What is the most likely diagnosis and appropriate acute management for a 29‑year‑old woman at 6–7 weeks gestation presenting with severe intractable vomiting, epigastric pain, blood‑tinged emesis, watery diarrhea, a three‑year history of gastro‑oesophageal reflux disease (GERD) discontinued upon learning of pregnancy, and a remote history of amoebic infection with a hepatic cyst?

Diagnosis and Acute Management

This patient has hyperemesis gravidarum (HG) complicated by gastroesophageal reflux disease, and requires immediate intravenous fluid resuscitation with thiamine supplementation before any dextrose administration, aggressive electrolyte replacement, and escalation to second-line antiemetics given the severity of her presentation. 1, 2

Diagnostic Criteria Supporting Hyperemesis Gravidarum

The clinical picture meets HG diagnostic criteria through multiple features:

• Onset at 6–7 weeks gestation with intractable vomiting aligns with typical HG timing (onset 4–6 weeks, peak 8–12 weeks) 2
• Blood-tinged vomitus indicates mucosal injury from repeated acid exposure and forceful vomiting 2
• Absence of fever argues against infectious gastroenteritis, which would present with fever >38°C and resolve within 1–3 days 2
• History of prior hospitalization for moderate-to-severe dehydration demonstrates severity exceeding typical nausea and vomiting of pregnancy 2
• Watery diarrhea can occur with HG due to intestinal irritation and reflex stimulation, though stool studies should be sent to exclude concurrent infection 2

The three-year GERD history, now untreated in pregnancy, compounds her symptoms. Progesterone-induced lower esophageal sphincter relaxation worsens acid reflux, creating a vicious cycle of gastric irritation triggering the vomiting reflex. 1

Immediate Stabilization Protocol

Fluid and Electrolyte Management

Initiate aggressive IV fluid resuscitation targeting urine output ≥1 L/day and resolution of ketonuria. 2 Normal saline (0.9% NaCl) with potassium chloride guided by daily electrolyte monitoring is the preferred initial fluid. 1

Critical electrolyte replacement priorities:

• Potassium and magnesium must be corrected aggressively because hypokalemia with hypomagnesemia prolongs the QT interval and increases ventricular arrhythmia risk—a documented complication of HG even with normal initial electrolytes 2, 3
• Check venous blood gas for metabolic alkalosis from hydrogen ion loss 2
• Monitor for orthostatic hypotension, decreased skin turgor, and dry mucous membranes as dehydration markers 2

Thiamine Supplementation (Non-Negotiable)

Administer thiamine 100 mg IV daily before any dextrose-containing fluids to prevent Wernicke encephalopathy. 1, 2 Pregnancy increases thiamine requirements, and HG can deplete stores within 7–8 weeks of persistent vomiting. 2 Continue for minimum 7 days, then maintain at 50 mg daily until adequate oral intake resumes. 1, 2

Pharmacologic Antiemetic Strategy

Given her severe presentation with blood-tinged emesis and prior hospitalization, she requires escalation beyond first-line therapy:

Second-Line Agent (Immediate)

Start metoclopramide 10 mg IV slowly over 1–2 minutes every 6–8 hours. 1, 2 Metoclopramide is preferred over promethazine due to fewer sedative effects and lower rates of extrapyramidal symptoms in hospitalized HG patients. 1, 2 Meta-analysis of 33,000 first-trimester exposures showed no increased risk of major congenital defects (OR 1.14,99% CI 0.93–1.38). 1

Withdraw immediately if extrapyramidal symptoms develop. 2

Ondansetron Consideration

At 6–7 weeks gestation, ondansetron use requires careful risk-benefit assessment. While ACOG recommends case-by-case decision-making before 10 weeks due to marginal increases in cleft palate (0.03% absolute increase) and ventricular septal defects (0.3% absolute increase), the absolute risks remain extremely low (11 per 10,000 births increasing to 14 per 10,000). 1

If metoclopramide proves inadequate within 24–48 hours, add ondansetron 8 mg IV every 8 hours. 1, 2 Recent evidence from oncology guidelines supports first-trimester use when severe symptoms threaten maternal health. 1

Third-Line Reserve

Methylprednisolone 16 mg IV every 8 hours for up to 3 days is reserved only for refractory cases unresponsive to metoclopramide and ondansetron. 1, 2 At 6–7 weeks, the slight increased risk of cleft palate is a concern, but this agent reduces rehospitalization rates in severe refractory HG. 2 Taper over 2 weeks to lowest effective dose; maximum duration 6 weeks. 1, 2

Addressing the GERD Component

Her untreated GERD significantly contributes to symptom severity. Once vomiting is controlled and oral intake resumes:

• Restart pregnancy-safe GERD maintenance therapy (specific agent not provided in evidence, but proton pump inhibitors are generally avoided in severe electrolyte disturbances per 2)
• Small, frequent, bland meals (BRAT diet: bananas, rice, applesauce, toast) prevent gastric overdistension 2, 4
• High-protein, low-fat meals minimize delayed gastric emptying 2, 4
• Separate solid and liquid intake to reduce gastric distension 4

Monitoring Parameters

Daily assessment until stable:

• Urine output (target ≥1 L/day) 2
• Weight trajectory (HG defined by ≥5% pre-pregnancy weight loss) 2
• Electrolytes, particularly potassium and magnesium 2
• Ketonuria resolution 2
• Liver enzymes (elevated in 40–50% of HG cases; values >1,000 U/L warrant hepatobiliary imaging) 2
• ECG to assess QT interval given electrolyte abnormalities and arrhythmia risk 2, 3

Ruling Out Alternative Diagnoses

Obtain abdominal ultrasound to exclude:

• Multiple or molar pregnancy (risk factor for HG) 2
• Gallstones or cholecystitis (can present similarly) 2
• Hepatic pathology (given her prior amoebic hepatic cyst) 2

Check thyroid function tests because biochemical hyperthyroidism occurs commonly with HG and can cause diarrhea, though it rarely requires treatment and resolves as HG improves. 2

Send stool studies to exclude concurrent infectious diarrhea, though the absence of fever and predominance of upper GI symptoms favor HG. 2

Prognosis and Counseling

• Symptoms typically resolve by week 16 in >50% of patients and by week 20 in 80%; 10% experience symptoms throughout pregnancy 1, 2
• Recurrence risk in subsequent pregnancies ranges from 40–92% 2
• Pre-emptive antiemetic therapy started before conception or at symptom onset in future pregnancies significantly reduces HG recurrence 5

Critical Pitfalls to Avoid

• Never administer dextrose-containing fluids before thiamine supplementation—this precipitates Wernicke encephalopathy 1, 2
• Do not tell the patient to "drink more water"—hypotonic fluids worsen losses; use glucose-electrolyte oral rehydration solutions when oral intake resumes 2
• Do not delay pharmacologic therapy waiting for dietary modifications alone—early aggressive treatment prevents progression to severe HG requiring hospitalization 1, 5
• Avoid drugs that prolong QT interval (certain antibiotics, additional antiemetics) in the setting of electrolyte abnormalities 2
• Do not dismiss blood-tinged emesis as benign—it indicates significant mucosal injury and warrants aggressive intervention 2

Multidisciplinary Coordination

Given her complex history (prior HG, amoebic hepatic cyst, severe GERD), coordinate care with:

• Maternal-fetal medicine for high-risk pregnancy management 2
• Gastroenterology for GERD optimization and hepatic history 2
• Nutrition services if weight loss persists despite therapy 2
• Mental health support, as anxiety and depression are common with severe HG 2