most generally accepted explanation for the pelvic brim being the point of demarcation is that the gravid uterus compresses the ureters at their most vulnerable points, which is as they pass over the iliac vessels at the brim. Dure-Smith (1968) has pointed out that the right ureter lies on top of the common iliac artery and vein at the pelvic brim, while the *Present address: Department of Radiology, Groote Schuur, Hospital, Cape Town, South Africa. f Reprints from: Department of Radiology, Leeds (St. James's) University Hospital, Leeds 9, England.
left ureter lies only on the vein at this point and is therefore less exposed to compression. There are proponents and opponents of less popular explanations for the dilatation and its anatomical characteristics: (1) a contributing hormonal or physiological cause, rather than a purely local compression (Lee and Mengert, 1934; von Wagenen and Jenkins, 1939; Fainstat, 1963; Marshall, Lyon and Minkler, 1966; Chan, 1969); (2) interposition of the sigmoid colon giving some protection to the left ureter (Hundley et ah, 1935; Dure-Smith, 1970); (3) compression of the ureters at the pelvic brim by engorged ovarian veins (Clark, 1971); (4) compression by the fetus (Kretschmer and Heaney, 1925; Schloss and Solomkin, 1952); and (5) hypertrophy of a lower ureteric muscle sheath (Hofbauer, 1928). There has been uncertainty as to whether urinary infection (during the present pregnancy or in the past) makes pregnancy dilatation more likely (Kretschmer and Heaney, 1925; Schumacher, 1930; McConnell and Gray, 1940) and disagreement regarding the influence of previous pregnancies (Duncan and Seng, 1928; Mengert and Lee, 1932). Many of the findings on normal patients in this field (extracted and shown in Table I) are provided by small or pre-war series, some of them consisting of retrograde urograms. There is little information on the relationship of onset and degree of dilatation to the stage of pregnancy, and much disagreement on its association with other factors. This investigation provides results obtained by an observer-agreement technique on a large, modern series of excretory urograms and aims to give some answer to the following questions: (1) How often does dilatation occur, and what is its range and mean of severity on either side? (2) At what stage of pregnancy does dilatation begin, and does it increase as pregnancy progresses? (3) Does left-sided predominance of dilatation ever occur and if so, how often and to what degree? (4) Does the dilatation ever extend further down than the pelvic brim?
638
AUGUST
1975
Urinary tract dilatation in pregnancy TABLE I PREVIOUS FINDINGS
Method of examination
Authors
Stage of pregnancy
Total No. of cases
Percentage dilated on right
Percentage dilated on left
Kretschmer and Heaney, 1925
A.U.
Uncertain
32
84
56
Duncan and Seng, 1928
A.U.
6 weeks—term
42
100
74
Gremme, 1931
I.V.U. I.V.U.
2-4 months 5-10 months
6 34
17 91
0 82
Baird, 1932
P.M.
7 months-term
84
85
72
Mengert and Lee, 1932
I.V.U.
30 weeks-term
41
100
p
Kretschmer et al., 1933
I.V.U. I.V.U.
2nd-5th month 6th month-term
54 44
65 98
46 55
Hundley et al, 1935
I.V.U.
9—15 weeks
13
15
15
McConnell and Gray, 1940
I.V.U.
Uncertain
40
78
60
Chan, 1969
I.V.U.
Last trimester
28
68
21
Fochem and Wagenbichler, 1969
I.V.U.
24 weeks—term
75
57
27
A.U. = ascending urogram; I.V.U. = intravenous urogram; P.M. = autopsy.
