What is the cause of lightheadedness, hand swelling, and blackouts in a 22-year-old female at 22 weeks gestation with low iron levels (16), urinary tract infection (positive leukocytes and trace protein in urine), and normal vital signs (blood pressure 115/78 mmHg, pulse rate 102 beats per minute, temperature 36.6°C, and oxygen saturation 99%)?

Lightheadedness and Syncope in Pregnancy: Likely Physiologic Anemia with Possible UTI

This patient's symptoms are most likely due to physiologic anemia of pregnancy exacerbated by borderline-low iron stores (hemoglobin 16 g/dL appears to be a typo and likely means 10-11 g/dL based on clinical context), with a concurrent asymptomatic urinary tract infection requiring treatment. The hand swelling is a normal pregnancy finding, while the lightheadedness and "blackouts" (presyncope) are concerning for inadequate cerebral perfusion from anemia and pregnancy-related hemodynamic changes.

Primary Diagnosis: Physiologic Anemia of Pregnancy

The lightheadedness and near-syncope are explained by the normal 40-50% plasma volume expansion in pregnancy that causes hemodilution, with plasma increasing more than red cell mass (20-30%), creating physiologic anemia. 1 At 22 weeks gestation, this patient is at the peak period for these hemodynamic changes. 2

Mechanism of Symptoms

• Inferior vena caval compression from the gravid uterus in supine position causes abrupt decreases in cardiac preload, leading to hypotension with weakness and lightheadedness that resolve quickly with position change. 2
• The slightly elevated pulse rate of 102 bpm represents the normal 10-20 beat per minute increase during pregnancy to maintain cardiac output. 2
• Her blood pressure of 115/78 mmHg shows the expected wide pulse pressure with disproportionately lower diastolic pressure due to decreased systemic vascular resistance. 2

Immediate Management Algorithm

Step 1: Confirm Anemia and Initiate Iron Therapy

Prescribe 60-120 mg of elemental iron daily as first-line treatment, as recommended by the American College of Obstetricians and Gynecologists. 1 The "iron level of 16" likely represents hemoglobin around 10-11 g/dL (below the 11 g/dL threshold at this gestational age), not serum iron. 1

• Recheck hemoglobin after 4 weeks, expecting at least 1 g/dL increase in hemoglobin or 3% increase in hematocrit. 1
• Counsel on iron-rich foods: red meat, poultry, fish, legumes, and fortified cereals. 1
• Advise taking iron with vitamin C-containing foods (citrus fruits, tomatoes, peppers) to enhance absorption. 1

Step 2: Treat the Urinary Tract Infection

The positive leukocytes and trace protein in urine indicate UTI requiring antibiotic treatment, even though she is asymptomatic. 2 Untreated UTI in pregnancy carries risks of progression to pyelonephritis and preterm labor.

• Prescribe pregnancy-safe antibiotics (nitrofurantoin, amoxicillin, or cephalexin) based on local resistance patterns
• Obtain urine culture to guide therapy if not already done
• The increased urinary frequency (7 times day and night) may represent UTI symptoms rather than "normal for her"

Step 3: Positional Management and Activity Modification

Instruct the patient to avoid supine positioning and to change positions slowly to prevent inferior vena caval compression and orthostatic symptoms. 2

• Sleep in left lateral position to optimize venous return
• Rise slowly from lying or sitting positions
• If lightheadedness occurs, immediately sit or lie down in left lateral position

Despite symptoms, maintain at least 150 minutes of moderate-intensity physical activity weekly, as recommended for pregnant women with hemoglobin >10 g/dL. 1 Complete inactivity increases risk of adverse pregnancy outcomes. 1

The Hand Swelling: Normal Pregnancy Finding

Edema occurs in up to 60% of normal pregnancies and is no longer used in diagnosis of preeclampsia. 2 The transient nature (10-15 minutes then improves) and normal blood pressure (115/78 mmHg) make this physiologic rather than pathologic.

• Her blood pressure is well below the 140/90 mmHg threshold for gestational hypertension. 2, 3
• The trace protein in urine is insufficient for preeclampsia diagnosis (requires >300 mg/L or dipstick 2+ or more). 2

Critical Pitfalls to Avoid

Do not dismiss fatigue and lightheadedness as "normal pregnancy symptoms" requiring only reassurance—these require evaluation and treatment. 1 This patient needs:

• Actual hemoglobin measurement if "iron level 16" is unclear—clarify whether this is hemoglobin, serum iron, or ferritin
• Treatment for both anemia and UTI, not observation alone
• Close monitoring for progression to preeclampsia given the proteinuria, even though blood pressure is currently normal 2

The constipation may worsen with iron supplementation—counsel on increased fluid intake (she's already drinking adequately), dietary fiber, and consider stool softeners if needed. 1

Follow-Up Plan

• Recheck hemoglobin in 4 weeks to confirm response to iron therapy 1
• Repeat urinalysis after completing antibiotics to ensure UTI clearance
• Monitor blood pressure at each prenatal visit given the trace proteinuria 2
• Educate on warning signs requiring immediate evaluation: severe headache, visual changes, severe abdominal pain, or worsening syncope 2