Thursday, 4 September 2008

A Minor Gripe - Work Up Of Constipation

Dear Bloggers

Today I would like to have a minor gripe. My gripe is about the overuse of abdominal X-rays to rule in / rule out constipation.

Patients with constipation may present with various symptoms including:
  • Nausea
  • Vomiting
  • Anorexia
  • Difficulty passing stool (straining)
  • Passage of hard stools
  • Abdominal pain
A rectal examination provides far more information than an abdominal X-ray when working up a patient with constipation. Feeling for hard stool, determining if there is occult blood, malaena or frank hemorrhage and determining if there is malignancy e.g. colorectal / prostate cancer is all possible and essential, something that a plain X-ray cannot do.

To perform an abdominal X-ray in order to avoid the rectal exam is in my opinion a neglection of duty to the patient. Patients may indeed have a full colon with stool and an X-ray may reveal that constipation is present, but it does not provide the mechanism which caused the constipation. For example, is the constipation due to sluggish bowel movement or a rectal cancer!?? A plain film will not always show you the cancer hiding in the rectum --- only the examining finger can do that or more advanced radiological studies.

In this technological age, aren't we forgetting our basic examination skills that have been tried and tested by the ingenious physicians of the past only to be replaced by fine CT pictures that cannot always provide the diagnosis that we are seeking. Without the background of thorough physical examination skills, soley relying on a machine to make a diagnosis is like building a brick house on sand --- it is destined to sink when we need shelter from the storm. We need a good foundation on which to build and that foundation is the physical examination.

Performing a rectal examination is free and does not cause radiation exposure whereas an X-ray does cost money (albeit pennies / yen) and there is significant radiation exposure. This latter point is something that many physicians forget. Never do harm to your patients and do not expose them to unnecessary procedures which might be harmful (immediately or long term) when another method might provide the same or better information with less harm.

Hence, when it comes to constipation please remember to do the rectal examination. If you are concerned about bowel obstruction then that would be an indication for an AXR but it cannot really be justified to take a plain film to rule out / rule in constipation when your finger can give the same information.

If you want to investigate further (after a rectal exam), then I would suggest utilising an ultrasound scan which is non-invasive and provides no radiation exposure.

X-rays and CT scans should be reserved for those patients in whom the diagnosis is unclear after the basic physical examination and ultrasound and in whom you want to rule out serious pathology. They should not be utilised as a first measure unless there is evidence of an acute pathology e.g. acute surgical abdomen, and by which other tests cannot provide the diagnosis. Remember that radiation from CT scans increases the risk of cancer -- please see a previous blog article from 2007 which explains this in more detail on the following link.

Please Consider......

Wednesday, 3 September 2008

Hypertension and Spinal Cord Injury

Dear Bloggers

I wanted to impart to you a rather rare case of a patient who had a history of spinal cord injury and who developed accelerated hypertension and cold upper extremities.

This male patient had a C-spine fracture and transection of the spinal cord 5 yrs before following a fall and he was left with quadriplegia and reliant on mechanical ventilation to breath.

He was normally otherwise well albeit fully dependent.

On the evening of admission, the patient developed a low grade fever but otherwise had no new symptoms.

The blood pressure was noted to be 220/110 mmHg and his carer noticed that his hands and arms were very cold to the touch.

He was admitted to the hospital via the emergency medical services.

There was no other other relevant medical history and the patient was taking no regular medications.

There was no relevant family history.

The patient was cared for at home and was nursed 24 hours a day on a pressure bed and had home mechanical ventilation. The patient was fed via PEG tube and required full help with toileting.

On examination

The patient was fully alert and was able to speak albeit softly. Temp 37.5 degrees C.

HEENT examination was grossly intact.

Cardiac: pulse 74/min, BP 220/110 mmHg, JVP not elevated, Heart Sounds 1 + 2. No added sounds and no murmurs.

Resp: RR= 14/min (ventilator setting), tracheostomy in vivo, spO2 98%, expansion equal, percussion resonant, chest sounds clear.

Abdomen: Soft, flat, non-tender (remember patient has spinal cord transection), no obvious masses, normal bowel sounds. Rectal examination not performed.

Extremties - DVT prevention stockings on both legs. No oedema, redness or pain.

Cranial Nerves: II - normal, pupils equal and reactive to light and accommodation. III, IV, VI - normal extra-ocular movements, V- normal motor and sensory modalities. VII - normal. VIII- normal, IX, X, XI - no gross abnormalities, XII - normal tongue movement.

PNS - Power 0/5 throughout all limbs, absent sensation up to C3 level, Babinski bilaterally extensor.


Lab studies were generally normal except for a slight rise in the WBC count of 12 x 10-9/L Urine analysis revealed turbid urine. WBC >100 / hpf, RBC 5-10 / hpf, nitrites +, protein 2+, bacteria 4+ (gram stain: Gram Negative Bacilli).

Urinary catheterisation revealed 1 L of urine in the bladder.


ECG - 74/min, no focal abnormality.


The diagnosis here is obviously a urinary tract infection with urinary retention.

However, why did the patient develop hypertension and peripheral vasoconstriction?

The answer is unique to spinal cord injury patients and it is termed Autonomic Dysreflexia.

Certain noxious stimuli such as Urinary Retention (associated with UTI), impaction of stool within the bowel, pressure sores, fractures or intra-abdominal disease lead to a dysfunction of the autonomic responses of the heart and vascular contractility. This lack of control of the sympathetic nervous system leads to vasoconstriction and hypertension. Interestingly, a parasympathetic response occurs above the level of the lesion albeit that it is not sufficient to offset the adverse actions of the sympathetic response.

