Life in the Fast Lane Medical Blog » CT

Gut ache or Gordian knot?

James Haridy — Fri, 23 Jul 2010 00:00:54 +0000

Life in the Fast Lane Medical Blog Gut ache or Gordian knot?

aka Gastrointestinal Gutwrencher 002

A 29 year old man presents to the ED with 4 hours of colicky left lower quadrant pain.

The pain came on rapidly, not long after breakfast, and is associated with nausea. It is aggravated by lying back, and eased by leaning forward and lying on his left side. He has passed flatus this morning but not opened his bowels. He has no urinary or bowel changes, and no past medical history of note.

On further questioning, he reports two similar episodes in the past ten days, both causing him to present to hospital, however the pain improved both times within 8h following treatment with analgesia and buscopan. He has been well in the intervening period.

On examination his vital signs are unremarkable, but there is marked guarding over the left umbilical area, with a palpable boggy and tender mass, roughly the size of a fist. Bowel sounds were not detected. His FBP, UEC and CRP are all within normal limits.

While awaiting a surgical consult a CT is performed. The CT findings are very similar to this image from RadioGraphics.rsna.org:

Click image to go to RadioGraphics.rsna.org

Questions

Q1. What is the diagnosis?

Clue: What is between P and D?

Answer and interpretation

Small bowel obstruction resulting from a left paraduodenal internal hernia

To make that diagnosis from a single CT slice shown would require Sherlockian powers of deduction beyond mortal comprehension… According to Takeyama N, et al (2005) this image shows:

…a saclike mass of dilated jejunal loops between the pancreatic head (P) and stomach. The descending mesocolon (D) and stomach are displaced laterally. The dilated inferior mesenteric vein is located at the anterior border of the encapsulated loops.

For more images of this patient read Takeyama N, et al (2005) here.

Q2. How common is this condition?

Answer and interpretation

Internal herniae are an extremely rare cause of small bowel obstruction.

Reported incidence is 0.2 – 0.9%. Paraduodenal herniae are the most common type of internal hernia, reportedly causing 53% of internal herniae. They are more commonly left sided (approximately 75%).

Q3. What is the cause of this condition?

Answer and interpretation

Internal herniae are an abnormal protrusion of a viscera (usually small bowel) through the peritoneum or mesentery into another abdominal compartment.

The underlying cause can be congenital, or acquired through such means as surgery, trauma or inflammation in surrounding tissues.

Q4. What other types of this condition exist and what is their relative incidence?

Answer and interpretation

The different types of internal hernia are:

Paraduodenal — 53%
Pericaecal — 13%
Foramen of Winslow — 8%
Transmesenteric and transmesocolic — 8%
Pelvic and supravesical — 6%
Sigmoid mesocolon — 6%
Transomental — 1-4%

Q4. What are the clinical features of this condition?

Answer and interpretation

Diagnosis is difficult due to the generalized nature of symptoms.

The most common reported symptoms are intermittent and nonspecific obstructive complains such as nausea, periumbilical pain and distension. Symptoms may be vague and intermittent, Patients often only present as acute obstruction when the hernia is incarcerated. Symptoms are often worse with eating or standing, and relieved by lying down or fasting.

Internal Hernias are rarely diagnosed on clinical grounds only.

Q5. How is this condition diagnosed?

Answer and interpretation

Abdominal CT (with IV contrast) is the most common method of diagnosing internal herniae.

The characteristic features on CT include:

Sac like cluster or mass of dilated bowel loops
Crowding, stretching or displacement of the mesenteric vascular pedicle
Signs of small bowel ischaemia — e.g. wall thickening, air in the bowel wall

References

Blachar A, Federle MP, Dodson SF. Internal hernia: clinical and imaging findings in 17 patients with emphasis on CT criteria. Radiology 2001; 218: 68–74. PMID: 11152781
Kohli A, Choudhury HS, Rajput D. Internal hernia : A case report. Indian J Radiol Imaging [serial online] 2006 [cited 2010 Jul 22];16:563-6. Available from: http://www.ijri.org/text.asp?2006/16/4/563/32269
Takeyama, N et al. CT of Internal Hernias, RadioGraphics 2005, 25, 997-1015. Available from: http://radiographics.rsna.org/content/25/4/997.full#sec-10

