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Screening for asymptomatic bacteriuria during antepartum care
Screening for asymptomatic bacteriuria during antepartum care JAMES A. MERRILL, M.D. JOHN P. COLMORE, M.D. R. G. WILKERSON, B.s. BARBARA F. BRADEN, M.D. PRESTON W. DESHAN, M.D. Oklahoma City, Oklahoma The Griess test was used as a screening procedure for bacteriuria in I ,983 pregnant outpatients in an antepartum clinic. The prevalence of asymptomatic bacteriuria was found to be 6.6 per cent. The unmodified test was positive in 81 per cent of 94 patients with significant bacteriuria and was positive in 0.7 per cent of patients with sterile urine. However, 10 per cent of the positive Griess reactions are associated with sterile urine. The test was modified in 1,003 patients by in vivo or in vitro nitration of the urine. The results of the Griess test were not significantly altered by this procedure. The standard Griess test was compared with the STAT-Test in 500 patients. The STAT-Test gave positive results in 73 per cent of 40 patients with significant bacteriuria. Because of the simplicity and reliability of this test and the importance of diagnosing bacteriuria during pregnancy, it is strongly recommended as a routine part of antepartum care.
persisted 8 weeks to 12 months after delivery if untreated, that radiographic evidence of urinary tract abnormalities were present in 61 of 131 patients and that bacteria were present in urine from ureters in 17 of 23 patients studied in the postpartum period. There may be a relationship between untreated bacteriuria during pregnancy and perinatal morbidity, including prematurity. 3. 5, 6 Thus routine screening of antepartum patients for bacteriuria is desirable. Unfortunately, it is often avoided for various reasons including the expense of urine bacterial colony counts. Therefore a screening test was sought which was inexpensive and easily performed by untrained personnel. In 1879, Griess, 14 a German chemist, developed a reagent for the detection of nitrite in solutions. The reagent, an acid solution of sulfanilic acid and alpha naphthylamine, undergoes a diazotization reaction with nitrites, forming a red azo dye. Cruickshank and Moyes15 used the Griess reagent to check
A N r M P o R T A N T aspect of antepartum care includes the early discovery of high risk patients and appropriate medical management.1' 2 Various studies indicate a significant prevalence ( 7 per cent) of asymptomatic bacteriuria during pregnancy and association of bacteriuria with maternal and fetal morbidity. 3 - 10 Often asymptomatic bacteriuria noted during pregnancy persists following delivery, is associated with active renal infection, and may be indicative of prior renal disease. 5 • 9 • 11 Approximately 50 per cent 5 • 8 • 12 · 1:l of pregnant women with asymptomatic bacteriuria eventually develop asymptomatic urinary tract infection before or shortly after delivery. Mulla12 found that 45 per cent of 70 gravid women with asymp· tomatic bacteriuria had a significant decrease in ability to concentrate urine. Whalley, Martin, and Peters 9 found that bacteriuria
From the Departments of Gynecology and Obstetrics and of Medicine, University of Oklahoma School of Medicine.
216
Volume ~9 Number 2
Antepartum screening for asymptomatic bacteriuria
for nitrite m urme and correlated it with urinary tract infections due to coliform or= ganisms which reduce nitrate in bladder urine to nitrite. Some other organisms also reduce nitrate. Results of evaluation of the Griess test as a screening procedure for asymptomatic bacteriuria have been variable. 7 ' s, n, 1a, 16 -1s They indicate that the Griess test is an effective, reliable method of screening for bacteriuria in outpatient women, but may not be satisfactory for screening hospitalized patients, since the latter group are likely to have a nitrate-deficient diet and have urinary tract infections due to organisms which are not strong nitrate reducers. Turner 8 studied urine specimens from 1,500 antepartum patients and found that 80 per cent of 108 patients with significant bacteriuria gave a positive Griess test. Slowinski and Smith17 studied urine specimens from 504 antepartum patients and found a positive Griess test in 73 per cent of the specimens with significant bacteriuria. With private patients, there was greater correlation with the urine culture than with clinic patients. Methods
We designed a pilot study to evaluate the Griess test as a screen for asymptomatic bacteriuria during pregnancy. A cleanvoided, midstream, self-collected urine specimen was obtained from consecutive women at the time of their initial visit to an antepartum clinic. All were asymptomatic. The Griess test was performed immediately on each of these specimens after which bacterial colony counts were done. The Griess reagent was prepared by dis, • ., r smvmg LJ urn. or sunamuc ac10 \ cnemically pure) in 450 ml. of 10 per cent acetic acid. This was added to a solution of 0.6 Gm. of alpha naphthylamine dissolved in 60 mi. of boiling distilled water. The reagent will remain stable for several months stored in a stoppered amber bottle in the refrigerator. Deterioration of the reagent is detected by the development of a pink color. The urine was tested by adding 1 mi. of reagent from a dropper bottle to 1 mi. of ~
~
1r
.,.
