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Urinary Tract Infection in Pregnancy

ICD 10 definition of urinary tract infections – infections affecting structures participating in the secretion and elimination of urine : the kidneys , ureters , urinary bladder and urethra.
Hw common ? UTI’s are common in pregnancy – they are the most common bacterial infection in pregnancy It may be asymptomatic UTI in pregnancy has been associated with
○ prelabour rupture of membranes
○ preterm labor and delivery
○ clinical and subclinical chorioamnionitis
○ postpartum fever in mother and neonatal infection Pyelonephritis can be life threatening
○ ↑ risk of perinatal and neonatal morbidity
○ preterm delivery and low birth weight
Cause –Pregnant ♀ are at ↑ ed risk of UTIs Beginning in week 6-7 and peaks during weeks 22-24 Physiological alterations in the urinary tract
○ dilatation of the ureters and renal pelvis
○ decreased ureteral peristalsis
○ bladder tone decreases –> increased urinary capacity
○ ↑ urinary statsis and uretrovesical reflux
○ blood volume expansion ↑ GFR and urinary output
○ glycosuria Other factors which may contribute include
○ anatomical changes for eg bladder displacement
 mechanical obstruction of ureters
○ hyperestrogenism
○ gestational bacterial virulence factors
As per site of infection –Urethra ( urethritis ) Bladder ( cystitis ) Kidney ( pyelonephritis ) Blood stream ( urosepsis )


Upper or Lower urinary tract where the kidneys are the threshold between the two levels
Pathogen –E Coli is the commonest cause ~ 80 %
 – other pathogens include

 Klebsiella pneumoniae Proteus mirabilis Enterobacter species Staphylococcus saprophyticus Group B beta-hemolytic streptococcus & genital mycoplasm Ureaplasma urealyticum ( rarely causes UTI , but of significance particularly in pregnancy due to association with chorioamnionitis )
Terminology –Asymptomatic bacteriuria 
○ positive culture without declared symptoms
○ culture from a single MSU specimen yeilds the same bacterial strain in any trimester in quantitative counts of > 100,000 colony forming units / ml Acute cystitis
○ involves only the lower urinary tract
○ inflammation of the bladder due to bacterial or non-bacterial causes
○ signs and symptoms include hematuria , dysuria , suprapubic discomfort , frequency , urgency and nocturia Pyelonephritis
○ most common UTr complication in pregnant ♀
○ fever , flank pain and tenderness and sig bacteriuria
○ other symptoms may include nausea , vomiting , frequency , urgency and dysuria
History-Fetal well-being Current symptoms ( urinary and systemic ) Previous h/o UTI –> recurrent episodes more common if previous history
Co-existing vaginal discharge 
( r/o STI – may have similar symptoms ) Medical history Predisposing factors ( see next box ) Frequency of sexual intercourse New sexual partner Spermicide use Low socioeconomic status
Risk factorsClosely associated with socioeconomic status- UTI occurs 
in up to 20 % of pregnancies in disadvantaged groups 
( Vasquez 2003 ) Diabetes mellitus Recurrent UTI Anatomical abnormalities of the urinary tract Higher parity Sickle cell disease Age less than 15 yrs at first UTI
Examination Check
○ temp
○ pulse
○ blood pressure
○ respiratory rate
○ oxygen saturation Abdominal examination Try and distinguish between upper and lower UTI – patients with pyelonephritis are
○ sicker
○ may be febrile ( > 38° ) , tachycardic and have renal angle as well as suprapubic tenderness Auscultate fetal heart rate
○ can be done from 12th week Procalcitonin has been shown to be better at predicting acute pyelonephritis than WBC/ CRP
Asymptomatic Bacteriuria Asymptomatic bacteriuria increases the risk of pyelonephritis in pregnant women- untreated 20-40 % of pregnant women may develop pyelonephritis later in pregnanct Treatment of asymptomatic bacteriuria in pregnancy is indicated and considered an accepted and recommended strategy CKS NHS suggests ○ screen for asymptomatic bacteriuria on the 1st ante-natal visit by sending urine for culture ○ if asymptomatic bacteriuria is found –> send a 2nd urine sample for culture If the 2nd urine culture confirms asymptomatic bacteriuria
○ treat with 7 days with a sensitive antibiotic
○ options when sensitivities are known
 Amoxicillin 250 mg tds * 7 days
 Nitrofurantoin 50 mg qds or 100 mg bd MR * 7 days
 Trimethoprim 200 mg bd for 7 days ( see caution about folate )
 Cefalexin 500 mg bd or 250 mg 6 hrly for 7 days Send urine for culture at every antenatal visit until delivery If group B streptococcus is isolated- inform antenatal services

