Renal infection and pregnancy outcome*

Renal infection and pregnancy outcome LARRY C. C . GILSTRAP , M.D. KENNETH

J. LEVENO, M.D.

F. GARY CUNNINGHAM, M.D. PEGGY

J.

WHALLEY, M.D.

ROARK,, R.N R.N.. MICKI L. ROARK Dallas, Taa.s Da.llas, Tl'xas To evaluate the impact of renal infection on pregnancy outcome, we studied a grollP groin> of pregnant women with asymptomatic renal bacteriuria and another anoth$!' group who had acute pyelonephritis. ~eIonephritis. In 248 women with asymptomatic bacteriuria, infection was 1ocaIize(t by the antIbody-coa~ baCteria method. These women were pr0spectiv8ly prospectively matched with abaderiuric control oontIOI suIijects suIIjeCts and we found SpecificaHy, the number of women with no adverse effects of treated renal or bladder infection. Specifically, hypertension and anemia in each group was similar, and infants born to these women were comparable regarding perinatal mortality, mean gestational., gestational • • and birth weight, weight. as well as indioes of maturity. A total of 487 women with acute pyetonephritis were e"ak,tatlldin e~lIfI,tatIIdin a case-cootrol ~ study and observations of the correlation of maternal anemia .and ~ pyeIonIphri1is were confirmed. c~, Women with antepartum infection had no increased adverse perinatal outcome; howeVer, in some women with intrapartum infection, pyelonephritis appeared to have initiated initialed premature labor. We concluded that treated renal infection, whether symptomatic or asymptomatic, does not significantly modify pregnancy outcome. (AM. J. De STET. GVNECOL. GVNECOL. 141 :709, 1981.)

and asymptomatic urinary tract infections during pregnancy frequently are cited as causing adverse pregnancy outcomes. Data from the preantibiotic era are generally used to support (he the premise that acute pyelonephritis causes increased prematurity 1- :,: however, if reviewed critically, the results are less l.han than conclusive. concl usive . More recently, there are other reports that link low birth weight and premature prematllre infants, pregnancy hypertension, and maternal anemia with symptomatic urinary infection. 6H- 9 Moreover, for the past two decades, asym asymptomatic ptomatic bacteriuria has also been invoked as a cause of similar pregnancy complications. In 1960, Kass 101 showed that acute pyelonephritis deKassll! Veloped in a significant number of pregnant women BOTH SYMPTOMATIC

From thf' thr Deportment Department of aIObstetrics Obstetrics and Gynecology, Thl' University of Texas Health Science Center. Centn. Presented in part at the Twenty-sixth Annual Meeting of the Society for Gynecologic Investigation, San Diego, Califarnia, California, March 21-24,1979; The Armed Forces District of the American College of Obstetricians and Gynecalagists, Gynecologists, October, 1980; and The Infectious Disease Societyfor Society for Obstetrics and Gynecolagy, Gynecology, May, 1981. 1981 . Reprint reqWlsts: reqWists: Dr. F. GaGary ry Cunnirlgham, Cunningham, Department of Obstetrics and Gynecology, University of Texas H Health of ealth Sciena Cmter, Dallas, Texas 75235 . 0OO2-9378/ 811220709+08$OO.80/0© 1981 The C. V. Mosby Co.

with asymptomatic bacteriuria and that its elimination substantially redu(:ed this complication. Adverse pregnancy effects attributed to pyelonephritis have also been linked to asymptomatic bacteriuria and include preterm delivery and growth-retarded or low-birth weight infants, as well as maternal hypertension and anemia.. IIll While some1~ somel~ - IH have shown such correlaanemia ~tt-t~ were unable to confirn them . Zinner 2t .;.; tions, others ~o-t4 attributed these diverse findings to nonuniform criteria for bacteriuria, as well as gestational age assessment. and failure to localize the site of bacteriuria. The importance of the latter factor has been emphasized by Kass,11 Kass, '1 as well as by Zinner,to Zinner ,to and both have called for investigations to assess effects of renal bacteriuria on pregnancy. In 1974, Thomas and associates t '; described the Huorescent antibody test to localize urinary traer infecur inary tract tion in which bacteria of renal origin are coated with antibody whereas bacteria from the bladder are not. Subsequently, it was shown that this method reliably predicts the site of of bacteriuria,n bacteriuria,t7. 2M ~8 and,and,. because it is simple and noninvasive, it is feasible for use in localizing bacteriuria in large populations who undergo screening. The purpose of the present investigation was to de-

