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The case of the month

September 2006 case of the month

A 37 year old Caucasian man – a recreational user of PDE5 inhibitors - presented with a painful erection of 10 hours duration. Corporal blood gas analysis confirmed a low flow priapism with a pH 7.2 and pO2 1.5kPa. Unfortunately the priapism was refractory to conservative measures of repeated aspiration of corporal blood and injection of the alpha agonist phenylephedrine. He was taken to the operating theatre where he underwent a successful corporal washout with no need for shunt surgery or prosthesis insertion. He was discharged from hospital but when he was subsequently reviewed in clinic he was found to have a persistent painless semi-erect penis. (Case provided by Mr Paul Anderson, Specialist registrar, Department of Urology, George Eliot Hospital, Nuneaton, UK, pcbanderson@talk21.com)

Question 1:
Which of the following drugs have been associated with low flow priapism?

Correct answer: D
Trazodone, an antidepressant that inhibits serotonin reuptake, has long been associated with priapism. More recently, however, there have been case reports linking the PDE5 inhibitor tadalafil and the alpha-blocker tamsulosin with ischemic priapism (other alpha blockers e.g. prazosin are known to very rarely cause priapism). Aspirin has never been associated with priapism.

Question 2:
The most appropriate way to investigate this patient would be:

Correct answer: C
Whilst one could carry out corporal blood gas analysis to confirm the clinical suspicion of high flow priapism, it is not necessary here and will simply distress your patient. The penis is entirely painless in contrast to his initial presentation. The first investigation I would recommend is the non-invasive test of penile colour Doppler to confirm “high flow” in the cavernous arteries, and give you your diagnosis. Arteriography will be required, but not as the first line test. There is no role for cavernosography.

Question 3:
This patient is most likely to require which treatment?

Correct answer: D
It is unlikely this patient’s high flow priapism will settle so something will need doing (however, it is possible that once you have explained the problem to your patient in detail they may wish to have no treatment after all they have previously been through).  Aspiration has no role here. Oral terbutaline has been used in the management of ischemic priapism, and certainly appears to have a role to play with pharmacologically induced prolonged erection. This patient requires superselective angiographic embolisation.

DISCUSSION
This patient had been obtaining PDE5 inhibitors from non medical sources, and whilst he was clearly unlucky to suffer an episode of ischaemic priapism, he was lucky that at the time he was taken to theatre his corporal smooth muscle appeared pink and viable (both macroscopically and on frozen section) and that he responded to a washout.  His subsequent high flow priapism was no doubt iatrogenic from damage to his cavernous artery at the time of smooth muscle biopsy.
His initial arteriogram below shows the site of high flow ‘leak’.

This was successfully occluded using gelfoam embolisation as can be seen in the post embolisation image.



When seen in clinic for follow up (one month post procedure), pleasingly he had normal erectile function.

References

  1. Saenz de Tejada I, Ware JC, Blanco R, et al. Pathophysiology of prolonged penile erection associated with trazodone use. J Urol 1991;145:60–64.
  2. King SH, Hallock M, Strote J, Wessells H. Tadalafil-associated priapism.
    Urology 2005;66:432e15-e18.
  3. Pahuja A, Bashir J,Williamson EM, Barber N.Unresolved priapism secondary to tamsulosin. Int J Impot Res 2005;17:293-294.
  4. Priyadarshi S. Oral terbutaline in the management of pharmacologically induced prolonged erection. Int J Impot Res 2004;16:424-426.