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Question 1
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A 63-year-old female patient arrives at the emergency department complaining of severe, sudden-onset abdominal pain that has been ongoing for an hour. She describes the pain as intense and cramping, with a severity rating of 9/10.
The patient has a medical history of hypertension, type 2 diabetes, and atrial fibrillation.
After undergoing a contrast CT scan, a thrombus is discovered in the inferior mesenteric artery, and the patient is immediately scheduled for an urgent laparotomy.
What structures are likely to be affected based on this diagnosis?Your Answer: Distal third of colon and the rectum superior to pectinate line
Explanation:The inferior mesenteric artery is responsible for supplying blood to the hindgut, which includes the distal third of the colon and the rectum superior to the pectinate line. In this case, the patient’s sudden onset of severe abdominal pain and history of atrial fibrillation suggest acute mesenteric ischemia, with the affected artery being the inferior mesenteric artery. Therefore, if a thrombus were to block this artery, the distal third of the colon and superior rectum would experience ischaemic changes. It is important to note that the ascending colon, caecum, ileum, appendix, greater omentum, and stomach are supplied by different arteries and would not be affected by a thrombus in the inferior mesenteric artery.
The Inferior Mesenteric Artery: Supplying the Hindgut
The inferior mesenteric artery (IMA) is responsible for supplying the embryonic hindgut with blood. It originates just above the aortic bifurcation, at the level of L3, and passes across the front of the aorta before settling on its left side. At the point where the left common iliac artery is located, the IMA becomes the superior rectal artery.
The hindgut, which includes the distal third of the colon and the rectum above the pectinate line, is supplied by the IMA. The left colic artery is one of the branches that emerges from the IMA near its origin. Up to three sigmoid arteries may also exit the IMA to supply the sigmoid colon further down the line.
Overall, the IMA plays a crucial role in ensuring that the hindgut receives the blood supply it needs to function properly. Its branches help to ensure that the colon and rectum are well-nourished and able to carry out their important digestive functions.
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This question is part of the following fields:
- Gastrointestinal System
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Question 2
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Which one of the following is not a result of cholecystokinin?
Your Answer: It increases the rate of gastric emptying
Explanation:The rate of gastric emptying is reduced.
Understanding Gastric Secretions for Surgical Procedures
A basic understanding of gastric secretions is crucial for surgeons, especially when dealing with patients who have undergone acid-lowering procedures or are prescribed anti-secretory drugs. Gastric acid, produced by the parietal cells in the stomach, has a pH of around 2 and is maintained by the H+/K+ ATPase pump. Sodium and chloride ions are actively secreted from the parietal cell into the canaliculus, creating a negative potential across the membrane. Carbonic anhydrase forms carbonic acid, which dissociates, and the hydrogen ions formed by dissociation leave the cell via the H+/K+ antiporter pump. This leaves hydrogen and chloride ions in the canaliculus, which mix and are secreted into the lumen of the oxyntic gland.
There are three phases of gastric secretion: the cephalic phase, gastric phase, and intestinal phase. The cephalic phase is stimulated by the smell or taste of food and causes 30% of acid production. The gastric phase, which is caused by stomach distension, low H+, or peptides, causes 60% of acid production. The intestinal phase, which is caused by high acidity, distension, or hypertonic solutions in the duodenum, inhibits gastric acid secretion via enterogastrones and neural reflexes.
The regulation of gastric acid production involves various factors that increase or decrease production. Factors that increase production include vagal nerve stimulation, gastrin release, and histamine release. Factors that decrease production include somatostatin, cholecystokinin, and secretin. Understanding these factors and their associated pharmacology is essential for surgeons.
In summary, a working knowledge of gastric secretions is crucial for surgical procedures, especially when dealing with patients who have undergone acid-lowering procedures or are prescribed anti-secretory drugs. Understanding the phases of gastric secretion and the regulation of gastric acid production is essential for successful surgical outcomes.
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This question is part of the following fields:
- Gastrointestinal System
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Question 3
Incorrect
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A 58-year-old woman presents to her GP with an incidental finding of megaloblastic anaemia and low vitamin B12 levels. She has a history of type 1 diabetes mellitus. What could be the probable cause of her decreased vitamin levels?