709

710 Gilstrap et al. al. 710 Gilstrap et

termine what termine what adverse adverse effects effects renal renal bacteriuria, bacteriuria, both both symptomatic and and asymptomatic, asymptomatic, may may have have on on maternal maternal symptomatic and fetal fetal health. To accomplish accomplish this, this, two two approaches approaches and health. To were used: used: One One was prospective investigation investigation in were was aa prospective in which pregnancy pregnancy outcomes outcomes in which in women women with with asymptomasymptomatic bacteriuria bacteriuria of atic of renal renal origin origin were were compared compared to to those those of aa group of group with with bladder bladder bacteriuria bacteriuria as as well well as as noninnoninfected fected control control subjects. subjects. The The second second approach approach was was aa case-control case-control study study in in which which pregnancy pregnancy outcomes outcomes of of aa large large number number of of women women with with acute acute pyelonephritis pyelonephritis were were analyzed analyzed and and compared compared to to women women without without infection. infection. Methods

Asymptomatic bacteriuria-Prospective Asymptomatic bacteriuria-Prospective evaluation. evaluation. Patient population. Women presenting presenting for for prenatal prenatal Patient population. Women care at Parkland Memorial Hospital from January care at Parkland Memorial Hospital from January,, 1977, through june, 1979, 1977, through June, 1979, were were considered considered for for incluinclusion in sion in the the study study if if they they met met the the following following criteria: criteria: (I) (I) urine culture culture demonstrating demonstrating 2: 2: 10:; 10:; of of aa single single urourourine pathogen per pathogen per milliliter milliliter of of urine urine on on two two or or more more conconsecutive secutive specimens specimens obtained obtained by by aa clean-voided clean-voided techtechnique, nique, (2) (2) no no urinary urinary tract tract infection infection symptoms, symptoms, (3) (3) initial initial prenatal visit prenatal visit prior prior to to the the twenty-eighth twenty-eighth week week of of gestagestation,, (4) (4) last last menstrual menstrual period period known known,, and and (5) (5) physical physical tion findings andlor findings andlor sonography sonography supporting supporting the the menstrual menstrual history history.. Women Women with with multiple multiple gestation, gestation, known known diabediabetes, tes, chronic chronic hypertension, hypertension, or or other other chronic chronic medical medical disdisorders were orders were excluded. excluded. matched with with an an Each woman Each woman with with these these criteria criteria was was matched abacteriuric control control subject subject by by age age (within (within 22 years), years), abacteriuric race, and parity parity (nulliparous, (nulliparous, para para 1, and multiparous) multiparous).. race, and I, and Each control control subject subject was was seen Each seen prior prior to to 28 28 weeks weeks and and criteria for criteria for determination determination of of gestational gestational age age were were the the for bacteriuric bacteriuric women. women . same as same as for Bacteriologic Bacteriologic methods. methods. Urine Urine specimens specimens were were refrigerrefrigerated immediately ated immediately and and usually usually processed processed within within 4 4 hours hours.. In In some some instances, instances, these these were were refrigerated refrigerated overnight overnight and processed and processed the the next next morning. morning. Inoculation Inoculation for for quantification was quantification was performed performed with with aa calibrated calibrated bacbacteriologic teriologic loop loop to to deliver deliver 0.01 0.01 ml ml of of uncentrifuged uncentrifuged urine onto urine onto eosin-methylene eosin-methylene blue blue and and blood blood agars. agars. Bacteria were Bacteria were identified identified by by standard standard biochemical biochemical techniques. techniques. The site The site of of infection infection was was determined determined by by means means of of the the fluorescent Huorescent antibody antibody test, test, as as described described by by Thomas Thomas and and associates,29 associates ,29 and and was was considered considered positive positive if if 25% 25% or or more more bacteria demonstrated bacteria demonstrated fluorescence. fluorescence. Those Those women women with with antibody-coated presumed to to have have renal renal antibody-coated bacteria bacteria were were presumed bacteriuria, bacteriuria, while while those those with with aa negative negative test test were were prepresumed to sumed to have have bladder bladder infection. infection. .Treatment Treatment and and follow-up. follow-up. Women Women with with bacteriuria bacteriuria were were treated initially treated initially with with nitrofurantoin, nitrofurantoin, 100 100 mg mg at at bedtime bedtime

