Hyperemesis gravidarum diagnosis, management and escalation algorithm

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hyperemesis gravidarum diagnosis management escalation algorithm 2024 guidelines

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Hyperemesis Gravidarum: Diagnosis, Management & Escalation Algorithm

Definition & Epidemiology

Hyperemesis gravidarum (HG) is a severe form of nausea and vomiting in pregnancy (NVP) characterised by:

Intractable nausea and vomiting causing starvation metabolism
>5% pre-pregnancy weight loss (ketonuria)
Dehydration, fluid-electrolyte, and acid-base imbalances
Nutritional deficiency

Incidence: ~0.5–2% of pregnancies. It is the second most common cause of pregnancy-related hospitalisation.

Timing: Symptoms begin at weeks 4–6, peak at weeks 8–12, and typically resolve by week 14–16. Up to 20% of women are affected until delivery. Recurs in 15–19% of subsequent pregnancies.

Pathophysiology & Risk Factors

Factor	Detail
hCG	Primary driver — stimulates emesis centres; highest in first trimester; conditions with elevated hCG (twins, molar pregnancy, trisomy 21) increase risk
Oestrogen/progesterone	Reduce gastric motility and slow GI transit
Thyroid stimulation	hCG α-subunit has TSH-like activity → transient gestational thyrotoxicosis in ~2/3 of HG cases
H. pylori infection	Higher prevalence in HG; eradication may reduce vomiting
Gut hormones	Ghrelin, leptin, and GI dysmotility contribute
Genetics	Familial clustering; higher in women with personal or family history

Risk factors: Young, nulliparous, non-Caucasian women; multiple gestation; female fetus; trophoblastic disease; hydrops fetalis; fetal triploidy/trisomy 21; hyperthyroidism; psychiatric disorders; prior history of HG.

Diagnosis

Diagnostic Criteria (no single universally accepted definition)

The following features, taken together, constitute HG:

Criterion	Details
Persistent vomiting	Unresponsive to dietary modification and first-line therapy
Weight loss	>5% of pre-pregnancy body weight
Ketonuria	Reflects starvation metabolism (note: RCOG 2024 states ketonuria alone is NOT an indicator of dehydration severity)
Dehydration	Dry mucous membranes, poor skin turgor, hypotension, tachycardia

Differential Diagnoses to Exclude

UTI / pyelonephritis
Gastroenteritis / peptic ulcer disease (H. pylori)
Cholecystitis, pancreatitis, hepatitis
Appendicitis
Gestational trophoblastic disease
Hyperthyroidism (not gestational — requires treatment)
Addison's disease

Severity Scoring — PUQE Score

The Pregnancy-Unique Quantification of Emesis (PUQE) assesses, over the past 12 hours:

Hours of nausea
Number of vomiting episodes
Number of retching episodes

Score	Severity
≤6	Mild
7–12	Moderate
≥13	Severe

The HyperEmesis Level Prediction (HELP) score is also validated and recommended by RCOG 2024 for severity classification.

Investigations

Investigation	Expected Findings
Urinalysis	Ketonuria, elevated specific gravity ± infection
Serum electrolytes	Hyponatraemia, hypokalaemia, hypomagnesaemia
Acid-base	Contraction (hypokalaemic hypochloraemic) metabolic alkalosis or elevated anion gap
Blood glucose	Low (starvation)
LFTs	Mildly elevated ALT/bilirubin in 25–40%; hyperamylasaemia (salivary) in ~25%
Renal function	May be impaired with severe dehydration
TFTs	Free T4 elevated, TSH suppressed (transient gestational thyrotoxicosis — usually does not require treatment)
USS	Rule out multiple gestation, molar pregnancy

Management

Step 1 — Non-Pharmacological (Outpatient, Mild NVP / Early HG)

Dietary modification: Frequent small meals; dry, starchy, bland foods; separate solids and liquids; avoid known triggers (odours, heat, fatty/spicy foods)
Ginger (250 mg QID) — evidence of modest benefit, safe in pregnancy
Acupressure (P6 point)
Psychological support and reassurance
Rest; avoid sensory triggers (olfactory, visual, auditory)

Step 2 — First-Line Pharmacotherapy (Mild–Moderate)