(5) Is there displacement of any part of the urinary tract? (6) Is there any association between the dilatation and fetal position, or maternal gravidity, or maternal urinary infection at any time? MATERIAL
Over the last few years, a proportion of patients presenting with antepartum haemorrhage to Leeds (St. James's) University Hospital and to St. Mary's Hospital, Leeds, were referred for angioplacentography for suspected placenta praevia (now replaced by ultrasound as the favoured first method). This single-film procedure was done with a cranially tilted X-ray beam coned to the pelvis and lower abdomen, a method both reducing fetal gonad radiation and helping to demarcate upper and lower uterine segments (Herlinger, 1968). Due to the coning, little of the fetus could be seen, and in some of these patients more definite information was required regarding fetal number, attitude, normality, and maturity. In some patients, therefore, a fulllength abdominopelvic film with a vertical beam centred on the lower costal margin (usually corresponding to the 4th lumbar vertebra) was done about 20 minutes after the aortic injection. As the angiographic medium (40 ml. of 60 per cent meglumine
iothalamate) is excreted by the kidneys, this film is also an excretion urogram. The other group of patients for this retrospective study was that in which acute or persistent symptoms during pregnancy led to a single-film intravenous urogram to exclude a serious urinary tract lesion. The single-film urograms which could be traced from these two groups in the 5|-year period from January 1967 to June 1972 inclusive amounted to 226 films, each from a separate pregnancy. The casenotes of all but 42 of these patients were found and studied. Any patient whose case-notes or films showed present, previous or subsequent urinary tract disease (other than episodes of infection) was excluded from the investigation. There were six such patients, suffering from chronic pyelonephritis, obstruction at the pelvi-ureteric junction, previous or present calculi, and haematuria due to sickle-cell disease, singly or in combination. METHOD AND RESULTS
The 220 films were assessed by each author independently, knowing nothing about the patients. The case-notes later provided information on the mother's gravidity and on fetal maturity at the
639
VOL.
48, No. 572 A. Schulman and H. Herlinger
time of the urogram. Where the notes were unavailable, some cases provided the necessary information on the radiograph-labelling or on the request card. In 22 cases, however, there was no such information, and fetal maturity had to be estimated from the radiographic appearance of the fetus. This method is unreliable, but all cases were later divided into five-week groups according to maturity (e.g., 26-30 weeks, 31-35 weeks, etc.) so that great accuracy was not finally necessary.
3). Subsequently, the grades given by the two observers were added, so that each side of the urinary tract in each patient had a final combined score of between 0 and 6 (see Figs. 1-5). For instance, if one observer had given a grading of 2 and the other had given a grading of 1, then the combined score for that side became 3. As a further precaution against overdiagnosis, we finally accepted a diagnosis of dilatation only if each observer had given at least grade 1 to that side. Therefore, the minimum requirement for a diagnosis of dilatation was a combined score of 2, with each observer contributing 1. There was a high index of observer agreement: of 427 sides assessed by both observers, the grades given were equal in 306 and differed by only one in the remainder. As an assessment of the volume of one side of the urinary tract, this combined scoring method was preferred to a measurement of ureteric width, because other sections of the drainage system were often more or less dilated than the ureter, and be-
Grading Each observer was first required to decide whether there was definite dilatation of the right or left upper urinary tract. Because of the absence of established criteria separating normality from dilatation, particularly on a single film from each patient, each observer decided on dilatation only if he was confident of it, and assigned all dubious cases to the non-dilated category (grade 0). Dilatation was graded as mild (grade 1), moderate (grade 2), or severe (grade
FIG. 1. Right side, combined score 2. Left side, combined score 0.
FIG. 2. Right side, combined score 1. Left side, combined score 3. Left ureter displaced laterally.
640
AUGUST 1975
Urinary tract dilatation in pregnancy
FIG. 4. Right side, combined score 5. Left side, combined score 4. Non-opacification of the right ureter is thought to be due to a combination of great dilatation and the supine position; no reason to suspect obstruction at pelvi-ureteric junction in this patient.
FIG. 3. Right side, combined score 4. Left side, combined score 3. Both ureters displaced laterally.
cause many ureters were opacified only poorly or in part. In comparing various results, standard statistical methods (Student's test) were used to obtain the statistical probability of significance (p). A p of 0-05 separated significant differences from the insignificant. Percentage of cases dilated and mean combined score above 20 weeks (Table II)
In each of the four stages between 21 weeks and term, the right and left sides were considered separately. As can be seen in the fourth column of Table II, the percentage dilated on the right side was more than twice that dilated on the left in each stage. These differences were of statistical significance in the three later stages. In the 21-25 weeks stage which only contained seven cases, the p value only just exceeded 0-05.
