Renal disease in pregnancy

Renal disease in pregnancy

Renal disease in pregnancy

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Physiologic Renal Changes - Kidney Overdrive

  • Hemodynamics: Pregnancy significantly ↑ renal workload.

    • ↑ Renal Blood Flow (RBF) & Glomerular Filtration Rate (GFR) by ~50%.
    • This leads to ↓ serum BUN and creatinine. Pre-gestational baseline values may signal underlying renal disease.
  • Anatomical Changes:

    • Progesterone relaxes ureteral smooth muscle, and the gravid uterus can cause compression, leading to physiologic hydronephrosis (Right > Left).

High-Yield: Trace glycosuria can be normal due to increased glucose filtration exceeding tubular reabsorptive capacity.

Ureter course and narrowing in pregnancy

Disease Classification - The Kidney Lineup

  • Pre-existing Renal Disease: Chronic conditions present before pregnancy.
    • Examples: Diabetic Nephropathy, Lupus Nephritis, IgA Nephropathy, Polycystic Kidney Disease.
  • Pregnancy-Acquired Renal Disease: Conditions developing during gestation.
    • Examples: Pre-eclampsia, Acute Kidney Injury (AKI) from sepsis or hemorrhage.

Risk Stratification: Baseline function dictates maternal/fetal risk.

Risk TierSerum Creatinine24-hr ProteinuriaAdverse Outcome Risk
Mild< 1.4 mg/dL< 1 g/dayLow to Moderate
Severe> 1.4 mg/dL> 1 g/dayHigh

Clinical Management - Bumps, Kidneys, & Babies

  • Antenatal Vigilance:

    • BP Monitoring: Frequent checks to manage hypertension.
    • Labs: Serial serum creatinine & 24-hr urine for protein to track renal function.
    • Fetal Surveillance: Serial ultrasounds to monitor for IUGR.
  • Pharmacotherapy:

    • Safe for HTN: Labetalol, Nifedipine, Methyldopa.
    • ⚠️ AVOID: ACE inhibitors & ARBs (teratogenic).
  • Delivery Planning:

    • Timing is individualized, balancing maternal stability, BP control, and fetal well-being. Worsening disease may require preterm delivery.

⭐ Patients with pre-existing renal disease have a ~20% risk of developing superimposed preeclampsia.

Maternal & Fetal Risks - Double Trouble

Pregnancy with renal disease presents a dual challenge, elevating risks for both mother and child. The degree of risk correlates directly with the severity of the underlying kidney condition and baseline hypertension.

Maternal ComplicationsFetal & Neonatal Complications
* Worsening renal function* Intrauterine Growth Restriction (IUGR)
* Superimposed pre-eclampsia* Preterm delivery (< 37 wks)
* ↑ Cesarean section rates* Low Birth Weight (LBW)
* Venous thromboembolism* ↑ Perinatal mortality

⭐ The strongest predictors of adverse fetal outcomes are the baseline maternal serum creatinine level and the degree of proteinuria before 20 weeks' gestation.

  • Physiologic hydronephrosis is common; GFR increases by 50%, leading to a ↓ in serum creatinine.
  • Chronic kidney disease (CKD) significantly elevates risk for preeclampsia, preterm delivery, and fetal growth restriction (FGR).
  • Asymptomatic bacteriuria requires mandatory screening and treatment to prevent progression to pyelonephritis.
  • ACE inhibitors and ARBs are contraindicated; use labetalol, nifedipine, or methyldopa for hypertension.
  • Lupus nephritis flares are common; conception is safest after ≥6 months of disease quiescence.
  • Proteinuria >300 mg/day is abnormal and warrants investigation.

Practice Questions: Renal disease in pregnancy

Test your understanding with these related questions

A 24-year-old primigravida presents to her physician for regular prenatal care at 31 weeks gestation. She has no complaints and the antepartum course has been uncomplicated. Her pre-gestational history is significant for obesity (BMI = 30.5 kg/m2). She has gained a total of 10 kg (22.4 lb) during pregnancy, and 2 kg (4.48 lb) since her last visit 4 weeks ago. Her vital signs are as follows: blood pressure, 145/90 mm Hg; heart rate, 87/min; respiratory rate, 14/min; and temperature, 36.7℃ (98℉). The fetal heart rate is 153/min. The physical examination shows no edema and is only significant for a 2/6 systolic murmur best heard at the apex of the heart. A 24-hour urine is negative for protein. Which of the following options describe the best management strategy in this case?

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Flashcards: Renal disease in pregnancy

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There is an increased incidence of preeclampsia in patients with pre-existing _____, diabetes, chronic renal disease, and autoimmune disorders

TAP TO REVEAL ANSWER

There is an increased incidence of preeclampsia in patients with pre-existing _____, diabetes, chronic renal disease, and autoimmune disorders

hypertension

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