November November 15, I:;, 1911 19HI1 GynecoL Am. J. Am. J. Dbstet. Dbstel. Gynecoi.

for 10 10 days. days. Prenatal Prenatal visits visits were were scheduled scheduled at at intervals intervals for consonant with with standard standard obstetric obstetric care, care, and and at at each each consonant subsequent visit urine specimen specimen was obtained for for culculsubsequent visit aa urine was obtained ture.. Women with recurrent recurrent bacteriuria bacteriuria following following ture Women with therapy were therapy were treated treated as as follows follows:: For For the the first first recurrecurrence ,, they they were were given given ampicillin, ampicillin, 250 250 mg rence mg four four limes times daily for for 10 daily 10 days days.. For For aa second second recurrence, recurrence, cephalexin, cephalexin, 250 mg, mg, was was given given four 250 four times times daily daily for for 10 10 days days .. If If there there was was persistent persistent infection infection despite despite three three courses courses of of ailantimicrobials, then was timicrobials, then nitrofurantoin, nitrofurantoin, 100 100 mg mg daily, daily, was given given for for the the remainder remainder of of gestation. gestation. Definitions Definitions of of adverse adverse outcomes. outcomes. When When admitted admitted for for dedelivery, the the hematocrit hematocrit was was measured measured and and all all women women livery, were evaluated evaluated for for pregnancy-induced pregnancy-induced hypertension. hypertension . were The latter was diagnosed if the diastolic The latter was diagnosed if the diastolic blood blood pres prescc sures were 90 greater on O(C
Volume 141 Number 6

Renal infection and pregnancy outcome

711

Table I. Demographic factors and gestational ages at enrollment of 248 women with pregnancy bacteriuria and their matched control subjects Bladder infection

Renal infection Bacteriuria (N = 114) Age (yr):

I

Control (N = 114)

20.7 ± 0.41 14-34

Mean ± SEM Range

Race (%):

Bacteriuria (N = 134)

Control (N = 134)

20.6 ± 0.36 14-40

21±0.37 16-33

20.6

:!:

0.33

15-38

Black White Hispanic

49 35 16

49 35 16

57 25

18

57 25 IH

0

43 31 26

43 31 26

37 31 32

37 31 32

16.6 ± 0.56

15.5 ± 0.50

16.1 ± 0.52

16.5 ± 0.50

Parity(%): I

2 or more

Weeks' gestation at enrollment

Mean ± SEM

Table II. Incidence of pregnancy-induced hypertension in 248 bacteriuric women and their noninfected control subjects Bladder infection*

Renal infection* Bacteriuria No.

Nulliparous Multiparous

14/49 0/65

All women

141114

I

Bactniuria

Control

%

No.

29

10/49 7/65

12

17/114

I

%

No.

20 II

10/50 10/84

15

20/134

I

Control

%

No.

20 12

12150 7/84

15

19/134

t

% 23 8

14

*p > 0.1 for all comparisons.

Results Asymptomatic bacteriuria. Of 318 women with confirmed bacteriuria, 70 were excluded for the following reasons: 39 were delivered elsewhere; technical problems were encountered in the laboratory in IS; there was inadequate follow-up in 11; and five had spontaneous abortions. Thus, 248 met the previously outlined criteria and completed the study. Age, race, parity, and gestational age at enrollment of these women and their control subjects were almost identical and are summarized in Table I. Escherichia coli was isolated from 7:3% of these women; Klebsiella pneumoniae was the second most common isolate (20%). Antibodycoated bacteria were demonstrated in 114 (46%) women; the remaining 134 (54%) women had negative tests. In 11 (4.4%) women, acute pyelonephritis developed despite therapy and continued surveillance. Five of these initially had asymptomatic renal bacteriuria and the other six had bladder infections. Maternal hyperten5ion and anemia. Pregnancy induced-hypertension developed in 13% of all bacteriuric women and 14% of abacteriuric control subjects. There was no significant difference in the incidences of hyper-