The mean combined score for each side of the urinary tract, taking into account all cases, was also calculated. As shown in Table II, that on the right side was more than twice that on the left side, and this difference reached statistical significance in every stage. Table II also shows a slight general tendency for both the percentage dilated and the mean combined score to rise with increasing maturity from 26 weeks onwards. However, this is not reflected in statistical significance on either side. How early in pregnancy does dilatation begin? There were only seven patients in the four stages between one and 20 weeks. The only one with any convincing dilatation was 11 weeks pregnant according to dates. Both sides of her urinary tract were mildly dilated (combined score of 2 on each side). She had had nine previous pregnancies (six of them
641
VOL.
48, No. 572 A. Schulman and H. Her linger earlier and while not pregnant had been reported as showing some bilateral dilatation. It could be argued, therefore, that this was a mild permanent dilatation (Spiro and Fry, 1970), not contributed to as yet by the present early pregnancy. In contrast, the seven patients assessed between 21 and 25 weeks showed a percentage dilated and mean combined score on both sides similar to the patients above 25 weeks (Table II). Although one cannot draw firm conclusions from such a small group, it suggests that dilatation is uncommon before mid term, but appears abruptly, both in incidence and in degree, shortly afterwards. Range of dilatation Severe dilatation was defined as a combined score of 5 or 6 (Figs. 4 and 5). On the right side, there were only nine such cases, all above 25 weeks (respectively two, two and five cases in the three subsequent stages). On the left side, there were only two cases, both in the 36 weeks-to-term stage. Expressed as percentages, the incidence of severe dilatation on the right side above 20 weeks was 4-5 per cent (nine out of 200), and on the left side was only 1 per cent (two out of 203). Which side is fuller? Each independent observer was required to choose which side of the urinary tract appeared the fuller, even in those cases in which he had graded the two sides equally (including grade 0). It was found that in only nine cases (4-3 per cent) did the observers disagree as to which side was the fuller, and we have concluded that in these cases, both sides of the urinary tract were of equal fullness.
FIG. 5. Right side, combined score 6. Left side, combined score 3. Left ureter displaced laterally. Same comments apply to the non-opacification of the right ureter as in Fig. 4.
going to term), with a history of urinary infection during the last one. A urogram done two years
TABLE II CASES ABOVE 20 WEEKS DIVIDED ACCORDING TO STAGE OF PREGNANCY: PERCENTAGES DILATED AND MEAN COMBINED SCORES
Stage of pregnancy (weeks) 36-term
31-35
26-30
21-25
Side
No. of cases assessed
R
63
L
64
R
95
L
96
R
35
L
36
R
7
L
7
642
° 0 of cases dilated
Mean combined score itS.E.M.
81
2-6+0-2 p< 0-001 1-20-10-2
74 p< 0-001 35 71 p
Urinary tract dilatation in pregnancy A. Schulman, M.B., M.R.C.P., F.R.C.R.* and H. Herlinger, M.D., D.M.R.D., D.C.H., D.T.M. and H.f Departments of Radiodiagnosis, Leeds (St. James's) University Hospital and the University of Leeds (Received October, 1974 and in revised form January, 1975)
ABSTRACT
Two radiologists individually studied 220 intravenous urograms done during pregnancy in patients with apparently normal urinary tracts, and an observer-agreement technique was used to obtain the results. The few cases seen in early pregnancy show that dilatation of the urinary tract is uncommon, or at least mild, before mid term. Shortly thereafter, however, dilatation appears abruptly and remains virtually unchanged both in incidence and degree until full term. After mid term, the right side is dilated in about three-quarters of cases and the left side in about one-third. In only 10 per cent was the left side fuller than the right; in 86 per cent, the right side was the fuller. Severe dilatation is infrequent, especially on the left. The dilatation never extends into the pelvis. The abdominal ureters are displaced outwards in a minority of cases, more often on the left. Little or no association was found between the dilatation and fetal position, maternal gravidity or urinary infection. These statistically derived conclusions should provide a firmer basis for what constitutes the limits of normality in the intravenous urogram during pregnancy.
