Why do patients experience hypoglycemia and vomiting after a cesarean section (C-section)?

Hypoglycemia and Vomiting After Cesarean Section

Hypoglycemia after cesarean section occurs primarily in diabetic patients due to perioperative insulin management issues, while vomiting is a common complication of neuraxial anesthesia related to hypotension, vagal stimulation, and opioid administration.

Hypoglycemia After C-Section

Primary Causes in Diabetic Patients

The most critical cause of postoperative hypoglycemia is the continuation of insulin therapy after delivery in patients with gestational or pre-existing diabetes, despite the immediate resolution of insulin resistance once the placenta is removed. 1

• For gestational diabetes patients, all insulin therapy must be stopped immediately postpartum because insulin resistance resolves rapidly after placental delivery, making continued insulin both unnecessary and potentially dangerous 1
• Blood glucose should be monitored before meals and 2 hours after meals for 48 hours postpartum to capture the critical stabilization window 1
• Treatment should only be restarted if fasting glucose exceeds 126 mg/dL or postprandial glucose exceeds 200 mg/dL, with mandatory diabetologist consultation 1

Recognition and Management of Hypoglycemia

Any unexplained malaise in a diabetic patient postoperatively should be considered hypoglycemia until proven otherwise, even if measured glucose appears normal. 2

• Hypoglycemia is defined as blood glucose <3.3 mmol/L (60 mg/dL), though symptoms may occur at higher levels 2
• Immediate glucose administration is required for glucose <3.3 mmol/L, even without clinical signs 2
• The oral route is preferred when the patient is conscious; IV glucose should be given if unconscious or unable to swallow 2
• Hypoglycemia results from imbalance between insufficient carbohydrate supply and poorly adapted insulin therapy, particularly frequent perioperatively due to prolonged fasting or irregular food intake 2

Risk Factors for Perioperative Hypoglycemia

• Hospitalized diabetic patients face particularly high risk due to severe glycemic variations 2
• Hypoglycemia unawareness occurs in nearly 40% of T1D patients and 10% of T2D patients on insulin 2
• Deterioration of renal or hepatic function may decrease clearance of antidiabetic drugs and increase hypoglycemia risk 2
• Certain medications increase hypoglycemia risk, including quinolones, heparin, β-blockers, and trimethoprim-sulfamethoxazole 2

Neonatal Hypoglycemia Considerations

Maternal hyperglycemia during pregnancy induces fetal hyperinsulinism, which persists 24-48 hours postpartum while maternal carbohydrate supplies cease immediately after birth. 2, 3

• Neonatal hypoglycemia prevalence is 10-40% in infants of mothers with type 1 diabetes, particularly with poor maternal glycemic control 2, 3
• The risk is highest with maternal type 1 diabetes, macrosomia, and prematurity 3
• Neonatal blood glucose ≤2.5 mmol/L (45 mg/dL) should be avoided due to associations with neurologic injury and long-term neurodevelopmental sequelae 3

Vomiting After C-Section

Primary Mechanisms

Vomiting after cesarean section under neuraxial anesthesia results from four main mechanisms: hypotension from sympathicolysis, increased vagal tone causing bradycardia, visceral stimulation during surgery, and intravenous opioid administration. 4

Prevention Strategies

The first-line approach to preventing intraoperative and postoperative nausea/vomiting is comprehensive management of circulatory parameters, including liberal perioperative fluid administration and vasopressor use as needed. 4

• Maternal hypotension may be reduced by using low-dose local anesthetics with intrathecal or spinal opioids or hyperbaric solutions for sufficient controllability of neuraxial distribution 4
• Combined spinal-epidural anesthesia or epidural anesthesia may be considered as alternatives to spinal anesthesia 4

Pharmacologic Management

The combination of granisetron plus dexamethasone is more effective than granisetron alone, achieving a 98% complete response rate versus 83% for granisetron alone during the intraoperative postdelivery period. 5

• Granisetron 3 mg plus dexamethasone 8 mg IV immediately after umbilical cord clamping provides superior prophylaxis 5
• The complete response rate during the first 24 hours postoperatively is 98% with combination therapy versus 85% with granisetron alone 5
• All granisetron-containing regimens (alone or in combination with droperidol or dexamethasone) are more effective than placebo or droperidol alone during the 3-24 hour postoperative period 6

Non-Pharmacologic Interventions

Acupressure applied to the Nei-Guan point 30 minutes prior to spinal anesthesia reduces nausea incidence from 35.5% to 13.2% with no side effects. 7

• Constant pressure via a specific wrist elastic band (without skin puncture) should be applied 30 minutes before spinal anesthesia 7
• The amount of vomitus and degree of discomfort are both reduced with acupressure 7

Opioid-Related Considerations

Opioids are associated with multiple adverse effects including nausea, vomiting, sedation, respiratory depression, and ileus. 2

• Multimodal opioid-sparing approaches using acetaminophen (1 g every 8 hours) produce superior analgesia, opioid-sparing effects, and independent antiemetic actions 2
• Gabapentin 600 mg given 2 hours before cesarean section lowers pain scores, opioid requirements, and postoperative nausea and vomiting 2

Clinical Pitfalls to Avoid

• Never continue insulin therapy postpartum in gestational diabetes patients without reassessing glucose levels 1
• Do not assume normal glucose readings exclude hypoglycemia in symptomatic diabetic patients—measure immediately when symptoms occur 2
• Avoid tight glycemic control targets (80-110 mg/dL) postoperatively as they significantly increase hypoglycemia risk without clear mortality benefit 2
• Reserve antiemetic drugs for treatment rather than routine prophylaxis due to off-label use concerns in pregnant women, except for established combinations like granisetron/dexamethasone 4
• Monitor for postoperative hypoglycemia when using tight glycemic control, as it occurs in 22.3% of patients versus 11.0% with conventional control 8