•..
,
1
217
unne m a clean test tube. Development of a pink to dark=red color indicates a positive test. Bacterial colony counts were obtained from the specimens by the standard pour plate method. Each specimen was diluted in tenfold increments through the fourth dilution (10'). The pour plates were incubated at 37.5° C. for 24 hours, after which the colonies were counted. Colony counts in the 10 5 and 10 6 range were quantitated from the 104 dilution. All organisms isolated were identified by standard biochemical reactions. No organisms were identified microscopically. The methods were the same with groups subsequent to the pilot study except for those modifications which will be described. Results
Table I shows the results in the pilot study of 608 patients. Forty-two or 6.9 per cent had significant bacteriuria. The Griess test was positive in 38 or 91 per cent. Three of the specimens which gave false negative tests had bacterial colony counts of 10\ while the 38 specimens which gave a true positive Griess reaction all had colony counts of 10 6 or greater. Of the 567 sterile urines, there were 4 positive Griess reactions or 0. 7 per cent false positive reactions. However, of the 43 positive Griess reactions, 9 per cent were associated with sterile urine or were false positive. To determine the effectiveness of the Griess test among hospitalized obstetric pa-
Table I. Pilot study ( 608 patients) Cuiiure
> 10
Total
5
42
10 4 Sterile
9 557
Griess positive 38 (91%) I
4 (0.7%; 9%)
Table II. Obstetric inpatients ( 496 patients) Culture
Total
> 10 4
Griess positive
62 16
41 (66%) 1 6
5
10 Sterile
418
September 15, 1967 Am. J. Obst. & Gynec.
218 Merrill et al.
Table III. Griess versus modified Griess versus Uroscreen (503 patients) Culture
>
10
5
1Q4 Sterile
Total
Griess positive
Modified Griess positive
Uroscreen positive
26 9 468
17 (65%) 3 3
22 (85%) 3 3
24 (92%) 5 38(8%;57%)
tients, 496 cathterized urine specimens collected from antepartum and postpartum inpatients were tested with Griess reagent and compared with colony counts on the same specimens. Table II indicates a 66 per cent reliability in detecting bacteriuria. The Griess test was not as reliable for inpatients as for outpatients. All further studies were done on women at the time of their initial visit to the antepartum clinic. It had been noted in this laboratory that false negative reactions were often the result of nitrate deficient urine rather than organismic inability to reduce nitrate. It was hoped that retesting negative specimens after addition of nitrate and incubation might decrease the incidence of false negative reactions. A study was designed to compare the immediate Griess test, a modified Griess test following ni:ration of the urine and the Uroscreen test. Urine collection and laboratory workup were similar to the pilot study. If the Griess test was not immediately positive, a modified test was done by adding 2 mi. of 10 per cent KN0 3 to 4 ml. of urine in a sterile capped tube and incubating it at 37.5° C. Each specimen was challenged at 1 hour and 2 hours. The Uroscreen test was done by adding 2 ml. of urine to a tube contammg triphenyltetrazolium chloride ( U roscreen). These specimens were incubated in the same water bath as the modified Griess tests and read hourly to 4 hours. Table III indicates the results with 503 patients. The reliability of the Griess test increased from 65 to 85 per cent with nitration and incubation of the urine. Although the Uroscreen test was more reliable in detecting bacteriuria, there were many more false positive reactions. Fifty-seven per cent of the positive reactions were associated with sterile urines.
