Which ONE of the following is the MOST common reason for large bowel/colonic obstruction?
Answer: B: Hernias or adhesions rarely cause large bowel obstructions. The most common reason for large bowel obstruction is colorectal cancer. Following neoplasms, diverticulitis and sigmoid volvulus are the next most common causes. Diverticulitis can cause mesenteric oedema and scarring from chronic inflammation, which results in strictures. Adhesions are the most common cause of SBO but account for only 1–8% of large bowel obstructions.
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A 69-year-old man presents to the ED with abdominal bloating over the past 4 hours. He has severe generalized abdominal pain and nausea but no vomiting. He has been unable to pass flatus for several hours. An abdominal X-ray demonstrates a large dilated loop of bowel that extends from the pelvis towards the right upper quadrant and looks like a bent inner tube. Multiple air fluid levels are seen within the small bowel loops.
Which ONE of the statements below describes the MOST appropriate management?
Answer: C: This patient has sigmoid volvulus. Sigmoid volvulus is more prevalent in the elderly population and in those who are institutionalized and debilitated. It presents with features similar to large bowel obstruction with abdominal distension, abdominal pain, nausea and obstipation. Vomiting is uncommon in sigmoid volvulus.
A distended loop of large bowel, lacking haustra markings, that extends from the pelvis towards the right upper quadrant and can extend as high as the diaphragm is consistent with the diagnosis of sigmoid volvulus. It is often described as a ‘bent inner tube’. Often multiple air fluid levels are visualized in the small bowel. It can be seen as often on the right side of the abdomen as it is on the left.
Patients with caecal volvulus have a presentation similar to that of SBO (nausea, vomiting, distension, abdominal pain and obstipation). It more frequently occurs in younger patients and those patients who have increased caecal mobility, which may be congenital. Other risk factors include previous abdominal surgery and adhesions, pregnancy or a history of Hirschsprung’s disease.
Caecal volvulus looks more like a coffee bean or kidney shape on abdominal X-ray. The air-filled caecum can be found in the mid-abdomen and extends towards the left upper quadrant. Interestingly abdominal X-ray is not helpful in about 50% of cases.
If the diagnosis of sigmoid volvulus is unclear a contrast enema can be helpful in establishing the diagnosis. The classic appearance is described as a ‘bird beak’ due to tapering of the colon at the torsion. The investigation is not therapeutic but is diagnostic. Management is directed at preventing the bowel becoming gangrenous.
Sigmoid volvulus should be initially treated with decompression via sigmoidoscopy and insertion of a rectal tube. If this fails then surgical intervention is required.
Mortality rate for sigmoid volvulus is 20%, but rises to 50% if the bowel becomes gangrenous. There is a very high recurrence rate for sigmoid volvulus so it is suggested that patients who are fit for surgery undergo a corrective procedure.
Use of bedside ultrasound for detecting abdominal aortic aneurysm in the ED is becoming increasingly common.
Which ONE of the following statements pertaining to this is TRUE?
Answer: A: It has been demonstrated from several studies that limited ED ultrasound for aortic aneurysm performed by emergency clinicians has a high sensitivity. Furthermore, the skill required to perform this can be acquired with minimal training.
A low-frequency curvilinear probe (or small phased array probe) with a frequency of 3.5–5 mHz should be used for abdominal aortic ultrasound. The lower frequency penetrates tissue better than higher frequency probes that have better resolution.
The diameter of the aorta should be measured from outer wall to outer wall. A false negative result may occur from measuring inner wall to inner wall because of intraluminal clot or plaque. The aorta should be measured in both transverse and longitudinal planes to ensure consistency of the measurements in providing an estimate of the true aortic diameter. Measurements should be taken of the proximal aorta and the distal aorta just proximal to the bifurcation. The study should include documentation of the maximum aortic diameter. Measurements >3 cm are suspicious of abdominal aortic aneurysm.
The use of bedside ultrasound in the ED is a rule-in test not a rule-out. Ultrasound is subject to operator factors and patient factors that can confound or assist the investigation. If there is high suspicion of a ruptured AAA but the bedside ultrasound is negative the patient should proceed to have further investigations, as it cannot be reliably ruled out.
It should be performed by trained emergency clinicians to answer specific clinical questions.
Abdominal aortic aneurysms (AAA) are at risk of rupture. Which ONE of the following statements is most CORRECT?
Answer: C: An aortoenteric fistula is formed when an aortic aneurysm erodes into the gastrointestinal tract. When this occurs between the aorta and the duodenum, gastrointestinal haemorrhage can occur. It can present with back pain or signs of intraperitoneal infection. If a patient over the age of 50 with a history of AAA presents with gastrointestinal bleeding, then aortoenteric fistula should be considered as a cause.
The size of the aortic diameter is the strongest risk factor for rupture. This risk increases when the diameter is >5 cm (1% risk of rupture if <5 cm, 17% if >5 cm). Rupture risk is also higher in women, smokers and patients with hypertension.
Most cases of ruptured abdominal aortic aneurysms present with pain, which may be present in the abdomen, chest, flank, back or groin. A pulsatile mass may not be present if the patient is hypotensive and it can be difficult to palpate if the patient is obese or has abdominal guarding or distension. Hypotension is not present in every patient with rupture because patients present at various stages. It is often a late sign and can occur unexpectedly. Nausea and vomiting are often present and can confuse the presenting complaint. On examination the abdomen may be tender, however, a non-tender abdomen isn’t always indicative that the aorta is intact. Cullen’s sign (periumbilical ecchymosis) and Grey Turner’s sign (flank ecchymosis) may be seen if there is retroperitoneal haematoma present. Other less common features include scrotal haematoma, inguinal mass and femoral nerve neuropathy secondary to compression.
A 63-year-old man with atrial fibrillation had pelvic radiotherapy 2 months ago. He now presents with lower abdominal pain, diarrhoea, rectal bleeding and tenesmus.
What is the MOST likely diagnosis?
Answer: A: Given the history of recent radiotherapy the patient most likely has acute radiation proctocolitis. Pelvic radiotherapy can result in proctitis in up to 50–70% of those receiving radiation therapy. It can be acute or chronic. The patient in question has acute radiation proctocolitis.
Acute radiation proctocolitis occurs during or shortly after (up to 6 months) the course of therapy. It presents with abdominal pain, tenesmus and rectal bleeding. An unfortunate effect may be urgency and faecal incontinence.
Some patients with severe acute radiation proctocolitis may progress to chronic proctocolitis, though most cases of acute proctocolitis are self-limiting. Chronic radiation proctocolitis can develop up to 2 years and rarely up to 30 years following cessation of radiotherapy. It occurs in 5–10% of patients who have undergone pelvic radiation therapy. Presentation can be similar to that of acute radiation proctocolitis. However, it can also present with symptoms and signs of obstruction, perforation, ulcerative disease or fistulas between the rectum and neighboring organs. Rectovaginal fistula is the most common.
Endoscopy may be helpful in the diagnosis. Chronic radiation proctocolitis can be difficult to differentiate between infectious colitis, inflammatory bowel disease or ischaemic colitis.
Treatment of acute radiation proctocolitis is supportive. Steroid enemas may be helpful in reducing inflammation. Reducing the radiation dose or ceasing therapy may improve symptoms.
Management of chronic proctocolitis is also supportive. Stool softeners and anti-inflammatory agents such as sulfasalazine are frequently prescribed. Complications should be addressed and referred on to the appropriate specialty. Fistulas and strictures generally require surgical intervention. Recurrence of the disease should also be excluded.
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