Life in the Fast Lane Medical Blog - Emergency Medicine education blog

CT Safety and Radiation Risk

Chris Nickson — Thu, 24 Jun 2010 13:04:14 +0000

Life in the Fast Lane Medical Blog CT Safety and Radiation Risk

Is it possible that looming just beyond the horizon is a future epidemic of radiation-induced cancers? Is it possible that it will be traced back to the rise of computed tomography and it’s growing universality as the investigation of choice for just about any medical condition you can think of?

Order your CTs wisely.

Many of the issues regarding the safety of CTs are explored in a recent must-read perspective article in the New England Journal of Medicine. Find it fulltext and free here. You might also want to use this handy online radiation risk calculator (hat tip to @PeterPietch) and explore this great blog review from Peter McCartney.

Life in the Fast Lane Medical Blog - Emergency Medicine education blog

Radiological Oddity #019

Mike Cadogan — Sun, 24 Jan 2010 17:15:06 +0000

Life in the Fast Lane Medical Blog Radiological Oddity #019

Life in the Fast Lane Medical Blog - Emergency Medicine education blog

Broken-hearted chest drain

Paul Young — Thu, 03 Dec 2009 10:34:35 +0000

Life in the Fast Lane Medical Blog Broken-hearted chest drain

aka Cardiovascular Curveball 001

This 86 year-old male presented with shortness of breath. He developed a complication after insertion of a left chest drain.

This CT scan demonstrates that complication:

Questions

Q1. What is the complication?

Show Answer

The chest drain is in the left ventricle.

Q2. Outline your management.

Show Answer

This complication was identified at the time by the presence of pulsatile bright red blood coming from the drain.

Clamping the drain to prevent exsanguination is a good first step!
Not taking the drain out is a good second step.
The next step is to prepare the patient for cardiac surgery to remove the drain and repair the heart. In this patient, removing the drain and repairing the heart was achieved via a mini thoractomy.

In addition to the issues of patient care, this is a sentinel event and appropriate reporting and follow-up needs to be undertaken. The CT below demonstrates how this complication arose…not everything that looks like a left pleural effusion on a plain chest X-ray is one!

Q3. How could this complication have been prevented?

Show Answer

Put your finger in the hole!

One of the most important steps in the insertion of an intercostal catheter is to insert a finger through the hole you have just made. Do this before inserting the intercostal catheter.
Using your finger you can detect any adhesions that may lead to penetration of the lung on insertion of the intercostal catheter, as well as the presence of underlying organs such as a beating heart!
In this case, the intercostal catheter is a one from a Seldinger kit. If you are going to use one of these kits, you should do an ultrasound to make sure that there really is a pleural effusion that can be safely drained.

Life in the Fast Lane Medical Blog - Emergency Medicine education blog

Quiz Radiology 021

Mike Cadogan — Sat, 07 Nov 2009 08:27:21 +0000

Life in the Fast Lane Medical Blog Quiz Radiology 021

Scenario

A head CT scan of an 83 year old woman has been performed, who has presented with a 3 day history of increasing confusion and unsteady gait following a fall. Her GCS is 12 (M5, V3, E4).

Question

a. Describe the CT scan. (50%)
b. What factors are important in determining this patient’s treatment? (50%)

Answer

Answer and Interpretation

FACEM VAQ Exam 2003.1 – Question 2
The overall pass rate for this question was 71 / 83 (85.5%).
Examiners felt that this was an easy question. They noted that a comprehensive description of the features of the subdural was expected given this was half of the question and hence marks.
In the second part it was expected input would be required from multiple sources including patient, family, physician and neurosurgeon.
Failures were due to not addressing these issues or by making an incorrect diagnosis.

ACEM Fellowship Visual Aid Questions

FACEM VAQ Overview
FACEM VAQ by YEAR
FACEM VAQ by SUBJECT

Life in the Fast Lane Medical Blog - Emergency Medicine education blog

Quiz Radiology 020

Mike Cadogan — Sat, 07 Nov 2009 06:33:37 +0000

Life in the Fast Lane Medical Blog Quiz Radiology 020

Scenario

An 45 year old man presents to your emergency department with vertigo and ataxia.