Table IV. In vivo KN0 3 supplementation (500 patients)* Culture
>
10 5 10 4
Total
Griess positive
37 11 452
29 (78%) 1
3
*Two hundred and thirty-five also had the STAT-Test. (See also Table VII.)
Incubation and nitration of urine improved the reliability of the Griess test. However, a necessary 2 or 4 hour incubation period reduces the ease and desirability of a test to be used for routine clinical screening. Therefore, nitration of the urine was accomplished by oral administration of KN0 3• At the preclinic interview, antepartum patients were given one 500 mg. KN0 3 tablet and instructed to take this the morning of their first visit to the clinic and not to urinate from then until arrival at the clinic. Urine specimens from 500 consecutive antepartum patients were collected and studied by urine culture and immediate Griess test. The results from Table IV indicate 78 per cent reliability in detecting bacteriuria. The organisms isolated from false negative specimens were incubated in broth containing 10 per cent KN03 to determine organismic nitrate reducing ability. All of the organisms were nitrate reducers. In 3 of the cases, however, the bladder urine was nitrate deficient and did not eventually show a positive reaction even following incubation for 24 hours. Table V demonstrates 81 per cent reliability of the Griess test following nitration of the urine, by either the in vivo or in vitro method. To the present time, we have studied
Antepartum screening for asymptomatic bacteriuria
Volume 99 Number 2
urine specimens from 1,483 antepartum outpatients without prior nitration. The reliability of the Griess test in the total series is 81 per cent as seen in Table VI. Of the sterile urine specimens, 0. 7 per cent gave a positive Griess test and 10 per cent of the positive Griess tests were associated with sterile urine (or were false positive). Therefore, despite the improvement in the reliability of the Griess test which was demonstrated when the same specimen was tested before and after nitration and incubation (Table III), the final results do not demonstrate a clear advantage of nitration (Table V versus Table VI), at least as accomplished in these studies. The frequency of false positive results was similar also. Urine specimens from 500 antepartum patients were studied to compare the reliability of the immediate Griess test using the stock solution, as described, and the STATTest.* Each specimen was tested immediately following collection. The Griess reaction with *Mallinckrodt Chemical Works, St. Louis, Missouri.
Table V. In vivo + in vitro KN0 3 (Tables III and IV) (1,003 patients) Culture
Total
5
> 104
63
10 Sterile
20 920
I
Griess positive 51 (81%) 4 6
Table VI. Standard Griess-total experience (1,483 patients*) Culture
Total
> 1054
I
Griess positive
10 Sterile *Antepartum outpatients only.
STAT-Test was done by dipping the cotton applicator of the test unit into the urine and allowing it to become fully saturated. The unit was then removed and the plastic container squeezed to break the glass ampule. The result was read in the same manner as when using stock solution. The results, as seen in Table VII, indicate 80 per cent reliability of the Griess reagent as compared with 73 per cent reliability of the STAT-Test unit. The differences were limited to the specimens which gave pink- or salmoncolored results. Comment
The published evidence is sufficient to satisfy us that bacteriuria during pregnancy, even in the absence of symptoms, is a potentially if not actually serious disease. The sequelae, if untreated, may not be appreciated or recognized for years hence; and the finding of bacteriuria during pregnancy may be the only hint of a correctable renal abnormality. The relationship of bacteriuria to fetal outcome is less clear. Reports of increased prematurity are unconfirmed. However, acute pyelonephritis and hypertension are certainly associated with diminished fetal salvage. For these reasons, it is important that bacteriuria be detected early, and, once detected, treatment should be directed toward eradicating urinary tract infection. In these studies, the prevalence of asymptomatic bacteriuria among antepartum patients (Tables IV and VI) was found to be 6.6 per cent. This is similar to other reports. Such a prevalence is certainly sufficient to warrant screening of all antepartum patients. Moreover, pregnancy affords an opportunity to screen a large segment of the female population who otherwise might not receive accurate evaluation or detection.
Table VII. Griess versus STAT-Test Culture
> 10
STAT-Test
5
40
10 4 Sterile
8 444
219
32 (80%) 0 4
(73%)
*Five hundred patients, 235 patients with oral nitrate supplementation, 265 patients without nitrate supplementation.
220
September 15, 1967 Am. J. Obst. & Gynec.