tension between women with renal bacteriuria and those with bladder bacteriuria or between these groups and their respective control subjects (Table II). Nulliparous women developed pregnancy~induced hyper~ tension more frequently, but this was related neither to bacteriuria nor to the site of infection. Women with bacteriuria had a lower mean hematocrit when compared to their abacteriuric control subjects; however, this was true in women with either renal or bladder bacteriuria (Table III). There were no differences in the incidence of anemia in either group of bacteriuric women when compared to their control subjects. PpTinataloutcome. The mean gestational ages at delivery as well as the :incidence of preterm deliveries were not significantly different when infants born to women with either renal or bladder bacteriuria were compared to those of the control subjects (Table IV). The mean birth weight of infants born to women with renal infection was 177 gm greater than that of infants of control subjects (P < 0.01;). For women with bladder bacteriuria it was not significantly different. The number of infants who weighed less than 2,500 gm was similar

712

Gilstrap et al.

:'I; ",'ember 15, 19tq

Am.

J

Obstet. Gynecol.

Table HI. Mean hematocrit values and incidence of anemia in 248 bacteriuric women and their noninfected control subjects Renal infection Bacteriuria (N = 114)

Mean hematocrit (vol/IOO ml ± SEM) Hematocrit <30/ 100 ml NS

34.9 ± 0.3

I

3 (2.6%)

Control (N = 114)

35.8 ± 0.3

Bladder infec/ioll

I

P value

Bacteriuria (N = 134)

<0.05

35.4 ± 0.28

NS

5 (3 .7%)

3 (2.6%)

I

I

Control (N = /34)

36.1 ± 0.26

P value

<0:05

2 (1.5 %)

NS

= Not significanl.

Table IV. Infant outcome of women with bacteriuria and noninfected control subjects Bladdeyinfection

Renal infection Bacteriuria (N = 114)

Mean gestational age at birth (weeks ± SEM) Preterm delivery «37 weeks) Mean birth weight (gm ± SEM) Low-birth weight infants «2,500 gm) Small for gestational age

39.9±0.18 5 (4%) 3,254 ± 54* II (10%) 9 (8%)

I

Control (N = 114)

Bac~riuria(N = 134)1

39.1 ±0.2

39.9 ± 0.22

7 (6%) 3,077 ± 52* 16 (14 %) 7 (6%)

II (8%) 3,073 ± 52 18 (13%) 10 (8%)

Control (N

= 134)

39.5 ± 0.14'.

5 (4%) 3,121 ± 42 16 (12%) 13 (10%)

*p < 0.05. All other comparisons not significant.

in each group, as was the number judged to be small for gestational age. There were three fetal and no neonatal deaths in women with bacteriuria and none in the control group ; One fetus died following total abruptio placentae. one died of asp hyxia caused by a true knot in the cord and the third died as a result of maternal ketoacidosis in a patient with previously undiagnosed diabetes. The latter woman had renal bacteriuria, and the other two had bladder infection. The stillbirth rate for women with bacteriuria was 12 per 1,000, almost identical to that of II per 1,000 for the approximately 14,000 women delivered at Parkland Memorial Hospital during the lRmonth study period . To determine if successful eradication of bacteriuria had an y beneficial effect, pregnancy outcomes were analyzed according to response of infection to therap y (Table V). Women were considered cured if bacteriuria was eradicated for the duration of pregnancy with treatment given as described. Those whose infection persisted despite this treatment, were judged to have treatment failures . The numbers are small, but th ere was no difference in preterm, small for gestational age. or low-birth weight infants when women were analyzed accordingly. Acute pyelonephritis. There were 656 women with pyelonephritis. In 122, infection developed post partum. Of the remaining 534, 33 women with antepartum pyelonephritis were delivered elsewhere, 13 had a twin gestation, and one could not be matched with a

