6.1 Urinary Tract Infections

EXPLANATION OF CONDITION

Urinary tract infection (UTI) is caused by bacteria in the urinary tract. Bacteria usually originate from the bowel and the most common causative organism is Escherichia coli, which accounts for 80–90% of all acute UTI. In pregnancy UTI may be manifest as the urethral syndrome, acute cystitis (2% of all pregnancies) or acute pyelonephritis (1–3% of pregnancies).

Features of the urethral syndrome are frequency and dysuria, whereas those of acute cystitis include frequency, urgency and dysuria, offensive smelling urine, haematuria and suprapubic discomfort. Urethral syndrome may be caused by sexually transmitted genital infections such as Chlamydia trachomatis. Acute pyelonephritis may present with pyrexia, rigors, abdominal/flank pain, nausea and vomiting^1–4.

The presence of >10⁵/ml of the same bacterial species in a midstream specimen of urine (MSU) in the absence of symptoms is called asymptomatic bacteriuria (ABU). This is of greatest significance in pregnancy, and in non-pregnant individuals with structurally abnormal urinary tracts, renal stones or diabetes mellitus^2,5,6.

COMPLICATIONS

• Acute symptomatic urinary tract infection
  
  
  
  • developed by ≥30% of women with asymptomatic bacteriuria
    
  • can lead to pyelonephritis
    
  • untreated infection may cause kidney damage^2,5,6
  
  
• Acute cystitis
  
  
  
  • not usually dangerous but may cause significant discomfort and inconvenience
    
  • usually an isolated event but can be recurrent and may follow sexual intercourse
    
  • if untreated may progress to acute pyelonephritis
  
  
• Pre-term labour
  
  
  
  • in many non-pregnant women uncomplicated asymptomatic bacteriuria resolves spontaneously
    
  • in pregnancy ABU is associated with premature delivery and low birth weight and is therefore treated with antibiotics
    
  • ABU occurs in 2–10% of all pregnancies¹
  
  
• Acute pyelonephritis
  
  
  
  • a more serious infection
    
  • if very severe, or inadequately treated, septicaemia may result in acute renal failure, multiple organ failure and death
    
  • repeated episodes of acute pyelonephritis may be associated with the development of renal scars⁴

NON-PREGNANCY TREATMENT AND CARE

• Identify causative organism by testing an MSU, and treat with appropriate antibiotics
  
• On completion of antibiotic therapy, an MSU is retested to ensure that the urine is now free of infection
  
• Treatment is not required in non-pregnant women with uncomplicated asymptomatic bacteriuria
  
• Affected individuals should be warned to be alert for symptoms suggestive of active urinary infection

Advise on ways to reduce the risk of recurrent UTI:

• Drink 2 l of fluid daily, with frequent voiding of urine
  
• Wipe from ‘front to back’ after passing urine
  
• Void to empty the bladder after intercourse
  
• Drinking cranberry juice may reduce the risk; the dosage is unclear, but approximately 200–300 ml (or by capsule), daily appears to be potentially effective^7–9
  
• Consider prophylactic antibiotics if recurrent UTI

If UTI is recurrent, consider investigation of underlying cause, such as renal stones or ureteric reflux, with:

• Renal ultrasound
  
• Abdominal X-ray
  
• Cystoscopy

Acute pyelonephritis may require:

• Hospitalisation
  
• Intravenous hydration, monitor fluid balance
  
• Intravenous antibiotics, changing to oral antibiotics when infection is controlled
  
• Monitor U&E, urine and blood cultures
  
• Four-hourly observation of temperature

PRE-CONCEPTION ISSUES AND CARE

• Investigate renal function, and possible underlying causes, prior to pregnancy if recurrent infections have occurred
  
• Treat and eliminate infections
  
• Women at risk should be counselled regarding the need for regular urine culture, and the possible requirement for antibiotic therapy during pregnancy
  