Merrill et ol
On the basis of our experience to date, we recommend that the Griess test be a part of antepartum care. As a routine screening procedure, the test appears to detect approximately 80 per cent of the cases of significant bacteriuria when done on cleanvoided midstream urine specimens collected by the patient at the initial visit. Oral administration of potassium nitrate a few hours prior to urine collection or in vitro nitration of the urine may impmve reliability, al-
though this has not been clearly demonstrated. As a routine procedure, the Griess test appears to offer at least as many advantages as some of the other procedures now considered routine in antepartum care. Positive reactions should, of course, be followed by urine bacterial cultures and treatment should not be instituted on the basis of the Griess test alone. Approximately 10 per cent of the positive reactions are associated with sterile urine specimens.
REFERENCES
1. Clifford, S. H.: New England J. Med. 271: 243, 1964. 2. Jacobson, H. N., and Reid, D. E.: New England J. Med. 271: 302, 1964. 3. Henderson, M.: Arch. Environ. Health 8: 527, 1964. 4. Kass, E. H.: Biology of Pyelonephritis, New York, 1959, Little, Brown & Company, p. 399. 5. Kass, E. H.: Ann. Int. Med. 56: 46, 1962. 6. LeBlanc, A. L., and McGanity, W.: Texas Rep. Bioi. & Med. 22: 61, 1964. 7. Smith, L., Thayer, W., Malta, E., and Utz, ].: Ann. Int. Med. 54: 66, 1961. 8. Turner, G.: Lancet 2: 1062, 1961. 9. Whalley, P. J., Martin, F. G., and Peters, P. C.: J. A. M. A. 193: 879, 1965. 10. Kaitz, A. L., and Hodder, E.: New England J. Med. 265: 667, 1961. 11. Kincaid-Smith, P., Bullen, M., Mills, J., Fur-
12. 13.
14. 15.
16. 17. 18.
rell, U., Huston, N., and Goon, F.: Lancet 2: 61, 1964. Mulla, N.: Ohio State M. J. 59: 154, 1963. Sleigh, J. D., Robertson, J. G., and Jndale, M. H.: J. Obst. & Gynaec. Brit. Comm. 71: 74, 1964. Griess, P.: Ber. deutsch. chem. Gesellsch. 12: 426, 1879. Cruickshank, ]., and Moyes, ].: Brit. M. J. 2: 712, 1914. Kahler, R. L., and Guse, L. B.: J. Lab. & Clin. Med. 49: 934, 1957. Slowinski, E. ]., and Smith, L. G.: AM. J. 0BST. & GYNEC. 7: 94, 1966. Smith, L. G., and Schmidt, J.: J. A. M. A. 181: 431, 1962.
800 Northeast Thirteenth Street Oklahoma City, Oklahoma 73104
persisted 8 weeks to 12 months after delivery if untreated, that radiographic evidence of urinary tract abnormalities were present in 61 of 131 patients and that bacteria were present in urine from ureters in 17 of 23 patients studied in the postpartum period. There may be a relationship between untreated bacteriuria during pregnancy and perinatal morbidity, including prematurity. 3. 5, 6 Thus routine screening of antepartum patients for bacteriuria is desirable. Unfortunately, it is often avoided for various reasons including the expense of urine bacterial colony counts. Therefore a screening test was sought which was inexpensive and easily performed by untrained personnel. In 1879, Griess, 14 a German chemist, developed a reagent for the detection of nitrite in solutions. The reagent, an acid solution of sulfanilic acid and alpha naphthylamine, undergoes a diazotization reaction with nitrites, forming a red azo dye. Cruickshank and Moyes15 used the Griess reagent to check
A N r M P o R T A N T aspect of antepartum care includes the early discovery of high risk patients and appropriate medical management.1' 2 Various studies indicate a significant prevalence ( 7 per cent) of asymptomatic bacteriuria during pregnancy and association of bacteriuria with maternal and fetal morbidity. 3 - 10 Often asymptomatic bacteriuria noted during pregnancy persists following delivery, is associated with active renal infection, and may be indicative of prior renal disease. 5 • 9 • 11 Approximately 50 per cent 5 • 8 • 12 · 1:l of pregnant women with asymptomatic bacteriuria eventually develop asymptomatic urinary tract infection before or shortly after delivery. Mulla12 found that 45 per cent of 70 gravid women with asymp· tomatic bacteriuria had a significant decrease in ability to concentrate urine. Whalley, Martin, and Peters 9 found that bacteriuria
From the Departments of Gynecology and Obstetrics and of Medicine, University of Oklahoma School of Medicine.