control with the use of the criteria given. Thus, there were 487 women with ac ute p yelonephritis who were matched with control subjects not having this complication . Of these, 435 had antepartum infection and 5g . had this complication while in labor. In each group. the mean age was 21.5 years with a range of 14 t039 yea.rs: 41 CJc were less than 20 years old. The majority (7 rCJc ) were black and had been pregnant at least once (70%). In Table VI. we have summarized pregnancy outcome . in these 487 infected women and their controlsubjects. Ma teTrw,l hypertension a rul anemia. There were i 5 i nulliparous women in each group ; 31 (20%) with pyelonephritis subsequently developed preg{lancy ~ in­ duced hypertension compared to 50 (33%) ofnonin~ fected control subjects (P < 0.02). Of 336 multiparolls women in each group, 30 (9CJc) of the index patients subsequently had hypertension compared to 48 (14%) of the control group (P < 0.05). T hese differences were similar when women with intrapartum and a'ntepartum infection were analyzed separately. At delivery, the mean hematocrit of women with acute renal infection during that pregnancy was 34.5 vol / lOO ml compared to a mean of 35.9 for their cqntrol subjects (P < 0.01) . A greater number of women whose pregnancy was complicated by pyelonephri~is had a hematocrit of less than 30 (8 CJc ) and less than 35 (52%) compared to noninfected control subjects (3 £7c, and 34%, respectively, P < 0.05). Once again. these differences were similar when women were compared for antepartum versus intrapartum infection.

Renal infection and pregnancy outcome

Volume 141 Number 6

713

Table V. Perinatal outcome in bacteriuric women analyzed according to response to treatment

Bacteriuric Trpatment response

No.

Renal bacteriuria (N = 114):

4

Cured (N = 93) Failed (N = 21)

Bladder hacteriuria (N = 134:

Cured (N = 110) Failed (N = 24)

II 2

I

No.

4 5

7

10 8

5 I

I

Control

B acteriuric

Control

%

Low-birth weight infants

Smallfor gestational age

Preterm delivery

I

9

10

14

3

14

10 4

9 17

6

9 2

8 8

6 10

7 2

6 8

5 4

;\'0.

6 0

6 2

8 5

I

Control

%

No.

No.

No.

I

%

%

%

Baeteriurie

I

13 3

% 15 15 12

13

Table VI. Comparison of adverse pregnancy factors in 487 women with antepartum (435) and intrapartum (52) pyelonephritis with their control subjects Factor Pregnancy hypertension:

Nulliparous (n = 151) Multiparous (n = 336) Total (n = 487)

Hematocrit:

Mean (voIlIOO ml ± SEM) Hematocrit <30 voIlIOO ml Hematocrit <35 voIlIOO ml

Birth wfight:

Mean (gm ± SEM) <2.500 gm Perinatal losses

Women with pyelonephritis (No.)

UninJ.~cted control subjects (No.)

Significance

31 (20)* 30 (9) 61 (12)

50 (33)

P < 0.02 P < (LOS P < 0.001

34.5 ± 0.29 39 (8) 252 (52)

35.9 ± 0.3 14 (3) 166 (34)

p= fLOl

3,044 ± 23 71 (15) 13 (2.7t)

3.059 ± 21

NS P < 0.05 NS

48 (14)

98 (20)

50 (10)

12 (2.5)

P < 0.05 P < 0.0'>

*Numbers in parentheses are percentages. tlncorrectly given as 1.2% in reference 32.

Pninatalou/cornl'. Infants born to women whose gestation was complicated by pyelonephritis had a mean birth weight of 3.044 gm compared to 3,059 gm in the control group. Women with acute pyelonephritis were more frequently delivered of infants who weighed <2.500 gm then the noninfected control subjects (15% versus I Wi, P < 0.(5). This statistical difference did not obtain when groups of women with antepartum and intrapartum infection were analyzed separately. In women with antepartum pyelonephritis. 13% of infants weighed less than 2,500 gm compared to 12% born to matched control su~jects. Women with intrapartum infection were more frequently delivered of such lowbirth weight infants (25%) compared to their matched control sll~jects (14';:0, but the difference was not statistically significant (X 2 = 2.23. P < 0.1), presumably because or the smaller number of intrapartum infections. There were 13 perinatal deaths in infants born to women who had pyelonephritis. Six were stillbirths, with weights ranging from 570 to 2,765 gm. These included a 1.300 gm anencephalic fetus and a 2,765 gm infant who died of a total abruptio placentae; in the remaining four the cause was not apparent. The seven