To investigate possible acute or serious urinary tract disease during pregnancy, it is occasionally necessary to perform an intravenous urogram during that pregnancy. It is well known that urinary tract dilatation frequently occurs as a normal accompaniment to pregnancy, particularly on the right side. However, to be able to make a confident distinction between normality and abnormality in pregnancy urography, it is essential to have a much more exact knowledge of the full range of normal appearances in this examination. This is especially so as generally only a single film is available because of the risks of radiation to the developing fetus. Early authors (quoted by Opitz, 1905) stated that the dilatation extends down to the pelvic brim and not below, and that the right-sided predominance is due to a greater kinking of the right ureter as it crosses the iliac vessels at the brim. The most generally accepted explanation for the pelvic brim being the point of demarcation is that the gravid uterus compresses the ureters at their most vulnerable points, which is as they pass over the iliac vessels at the brim. Dure-Smith (1968) has pointed out that the right ureter lies on top of the common iliac artery and vein at the pelvic brim, while the *Present address: Department of Radiology, Groote Schuur, Hospital, Cape Town, South Africa. f Reprints from: Department of Radiology, Leeds (St. James's) University Hospital, Leeds 9, England.
left ureter lies only on the vein at this point and is therefore less exposed to compression. There are proponents and opponents of less popular explanations for the dilatation and its anatomical characteristics: (1) a contributing hormonal or physiological cause, rather than a purely local compression (Lee and Mengert, 1934; von Wagenen and Jenkins, 1939; Fainstat, 1963; Marshall, Lyon and Minkler, 1966; Chan, 1969); (2) interposition of the sigmoid colon giving some protection to the left ureter (Hundley et ah, 1935; Dure-Smith, 1970); (3) compression of the ureters at the pelvic brim by engorged ovarian veins (Clark, 1971); (4) compression by the fetus (Kretschmer and Heaney, 1925; Schloss and Solomkin, 1952); and (5) hypertrophy of a lower ureteric muscle sheath (Hofbauer, 1928). There has been uncertainty as to whether urinary infection (during the present pregnancy or in the past) makes pregnancy dilatation more likely (Kretschmer and Heaney, 1925; Schumacher, 1930; McConnell and Gray, 1940) and disagreement regarding the influence of previous pregnancies (Duncan and Seng, 1928; Mengert and Lee, 1932). Many of the findings on normal patients in this field (extracted and shown in Table I) are provided by small or pre-war series, some of them consisting of retrograde urograms. There is little information on the relationship of onset and degree of dilatation to the stage of pregnancy, and much disagreement on its association with other factors. This investigation provides results obtained by an observer-agreement technique on a large, modern series of excretory urograms and aims to give some answer to the following questions: (1) How often does dilatation occur, and what is its range and mean of severity on either side? (2) At what stage of pregnancy does dilatation begin, and does it increase as pregnancy progresses? (3) Does left-sided predominance of dilatation ever occur and if so, how often and to what degree? (4) Does the dilatation ever extend further down than the pelvic brim?
638
AUGUST
1975
Urinary tract dilatation in pregnancy TABLE I PREVIOUS FINDINGS
Method of examination
Authors
Stage of pregnancy
Total No. of cases
Percentage dilated on right
Percentage dilated on left
Kretschmer and Heaney, 1925
A.U.
Uncertain
32
84
56
Duncan and Seng, 1928
A.U.
6 weeks—term
42
100
74
Gremme, 1931
I.V.U. I.V.U.
2-4 months 5-10 months
6 34
17 91
0 82
Baird, 1932
P.M.
7 months-term
84
85
72
Mengert and Lee, 1932
I.V.U.
30 weeks-term
41
100
p
Kretschmer et al., 1933
I.V.U. I.V.U.