216
Volume ~9 Number 2
Antepartum screening for asymptomatic bacteriuria
for nitrite m urme and correlated it with urinary tract infections due to coliform or= ganisms which reduce nitrate in bladder urine to nitrite. Some other organisms also reduce nitrate. Results of evaluation of the Griess test as a screening procedure for asymptomatic bacteriuria have been variable. 7 ' s, n, 1a, 16 -1s They indicate that the Griess test is an effective, reliable method of screening for bacteriuria in outpatient women, but may not be satisfactory for screening hospitalized patients, since the latter group are likely to have a nitrate-deficient diet and have urinary tract infections due to organisms which are not strong nitrate reducers. Turner 8 studied urine specimens from 1,500 antepartum patients and found that 80 per cent of 108 patients with significant bacteriuria gave a positive Griess test. Slowinski and Smith17 studied urine specimens from 504 antepartum patients and found a positive Griess test in 73 per cent of the specimens with significant bacteriuria. With private patients, there was greater correlation with the urine culture than with clinic patients. Methods
We designed a pilot study to evaluate the Griess test as a screen for asymptomatic bacteriuria during pregnancy. A cleanvoided, midstream, self-collected urine specimen was obtained from consecutive women at the time of their initial visit to an antepartum clinic. All were asymptomatic. The Griess test was performed immediately on each of these specimens after which bacterial colony counts were done. The Griess reagent was prepared by dis, • ., r smvmg LJ urn. or sunamuc ac10 \ cnemically pure) in 450 ml. of 10 per cent acetic acid. This was added to a solution of 0.6 Gm. of alpha naphthylamine dissolved in 60 mi. of boiling distilled water. The reagent will remain stable for several months stored in a stoppered amber bottle in the refrigerator. Deterioration of the reagent is detected by the development of a pink color. The urine was tested by adding 1 mi. of reagent from a dropper bottle to 1 mi. of ~
~
1r
.,.
•..
,
1
217
unne m a clean test tube. Development of a pink to dark=red color indicates a positive test. Bacterial colony counts were obtained from the specimens by the standard pour plate method. Each specimen was diluted in tenfold increments through the fourth dilution (10'). The pour plates were incubated at 37.5° C. for 24 hours, after which the colonies were counted. Colony counts in the 10 5 and 10 6 range were quantitated from the 104 dilution. All organisms isolated were identified by standard biochemical reactions. No organisms were identified microscopically. The methods were the same with groups subsequent to the pilot study except for those modifications which will be described. Results
Table I shows the results in the pilot study of 608 patients. Forty-two or 6.9 per cent had significant bacteriuria. The Griess test was positive in 38 or 91 per cent. Three of the specimens which gave false negative tests had bacterial colony counts of 10\ while the 38 specimens which gave a true positive Griess reaction all had colony counts of 10 6 or greater. Of the 567 sterile urines, there were 4 positive Griess reactions or 0. 7 per cent false positive reactions. However, of the 43 positive Griess reactions, 9 per cent were associated with sterile urine or were false positive. To determine the effectiveness of the Griess test among hospitalized obstetric pa-
Table I. Pilot study ( 608 patients) Cuiiure
> 10
Total
5
42
10 4 Sterile
9 557
Griess positive 38 (91%) I
4 (0.7%; 9%)
Table II. Obstetric inpatients ( 496 patients) Culture
Total
> 10 4
Griess positive
62 16
41 (66%) 1 6
5
10 Sterile
418
September 15, 1967 Am. J. Obst. & Gynec.