neonatal deaths were in infants who weighed from 530 to 3,500 gm. These infants died as a result of hyaline membrane disease or intracranial hemorrhage. In the control women, there were 12 perinatal losses. Five stillborn infants weighed from 635 to 1,755 gm and two were caused by abruptio placentae while the other three were unexplained. Among the seven neonatal deaths, the birth weights ranged fimn 600 to 1,410 gm. The cause of death was hyaline membrane disease in six and abruptio placentae was contributory in one. Comment

Although reports from the preamihiotic era are often cited to support an association of prematurity with acute pyelonephritis, these reports are less than conclusive if reviewed critically. For example. Leavitt." in 1917, reported that 40% of women with acute pyelitis in pregnancy had "miscarriages·'; however. gestational age and/or birth weight was not defined. In 1930, Crabtree and Prather 4 reported that 25 of 46 such women had "immediate delivery," but the length of gestation was not given. In a report by Dodds;; in 1932, of 15 possible "premature births." labor was in-

714 714

Gilstrap Gilstrap et et al. al.

duced five because because infection infection failed failed to to respond to duced in in five respond to therapy, therapy, one one woman woman had had eclampsia, eclampsia, and and one one had had twins. twins. thus thus leaving leaving only only eight eight women women who who likely likely had had premapremature 19~7, ture labor. labor. Unlike Unlike these, these, McLane McLane and and Traut,a:l Traut,a:l in in 1937, reported prematurity reported prematurity in in only only 9% of of 106 women women with with pyelonephritis pyelonephritis.. From the the paucity paucity of of reports reports thereafter. thereafter, one one infers From infers that that the the availability availability of of chemotherapy chemotherapy lessened lessened the the anxanxiety iety caused caused by by pyelonephritis pyelonephritis coincidental coincidental with with pregpregnancy. In 1967, Hibbard Hibbard and and associates associates 66 described described 345 345 nancy. In women with antepartum pyelonephritis pyelonephritis and and reported reported women with antepartum that infants weighed that 17% of of their their infants weighed less less than than 2,500 2,500 gm. gm. is insignificant when compared which insignificant when compared to to 14(;(. 14(;(. of of ununwhich is infected Sever and and assoassoinfected control control subjects. subjects. Conversely, Conversely, Sever ciates ciates~H using using data data from from the the Collaborative Collaborative Perinatal Perinatal reported that that 3.4% of of pregnant pregnant women women had had Project, Project, reported symptomatic urinary urinary infections. infections. II n n a acase-control symptomatic case-control studv study of 1.524 1.524 pregnant pregnant women, they showed showed aa significantlv significantlv of women, they higher incidence higher incidence of of anemia, anemia, low-birth low-birth weight weight infants. infants . and toxemia and toxemia in in the the infected infected women. women . Two inTwo decades decades ago, ago, the the importance importance of of urinary urinarv induring pregnancy pregnancy took new direction direction when when fections during fections took aa new lll described an association between asymptomatic Kass III ylost imbacteriuria and adverse pregnancy outcome. :'vlost pOI·tant, he he showed showed that that eradication eradication of of maternal maternal bacbacpOl·tant, teriuria significantly significantly reduced reduced the the incidence incidence of of sympsympteriuria tomatic urinary tomatic urinary infections, infections, and and this this observation observation has has repeatedly been confirmed. II . ~II. a~ Kass also reported confirmed."· ~". a4 that bacteriuria that bacteriuria caused caused an an increase increase in in premature premature deli\'deli\'ery and that that this this was was almost almost abolished abolished with with antimicroantimicroery and treatment. Although Although some some have have affirmed affirmed an an assoassobial treatment. bial of maternal maternal bacteriuria bacteriuria with with increased increased preterm pretenn ciation of ciation delivery, It. I;; delivery,lt. I;; others others have have not not done done sO.tOSO.tll- t4 t~ Analysis Analysis for for effects effects of of treatment treatment has has compounded compounded the the confusion confusion .. For example, example, LeBlanc LeBlanc and and McGanity, McGanity,13 as well well as as For 13 as Brumfitt,l:i found that that treatment treatment given given for for bacteriuria bacteriuria Brumfitt,!C' found reduced Kincaid-Smith and reduced prematurity, prematurity, whereas whereas Kincaid-Smith and BulBullen 1I~4 reported reported that that eradication eradication of of bacteriuria bacteriuria had had no no len inHuence. inHuence. Summarizing recent Summarizing these these conHicting conHicting reports reports in in aa recent issues in editorial, Zinner editorial, Zinner tt..;i observed observ ed that that "few "few issues in infecinfechave produced produced as as much much controversy controversy as as tious disease tious disease have decades age age .... .... "" The The controcontroKass' observation observation two two decades Kass' versy concerns concerns not not only only preterm preterm delivery delivery but but also also interinterversy relationships low-birth weight relationships of of bacteriuria bacteriuria with with low-birth weight growth-retarded infants as well as pregnancypregnancyand lor growth-retarded and/or infants,, as well as induced hypertension hypertension and and maternal maternal anemia. anemia. HypothetHypothetinduced these diverse diverse findings findings may may be be explained explained in that ically, these in that ically, there exists exists aa subgroup subgroup of of bacteriuric bacteriuric women women at at greater greater there risk fi)r risk fiJI' these these complications. complications. It It has has been been suggested suggested that th at localization of localization of renal renal infection infection might might identify identify such such aa group."· z;;. group.'" 2;;. 34-36 3~-36 To To address address this this hypothesis hypothesis we we have have utilized the utilized the antibody-coated antibody-coated bacteria bacteria technique technique to to

