A 29-year-old woman, gravida 1, para 0, at 33 weeks' gestation comes to her doctor for a routine visit. Her pregnancy has been uncomplicated. She has systemic lupus erythematosus and has had no flares during her pregnancy. She does not smoke cigarettes, drink alcohol, or use illicit drugs. Current medications include iron, vitamin supplements, and hydroxychloroquine. Her temperature is 37.2°C (98.9°F), pulse is 70/min, respirations are 17/min, and blood pressure is 134/70 mm Hg. She appears well. Physical examination shows no abnormalities. Ultrasound demonstrates fetal rhythmic breathing for > 30 seconds, amniotic fluid with deepest vertical pocket of 1 cm, one distinct fetal body movement over 30 minutes, and no episodes of extremity extension over 30 minutes. Nonstress test is reactive and reassuring. Which of the following is the next best step in management?

Administer corticosteroids and continue close monitoring

Discontinue hydroxychloroquine and continue close monitoring

Reassurance with expectant management

A 26-year-old G1P0 presents to her first obstetric visit after having a positive urine pregnancy test at home. Her last menstrual period was 9 weeks ago. She has no past medical history, but her mother has rheumatoid arthritis. The patient states that for several weeks, she has felt especially warm, even when her co-workers do not, and had muscle weakness. She also complains of mood swings and fatigue. At this visit, her temperature is 99.0°F (37.2°C), blood pressure is 140/81 mmHg, pulse is 106/min, and respirations are 17/min. Physical exam is notable for 3+ deep tendon reflexes bilaterally and 4/5 strength in both hips and shoulders. Ultrasound confirms the presence of a heart beat and shows a crown rump length that is consistent with a gestational age of 9 weeks and 3 days. Which of the following is the best therapy for this patient?

Radioactive thyroid ablation (I-131)

A 51-year-old woman comes to the physician because of fatigue and progressive pain and stiffness in her hands for 3 months. She used to play tennis but stopped 1 month ago because of difficulties holding the racket and her skin becoming “very sensitive to sunlight.” Her last menstrual period was 1 year ago. She has diabetes mellitus controlled with insulin. She does not smoke or drink alcohol. Vital signs are within normal limits. The patient appears tanned. The second and third metacarpophalangeal joints of both hands are tender to palpation and range of motion is limited. Which of the following is the most appropriate next step in diagnosis?

Testing for parvovirus B19 antibodies

Testing for anti-nuclear antibodies

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

A 66-year-old woman comes to the physician because of a 1-week history of pruritic blister formation. Physical examination shows multiple 1–3 cm bullae on the palms, soles, lower legs, and inguinal folds. Gentle rubbing of the skin does not result in sloughing of the epidermis. Immunofluorescence studies of a perilesional skin biopsy specimen are most likely to show deposition of antibodies in which of the following areas?

Between epidermal keratinocytes

Autoimmune disorders in pregnancy for USMLE Step 1: High-Yield OB/GYN Lessons

Systemic Lupus Erythematosus (SLE) - The Great Imitator

Maternal Risks: Disease flares (especially postpartum), lupus nephritis, ↑ risk of preeclampsia, thromboembolism, and maternal mortality.
Fetal Risks: Miscarriage, Intrauterine Growth Restriction (IUGR), preterm birth, and stillbirth.
Neonatal Lupus Syndrome:
- Caused by passive placental transfer of maternal anti-Ro/SSA and/or anti-La/SSB antibodies.
- Manifests as transient skin rash, hematologic abnormalities, or permanent congenital heart block (CHB).

Neonatal Lupus: Pathophysiology, ECG, Rash, Clinical Facts

Management:
- Pre-conception: Plan pregnancy during disease remission (ideally >6 months).
- Antepartum: Continue Hydroxychloroquine (HCQ) to prevent flares. Start low-dose aspirin (LDA) by 12 weeks to reduce preeclampsia risk.

⭐ The presence of anti-Ro/SSA antibodies carries a 1-2% risk for congenital heart block; this risk increases to ~20% in subsequent pregnancies if a prior child was affected.

Antiphospholipid Syndrome (APS) - Clots & Losses

Pathophysiology: Prothrombotic autoimmune state where antibodies target cell membrane phospholipids, leading to hypercoagulability.
Diagnostic Criteria (Sapporo):
- Clinical (≥1): Vascular thrombosis OR pregnancy morbidity (≥3 losses <10 wks; ≥1 loss >10 wks; premature birth <34 wks due to eclampsia/placental insufficiency).
- Lab (≥1, on 2 occasions >12 wks apart): Lupus anticoagulant, Anti-cardiolipin IgG/IgM, Anti-β2 glycoprotein I IgG/IgM.
Management: Low-dose aspirin (LDA) + prophylactic heparin (LMWH).

⭐ Paradoxical Lab Finding: APS can cause a prolonged aPTT in vitro (due to interference by lupus anticoagulant) but causes thrombosis in vivo.

RA, Thyroid & More - Rogues' Gallery

Rheumatoid Arthritis (RA):
- Often improves during pregnancy.
- Safe meds: Hydroxychloroquine, Sulfasalazine.
- ⚠️ AVOID Methotrexate (teratogen).
Thyroid Disorders:
- Graves' (Hyper): Maternal TSH-receptor Abs (TSI) cross placenta → fetal thyrotoxicosis. Tx: PTU (1st tri), then Methimazole.
- Hashimoto's (Hypo): ↑ risk of miscarriage, preeclampsia. Monitor TSH; ↑ Levothyroxine dose is common.
Myasthenia Gravis:
- AChR-Abs can cause transient neonatal myasthenia.
- ⚠️ AVOID Magnesium Sulfate (can trigger myasthenic crisis).
Sjögren's Syndrome:
- Associated with Anti-Ro (SSA) & Anti-La (SSB) antibodies.
⭐ Presence of anti-Ro/SSA antibodies confers a 1-2% risk of fetal congenital heart block, which can be detected by fetal echocardiography.

Fetal Echocardiogram: Complete Heart Block & Bradycardia

Pregnancy Pharmacopoeia - Safe Meds Guide

Goal: Use lowest effective dose; multidisciplinary management is key.
Biologics (TNF-α inhibitors): Generally safe, but often stopped in the 3rd trimester to reduce neonatal infection risk.

⭐ Hydroxychloroquine is crucial and safe to continue in pregnant SLE patients; it reduces the risk of cardiac and cutaneous neonatal lupus and maternal flares.

High-Yield Points - ⚡ Biggest Takeaways

SLE flares are common postpartum; hydroxychloroquine is protective and safe throughout pregnancy.

Anti-Ro/SSA and Anti-La/SSB antibodies are linked to congenital heart block.

Antiphospholipid syndrome (APS) requires low-dose aspirin and heparin to prevent thrombosis and pregnancy loss.

Rheumatoid arthritis often improves during pregnancy, while SLE tends to worsen.

Avoid magnesium sulfate in mothers with Myasthenia Gravis to prevent a myasthenic crisis.

Maternal Graves' disease can cause fetal thyrotoxicosis via placental transfer of TSI antibodies.

Continue reading on Oncourse

CONTINUE READING — FREE

or get the app

App Store|Google Play