218 Merrill et al.
Table III. Griess versus modified Griess versus Uroscreen (503 patients) Culture
>
10
5
1Q4 Sterile
Total
Griess positive
Modified Griess positive
Uroscreen positive
26 9 468
17 (65%) 3 3
22 (85%) 3 3
24 (92%) 5 38(8%;57%)
tients, 496 cathterized urine specimens collected from antepartum and postpartum inpatients were tested with Griess reagent and compared with colony counts on the same specimens. Table II indicates a 66 per cent reliability in detecting bacteriuria. The Griess test was not as reliable for inpatients as for outpatients. All further studies were done on women at the time of their initial visit to the antepartum clinic. It had been noted in this laboratory that false negative reactions were often the result of nitrate deficient urine rather than organismic inability to reduce nitrate. It was hoped that retesting negative specimens after addition of nitrate and incubation might decrease the incidence of false negative reactions. A study was designed to compare the immediate Griess test, a modified Griess test following ni:ration of the urine and the Uroscreen test. Urine collection and laboratory workup were similar to the pilot study. If the Griess test was not immediately positive, a modified test was done by adding 2 mi. of 10 per cent KN0 3 to 4 ml. of urine in a sterile capped tube and incubating it at 37.5° C. Each specimen was challenged at 1 hour and 2 hours. The Uroscreen test was done by adding 2 ml. of urine to a tube contammg triphenyltetrazolium chloride ( U roscreen). These specimens were incubated in the same water bath as the modified Griess tests and read hourly to 4 hours. Table III indicates the results with 503 patients. The reliability of the Griess test increased from 65 to 85 per cent with nitration and incubation of the urine. Although the Uroscreen test was more reliable in detecting bacteriuria, there were many more false positive reactions. Fifty-seven per cent of the positive reactions were associated with sterile urines.
Table IV. In vivo KN0 3 supplementation (500 patients)* Culture
>
10 5 10 4
Total
Griess positive
37 11 452
29 (78%) 1
3
*Two hundred and thirty-five also had the STAT-Test. (See also Table VII.)
Incubation and nitration of urine improved the reliability of the Griess test. However, a necessary 2 or 4 hour incubation period reduces the ease and desirability of a test to be used for routine clinical screening. Therefore, nitration of the urine was accomplished by oral administration of KN0 3• At the preclinic interview, antepartum patients were given one 500 mg. KN0 3 tablet and instructed to take this the morning of their first visit to the clinic and not to urinate from then until arrival at the clinic. Urine specimens from 500 consecutive antepartum patients were collected and studied by urine culture and immediate Griess test. The results from Table IV indicate 78 per cent reliability in detecting bacteriuria. The organisms isolated from false negative specimens were incubated in broth containing 10 per cent KN03 to determine organismic nitrate reducing ability. All of the organisms were nitrate reducers. In 3 of the cases, however, the bladder urine was nitrate deficient and did not eventually show a positive reaction even following incubation for 24 hours. Table V demonstrates 81 per cent reliability of the Griess test following nitration of the urine, by either the in vivo or in vitro method. To the present time, we have studied
Antepartum screening for asymptomatic bacteriuria
Volume 99 Number 2
urine specimens from 1,483 antepartum outpatients without prior nitration. The reliability of the Griess test in the total series is 81 per cent as seen in Table VI. Of the sterile urine specimens, 0. 7 per cent gave a positive Griess test and 10 per cent of the positive Griess tests were associated with sterile urine (or were false positive). Therefore, despite the improvement in the reliability of the Griess test which was demonstrated when the same specimen was tested before and after nitration and incubation (Table III), the final results do not demonstrate a clear advantage of nitration (Table V versus Table VI), at least as accomplished in these studies. The frequency of false positive results was similar also. Urine specimens from 500 antepartum patients were studied to compare the reliability of the immediate Griess test using the stock solution, as described, and the STATTest.* Each specimen was tested immediately following collection. The Griess reaction with *Mallinckrodt Chemical Works, St. Louis, Missouri.