Question

a. Describe the CT. (30%)
b. What further investigations are indicated in this case? (70%)

Answer

Answer and Interpretation

FACEM VAQ Exam 2003.2 – Question 5
The overall pass rate for this question was 48 / 82 (58.5%).
A CT scan is performed. A CT scan showing bilateral areas of decreased attenuation in the cerebellum is shown.
This proved to be a testing question that highlighted many candidates’ inability to interpret CT scans.
It was considered to be an excellent test of consultant level knowledge.
To pass candidates needed to accurately report the areas of decreased attenuation and relate this to possible causes including cardiac, embolic, vascular and malignancy. Appreciating possible causes would then lead to common sense investigations as would occur “on the floor” in the ED.
Failures resulted from neglecting many of these issues or due to misreading the CT as a haemorrhage.

ACEM Fellowship Visual Aid Questions

FACEM VAQ Overview
FACEM VAQ by YEAR
FACEM VAQ by SUBJECT

Life in the Fast Lane Medical Blog - Emergency Medicine education blog

Quiz Radiology 016

Mike Cadogan — Sat, 07 Nov 2009 04:26:33 +0000

Life in the Fast Lane Medical Blog Quiz Radiology 016

Scenario

A 72 year old man undergoes this investigation in your emergency department after his presentation with a first ever generalised seizure.
He has normal vital signs and no focal neurological signs on examination.

Question

a. Describe and interpret the CT. (50%)
b. Outline your further investigation. (50%)

Answer

Answer and Interpretation

FACEM VAQ Exam 2004.1 – Question 2
The overall pass rate for this question was 53 / 69 (76.8%).
Examiners expected that candidates would accurately size and locate the lesion and in particular emphasise that it was ring enhancing.
It was mandatory that the differentials offered include
metatasis which is by far the most likely cause in this age group.
Expected investigation needed to include not just that of the lesion but of the patient as a whole and include likely causes and complications of metastatic malignancy in this age group.
Failures stemmed largely from an inability to appreciate the likely diagnosis and then the investigations needed that would follow from this.

ACEM Fellowship Visual Aid Questions

FACEM VAQ Overview
FACEM VAQ by YEAR
FACEM VAQ by SUBJECT

Life in the Fast Lane Medical Blog - Emergency Medicine education blog

Radiology Oddity #016

Mike Cadogan — Tue, 03 Nov 2009 15:50:18 +0000

Life in the Fast Lane Medical Blog Radiology Oddity #016

It is another busy night in ED. The ‘Bat-Phone’ rings, gently pricking the ear to attention in anticipation of the next code…

We are bringing in a 60 year old lady with profuse diaphoresis, hypotensive with a systolic of 70 and altered conscious state…

Initial examination confirms an unwell lady, drained of colour, drenched in sweat taking short shallow breaths. Following application of oxygen, comprehensive non-invasive monitoring, IV access and analgesia you decide to perform a rapid bedside abdominal USS (even though you are by no means an expert in wielding the mighty sono sword)…but it is late, the really clever sonoboys are all tucked up in bed…so it’s all up to you – SonoMan^®

Through the vagaries of shadows that are beholden to the sonographic snowland you think you see a cave-like compressible opening around 5-6cm in diameter…but lets face it – the howling blizzard you just demonstrated on the sono-machine-thing hasn’t really helped you refine your differential diagnosis

So you send your patient to the ‘Donut of Death’ for a dose of real radiation

Now what Doc?

Abdominal CT scan

Additional images (for @scanman)

Acalculous Cholecystitis

Life in the Fast Lane Medical Blog - Emergency Medicine education blog

a.	Describe the CT scan.	(50%)
b.	What factors are important in determining this patient’s treatment?	(50%)

a.	Describe the CT.	(30%)
b.	What further investigations are indicated in this case?	(70%)

a.	Describe and interpret the CT.	(50%)
b.	Outline your further investigation.	(50%)