This can occur in patients with spinal cord lesions above the T6 cord level and the frequency of those affected is variable. It is unusual in the immediate aftermath of injury but usually occurs within the first year.

Patients can present with various symptoms and signs and include:

  • headache
  • nausea
  • bradycardia or tachycardia
  • sweating
  • hypertension
  • nasal congestion
  • altered mental state e.g. anxious
Patients may exhibit no symptoms at all whereas others may develop profound bradycardia leading to cardiac arrest or hypertensive crisis causing intracerebral bleeding and convulsions.

Patients can be managed in several ways and include sitting them up to cause the BP to drop, searching for inciting stimuli (e.g. urinary outflow obstruction / UTI), acute reduction of BP (nitrates, peripheral calcium channel blocker, ACE-I, hydralazine, IV labetolol).

In this case, the history of spinal cord injury and the symptoms of peripheral vasoconstriction plus profound hypertension made the diagnosis of autonomic dysreflexia a certain diagnosis at the bedside and after the hunt for the inciting cause, a UTI and urinary outflow obstruction were found.

Treatment with urinary catheter insertion to relieve the obstruction and antibiotics caused the BP to drop within several hours, with a resting BP of 100/60 mmHg without the need for acute anti-hypertensive therapy. The perfusion to the upper limbs normalised spontaneously.

For more in-depth reading concerning patients with spinal cord injuries, please read UpToDate 16.2

Have a great day.... :-)

Monday, 1 September 2008

The Meningitis Quandry

Dear Bloggers

Today, I would like to discuss an area of medical uncertainty - the partially treated meningitis!

Sometimes a patient will present to the doctor with the classical features of meningitis and antibiotics are started before the lumbar puncture can be performed because for example, of the potential delay in obtaining a cranial CT scan or that the patient is too far from the nearest hospital and a delay in giving antibiotics might be deleterious. Note that GPs in the UK have traditionally administered i.m. or i.v. benzylpenicillin to patients with suspected meningitis before they are taken to hospital.

This of course is the correct management because a significant delay can result in adverse outcomes in meningitis.

However, partially treated bacterial meningitis can cause the conversion from a predominantly neutrophil predominant CSF cell count to a predominantly lymphocytic cell count. Therefore, on initial examination, it may look as if the patient has a viral meningitis!

How do we differentiate between viral and partially treated bacterial meningitis? Now that can be almost impossible ! However, there are some features of the CSF that can guide us although none are absolutes.

Bacterial meningitis has CSF that tends to appear turbid on gross visual examination and upon analysis, the glucose is usually <50%>

Conversely, viral meningitis fluid appears macroscopically clear, has lymphocyte predominant cells (early infection may show neutrophils!!), the CSF glucose >50% of the level of the serum glucose in most cases and the protein is usually raised only mildly (by <1.5mg/dl)

Protein levels are usually only mildly raised in viral infections (as above) whereas they can be >1.5mg/dl in bacterial infections.

Of course, gram stain can be negative in partially treated meningitis and so this cannot be relied up.

There is evidence to suggest that CSF can still remain positive for organisms up to approximately 4 hours after the administration of antibiotics, so this can be helpful to still look for the organisms within this time frame.

Blood cultures should always be taken in meningitis patients as bacteraemia can give positive results allowing isolation of a potential organism with a subsequent tailoring of therapy.

Remember that certain bacterial infections can present with a lymphocyte predominant cell count and they include listeria monocytogenes infection (consider in the over 50s age group) and tuberculosis. TB meningitis can produce a macroscopic fibrin web.

Fungal infection with cryptococcus neoformans can also produce lymphocyte predominant CSF and this should be considered in patients with severe liver disease and not just HIV patients. In HIV patients, the rest of the CSF can appear normal and hence, the CRAG testing and Indian Ink stain are the mainstay of confirming the diagnosis.

Hence, it is not as clear cut to make a diagnosis between viral and bacterial meningitis when antibiotic treatment has muddied the waters, as the vast majority of handbooks and textbooks out in the world arena would suggest-- I know as I have reviewed several recently and they all differ markedly in respect of the analysis of CSF. Most texts simply differentiate between how to make the diagnosis of viral versus bacterial meningitis and very few actually discuss partially treated meningitis.

One such book that does address this important point is the Oxford Textbook of Medicine and please consider reviewing this for more in-depth reading. Another good book has been written by Dr Makoto Aoki, Specialist in Infectious Disease medicine in Japan. This text is currently written in Japanese -- an English version is however a must please! :-)

So, when faced with the viral meningitis versus partially treated meningitis patient what do you do?

Firstly, still take the blood cultures even whilst on antibiotics - they may still prove to be positive.

Secondly, examine the CSF for bacteria, and if microscopically negative ( as in partial treatment meningitis ), send fluid for culture and rapid analysis e.g. meningococcus (PCR), pneumococcus (latex agglutination), HSV (PCR), TB (PCR) depending upon the clinical scenario and what you consider are the likely causes in your patient.
CSF can be stained for Acid Fast Bacilli and if in doubt, repeat CSF samples should be taken separately over several days (total of 3 samples) and fluid should also be sent for long term culturing. 90% of patients with TB meningitis also have a positive tuberculin skin test and it is still worthwhile performing. A negative skin test does not rule out TB.

Thirdly, continue the antibiotics until such time that it can be established (if possible) that it is or is not a bacterial infection e.g. PCR and cultures results (CSF and blood).

In the under 50s, adults should receive cetriaxone plus vancomycin [current UK guidelines 2005 suggest only using Cefotaxime] whereas over 50s require additional ampicillin therapy to cover listeria infection.

I would hope that future handbooks and textbooks fully address the problem of partial treatment meningitis.

It just goes to show that patients do not write the textbooks and that nothing is ever fixed in stone.

Have a great week....!