Diabetes in pregnancy

Surgical approach (obstetrics context)

• Not a single operation; anaesthetic involvement usually around induction of labour, operative vaginal delivery, or Caesarean section (CS) for maternal/fetal indications.
• Typical obstetric pathway in diabetes:
  • Antenatal: tighter surveillance (growth scans, Dopplers, CTG), screen/monitor for pre-eclampsia; plan timing of delivery (often earlier if complications).
  • Intrapartum: continuous fetal monitoring; avoid prolonged labour; manage glucose/ketones; low threshold for operative delivery if fetal compromise.
  • CS: standard lower-segment transverse uterine incision; increased risk of PPH and infection; neonatal team present due to hypoglycaemia/respiratory issues.

Anaesthetic management (typical scenarios)

• Labour analgesia
  • Type of anaesthesia: Regional (epidural) preferred if any risk of operative delivery; facilitates urgent CS.
  • Airway: N/A (but anticipate GA risk if conversion/urgent CS).
  • Duration: variable (hours). Pain: moderate–severe without neuraxial.
  • Glucose: hourly capillary glucose in established labour if insulin-treated; consider VRIII if not maintaining target.
• Elective Caesarean section
  • Type of anaesthesia: Regional (spinal or CSE) usually first-line.
  • GA: reserve for contraindications to neuraxial or urgent category-1; higher aspiration/airway risk in pregnancy; diabetes may add autonomic neuropathy/gastroparesis (type 1 long-standing).
  • ETT/SGA: if GA, ETT with RSI; SGA generally not first choice for obstetric GA.
  • Duration: ~45–90 min. Pain: moderate (multimodal; neuraxial opioids if appropriate).
  • Glucose: morning list; follow local obstetric diabetes protocol; many require VRIII with dextrose-saline and K+; avoid hypoglycaemia peri-delivery.
• Emergency Caesarean section
  • Type: top-up epidural if working; otherwise spinal if time and no contraindication; GA if immediate threat or neuraxial not feasible.
  • Key added risks: fetal compromise (macrosomia/placental dysfunction), maternal DKA (rare but catastrophic), aspiration risk, haemorrhage.

Definitions and classification

• Diabetes in pregnancy includes:
  • Pre-existing diabetes: type 1 or type 2 diagnosed pre-pregnancy.
  • Gestational diabetes (GDM): glucose intolerance first recognised in pregnancy (usually 2nd/3rd trimester).
• Why anaesthetists care: higher rates of operative delivery, hypertensive disease, obesity/OSA, infection, PPH, and neonatal complications (hypoglycaemia, respiratory distress).

Physiology and glycaemic targets

• Pregnancy metabolic changes:
  • Early pregnancy: increased insulin sensitivity → risk of hypoglycaemia (esp. type 1).
  • Late pregnancy: placental hormones (hPL, cortisol, progesterone, GH) → insulin resistance → rising insulin requirements.
  • Accelerated starvation: fasting predisposes to ketosis; DKA can occur at lower glucose than non-pregnant.
• Intrapartum glucose targets (local protocols vary): aim ~4–7 mmol/L (some use 4–6 or 4–8). Avoid maternal hypoglycaemia and wide swings.
• Ketone monitoring: consider if unwell, vomiting, prolonged fasting, hyperglycaemia, or type 1; treat ketonaemia urgently.

Maternal complications relevant to anaesthesia

• Acute: hypoglycaemia, hyperglycaemia, DKA, dehydration, electrolyte disturbance (K+ shifts with insulin).
• Chronic (esp. long-standing type 1/type 2):
  • Cardiovascular: IHD, cardiomyopathy; autonomic neuropathy → labile BP/HR, impaired response to hypotension, gastroparesis.
  • Renal: diabetic nephropathy → proteinuria, reduced GFR; affects drug handling and fluid strategy; higher pre-eclampsia risk.
  • Retinopathy: may worsen in pregnancy; avoid severe hypertension; neuraxial is not contraindicated but manage BP carefully.
  • Neuropathy: peripheral/autonomic; consider positioning/pressure care; possible increased aspiration risk if gastroparesis.
• Obesity/OSA common in type 2/GDM → difficult airway, difficult neuraxial, VTE risk, postoperative respiratory depression.

Fetal/neonatal issues relevant to theatre

• Macrosomia → shoulder dystocia risk; higher CS/operative delivery rates.
• Placental dysfunction (esp. vascular disease) → fetal growth restriction and compromise.
• Neonatal: hypoglycaemia (hyperinsulinaemia), respiratory distress, polycythaemia, jaundice; ensure neonatal team and early feeding/IV glucose plan.