Your Answer: Malabsorption
Correct Answer: Pernicious anaemia
Explanation:Pernicious anaemia is a condition that results in a deficiency of vitamin B12 due to an autoimmune disorder affecting the gastric mucosa. The term pernicious refers to the gradual and subtle harm caused by the condition, which often leads to delayed diagnosis. While pernicious anaemia is the most common cause of vitamin B12 deficiency, other causes include atrophic gastritis, gastrectomy, and malnutrition. The condition is characterized by the presence of antibodies to intrinsic factor and/or gastric parietal cells, which can lead to reduced vitamin B12 absorption and subsequent megaloblastic anaemia and neuropathy.
Pernicious anaemia is more common in middle to old age females and is associated with other autoimmune disorders such as thyroid disease, type 1 diabetes mellitus, Addison’s, rheumatoid, and vitiligo. Symptoms of the condition include anaemia, lethargy, pallor, dyspnoea, peripheral neuropathy, subacute combined degeneration of the spinal cord, neuropsychiatric features, mild jaundice, and glossitis. Diagnosis is made through a full blood count, vitamin B12 and folate levels, and the presence of antibodies.
Management of pernicious anaemia involves vitamin B12 replacement, usually given intramuscularly. Patients with neurological features may require more frequent doses. Folic acid supplementation may also be necessary. Complications of the condition include an increased risk of gastric cancer.
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This question is part of the following fields:
- Gastrointestinal System
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Question 4
Incorrect
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A 32-year-old woman is being evaluated for an abdominal mass. She delivered her first child vaginally and without any issues. Biopsy results indicate the presence of differentiated fibroblasts in sheets, which is indicative of a desmoid tumor. What is a potential risk factor for this type of tumor?
Your Answer: BRCA1
Correct Answer: APC mutations
Explanation:Desmoid tumours are more likely to occur in individuals with APC mutations.
Pancreatic and hepatic cancer have been linked to CA-199.
Breast cancer is strongly linked to BRCA1 and BRCA2 mutations.
Burkitt’s lymphoma, a high-grade B-cell neoplasm, is associated with translocation of the C-myc gene.
Desmoid tumours are growths that arise from musculoaponeurotic structures and are made up of clonal proliferations of myofibroblasts. They are typically firm and have a tendency to infiltrate surrounding tissue. These tumours are often seen in patients with familial adenomatous polyposis coli, and are most commonly found in women after childbirth in the rectus abdominis muscle. Bi allelic APC mutations are usually present in desmoid tumours.
The preferred treatment for desmoid tumours is radical surgical resection, although radiotherapy and chemotherapy may be considered in some cases. Non-surgical therapy is generally less effective than surgical resection. In certain cases of abdominal desmoids, observation may be preferred as some tumours may spontaneously regress. However, desmoids have a high likelihood of local recurrence. These tumours consist of sheets of differentiated fibroblasts.
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This question is part of the following fields:
- Gastrointestinal System
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Question 5
Incorrect
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A 25-year-old woman presents to the gastrointestinal clinic with a history of abdominal bloating, diarrhoea, and fatigue for the past 6 months. She experiences severe cramps after most meals and struggles to focus on her work at the office.
After conducting investigations, it is found that her tissue transglutaminases (TTG) are positive. What is a potential complication of the suspected underlying diagnosis?Your Answer: Sclerosing cholangitis
Correct Answer: Hyposplenism
Explanation:Hyposplenism is a possible complication of coeliac disease. The patient’s symptoms and positive tissue transglutaminases support the diagnosis of coeliac disease, which can lead to malabsorption of important nutrients like iron, folate, and vitamin B12. Hyposplenism may occur due to autoimmune processes and loss of lymphocyte recirculation caused by inflammation in the colon. However, hepatomegaly, pancreatitis, and polycythaemia are not associated with coeliac disease.
Understanding Coeliac Disease
Coeliac disease is an autoimmune disorder that affects approximately 1% of the UK population. It is caused by sensitivity to gluten, a protein found in wheat, barley, and rye. Repeated exposure to gluten leads to villous atrophy, which causes malabsorption. Coeliac disease is associated with various conditions, including dermatitis herpetiformis and autoimmune disorders such as type 1 diabetes mellitus and autoimmune hepatitis. It is strongly linked to HLA-DQ2 and HLA-DQ8.
To diagnose coeliac disease, NICE recommends screening patients who exhibit signs and symptoms such as chronic or intermittent diarrhea, failure to thrive or faltering growth in children, persistent or unexplained gastrointestinal symptoms, prolonged fatigue, recurrent abdominal pain, sudden or unexpected weight loss, unexplained anemia, autoimmune thyroid disease, dermatitis herpetiformis, irritable bowel syndrome, type 1 diabetes, and first-degree relatives with coeliac disease.
