Obstetric Topic 13. Pregnancy and kidney diseases. Urinary tract infections

I. Kidney Disease in Pregnancy

Classification

• Acute kidney injury: preeclampsia/HELLP, hemorrhage, sepsis, DIC, acute tubular necrosis, obstruction.
• Chronic kidney disease: glomerulonephritis, lupus nephritis, diabetic nephropathy, polycystic kidney disease.
• Pregnancy usually worsens renal disease mainly when hypertension, proteinuria or impaired renal function already exist.
• Renal insufficiency → ↑ preeclampsia, preterm delivery, IUGR and stillbirth risk.

Management

• High-risk pregnancy → obstetrician + nephrologist follow-up.
• Monitor: BP, weight/edema, serum creatinine, urea, electrolytes, urine protein, urine culture when indicated.
• Fetal surveillance: serial growth ultrasound if CKD, hypertension, proteinuria or renal deterioration.
• Treat: infection, anemia, hypertension, fluid imbalance.
• Avoid nephrotoxic/fetotoxic drugs: ACE inhibitors, ARBs, NSAIDs when renal disease/late pregnancy, aminoglycosides unless necessary.
• Delivery: based on maternal renal status, BP, preeclampsia and fetal growth; vaginal delivery possible, cesarean for obstetric/maternal indications.

Special Points

• Superimposed preeclampsia is difficult to diagnose if baseline hypertension/proteinuria exists.
• AKI with anuria + hematuria + flank pain after DIC/shock → consider acute cortical necrosis.
• Renal transplant pregnancy: very high risk; consider only with stable graft function, no recent rejection and controlled BP.
• SLE/lupus nephritis: pregnancy during remission is safest; check anti-Ro/SSA, anti-La/SSB and antiphospholipid antibodies.
• Safe SLE drugs: hydroxychloroquine, azathioprine, prednisolone when indicated.

II. UTI in Pregnancy

Why Common

• Pregnancy → progesterone ureteral dilation + hypoperistalsis + uterine compression + urinary stasis.
• Most common pathogen: Escherichia coli; also Klebsiella, Proteus, Enterococcus, GBS.
• UTI/ASB complications: pyelonephritis, preterm labor, PROM, low birth weight.

Types

• Asymptomatic bacteriuria: ≥10⁵ CFU/mL in urine culture without symptoms.
• Acute cystitis: dysuria, frequency, urgency, suprapubic pain; no fever/flank pain.
• Acute pyelonephritis: fever, chills, nausea/vomiting, flank pain, CVA tenderness, toxic appearance.

Diagnosis

• Screen ASB: urine culture once early in prenatal care.
• Symptomatic UTI: symptoms + urinalysis; confirm with urine culture.
• Urinalysis: leukocytes/pyuria, nitrite, bacteriuria; fever supports upper infection.
• Pyelonephritis: fever ≥38 C + UTI urine findings + flank pain/CVA tenderness.
• Renal ultrasound: no improvement after 48-72 h, severe pain, obstruction/stone/abscess suspicion.

Treatment

• ASB or cystitis: oral antibiotic for 5-7 days; tailor to culture.
• Options: nitrofurantoin, amoxicillin-clavulanate, cephalexin or fosfomycin depending sensitivity/local protocol.
• Avoid empiric ampicillin/amoxicillin alone when E. coli resistance is high.
• Nitrofurantoin/fosfomycin: good for lower UTI; not for pyelonephritis.
• TMP-SMX: avoid if possible in 1st trimester and near term; use only when benefit outweighs risk and no better option.
• Fluoroquinolones: generally avoided in pregnancy.
• Pyelonephritis: hospitalize → IV ceftriaxone or other beta-lactam regimen + hydration + paracetamol → switch to PO when improved.
• Pyelonephritis total antibiotic duration: usually 14 days.
• Recurrent UTI or pyelonephritis: consider suppressive nitrofurantoin or cephalexin according to culture.