Agent	Dose	Class
Doxylamine + pyridoxine (Diclegis/Xonvea)	10/10 mg: start 2 tabs hs; may add 1 tab AM + 1 tab midday	Antihistamine + B6; FDA-approved first-line
Pyridoxine (Vitamin B6)	10–25 mg PO TDS	B6 monotherapy
Promethazine	12.5–25 mg PO/IV/IM/PR q4–6h (max 100 mg/day)	Phenothiazine
Prochlorperazine	5–10 mg PO/IM q6–8h	Phenothiazine
Chlorpromazine	10–25 mg PO/IV q4–6h	Phenothiazine
Dimenhydrinate	50 mg PO/IV q4–6h	Antihistamine

Step 3 — Second-Line Pharmacotherapy (Moderate–Severe, hospital/IV)

Agent	Dose	Notes
Metoclopramide	5–10 mg PO/IV/IM q6–8h	RCOG 2024: second-line due to extrapyramidal risk; IV doses by slow bolus over ≥3 min
Ondansetron	4–8 mg PO/IV q8h	RCOG 2024 Grade B: safe and effective; slightly increased absolute risk of orofacial clefting with first-trimester use (weigh risk/benefit); avoid before 10 weeks if possible
Domperidone	10 mg PO TDS	Used in some guidelines

Step 4 — Inpatient Management (Severe HG — Admission Criteria Below)

IV Fluid Resuscitation

Normal saline (0.9% NaCl) with KCl in each bag — RCOG 2024 preferred fluid (NOT Hartmann's/Ringer's as default)
Infuse 2 L at 500 mL/h; maintain urine output >100 mL/h
⚠️ CRITICAL: Administer Thiamine 100 mg IV BEFORE any dextrose-containing fluid to prevent Wernicke encephalopathy
Following initial resuscitation: D5/0.45% NaCl with electrolytes until ketonuria clears
Correct hypokalaemia, hyponatraemia, hypomagnesaemia — hyponatraemia must be corrected slowly (risk of central pontine myelinolysis)

Electrolyte Supplementation

Potassium: Replace IV per local protocol until normalised
Magnesium: Monitor ionised calcium and magnesium; replace if deficient
Thiamine (Vitamin B1): 100 mg IV/PO TDS — ALL admitted patients, before any glucose load

Antiemetics (Inpatient)

Continue/escalate through the stepwise regimen above
Combine agents from different classes if single antiemetic ineffective

Step 5 — Corticosteroids (Last-resort before enteral/TPN)

Used only when all antiemetics have failed. Avoid in first 10 weeks (organogenesis) if possible — risk of orofacial clefting (~1–2/1000 treated).

Regimen	Evidence
Methylprednisolone 16 mg PO/IV q8h × 3 days, then 2-week taper	RCT: reduced readmission vs promethazine
Hydrocortisone 300 mg IV daily × 3 days, then oral taper over 1 week	RCT: reduced vomiting vs metoclopramide
Oral prednisolone then convert to IV hydrocortisone	Trend toward benefit; improved well-being and weight gain

Step 6 — Nutritional Support (Refractory HG)

Enteral Nutrition

Nasogastric (NG) feeding — preferred first approach over TPN
Indicated when patient cannot maintain weight despite all medical therapy
May be managed as outpatient with home feeding

Total Parenteral Nutrition (TPN)

Last resort only due to significant complication risk:
- Catheter sepsis: 25%
- Venous thrombosis: 3%
- Peripheral inserted central catheter (PICC): overall complication rate 50%, severe complications 22%
Use peripherally inserted lines in preference to central venous catheters (morbidity 9% vs 50%)
Use soybean/safflower oil-based lipid emulsions (not cottonseed oil)

Escalation Algorithm

NAUSEA & VOMITING IN PREGNANCY
          │
          ▼
  ┌─────────────────────────────────┐
  │ PUQE Score + Clinical Assessment│
  └─────────────────────────────────┘
          │
    ┌─────┴──────────────┐
    ▼                    ▼
 MILD (≤6)          MODERATE–SEVERE (≥7)
    │                    │
 Dietary Mx          ┌───┴─────────┐
 Ginger              │  Oral tolerated? │
 Pyridoxine          └───────┬─────┘
    │                   YES  │  NO
    │                    ▼   ▼
    │          Step 2 antiemetics ──► IV access, admission
    │          (doxylamine/pyridoxine,    criteria met?
    │           promethazine)
    │                    │
    │              Not responding?
    │                    │
    │                    ▼
    │          Step 3: Ondansetron
    │               Metoclopramide
    │             (combine classes)
    │                    │
    │              Still vomiting?
    │           Weight loss >5%?
    │                    │
    │                    ▼
    │         ┌─────────────────────┐
    │         │    ADMIT (if any):  │
    │         │ • Ketonuria +       │
    │         │   dehydration signs │
    │         │ • Can't keep PO     │
    │         │ • Weight loss >5%   │
    │         │ • Electrolyte abnl  │
    │         │ • Hypotension/tachy │
    │         │ • Neurological Sx   │
    │         └─────────┬───────────┘
    │                   │
    │                   ▼
    │     IV FLUIDS (0.9% NaCl + KCl)
    │     THIAMINE 100 mg IV FIRST ⚠️
    │     IV antiemetics (multidrug)
    │     Electrolyte correction
    │                   │
    │              Refractory?
    │                   │
    │                   ▼
    │       CORTICOSTEROIDS (methylprednisolone
    │       16 mg q8h × 3d → taper) — avoid <10 wk
    │                   │
    │              Still refractory?
    │                   │
    │                   ▼
    │         ENTERAL NUTRITION (NG tube)
    │                   │
    │              Still unable?
    │                   │
    │                   ▼
    │         TPN (PICC preferred; last resort)
    │                   │
    │         Consider H. pylori testing/
    │         eradication (non-teratogenic
    │         regimen) if not done
    │
    └──────────────────────────────────┘
                   │
    Escalate MFM involvement throughout

