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?

Observation in the outpatient settings

Treatment in outpatient settings with labetalol

Treatment in the outpatient settings with nifedipine

Treatment in the inpatient settings with methyldopa

Admission to hospital for observation

A 35-year-old woman, gravida 2, para 1, at 16 weeks' gestation comes to the office for a prenatal visit. She reports increased urinary frequency but otherwise feels well. Pregnancy and delivery of her first child were uncomplicated. Her vital signs are within normal limits. Pelvic examination shows a uterus consistent in size with a 16-week gestation. Urinalysis shows mild glucosuria. Laboratory studies show a non-fasting serum glucose concentration of 110 mg/dL. Which of the following is the most likely explanation for this patient's glucosuria?

Increased glomerular filtration rate

Increased glomerular filtration barrier permeability

A 22-year-old primigravida is admitted to the obstetrics ward with leg swelling at 35 weeks gestation. She denies any other symptoms. Her pregnancy has been uneventful and she was compliant with the recommended prenatal care. Her vital signs were as follows: blood pressure, 168/95 mm Hg; heart rate, 86/min; respiratory rate, 16/min; and temperature, 36.7℃ (98℉). The fetal heart rate was 141/min. The physical examination was significant for 2+ pitting edema of the lower extremity. A dipstick test shows 1+ proteinuria. On reassessment 15 minutes later without administration of an antihypertensive, her blood pressure was 141/88 mm Hg, and the fetal heart rate was 147/min. A decision was made to observe the patient and continue the work-up without initiating antihypertensive therapy. Which of the following clinical features would make the suspected diagnosis into a more severe form?

24-hour urinary protein of 5 g/L

Blood pressure of 165/90 mm Hg reassessed 4 hours later

A 27-year-old woman presents to her primary care physician for a concern about her pregnancy. This is her first pregnancy, and she is currently at 33 weeks gestation. She states that she has experienced diffuse swelling of her ankles and legs and is concerned that it is abnormal. Otherwise, she has no concerns. The patient has a past medical history of obesity and diabetes. Her temperature is 98.5°F (36.9°C), blood pressure is 147/92 mmHg, pulse is 80/min, respirations are 15/min, and oxygen saturation is 97% on room air. Physical exam reveals bilateral edema of the lower extremities. Which of the following is the best next step in management?

Spot protein to creatinine ratio

Reassurance and followup in 1 week

A 32-year-old woman, gravida 2, para 1, at 32 weeks' gestation comes to the physician for a prenatal visit. She reports that she has had frequent headaches and dizziness recently. Pregnancy and delivery of her first child were uncomplicated. There is no personal or family history of serious illness. Medications include folic acid and a multivitamin. Her temperature is 37°C (98.6°F), pulse is 90/min, and blood pressure is 170/100 mm Hg. Pelvic examination shows a uterus consistent in size with a 32-week gestation. Physical examination shows 2+ edema in the lower extremities. Laboratory studies show: Hematocrit 37% Leukocyte count 9000/mm3 Platelet count 60,000/mm3 Serum Na+ 140 mEq/L Cl- 104 mEq/L K+ 4.4 mEq/L Creatinine 1.0 mg/dL Aspartate aminotransferase 20 U/L Alanine aminotransferase 20 U/L Which of the following is the most appropriate next step in management?

Magnesium sulfate and labetalol therapy

A 25-year-old woman presents to her physician with a missed mense and occasional morning nausea. Her menstrual cycles have previously been normal and on time. She has hypothyroidism resulting from Hashimoto thyroiditis diagnosed 2 years ago. She receives levothyroxine (50 mcg daily) and is euthyroid. She does not take any other medications, including birth control pills. At the time of presentation, her vital signs are as follows: blood pressure 120/80 mm Hg, heart rate 68/min, respiratory rate 12/min, and temperature 36.5℃ (97.7℉). The physical examination shows slight breast engorgement and nipple hyperpigmentation. The gynecologic examination reveals cervical softening and increased mobility. The uterus is enlarged. There are no adnexal masses. The thyroid panel is as follows: Thyroid stimulating hormone (TSH) 3.41 mU/L Total T4 111 nmol/L Free T4 20 pmol/L Which of the following adjustments should be made to the patient’s therapy?

Increase levothyroxine dosage by 20%–30%

Decrease levothyroxine dosage by 30%

The patient is euthyroid, so no adjustments should be made

Increase levothyroxine dosage by 5% each week up to 50%

A 25-year-old woman, gravida 2, para 1, at 25 weeks' gestation comes to the emergency department because of a 1-day history of fever and right-sided flank pain. During this period, she also had chills, nausea, vomiting, and burning on urination. Her last prenatal visit was 10 weeks ago. Pregnancy and delivery of her first child were uncomplicated. Her temperature is 39°C (102.2°F), pulse is 110/min, respirations are 20/min, and blood pressure is 110/70 mm Hg. Physical examination shows costovertebral angle tenderness on the right. The abdomen is soft and nontender, and no contractions are felt. Pelvic examination shows a uterus consistent in size with a 25-week gestation. Fetal heart rate is 170/min. Laboratory studies show: Leukocyte count 15,000/mm3 Urine Nitrite 2+ Protein 1+ Blood 1+ RBC 5/hpf WBC 500/hpf Blood and urine samples are obtained for culture and drug sensitivity. Which of the following is the most appropriate next step in management?

Inpatient treatment with intravenous ceftriaxone

Outpatient treatment with oral ciprofloxacin

Inpatient treatment with intravenous ampicillin and gentamicin

Admit the patient and request an emergent obstetrical consult

Renal disease in pregnancy for USMLE Step 1: High-Yield OB/GYN Lessons

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 Tier	Serum Creatinine	24-hr Proteinuria	Adverse Outcome Risk
Mild	< 1.4 mg/dL	< 1 g/day	Low to Moderate
Severe	> 1.4 mg/dL	> 1 g/day	High

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 Complications	Fetal & 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.

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