6 Effect of a water load test on gastric myoelectrical activity and upper gastrointestinal symptoms in patients with nausea and vomiting of pregnancy

Abstract

Nausea and vomiting of pregnancy (NVP) is a common syndrome in which symptoms predominate in the first trimester of pregnancy. Symptoms range from mild to severe and afflict up to 80% of pregnant women. The underlying mechanisms of NVP remain poorly understood. Provocative gastric function testing has not been performed in these patients.Aims: The aim of this study were to determine the effects of the water load test (WLT) on gastric myoelectrical activity, nausea, and other upper gastrointestinal symptoms in pregnant women.Method: 46 women with NVP were studied prospectively. Gastric myoelectrical activity was recorded throughout the study by electrogastrography (EGG). A 15 min baseline period was followed by a WLT during which patients ingested water until full over a 5 min period. After the WLT, an additional 30 min of EGG was recorded. EGG responses were categorized into four groups: normal (2.5–3.7 cpm), bradygastria (1.0–2.5 cpm), tachygastria (3.7–10.0 cpm), and mixed gastric dysrhythmia (tachygastria and bradygastria). Nausea, bloating, stomach fullness, and abdominal discomfort were recorded before, and 10, 20, and 30 minutes after the WLT on 100 mm visual analogue scales.Results: In response to the WLT, 14% of the women exhibited normal EGG responses, while significantly more (86%) exhibited gastric dysrhythmias (p < 0.01). Of the dysrhythmic EGG responses, 57% were tachygastria, 11% were bradygastria, and 18% were mixed gastric dysrhythmia. Patients with tachygastria ingested less water (338 ml) than patients with normal (371 ml), bradygastria (415 ml), or mixed gastric dysrhythmia (394 ml) patterns, but the differences were not statistically significant. 46% of the women reported nausea at baseline; significantly more women (72%) reported nausea after the WLT (p < 0.05). At 20 min after the WLT, a significant, direct relationship was observed between nausea severity and tachygastria (p < 0.05). The other upper gastrointestinal symptoms were not significantly increased by the WLT. Conclusions: (1) 86% of the pregnant women in this sample developed gastric dysrhythmias in response to the WLT. (2) Tachygastria was the most common dysrhythmia, and increased tachygastria was correlated with increased nausea. Gastric dysrhythmias are evoked by the WLT in women with NVP, suggesting these dysrhythmias have a pathophysiological role in the mechanism of NVP, and are a target for future therapies.