Hyperemesis Gravidarum

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Hyperemesis Gravidarum: Intro & Risks - Beyond Morning Sickness

  • Severe, intractable nausea & vomiting of pregnancy (NVP).
  • Diagnostic pointers:
    • Persistent vomiting unrelated to other causes
    • Weight loss >5% of pre-pregnancy body weight
    • Ketonuria, dehydration
    • Electrolyte imbalances (e.g., hypokalemia)
  • Onset usually <9 weeks gestation; often resolves by 20 weeks.
  • Risk Factors:
    • Multiple gestation (e.g., twins)
    • Molar pregnancy (hydatidiform mole)
    • History of HG in prior pregnancy
    • Female fetus
    • Hyperthyroidism
    • Nulliparity

⭐ HG is strongly associated with elevated levels of human chorionic gonadotropin (hCG) and estradiol, often seen in molar or multiple pregnancies.

HG Pathophysiology - Hormonal Havoc

  • hCG Overdrive: ↑↑ Human Chorionic Gonadotropin (hCG) is a key culprit.
    • Specific hCG isoforms are more emetogenic.
    • hCG structurally similar to TSH, can stimulate thyroid → gestational transient thyrotoxicosis.
  • Estrogen & Progesterone: ↑ Estrogen may sensitize vomiting centers. ↑ Progesterone relaxes GI smooth muscle, delaying gastric emptying.
  • GDF15: Placental Growth Differentiation Factor 15 (GDF15) acts directly on brainstem chemoreceptor trigger zone. GDF15 and Hyperemesis Gravidarum Pathophysiology

⭐ hCG levels often peak around 9-10 weeks gestation, coinciding with the typical peak of HG symptoms.

HG Clinical Features & Diagnosis - Unmasking the Misery

  • Key Manifestations:
    • Severe, intractable Nausea & Vomiting (NVP).
    • Significant weight loss: >5% of pre-pregnancy body weight.
    • Ketonuria (marker of starvation).
    • Dehydration signs: Tachycardia, hypotension, dry mucous membranes, oliguria.
    • Electrolyte imbalances: Hypokalemia, hyponatremia, hypochloremic alkalosis.
    • Ptyalism (excessive salivation).
    • Rare: Wernicke's encephalopathy (thiamine deficiency).
  • Diagnostic Process:
    • Primarily a clinical diagnosis of exclusion.
    • Rule out other causes (e.g., UTI, gastroenteritis, molar pregnancy, thyroid disease).
    • ⭐ Gestational transient thyrotoxicosis (↓TSH, ↑free T4) is common (50-60%), typically resolving by 20 weeks without specific antithyroid treatment.

HG Complications & Workup - Danger Signs

  • Maternal:
    • Weight loss >5%
    • Dehydration, electrolyte imbalance (↓K⁺, ↓Na⁺, alkalosis)
    • Ketonuria
    • Wernicke's encephalopathy (thiamine deficiency) 📌 (B1)
    • Mallory-Weiss tear, liver/renal issues
  • Fetal: IUGR, low birth weight, preterm birth.
  • Workup:
    • Urine ketones, electrolytes, LFTs, RFTs, TSH.
    • USG: Exclude molar/multiple pregnancy.
  • Danger Signs: Persistent vomiting, weight loss >5%, dehydration (↓urine, tachycardia), neurological symptoms (confusion, ataxia), jaundice.

    ⭐ Prophylactic thiamine (B1) is crucial in severe HG to prevent Wernicke's encephalopathy. Clinical signs of Wernicke's encephalopathy in pregnancy

HG Management - Stemming the Storm

  • Initial: Small, frequent, bland meals; avoid triggers. Hydration (ORS).
  • Pharmacotherapy (Stepwise):
    • 1st Line: Pyridoxine (Vit B6) ± Doxylamine.
    • 2nd Line: Antihistamines (Promethazine), Dopamine antagonists (Metoclopramide).
    • 3rd Line: Ondansetron (⚠️ QTc prolongation; caution in 1st trimester).
    • Refractory: Corticosteroids (e.g., Prednisolone 10-20mg TDS, after 10 weeks gestation, taper slowly).
  • Severe HG (Inpatient):
    • IV fluids: Normal Saline + KCl. Correct dehydration & electrolytes.
    • Thiamine 100mg IV/IM daily (prevent Wernicke's).
    • Nutritional support: Enteral/Parenteral if oral intake fails.

⭐ In severe HG, always administer thiamine before glucose-containing IV fluids to prevent precipitating Wernicke's encephalopathy.

High‑Yield Points - ⚡ Biggest Takeaways

  • Severe NVP causing >5% weight loss, dehydration, ketonuria, and electrolyte imbalance (hypokalemia).
  • Onset usually <9 weeks, peaks 10-12 weeks, typically resolves by 20 weeks.
  • Strongly linked to high hCG levels (e.g., molar pregnancy, multiple gestations).
  • Diagnosis of exclusion: rule out UTI, gastroenteritis, thyrotoxicosis.
  • Management: IV hydration, antiemetics (e.g., ondansetron), thiamine to prevent Wernicke's encephalopathy.
  • Ptyalism can occur; risk factors include nulliparity and prior HG history.

Practice Questions: Hyperemesis Gravidarum

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