November 15. November 15 . 19RI 1911 1 Am.. .J. J. Obstel. GvnemJ. Am Obslt'l. Gvneml.

identify of pregnant pregnant women with asymptomasymptomidentify aa group group of women with atic Toimprove the the sensitivity sensitivity of of this lhi~ atic renal renal bacteriuria. bacteriuria. Toimprove test, test, we we used used the the criteria criteria of of ~25% ~25 % bacterial bacterial Huorc,Huore,cence cence to to define define aa positive positive test. test. HoweYer, HoweYer, as as pointed pointed out. out. by Mundt and and Polk,:l' Polk.:l' even even with with this this precaution, precaution, 2W1c 20% of ot by Mundt such tests such tests may may be be false false positive. positive. lising Using this this technique technique we we found no no differences differences in in indices indices of of prematurity prematurity when wRen found compared to to those those in in carefully carefully matched matched abacterimi<; abacteriuri<::; compared control subjects. subjects. Similarly. Similarly. asymptomatic asymptomatic bladder bladder ' inincontrol fection was not associated with with increased increased prematurity. prematurity. fection was not associated In the the case-control case-control study study of of women women with with acme acute In pyelonephritis, mean infant birth pyelonephritis, mean infant birth weights weights were were similar similar to of the the control control group. group. However, However, there there was was aa to those those of higher higher incidence incidence of of low-birth low-birth weight weight infants infants «2.500 «2.500 gm) women with with intrapartum infection. gm) born born to to the the 52 52 women intrapartum infection. This temporal This temporal relationship relationship of of acute acute pyelonephritis pyelonephritis to to low-birth weight low-birth weight infants infants when when this this infection infection complicomplicates labor labor suggests suggests aa causal cates ca usal role role in in the the initiation initiation of of '' preterm labor. preteI'm Another concern concern of of maternal maternal bacteriuria bacteriuria has has been been its its Another alleged perinatalloss.'l. IC, loss.'" 14. I~ .' ", alleged association association with with increased increased perinatal II n n the the present present study, study, perinatal pe rinatal mortality mortality in in those those .. women with \\'omen with acute acute pyelonephritis pyelonephritis was was almostidentical almost identical to that that in in the the matched matched control control group. group. with with even even distridistrito bution bet"'een bel\\'een stillbirths stillbirths and and neonatal neonatal deaths. deaths. Simibution Similarily. laril y. there there was was but but one one stillbirth stillbirth in in the the group group of of . women The corticorti women with with asymptomatic asymptomatic renal renal bacteriuria. bacteriuria. The paratively large 'omen studied,mupled parati\'e1y large number number of of "\mmen studied,wlIpled ' with the the small small number number of of perinatal perinatal deaths, deaths, prompted with prompted us to to conclude conclude that little impact on us that renal renal infection infection has has little impact on perinatal wastage. wastage. perinatal Historically, the the kidney kidney has has been been the the focus focus of of exteriextenHistorically, sive investigations of in the si\'e investigations of its its role role in the pathogenesis pathogenesis of of preeclampsia. this plausible preeclampsia. Because Because of of this plausible relationship. relationship. -it is not surprising that )'enal I'enal infection has been assoCiassociated with with pregnancy pregnancy hypertension. hypertension. Using dissimilar ated Usirrgdissimilar definitions many have have reported an increased increased incidence definitions ,, many reported an incidence of gestational gestational hypertension hypertension in in women with bacteribacteri- ' of \\'omen with lIria. uria . 