Table V. In vivo + in vitro KN0 3 (Tables III and IV) (1,003 patients) Culture
Total
5
> 104
63
10 Sterile
20 920
I
Griess positive 51 (81%) 4 6
Table VI. Standard Griess-total experience (1,483 patients*) Culture
Total
> 1054
I
Griess positive
10 Sterile *Antepartum outpatients only.
STAT-Test was done by dipping the cotton applicator of the test unit into the urine and allowing it to become fully saturated. The unit was then removed and the plastic container squeezed to break the glass ampule. The result was read in the same manner as when using stock solution. The results, as seen in Table VII, indicate 80 per cent reliability of the Griess reagent as compared with 73 per cent reliability of the STAT-Test unit. The differences were limited to the specimens which gave pink- or salmoncolored results. Comment
The published evidence is sufficient to satisfy us that bacteriuria during pregnancy, even in the absence of symptoms, is a potentially if not actually serious disease. The sequelae, if untreated, may not be appreciated or recognized for years hence; and the finding of bacteriuria during pregnancy may be the only hint of a correctable renal abnormality. The relationship of bacteriuria to fetal outcome is less clear. Reports of increased prematurity are unconfirmed. However, acute pyelonephritis and hypertension are certainly associated with diminished fetal salvage. For these reasons, it is important that bacteriuria be detected early, and, once detected, treatment should be directed toward eradicating urinary tract infection. In these studies, the prevalence of asymptomatic bacteriuria among antepartum patients (Tables IV and VI) was found to be 6.6 per cent. This is similar to other reports. Such a prevalence is certainly sufficient to warrant screening of all antepartum patients. Moreover, pregnancy affords an opportunity to screen a large segment of the female population who otherwise might not receive accurate evaluation or detection.
Table VII. Griess versus STAT-Test Culture
> 10
STAT-Test
5
40
10 4 Sterile
8 444
219
32 (80%) 0 4
(73%)
*Five hundred patients, 235 patients with oral nitrate supplementation, 265 patients without nitrate supplementation.
220
September 15, 1967 Am. J. Obst. & Gynec.
Merrill et ol
On the basis of our experience to date, we recommend that the Griess test be a part of antepartum care. As a routine screening procedure, the test appears to detect approximately 80 per cent of the cases of significant bacteriuria when done on cleanvoided midstream urine specimens collected by the patient at the initial visit. Oral administration of potassium nitrate a few hours prior to urine collection or in vitro nitration of the urine may impmve reliability, al-
though this has not been clearly demonstrated. As a routine procedure, the Griess test appears to offer at least as many advantages as some of the other procedures now considered routine in antepartum care. Positive reactions should, of course, be followed by urine bacterial cultures and treatment should not be instituted on the basis of the Griess test alone. Approximately 10 per cent of the positive reactions are associated with sterile urine specimens.
REFERENCES
1. Clifford, S. H.: New England J. Med. 271: 243, 1964. 2. Jacobson, H. N., and Reid, D. E.: New England J. Med. 271: 302, 1964. 3. Henderson, M.: Arch. Environ. Health 8: 527, 1964. 4. Kass, E. H.: Biology of Pyelonephritis, New York, 1959, Little, Brown & Company, p. 399. 5. Kass, E. H.: Ann. Int. Med. 56: 46, 1962. 6. LeBlanc, A. L., and McGanity, W.: Texas Rep. Bioi. & Med. 22: 61, 1964. 7. Smith, L., Thayer, W., Malta, E., and Utz, ].: Ann. Int. Med. 54: 66, 1961. 8. Turner, G.: Lancet 2: 1062, 1961. 9. Whalley, P. J., Martin, F. G., and Peters, P. C.: J. A. M. A. 193: 879, 1965. 10. Kaitz, A. L., and Hodder, E.: New England J. Med. 265: 667, 1961. 11. Kincaid-Smith, P., Bullen, M., Mills, J., Fur-
12. 13.
14. 15.
16. 17. 18.
rell, U., Huston, N., and Goon, F.: Lancet 2: 61, 1964. Mulla, N.: Ohio State M. J. 59: 154, 1963. Sleigh, J. D., Robertson, J. G., and Jndale, M. H.: J. Obst. & Gynaec. Brit. Comm. 71: 74, 1964. Griess, P.: Ber. deutsch. chem. Gesellsch. 12: 426, 1879. Cruickshank, ]., and Moyes, ].: Brit. M. J. 2: 712, 1914. Kahler, R. L., and Guse, L. B.: J. Lab. & Clin. Med. 49: 934, 1957. Slowinski, E. ]., and Smith, L. G.: AM. J. 0BST. & GYNEC. 7: 94, 1966. Smith, L. G., and Schmidt, J.: J. A. M. A. 181: 431, 1962.
800 Northeast Thirteenth Street Oklahoma City, Oklahoma 73104