Complications of coeliac disease include anemia, hyposplenism, osteoporosis, osteomalacia, lactose intolerance, enteropathy-associated T-cell lymphoma of the small intestine, subfertility, and unfavorable pregnancy outcomes. In rare cases, it can lead to esophageal cancer and other malignancies.
The diagnosis of coeliac disease is confirmed through a duodenal biopsy, which shows complete atrophy of the villi with flat mucosa and marked crypt hyperplasia, intraepithelial lymphocytosis, and dense mixed inflammatory infiltrate in the lamina propria. Treatment involves a lifelong gluten-free diet.
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This question is part of the following fields:
- Gastrointestinal System
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Question 6
Incorrect
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A 4-year-old boy is brought to the GP by his mother due to concerns about his growth and weight gain. The mother has noticed that her son is smaller than other children his age and has difficulty putting on weight. Additionally, she has observed that his stools have become pale and greasy, and he frequently experiences bloating. Upon examination, the boy appears underweight and pale, with abdominal distension and muscle wasting in the buttocks. Based on this history and examination, what is the most likely diagnosis?
Your Answer: Crohn's disease
Correct Answer: Coeliac disease
Explanation:Coeliac disease typically presents in children around the age when they start consuming wheat and cereal, but some individuals may not show symptoms until later in life. It is crucial for healthcare professionals to be able to identify this condition, both in clinical settings and for exams.
Coeliac Disease in Children: Causes, Symptoms, and Diagnosis
Coeliac disease is a condition that affects children and is caused by sensitivity to gluten, a protein found in cereals. This sensitivity leads to villous atrophy, which causes malabsorption. Children usually present with symptoms before the age of 3, coinciding with the introduction of cereals into their diet. The incidence of coeliac disease is around 1 in 100, and it is strongly associated with HLA-DQ2 and HLA-DQ8. Symptoms of coeliac disease include failure to thrive, diarrhoea, abdominal distension, and anaemia in older children. However, many cases are not diagnosed until adulthood.
Diagnosis of coeliac disease involves a jejunal biopsy showing subtotal villous atrophy, as well as screening tests for anti-endomysial and anti-gliadin antibodies. The biopsy shows complete atrophy of the villi with flat mucosa and marked crypt hyperplasia, as well as dense mixed inflammatory infiltrate in the lamina propria. Another biopsy may show flat mucosa with hyperplastic crypts and dense cellular infiltrate in the lamina propria, as well as an increased number of intraepithelial lymphocytes and vacuolated superficial epithelial cells. Overall, coeliac disease is a serious condition that requires early diagnosis and management to prevent long-term complications.
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This question is part of the following fields:
- Gastrointestinal System
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Question 7
Incorrect
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A 50-year-old man undergoes a colonoscopy and a colonic polyp is identified. It is located on a stalk in the sigmoid colon and has a lobular appearance. What is the most likely cause of this condition?
Your Answer: Metaplasia
Correct Answer: Dysplasia
Explanation:The majority of colonic polyps mentioned earlier are adenomas, which can be accompanied by dysplasia. The severity of dysplasia is directly proportional to the level of clinical apprehension.
Understanding Colonic Polyps and Follow-Up Procedures
Colonic polyps can occur in isolation or as part of polyposis syndromes, with greater than 100 polyps typically present in FAP. The risk of malignancy is related to size, with a 10% risk in a 1 cm adenoma. While isolated adenomas seldom cause symptoms, distally sited villous lesions may produce mucous and electrolyte disturbances if very large.
Follow-up procedures for colonic polyps depend on the number and size of the polyps. Low-risk cases with 1 or 2 adenomas less than 1 cm require no follow-up or re-colonoscopy for 5 years. Moderate-risk cases with 3 or 4 small adenomas or 1 adenoma greater than 1 cm require a re-scope at 3 years. High-risk cases with more than 5 small adenomas or more than 3 with 1 of them greater than 1 cm require a re-scope at 1 year.
Segmental resection or complete colectomy may be necessary in cases of incomplete excision of malignant polyps, malignant sessile polyps, malignant pedunculated polyps with submucosal invasion, polyps with poorly differentiated carcinoma, or familial polyposis coli. Screening from teenager up to 40 years by 2 yearly sigmoidoscopy/colonoscopy is recommended. Rectal polypoidal lesions may be treated with trans anal endoscopic microsurgery.