Pre-anaesthetic assessment (labour ward / pre-op)

• Clarify diabetes type, duration, treatment (diet/metformin/insulin/CSII pump), hypoglycaemia awareness, recent control (HbA1c), episodes of DKA/hypoglycaemia.
• Screen for end-organ disease: BP/preeclampsia, renal function/urine protein, ECG if indicated, symptoms of gastroparesis/autonomic neuropathy.
• Airway and aspiration risk: obesity, reflux, gastroparesis; plan RSI if GA.
• IV access and bloods: FBC, U&E (K+), glucose; group & save/crossmatch depending on obstetric risk.
• Agree glucose management plan with obstetric/diabetes team: frequency of glucose checks; criteria for VRIII; perioperative insulin adjustments.

Intrapartum management (labour)

• Analgesia: early epidural is often advantageous (high conversion to operative delivery; obesity; fetal compromise).
• Glucose monitoring: typically hourly if insulin-treated or on VRIII; 2-hourly may be acceptable in diet-controlled early labour per local policy.
• VRIII indications (common): type 1 in established labour; type 2/GDM needing insulin with poor control; inability to maintain target; prolonged fasting/vomiting; perioperative period for CS.
• Fluids with VRIII: usually dextrose-containing fluid with sodium (e.g., 5% dextrose in 0.9% saline) ± K+ as per protocol; avoid hyponatraemia and monitor K+.
• If unwell: check ketones, VBG/ABG, lactate, U&E; consider DKA even with modest hyperglycaemia; escalate early (ICU/medical).

Caesarean section: neuraxial considerations

• Regional preferred: spinal/CSE; epidural top-up if functioning.
• Hypotension: treat promptly (left uterine displacement; phenylephrine/ephedrine per local practice). Consider autonomic neuropathy in long-standing diabetes → exaggerated hypotension.
• Steroids: if given for fetal lung maturity, anticipate hyperglycaemia and increased insulin needs.
• Antibiotics and infection: ensure timely prophylaxis; diabetes increases wound infection risk.
• Post-delivery: insulin requirements drop rapidly once placenta delivered; adjust/stop VRIII per protocol to avoid hypoglycaemia.

Caesarean section: GA considerations

• Indications: category-1 urgency, failed neuraxial, contraindications to neuraxial, severe maternal compromise.
• Aspiration risk: pregnancy + possible diabetic gastroparesis; RSI with cuffed ETT; consider H2 blocker/non-particulate antacid/metoclopramide per local policy.
• Glucose: check pre-induction; avoid hypoglycaemia (especially if long fasting + insulin). Continue VRIII if running; ensure dextrose source.
• Haemodynamics: manage sympathectomy/induction hypotension; consider invasive BP if severe pre-eclampsia/major comorbidity.

Perioperative diabetes medication management (common UK approach; follow local policy)

• Diet-controlled GDM: usually no insulin/VRIII; monitor glucose in labour/CS; treat if above target.
• Metformin: often continued antenatally; perioperative handling varies—if fasting for surgery/CS and risk of renal impairment/hypoperfusion, withhold and use insulin/VRIII as needed.
• Basal-bolus insulin (general principles):
  • Continue some basal insulin to prevent ketosis (especially type 1).
  • Omit/adjust rapid-acting doses if not eating; use VRIII if needed to maintain target.
• Insulin pump (CSII): if competent patient and short procedure with stable control, may continue with close monitoring; otherwise convert to VRIII. Ensure a clear plan for who manages the pump.

Diabetic ketoacidosis (DKA) in pregnancy: recognition and immediate management

• Triggers: infection, vomiting/starvation, missed insulin, steroids, β-agonists, labour stress, pump failure.
• Features: tachypnoea/Kussmaul, dehydration, abdominal pain, altered mental state; ketonaemia/ketonuria; metabolic acidosis; glucose may be only moderately raised.
• Immediate actions (anaesthetic/critical care mindset):
  • Call for senior help: obstetrics, anaesthesia, ICU, diabetes/medicine; continuous fetal monitoring but maternal resuscitation first.
  • ABG/VBG, ketones, glucose, U&E (K+), lactate; treat precipitant (e.g., antibiotics).
  • IV fluids (0.9% saline initially), fixed-rate insulin infusion, careful K+ replacement; consider dextrose infusion once glucose falls to avoid hypoglycaemia while clearing ketones.
  • High maternal/fetal mortality risk; delivery is not primary treatment unless obstetric indication persists after stabilisation.

Postpartum considerations

• Insulin needs fall immediately after delivery; for type 1, reduce to pre-pregnancy doses (often ~50–70% of late pregnancy dose) guided by glucose and local protocol.
• GDM: insulin usually stopped; monitor glucose; arrange postpartum diabetes screening (e.g., HbA1c/OGTT per local guidance) and counsel on future type 2 risk.
• Breastfeeding increases hypoglycaemia risk in insulin-treated mothers; advise snacks/monitoring.
• Thromboprophylaxis: diabetes often coexists with obesity/CS → follow VTE risk assessment.