It is the scaphoid bone that articulates with the radius at this level. It is located at the radial side of the wrist and is considered the largest bone in the proximal row of carpal bones. It articulates with the radius via its superior surface. This bone also articulates with trapezium and trapezoid bones via the inferior surface, capitate and lunate medially.

As the stone is smaller in size, there is a strong likelihood (75%) of it to be passed spontaneously. Furthermore, distally sited stones are more likely to pass spontaneously than proximally sited ones. Hence, it should be arranged to review the patient in two weeks with a KUB X-ray.

Urolithiasis affects up to 15% of the population worldwide. The development of sudden-onset, colicky loin to groin pain is a classical feature in the history. It is nearly always associated with haematuria that is either micro- or macroscopic. The most sensitive and specific diagnostic test is helical, non-contrast CT scanning.

Management options for urolithiasis are:
1. Most renal stones measuring <5mm in maximum diameter typically pass within four weeks of onset of symptoms. More intensive and urgent treatment is indicated in the presence of ureteric obstruction, renal developmental abnormality such as horseshoe kidney, and previous renal transplant.
2. Ureteric obstruction due to stones together with infection is a surgical emergency and the system must be decompressed. Options include nephrostomy tube placement, insertion of ureteric catheters, and ureteric stent placement.
3. In the non-emergency setting, the preferred options for treatment include extracorporeal shock wave lithotripsy, percutaneous nephrolithotomy, ureteroscopy, and open surgery (selected cases). Minimally invasive options are the most popular first-line treatment.

Answer: Meckel’s diverticulum

Meckel’s diverticulum is the most common congenital malformation of the gastrointestinal tract (present in 2%-4% of population) due to persistence of the congenital vitello-intestinal duct. Bleeding from Meckel’s diverticulum due to ectopic gastric mucosa is the most common clinical presentation, especially in younger patients, but it is rare in the adult population. This is due to the persistence of the proximal part of the congenital vitello-intestinal duct. It is a true diverticulum, typically located on anti-mesenteric border, and contains all three coats of intestinal wall with its separate blood supply from the vitelline artery. Meckel’s diverticulum is lined mainly by the typical ileal mucosa as in the adjacent small bowel. However, ectopic gastric, duodenal, colonic, pancreatic, Brunner’s glands, hepatobiliary tissue and endometrial mucosa may be found, usually near the tip. The main mechanism of bleeding is the acid secretion from ectopic mucosa, leading to ulceration of adjacent ileal mucosa. It is possible that the recurrent intussusception may cause trauma, inflammation, mucosal erosion and bleeding. The pathogenic role of Helicobacter pylori in the development of gastritis and bleeding in the ectopic gastric mucosa is still debatable. NSAIDs’ effect on the ectopic gastric mucosa is yet to be proved. Bleeding from Meckel’s diverticulum can cause the iron deficiency anaemia, but it may also cause megaloblastic anaemia due to the bacterial overgrowth and vitamin B12 deficiency as a result of the dilatation and stasis in adjacent obstructed ileal loop. The presence of bleeding with hypoalbuminemia and low ferritin due to ongoing slow unrecognized bleeding may lead to the diagnosis of inflammatory bowel disease.

Lymphadenopathy is common in children and is usually reactive in nature. The description fits that of a benign, reactive lymph node.

Boundaries of the posterior mediastinum include:
Superior: a plane through the sternal angle and T4/5
Inferior: the diaphragm
Anterior: the middle mediastinal structures
Posterior the spinal cord.
Structures in the posterior mediastinum include the descending thoracic aorta, the azygos system, oesophagus, thoracic duct and lymph nodes. The great vessels and structures at the root of the lung are part of the middle mediastinum. In this case, the lymph nodes is the correct answer.

The proximal part of the duodenum is supplied by the gastroduodenal artery. This artery is found descending behind the first part of the duodenum after branching from the hepatic artery. If gastric content was to be expelled in the posterior portion of the first part of the duodenum, then this artery would be most likely to be damaged. The common hepatic artery and the left gastric artery are branches of the coeliac trunk that are found superior to the duodenum. The proper hepatic artery is a branch of the common hepatic artery also found superior to the duodenum. The superior mesenteric artery is found behind the pancreas as a branch of the aorta that is at the bottom of the L1 level. The right gastric artery arises above the pylorus from the proper hepatic artery and supplies the lesser curvature of the stomach. The intestinal arteries supply the ileum and the jejunum.

The adrenal (suprarenal) glands are organs of the endocrine system located on top of each of the kidneys. The left suprarenal gland, in question, is crescent in shape and slightly larger than the right suprarenal gland. It is posteriorly located to the lateral aspect of the head of the pancreas which is thus the most likely to be injured. The other organs like the duodenum, liver and the inferior vena cava are related to the right suprarenal gland. The spleen and the colon are not in close proximity with the left suprarenal gland and are not likely to be the organs injured.

Cancer stage is based on four characteristics: the size of cancer, whether the cancer is invasive or non-invasive, whether the cancer has spread to the lymph nodes, and whether the cancer has spread to other parts of the body, in this case beyond the breast. Staging is important as it is often a good predictor of outcomes and treatment is adjusted accordingly.

The beginning of ventricular systole corresponds to the beginning of the QRS complex in the ECG. The beginning of the ventricular systole also corresponds to the closure of the atrioventricular valves, causing the first heart sound (S1). S2, the second heart sound is due to closure of the aortic and pulmonary valves at the end of ventricular systole.

Achalasia is an oesophageal motility disorder where inappropriate contractions in the oesophagus lead to reduced peristalsis and failure of the lower oesophageal sphincter to relax properly in response to swallowing. Classical triad of symptoms include dysphagia to fluids followed by solids, chest pain and regurgitation of undigested food. Other symptoms include belching, hiccups, weight loss and cough. Diagnosis is by:
– X-ray with a barium swallow or oesophagography : narrowing at the gastroesophageal junction (‘bird/parrot beak’ or ‘rat tail’ appearance) and various degrees of mega-oesophagus (oesophageal dilatation) as the oesophagus is gradually stretched by retained food. Effectiveness of treatment can be measured with a 5-minute timed barium swallow.
– Manometry – probe measures the pressure waves in different parts of oesophagus and stomach while swallowing.
– Endoscopy
– CT scan to exclude other causes like malignancy
– Pathological examination showing defect in the nerves which control oesophageal motility (myenteric plexus).
In Chagas disease, there is destruction of ganglion cells by Trypanosoma cruzi.