'tl t . 11-1. ·1. !C,. IC,. 17. 17. IH. IH. tt tt while while others others have have not not confirmed confirmed .. to . 21. this.to. tl. tt·1 ,l In the present study. we found no evidence' this. that whether as that renal renal infection, infection, whether as asymptomatic asymptomatic bacteribacterianteparlllm pyelonephritis. c;alISuria 11 ria or or as as acute acute antepartum pyelonephritis, was was causally related to to the the de\elopment development of of pregnancy"induceq pregnancy"induceq ally related hypertension. hypertension. Maternal anemia anemia is is reported reported to to be be associated associated with Maternal \\'ith 17 and asymptomatic asymptomatic bacteriuria,!';, bacteriuria , I.;. 17 and we~M we~H aswelI as welI __as as Brumfitt1l7' have Brumfitt have described described an an association association with with . aCL\le aCLtte pyelonephritis. Our prior observations obser~'ations are confirmed ' in that of women women with with pyelonephritis, pyelonephritis, reported that 30% of reporte(j in here, had here, had aa hematocrit hematocrit of of < <30 30 voll vol! 100 100 rnl ml when when admitadmitled ted for for acute acute infection. infection. This This anemia anemia appears appears to to be be aa result of increased increased erythrocyte erythrocyte destruction destruction determined determined .. result of red blood blood cell cell tagging, tagging, as as weU weU as as decreased decreased by .;ICr by .;ICr red c

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Renal infection and pregnancy outcome

Volume 141 Number 6

production manifest by persistent reticulocytopenia, presumably caused by endotoxemia.:l8 That some women have delayed red blood cell mass recovery is illustrated in that 7% were still anemic at the time of delivery. Although there was a slight, albeit significa ntly lower mean hematocrit in both groups of asymptomatic women, the incidence of anemia was similar to that expected for healthy iron-sufficient women at term.:ll) In summan', while the relationship of untreated bacteriuria to subsequent acute pyelonephritis in pregnancy has repeatedly been confi rmed, other adverse effects frequently associated with either symptomatic or asymptomatic infections remain controversial. To explain the inconsistent findings in the group with asymptomatic infeClions. the concept was advanced that wo men with renal bacteriuria were a subgroup at higher risk. Data presented here show that women with asy mptomatic renal bacteriuria are at no greater risk

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715

than abacteriuric women for developing pregnancyinduced hypertension. nor are their progeny at greater risk for prematurity. The unquestionable connection of asy mptomatic bacte riuria to acute pyelonephritis precluded an investigation of the gestational effects of untreated infections . I n contrast, symptomatic infections are associated with maternal anemia and ma y be implicated in delivery of low-birth weight infants when acute pyelonephritis a nd labor occur simultaneously. Although the impact of asymptomatic rellal infection on ultimate pregnancy outcome is minimal. the need for screening and eradication of asymptomatic bacteriuria ill order to prevent pyelonephritis cannot be minimized. \t\' e acknowledge the assistance of the P ar kland Hospital Obstetric and Gynecology house stall. as well as that or Barbara McElwee. R. N .. and her clinic IlUrsing starr. The technical assista nce of Ms. Brenda Nobles was im·aluable.

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