Admission Criteria (Any One of the Following)

Criterion
Persistent vomiting despite oral antiemetics
Inability to tolerate oral fluids/medications
Ketonuria plus clinical signs of dehydration
Weight loss >5% of pre-pregnancy weight
Hypotension or tachycardia
Electrolyte abnormalities (hypokalaemia, hyponatraemia)
Neurological symptoms (confusion, diplopia, nystagmus — risk of Wernicke's)

Key Complications to Monitor

Complication	Mechanism	Prevention/Treatment
Wernicke encephalopathy	Thiamine (B1) deficiency	Thiamine IV before any glucose infusion; 100 mg TDS
Central pontine myelinolysis	Rapid correction of hyponatraemia	Correct Na⁺ slowly (<10–12 mmol/L per 24h)
Mallory-Weiss tear / Boerhaave syndrome	Forceful repeated vomiting	Consider OGD if haematemesis
Retinal haemorrhage	Severe vomiting (Valsalva)	Early treatment of HG
Pneumomediastinum	Oesophageal air leak	CXR if chest pain
Korsakoff psychosis	Thiamine deficiency sequela	Early thiamine supplementation
Fetal growth restriction / LBW	Poor maternal weight gain	Nutritional support; target ≥7 kg weight gain
VTE	Dehydration + immobility	Hydration, consider LMWH if prolonged admission

H. pylori in HG

Several meta-analyses show higher H. pylori prevalence in women with HG. A non-teratogenic eradication regimen has been shown to reduce vomiting. Testing (urea breath test or stool antigen) is reasonable in refractory cases.

Transient Gestational Thyrotoxicosis

Occurs in ~2/3 of HG patients
TSH suppressed, free T4 elevated — driven by hCG cross-reactivity
No antithyroid treatment required — resolves with HG
Distinguish from true hyperthyroidism: absence of goitre, ophthalmopathy, prior thyroid history, anti-TSH receptor antibodies negative

Fetal & Obstetric Outcomes

Poor weight gain (<7 kg) in HG is associated with: low birth weight, small for gestational age, prematurity, low 5-minute Apgar scores
Pregnancy termination occurs in ~2% of affected women due to severity
Maternal psychological morbidity (depression, PTSD) is significant and should be addressed

Summary of Antiemetic Safety in Pregnancy

Drug	Safety
Doxylamine/pyridoxine	FDA-approved; extensive safety data
Pyridoxine (B6)	Safe
Promethazine / prochlorperazine	Widely used; generally considered safe
Metoclopramide	Safe; extrapyramidal risk — second-line (RCOG)
Ondansetron	Safe; very small absolute increase in orofacial clefting; use after 10 weeks if possible; second-line when first-line fails (RCOG 2024 Grade B)
Corticosteroids	Caution: avoid <10 weeks; ~1–2/1000 risk of orofacial clefting; last-line before nutritional support

Key References:

Rosen's Emergency Medicine: Concepts and Clinical Practice, 9e — Chapter on Obstetric Emergencies
Creasy & Resnik's Maternal-Fetal Medicine, 8e — Chapter 16
Sleisenger and Fordtran's Gastrointestinal and Liver Disease, 11e — Chapter 8
Nelson-Piercy C et al. The Management of Nausea and Vomiting in Pregnancy and Hyperemesis Gravidarum (RCOG Green-top Guideline No. 69). BJOG. 2024. PMID: 38311315 (note: erratum published PMID 40536112)

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