2nd-5th month 6th month-term
54 44
65 98
46 55
Hundley et al, 1935
I.V.U.
9—15 weeks
13
15
15
McConnell and Gray, 1940
I.V.U.
Uncertain
40
78
60
Chan, 1969
I.V.U.
Last trimester
28
68
21
Fochem and Wagenbichler, 1969
I.V.U.
24 weeks—term
75
57
27
A.U. = ascending urogram; I.V.U. = intravenous urogram; P.M. = autopsy.
(5) Is there displacement of any part of the urinary tract? (6) Is there any association between the dilatation and fetal position, or maternal gravidity, or maternal urinary infection at any time? MATERIAL
Over the last few years, a proportion of patients presenting with antepartum haemorrhage to Leeds (St. James's) University Hospital and to St. Mary's Hospital, Leeds, were referred for angioplacentography for suspected placenta praevia (now replaced by ultrasound as the favoured first method). This single-film procedure was done with a cranially tilted X-ray beam coned to the pelvis and lower abdomen, a method both reducing fetal gonad radiation and helping to demarcate upper and lower uterine segments (Herlinger, 1968). Due to the coning, little of the fetus could be seen, and in some of these patients more definite information was required regarding fetal number, attitude, normality, and maturity. In some patients, therefore, a fulllength abdominopelvic film with a vertical beam centred on the lower costal margin (usually corresponding to the 4th lumbar vertebra) was done about 20 minutes after the aortic injection. As the angiographic medium (40 ml. of 60 per cent meglumine
iothalamate) is excreted by the kidneys, this film is also an excretion urogram. The other group of patients for this retrospective study was that in which acute or persistent symptoms during pregnancy led to a single-film intravenous urogram to exclude a serious urinary tract lesion. The single-film urograms which could be traced from these two groups in the 5|-year period from January 1967 to June 1972 inclusive amounted to 226 films, each from a separate pregnancy. The casenotes of all but 42 of these patients were found and studied. Any patient whose case-notes or films showed present, previous or subsequent urinary tract disease (other than episodes of infection) was excluded from the investigation. There were six such patients, suffering from chronic pyelonephritis, obstruction at the pelvi-ureteric junction, previous or present calculi, and haematuria due to sickle-cell disease, singly or in combination. METHOD AND RESULTS
The 220 films were assessed by each author independently, knowing nothing about the patients. The case-notes later provided information on the mother's gravidity and on fetal maturity at the
639
VOL.
48, No. 572 A. Schulman and H. Herlinger
time of the urogram. Where the notes were unavailable, some cases provided the necessary information on the radiograph-labelling or on the request card. In 22 cases, however, there was no such information, and fetal maturity had to be estimated from the radiographic appearance of the fetus. This method is unreliable, but all cases were later divided into five-week groups according to maturity (e.g., 26-30 weeks, 31-35 weeks, etc.) so that great accuracy was not finally necessary.
3). Subsequently, the grades given by the two observers were added, so that each side of the urinary tract in each patient had a final combined score of between 0 and 6 (see Figs. 1-5). For instance, if one observer had given a grading of 2 and the other had given a grading of 1, then the combined score for that side became 3. As a further precaution against overdiagnosis, we finally accepted a diagnosis of dilatation only if each observer had given at least grade 1 to that side. Therefore, the minimum requirement for a diagnosis of dilatation was a combined score of 2, with each observer contributing 1. There was a high index of observer agreement: of 427 sides assessed by both observers, the grades given were equal in 306 and differed by only one in the remainder. As an assessment of the volume of one side of the urinary tract, this combined scoring method was preferred to a measurement of ureteric width, because other sections of the drainage system were often more or less dilated than the ureter, and be-
Grading Each observer was first required to decide whether there was definite dilatation of the right or left upper urinary tract. Because of the absence of established criteria separating normality from dilatation, particularly on a single film from each patient, each observer decided on dilatation only if he was confident of it, and assigned all dubious cases to the non-dilated category (grade 0). Dilatation was graded as mild (grade 1), moderate (grade 2), or severe (grade
FIG. 1. Right side, combined score 2. Left side, combined score 0.