testing –Send urine for culture and sensitivity –> all pregnant women with a suspected UTI
○ before starting treatment
○ seven days after treatment 
( test of cure )
○ Nitrite accurately predicts UTI
○ Highly specific but not highly sensitive
○ Leukocyte esterase – is produced by neutrophils and may happen in pyuria
○ Chlamydia and ureaplasma urolyticum may be associated with pyuria and negative urine cultures
 Negative nitrite and leucocyte esterase can be used to r/o UTI in pregnancy
Choice of antibiotics –Prescribe antibiotics to all women with a suspected
 UTI during pregnancy- also check local guidance
 Nitrofurantoin 50 mg qds or 100 mg ( MR ) bd for 7 days
○ avoid in term and breastfeeding ( risk neonatal haemolysis )
It has been used extensively and is considered safe in pregnancy
Not appropriate for treating pyelonephritis
 Trimethoprim 200 mg bd for 7 days ( off label use )- good evidence to support use in pregnancy is lacking – used commonly
○ give folic acid 5 mg daily – first trimester
○ avoid use if folate deficient or taking a folate antagonist
○ avoid in first trimester ( teratogenic )
○ Breast feeding- safe in short term
 Cefalexin 500 mg bd or 250 mg 6 hrly for 7 days
○ safe in all stages of pregnancy and breast feeding
 Amoxicillin 500 mg tds for 7 days
○ safe in all stages of pregnancy and breast feeding
○ increasing resistance
 Co-amoxiclav 625 mg tds
 Fosfomycin 3g single dose ( BNF says use only if potential benefit outweighs risk )
Advice / admit –Suspected pyelonephritis –> admit Specialist advice
○ symptoms that fail to respond to appropriate antibiotic Rx guided by urine culture
○ recurrent UTIs 

Follow-up-Follow up results in case resistant pathogens are found Repeat urine culture seven days after finishing antibiotic treatment If group B streptococcus is isolated- inform antenatal services If no bacterial growth- consider an alternative cause of symptoms
Why important –UTI in pregnancy is associated with adverse outcomes
 for the mother and the baby Association with pre-eclampsia Chrioamnionitis -GBS bacteriuria strong association Pre-term delivery ↑ ed risk UTI and neonatal GBS disease Maternal UTI and neonatal UTI – some evidence to show association


Health Navigator New Zealand PIL UTI in pregnancy
Baby centre UK
American Pregnancy Association
Antibiotic and dosage guide from Goucestershire Hospitals NHS Trust
Management of UTIs in pregnancy in Primary Care from Oxfordshire Commissioning Group
An article from CDC on choice of antibiotics Ailes EC, Summers AD, Tran EL, et al. Antibiotics Dispensed to Privately Insured Pregnant Women with Urinary Tract Infections — United States, 2014. MMWR Morb Mortal Wkly Rep 2018;67:18–22. DOI: icon.
Western Australia North Metropolitan Health Service Women and Newborn Health service Infections: Urinary Tract infection in pregnant women guideline
World Health Organisation on asymptomatic bacteriuria in pregnancy

  1. A likely urinary tract infection in a pregnant woman BMJ 2017 ;357:j1777
  2. Urinary tract infections in adults NICE guidance QS90 June 2015
  3. Urinary tract infections ( lower ) – women CKS NHS
  4. Management of suspected bacterial urinary infection in adults SIGN 88 July 2012
  5. Treatments for symptomatic urinary tract infections during pregnancy Cochrane Database of Systemic Reviews Juan C Vazquez , Edgardo Abalos January 2011
  6. Urinary-tract infections BNF May 2017
  7. Renal Disease in Pregnancy Patient UK
  8. Guideline on urological infections  European Association of Urology- EAU March 2013
  9. Primary Care Antimicrobial Guidelines All Wales Medicines Strategy Group September 2015
  10. Urinary Tract Infections During Pregnancy Am Fam Physician. 2000 feb 1;61 (3) :713-720
  11. Mandell , Douglas and Bennett’s Principles and Practice of Infectious Diseases Updated Edition January 2015
  12. Urinary Tract Infections in Pregnancy Medscape Emilie Katherine Johnson et al Jul 2016
  13. Health Protection Agency : uncomplicated urinary tract infections audit in primary care
  14. BPAC NZ Managing urinary tract infections in pregnancy
  15. Oxford Maternal and Perinatal Health Institute – Urinary Tract Infections in Pregnancy accessed via


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