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ANSWERS TO CHAPTER – GASTROENTEROLOGY 1 1. ANATOMY OF THE ALIMENTARY TRACT 1. H – Second part of the duodenum These Brunner’s glands of the duodenum are characteristic. The C-shaped formation of the duodenum surrounds the head, body and uncinate process of the pancreas, and is centred at the level of the second lumbar vertebra. 2. G – Pylorus This is the transpyloric plane. The stomach has circular, longitudinal and oblique muscle layers, the circular layer producing the prominent pyloric sphincter. 3. I – Sigmoid colon mesentery The V-shaped root of the sigmoid mesentery also crosses the left common iliac artery and the left sacroiliac joint. The small-intestinal mesentery passes from the duodenojejunal flexure at the level of the second lumbar vertebra, obliquely downwards to the right sacroiliac joint, crossing the left psoas muscle, the aorta, inferior vena cava, the right gonadal vessels, the right psoas and the right ureter. 4. B – Ascending colon The ascending colon overlies the iliacus and quadratus lumborum, and is overlaid anteriorly by the peritoneum and small intestine. The descending colon in addition lies on the diaphragm above and curves medially onto the psoas muscle inferiorly. 5. E – Jejunum The jejunum has prominent villi for absorption, in contrast to the duodenum and colon where they are absent. 2. VOMITING 1. C – Drug therapy Vomiting in this case is due to digoxin toxicity. Hypokalaemia secondary to the use of diuretic predisposes to digoxin toxicity. Vomiting itself is another cause of hypokalaemia, which can aggravate the situation. Patients are usually nauseated and have a slow heart rate. 2. F – Gastroenteritis due to Staphylococcus aureus The short history in this case is typical of staphylococcal gastroenteritis caused by preformed enterotoxin (an exotoxin) from food contaminated with Staphylococcus aureus. The vomiting starts shortly after ingestion of the offending dish (a wide variety of foodstuffs can be contaminated). Other causative organisms of vomiting-predominant food poisoning include Bacillus cereus, but the history is typically shorter (1–2 hours) and symptoms start much later after ingestion of the contaminated food (approximately 8 hours after ingestion). Vomiting also occurs with enteric infections with bacteria such 161
E M Q s F O R M E D I C A L S T U D E N T S – V O L U M E 2 as Salmonella, Campylobacter and Shigella, but the predominant symptoms in such cases are invariably lower abdominal pain, diarrhoea or dysentery. 3. G – Gastric outflow obstruction Gastric outflow obstruction has been caused in this case by neonatal pyloric stenosis. This patient is the right age for this (3–6 weeks), and has the characteristic history of this disorder (projectile vomiting after each meal). The finding of the so-called ‘pyloric tumour’ caused by pyloric contraction during feeding provides further confirmation. The disorder is due to hypertrophy of circular muscle of the pyloric region of the stomach. The baby is classically well and seeking more feed after vomiting but dehydration and severe electrolyte disturbances (especially acid-base disorder and hypokalaemia) will eventually arise. The condition is treated surgically with a Ramstedt pyloromyotomy. 4. I – Small-intestinal obstruction This is the classic clinical description of a patient presenting with small-bowel obstruction – colicky, central abdominal pain, distension, nausea and vomiting (eventually bilestained). In this woman’s case, the cause is probably adhesions secondary to her previous intra-abdominal inflammation/sepsis. In contrast, gastric outflow obstruction does not cause bilious vomiting and large-intestinal obstruction is characterised by lower abdominal colic and constipation, with vomiting (faeculant) being a later feature. 5. A – Acute abdomen This is a case of acute abdomen, probably appendicitis. Acute inflammation affecting any part of the gastrointestinal tract will lead to a localised ileus (or generalised ileus in the case of generalised peritonitis) and to nausea and vomiting. Common examples include pancreatitis, cholecystitis and appendicitis. NB: A complete overview of all the causes of vomiting (not possible in one EMQ) should include the following: • Central – intracranial, labyrinthine • Metabolic and endocrine – uraemia, pregnancy, diabetes • Iatrogenic – cancer chemotherapy, digoxin, opiates • Obstructive – any level (see above) • Mucosal – appendicitis, gastritis, cholecystitis. 3. HAEMATEMESIS 1. B – Gastric erosions The most likely cause is gastric erosions. Stress ulceration leading to erosions of the stomach (and to some extent also of the duodenum) is a complication of significant burns (Curling’s ulcer), as well as other traumatic injuries, systemic sepsis, intracranial lesions (Cushing’s ulcer) and organ failure (eg uraemia). The risk of bleeding can be reduced by giving a mucosa-protecting agent such as sucralfate or prophylactic antacid treatments (eg ranitidine). These agents are therefore commonly used in an intensive-care environment. 162
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