FIG. 2. Right side, combined score 1. Left side, combined score 3. Left ureter displaced laterally.
640
AUGUST 1975
Urinary tract dilatation in pregnancy
FIG. 4. Right side, combined score 5. Left side, combined score 4. Non-opacification of the right ureter is thought to be due to a combination of great dilatation and the supine position; no reason to suspect obstruction at pelvi-ureteric junction in this patient.
FIG. 3. Right side, combined score 4. Left side, combined score 3. Both ureters displaced laterally.
cause many ureters were opacified only poorly or in part. In comparing various results, standard statistical methods (Student's test) were used to obtain the statistical probability of significance (p). A p of 0-05 separated significant differences from the insignificant. Percentage of cases dilated and mean combined score above 20 weeks (Table II)
In each of the four stages between 21 weeks and term, the right and left sides were considered separately. As can be seen in the fourth column of Table II, the percentage dilated on the right side was more than twice that dilated on the left in each stage. These differences were of statistical significance in the three later stages. In the 21-25 weeks stage which only contained seven cases, the p value only just exceeded 0-05.
The mean combined score for each side of the urinary tract, taking into account all cases, was also calculated. As shown in Table II, that on the right side was more than twice that on the left side, and this difference reached statistical significance in every stage. Table II also shows a slight general tendency for both the percentage dilated and the mean combined score to rise with increasing maturity from 26 weeks onwards. However, this is not reflected in statistical significance on either side. How early in pregnancy does dilatation begin? There were only seven patients in the four stages between one and 20 weeks. The only one with any convincing dilatation was 11 weeks pregnant according to dates. Both sides of her urinary tract were mildly dilated (combined score of 2 on each side). She had had nine previous pregnancies (six of them
641
VOL.
48, No. 572 A. Schulman and H. Her linger earlier and while not pregnant had been reported as showing some bilateral dilatation. It could be argued, therefore, that this was a mild permanent dilatation (Spiro and Fry, 1970), not contributed to as yet by the present early pregnancy. In contrast, the seven patients assessed between 21 and 25 weeks showed a percentage dilated and mean combined score on both sides similar to the patients above 25 weeks (Table II). Although one cannot draw firm conclusions from such a small group, it suggests that dilatation is uncommon before mid term, but appears abruptly, both in incidence and in degree, shortly afterwards. Range of dilatation Severe dilatation was defined as a combined score of 5 or 6 (Figs. 4 and 5). On the right side, there were only nine such cases, all above 25 weeks (respectively two, two and five cases in the three subsequent stages). On the left side, there were only two cases, both in the 36 weeks-to-term stage. Expressed as percentages, the incidence of severe dilatation on the right side above 20 weeks was 4-5 per cent (nine out of 200), and on the left side was only 1 per cent (two out of 203). Which side is fuller? Each independent observer was required to choose which side of the urinary tract appeared the fuller, even in those cases in which he had graded the two sides equally (including grade 0). It was found that in only nine cases (4-3 per cent) did the observers disagree as to which side was the fuller, and we have concluded that in these cases, both sides of the urinary tract were of equal fullness.
FIG. 5. Right side, combined score 6. Left side, combined score 3. Left ureter displaced laterally. Same comments apply to the non-opacification of the right ureter as in Fig. 4.
going to term), with a history of urinary infection during the last one. A urogram done two years
TABLE II CASES ABOVE 20 WEEKS DIVIDED ACCORDING TO STAGE OF PREGNANCY: PERCENTAGES DILATED AND MEAN COMBINED SCORES
Stage of pregnancy (weeks) 36-term
31-35
26-30
21-25
Side
No. of cases assessed
R
63
L
64
R
95
L
96
R
35
L
36
R
7
L
7
642
° 0 of cases dilated
Mean combined score itS.E.M.
81
2-6+0-2 p< 0-001 1-20-10-2
74 p< 0-001 35 71 p
