Granisetron Versus Metoclopramide Effects on Gastric Volume by Sonographic Assessment on Patients Undergoing Caesarean Section.

Nausea and vomiting in the perioperative period are common sequelae during abdominal operations, with variable rates up to 80%, as reported in the literature. Perioperative nausea and vomiting associated with pregnancy originate from multiple factors. Pregnancy hormones induced lowering of the lower oesophageal sphincter tone, elevated gastric pressure by the effect of gravid uterus, hypotension, manipulation of the uterus during the operation that leads to visceral stimulation, and the use of opioids; which represent some of the proposed causative factors .

There is a lack of cost-effectiveness and consensus about prophylactic antiemetic use before abdominal surgeries. However, there is enough data reported in the literature that suggests the prophylactic use of antiemetic therapy for patients undergoing cesarean section (CS) under either general or regional anesthesia and as rescue medication for the treatment of episodes of intraoperative and postoperative nausea and vomiting.

Metoclopramide studied intensively as one of the best premedications in patients undergoing abdominal surgeries, especially in the obstetric population. It has a favorable effect on reducing the gastric fluid volume during the operation and consequently decreasing the incidence of aspiration pneumonia .

Granisetron is a selective 5-HT3 receptor antagonist with little or no affinity for other serotonin receptors is classified as drug group B in pregnant patients and approved by the FDA (Food and Drug Administration) for the treatment of post-operative nausea and vomiting in adults . 5-HT3 receptor antagonists exert appropriate clinical efficacy and low incidence of adverse drug reactions. In comparison with ondansetron, granisetron is a more potent antagonist with a longer duration of action .

Different methods such as paracetamol absorption, polyethylene glycol dilution (PEG), and electric impedance tomography (EIT) suggested as methods for visualizing the structure, volume, and time to the emptying of the stomach. Gastric scintigraphy remains the gold standard for such detections . However, scintigraphy is discouraged in routine clinical settings and pregnant patients owing to the risk of radiation exposure, low cost-effectiveness, and intricate instrumental setups.

Gastric ultrasonography (GUS) has emerged as an accessible, cost-effective, safe, and portable diagnostic modality for visualizing the gastric morphology. Different studies suggest that gastric contents and volume measured through GUS significantly correlated to the cross-sectional antral area. As a result, the reliability and reproducibility of bedside GUS cannot be challenged.