• Advise that there is an increased risk of UTI in pregnancy. This is as a result of relaxation and dilation of the ureters due to hormonal changes and compression at the pelvic brim by the enlarging uterus and ovarian vein². As the pregnancy advances, upward displacement of the bladder into the abdomen results in elongation of the urethra. Under these circumstances, incomplete bladder emptying allows urinary stasis, which in turn encourages infection. If this is accompanied by vesicoureteral reflux ascending bacterial migration and infection is facilitated²

6.2 Chronic Kidney Disease

EXPLANATION OF CONDITION

Chronic kidney disease (CKD) implies longstanding kidney problems often, but not always, associated with loss of excretory function. CKD is classified according to estimated glomerular filtration rate (eGFR). Five stages are recognised:

Estimated GFR is automatically reported by chemical pathology laboratories using a formulaic calculation based on serum creatinine², but it is not validated in pregnancy.

Proteinuria in the first trimester of pregnancy may be the first indication of CKD, as this is often the first time a woman’s urine has been tested.

COMPLICATIONS

• Hypertension – common with CKD
  
• Fluid retention – may cause ankle oedema and contribute to hypertension
  
• Anaemia – increased risk as the kidney produces erythropoietin which stimulates the bone marrow to produce red blood cells; erythropoietin is often deficient
  
• Heavy proteinuria – in the nephrotic range (>3 g per 24 hours); can cause hypoalbuminaemia and oedema
  
• Metabolic acidosis – can develop
  
• Renal bone disease – may occur
  
• UTI – increased risk of infection
  
• Impaired renal function – this may relentlessly and predictably deteriorate over time
  
• Patients may be given dietary restrictions to help control BP and potassium levels within safe limits

NON-PREGNANCY TREATMENT AND CARE

• Investigations into the cause of CKD may include renal ultrasound scanning or occasionally renal biopsy
  
• Some causes of CKD may require specific treatments, such as immunosuppression with steroids
  
• Regular monitoring of renal function in nephrology clinic or primary care
  
• Antihypertensive medication
  
• Diuretics to treat fluid retention
  
• Subcutaneous erythropoietin for anaemia
  
• Referral to a dietician if dietary restrictions are required to maintain safe blood chemistry levels
  
• Patient education about disease and treatment
  
• Dialysis or transplantation is required for stage 5 CKD

PRE-CONCEPTION ISSUES AND CARE

• Referral to a renal/obstetric or maternal medicine clinic for personalised specialised advice and counselling
  
• The predicted outcome of a pregnancy depends on, and is directly proportional to:
  
  
  
  • how well controlled the BP is at booking
    
  • the level of renal impairment
    
  • magnitude of proteinuria
    
  • the underlying disorder responsible for CKD^3–6
  
  
• Ascertain cause of CKD; if actively under investigation it is prudent to await results before conception
  
• Always consider previous obstetric history and underlying medical conditions, e.g. patients with lupus nephritis could also have antiphospholipid syndrome⁷
  
• With progressively worsening CKD, decreasing fertility and need for early conception is balanced against the risk of deteriorating renal function in a pregnancy
  
• Optimal BP control is essential, and alteration to medications may be required
  
  
  
  • ACE inhibitors are commonly used for patients in CRF because of their protective effect on the kidneys, but they are contraindicated in pregnancy as they cause fetal anuria and subsequent oligohydramnios⁸
  
  
• Heavily proteinuric patients are at increased risk of thrombo-embolism in pregnancy
  
  
  
  • prophylactic daily injections of low-molecular-weight heparin might be considered if they become preg­nant; must be balanced against the increased risk of bleeding⁹
  
  
• Some individuals have familial renal disease and may require referral to clinical genetics for counselling
  
• Pre-eclampsia risk increases with CKD, being difficult to differentiate from deterioration of underlying CKD
  
• Increased risk of UTI, so regular MSU testing required with early treatment of symptoms
  
• If there is significant proteinuria, it may be difficult to measure accurately the alpha-feta protein (AFP) level
  
  
  
  • meaningful interpretation of Down’s syndrome screen­ing blood test, usually offered around the 15th week of pregnancy, may not be possible
    
  • if the kidney is leaking protein, AFP may also, theoretically, be lost in the urine
  
  
• Once pregnant, the woman will need to have regular hospital appointments, at a specialised centre

6.3 Dialysis in Pregnancy

EXPLANATION OF CONDITION

Dialysis is a means of removing waste products and water from the body of patients whose kidneys have failed and have lost their ability to excrete water and dissolved waste products as urine (Appendix 6.3.1). These patients would otherwise die.

