Dizziness and Vomiting with Missed Period: Pregnancy-Related Nausea and Vomiting
First, confirm pregnancy with a urine or serum pregnancy test, as dizziness and vomiting in the context of a missed menstrual period most likely represent nausea and vomiting of pregnancy (NVP), which affects 30-90% of pregnant women and typically begins at 4-6 weeks gestation. 1
Initial Assessment and Diagnosis
Pregnancy confirmation is the critical first step, as these symptoms in the context of a missed period strongly suggest NVP, which is driven by elevated human chorionic gonadotropin (hCG) and estrogen levels combined with progesterone-induced delayed gastric emptying. 2, 1, 3
Key Clinical Features to Assess:
- Severity of symptoms: Use the Motherisk Pregnancy Unique Quantification of Emesis score to quantify vomiting severity 2
- Signs of dehydration: Check for orthostatic hypotension, decreased skin turgor, and dry mucous membranes 2
- Weight loss: Document if >5% of prepregnancy weight has been lost, which indicates progression to hyperemesis gravidarum (HG) 2
- Timing: NVP typically peaks at 8-12 weeks gestation and subsides by week 20 in most cases 1
Laboratory Evaluation if Severe:
- Electrolytes, renal function, and liver enzymes (elevated in 40-50% of HG cases) 2
- Thyroid function tests (biochemical hyperthyroidism occurs with HG but rarely requires treatment) 2
- Thiamine (vitamin B1) levels if prolonged vomiting to prevent Wernicke encephalopathy 2, 4
Treatment Algorithm
Step 1: Dietary and Lifestyle Modifications (First-Line for All Cases)
Begin immediately with dietary changes, as early intervention prevents progression to hyperemesis gravidarum. 3
- Small, frequent meals (5-6 times daily) rather than three large meals to prevent gastric overdistension 2, 3
- BRAT diet (bananas, rice, applesauce, toast) provides bland, easily digestible carbohydrates 2, 3
- High-protein, low-fat meals specifically, as fat delays gastric emptying and worsens symptoms 2, 3
- Avoid triggers: spicy, fatty, acidic, and fried foods 2, 3
- Separate solids from liquids to reduce gastric distension 3
Step 2: Non-Prescription Supplements (If Dietary Changes Insufficient)
Add vitamin B6 (pyridoxine) 10-25 mg every 8 hours as recommended by ACOG for persistent symptoms. 2, 3
Step 3: Pharmacologic Therapy (If Symptoms Persist)
Doxylamine is FDA-approved and ACOG-recommended as first-line pharmacologic therapy for NVP refractory to non-pharmacologic measures. 2, 3
- Doxylamine/pyridoxine combination (10 mg/10 mg or 20 mg/20 mg) is safe, well-tolerated, and not teratogenic 2, 3, 5
- Alternative H1-receptor antagonists: promethazine or dimenhydrinate if doxylamine unavailable 2
- Ondansetron is commonly used for severe cases but should be reserved for hyperemesis gravidarum when first-line agents fail 5
Step 4: Hospitalization and Aggressive Management (For Hyperemesis Gravidarum)
If weight loss exceeds 5% of prepregnancy weight, dehydration is present, or electrolyte imbalances develop, hospitalize for intravenous therapy. 2, 4
- IV fluid and electrolyte replacement 2, 4
- Thiamine 100 mg daily for minimum 7 days to prevent Wernicke encephalopathy and refeeding syndrome, followed by 50 mg daily maintenance 2, 4
- Conventional antiemetics as above, escalating as needed 4
- Psychological support as HG causes significant emotional distress 2, 4
Critical Pitfalls to Avoid
- Do not delay treatment: Early intervention with dietary modifications and vitamin B6 prevents progression to hyperemesis gravidarum, which affects 0.3-2% of pregnancies and can lead to severe maternal morbidity 2, 1, 3
- Do not withhold antiemetics due to unfounded teratogenicity fears: Doxylamine/pyridoxine is proven safe and effective 4, 5
- Do not forget thiamine supplementation in severe or prolonged vomiting to prevent Wernicke encephalopathy, which can be fatal 2, 4
- Rule out other causes if symptoms are atypical: thyroid storm (fever, tachycardia, altered mental status), molar pregnancy, or multiple gestation should be considered with ultrasound 2