The vomiting centre (mainly histamine and acetylcholine receptors) in the medulla oblongata can be activated by four main input systems shown in Figure 13.1: the vestibular system, the central nervous system, the chemoreceptor trigger zone (in the fourth ventricle of the brain), and cranial nerves IX and X. With these four inputs in mind, it becomes easier to understand some of the pathologies that can activate the vomiting centre and cause nausea and vomiting, as is shown in Figure 13.2. • Contents ■ Undigested: oesophageal disorders, e.g. achalasia, pharyngeal pouch ■ Partially digested: gastric outlet obstruction, gastroparesis (delayed stomach emptying, e.g. seen in diabetes mellitus) ■ Bile (green): small bowel obstruction (distal to the ampulla of Vater) ■ Faeculent: distal intestinal or colonic obstruction. Note: the only time you will see faecal (i.e. true faeces), as opposed to faeculent (i.e. foul looking), vomiting is in patients with a gastrocolonic fistula… or coprophagia ■ Blood/coffee-ground: haematemesis (see Chapter 5) ■ Large volume: less likely to be functional. • Timing ■ Early morning: classically in pregnancy and raised intracranial pressure. ■ Duration: this is useful in identifying the severity (patients with severe nausea and vomiting present early) and a longer time course makes acute pathologies such as bowel obstruction less likely, as untreated this will either deteriorate or resolve. • Association with eating? ■ Vomiting within an hour of eating suggests an obstruction high in the gastrointestinal (GI) tract proximal to the gastric outlet. If this is the case, you should ask about peptic ulcer disease (or a history of dyspepsia) as this can cause scarring and pyloric stenosis. ■ Vomiting after a longer postprandial delay is consistent with an obstruction lower in the GI tract, usually in the small bowel. ■ Early satiety, postprandial bloating, and abdominal discomfort together suggest gastroparesis or outlet obstruction. • Use the SOCRATES mnemonic to characterize the pain (see Chapter 12). • The site is indicative of certain pathologies (e.g. right upper quadrant suggests a hepatobiliary cause, epigastric suggests a pancreatic or gastroduodenal cause). However, localization of pain is far from accurate in abdominal pathology due to the neural wiring and embryology, and also anatomical variations.
Suicidal acid ingestion leading to gastric outlet obstruction treated by early definitive surgery—case report