Two types of dialysis are available.

Haemodialysis

In haemodialysis (HD) blood is circulated through a machine where it is purified before being returned to the patient. This type of dialysis is usually performed on three occasions per week in hospital. HD patients require access to their circulation, usually in the form of an arteriovenous fistula or a semi-permanent plastic catheter inserted into a large vein.

Peritoneal Dialysis

In peritoneal dialysis (PD) the patient has a soft tube inserted into the peritoneal cavity. This is used to drain up to 2.5 l of fluid in and out of the peritoneal cavity, typically four times a day, by patients in their own home.

Each patient has an individual dialysis prescription and a target ‘dry’ weight to ensure that the correct amounts of waste products and fluid are removed by their dialysis.

Women of childbearing age receiving dialysis either have reduced fertility or are infertile.

COMPLICATIONS

• Dialysis is an imperfect substitute for normally functioning kidneys and dialysis patients have a reduced life expectancy
  
• Nearly all dialysis patients are hypertensive and anaemic due to the failure of damaged kidneys to produce erythropoietin
  
• Dialysis patients suffer from secondary hyperparathyroidism and renal osteodystrophy
  
• Dialysis patients have greatly increased morbidity and mortality, predominantly as a result of infection and especially cardiovascular disease, including heart disease, cerebrovascular disease and peripheral vascular disease
  
• Arteriovenous fistulae can clot off and become blocked, and permcaths can become blocked or infected; an urgent alternative has to be arranged
  
• Patients receiving peritoneal dialysis can develop peritonitis as a result of bacteria entering the peritoneal cavity through the dialysis tube; treatable with antibiotics but a potentially very serious complication

NON-PREGNANCY TREATMENT AND CARE

The patient needs close supervision and care from a multidisciplinary team including doctors, nurses, dieticians, pharmacists and dialysis technicians.

Treatment

• Dialysis – to be performed regularly
  
• Nearly all patients need antihypertensive medication and erythropoietin injections to prevent severe anaemia
  
• Strict dietary restrictions to limit intake of fluid, potassium and phosphate
  
• Regular review clinics are required to assess adequacy of dialysis treatment and to prevent dialysis complications

PRE-CONCEPTION ISSUES AND CARE

Because of the low likelihood of pregnancy occurring in women receiving dialysis, very few actually seek pre-conceptual advice. However, conception is possible and those of childbearing age should take appropriate contraception precautions to avoid an unwanted pregnancy.

Psychosexual problems are common in dialysis patients and may limit the ability to conceive.

Refer to a joint renal/obstetric or maternal medicine clinic, where they can be seen jointly by a consultant nephrologist and obstetrician and specialised midwife. In some cases this may involve considerable travelling to the appropriate unit.

Advise that pregnancy is at high risk of problems such as:

• Anaemia
  
• Hypertension
  
• Pre-eclampsia
  
• IUGR
  
• Polyhydramnios
  
• Premature labour
  
• Haemodialysis – HD requirements will increase, and to help stabilise the blood values dialysis would be performed approximately 6 days a week (compared with three occasions per week as described above)
  
• Peritoneal dialysis – As the pregnancy advances, then smaller, more frequent fluid exchanges may need to be performed; changing to haemodialysis may have to be considered
  
• If renal transplantation is imminent it may be sensible to wait until after transplantation before trying for a pregnancy
  
• Down’s screening tests will not be interpretable in dialysis patients; nuchal translucency screening or diagnostic tests would have to be considered if requested
  
• The underlying renal disorder may have an impact on the pregnancy, and this will need to be considered
  
• Current medications will need review, and probable alteration, by the renal team

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