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This question is part of the following fields:
- Gastrointestinal System
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Question 8
Correct
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A 2-year-old child is evaluated for inability to pass stool. After further testing, a rectal biopsy confirms a diagnosis of Hirschsprung's disease.
Can you explain the pathophysiology behind this condition?Your Answer: Failure of the development of the parasympathetic plexuses
Explanation:Hirschsprung’s disease is caused by a failure in the development of the parasympathetic plexuses, which are responsible for allowing the distal part of the large intestine to relax. Without these plexuses, the colon remains tightly sealed, preventing the passage of stool and leading to symptoms such as failure to pass meconium and constipation.
Understanding Hirschsprung’s Disease
Hirschsprung’s disease is a rare condition that affects 1 in 5,000 births. It is caused by a developmental failure of the parasympathetic Auerbach and Meissner plexuses, resulting in an aganglionic segment of bowel. This leads to uncoordinated peristalsis and functional obstruction, which can present as constipation and abdominal distension in older children or failure to pass meconium in the neonatal period.
Hirschsprung’s disease is three times more common in males and is associated with Down’s syndrome. Diagnosis is made through a rectal biopsy, which is considered the gold standard. Treatment involves initial rectal washouts or bowel irrigation, followed by surgery to remove the affected segment of the colon.
In summary, Hirschsprung’s disease is a rare but important differential diagnosis in childhood constipation. Understanding its pathophysiology, associations, possible presentations, and management is crucial for healthcare professionals to provide appropriate care for affected individuals.
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This question is part of the following fields:
- Gastrointestinal System
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Question 9
Incorrect
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A 65-year-old man who is a heavy smoker complains of dyspepsia. Upon testing, he is diagnosed with helicobacter pylori infection. Later, he experiences an episode of haematemesis and faints. Which blood vessel is most likely responsible for this?
Your Answer: Portal vein
Correct Answer: Gastroduodenal artery
Explanation:It is probable that he has a duodenal ulcer located at the back. Such ulcers can penetrate the gastroduodenal artery and result in significant bleeding. While gastric ulcers can also invade vessels, they are not typically associated with major bleeding of this type.
The Gastroduodenal Artery: Supply and Path
The gastroduodenal artery is responsible for supplying blood to the pylorus, proximal part of the duodenum, and indirectly to the pancreatic head through the anterior and posterior superior pancreaticoduodenal arteries. It commonly arises from the common hepatic artery of the coeliac trunk and terminates by bifurcating into the right gastroepiploic artery and the superior pancreaticoduodenal artery.
To better understand the relationship of the gastroduodenal artery to the first part of the duodenum, the stomach is reflected superiorly in an image sourced from Wikipedia. This artery plays a crucial role in providing oxygenated blood to the digestive system, ensuring proper functioning and health.
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This question is part of the following fields:
- Gastrointestinal System
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Question 10
Incorrect
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A 48-year-old female patient complains of pain in the right hypochondrium. Upon palpation of the abdomen, she experiences tenderness in the right upper quadrant and reports that the pain worsens during inspiration. Based on the history and examination, the probable diagnosis is cholecystitis caused by a gallstone. If the gallstone were to move out of the gallbladder, which of the ducts would it enter first?
Your Answer: Pancreatic duct
Correct Answer: Cystic duct
Explanation:The biliary tree is composed of various ducts, including the cystic duct that transports bile from the gallbladder. The right and left hepatic ducts in the liver merge to form the common hepatic duct, which then combines with the cystic duct to create the common bile duct. The pancreatic duct from the pancreas also connects to the common bile duct, and they both empty into the duodenum through the hepatopancreatic ampulla (of Vater). The accessory duct, which may or may not exist, is a small supplementary duct(s) to the biliary tree.
The gallbladder is a sac made of fibromuscular tissue that can hold up to 50 ml of fluid. Its lining is made up of columnar epithelium. The gallbladder is located in close proximity to various organs, including the liver, transverse colon, and the first part of the duodenum. It is covered by peritoneum and is situated between the right lobe and quadrate lobe of the liver. The gallbladder receives its arterial supply from the cystic artery, which is a branch of the right hepatic artery. Its venous drainage is directly to the liver, and its lymphatic drainage is through Lund’s node. The gallbladder is innervated by both sympathetic and parasympathetic nerves. The common bile duct originates from the confluence of the cystic and common hepatic ducts and is located in the hepatobiliary triangle, which is bordered by the common hepatic duct, cystic duct, and the inferior edge of the liver. The cystic artery is also found within this triangle.
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This question is part of the following fields:
- Gastrointestinal System
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