Page 107 - Remedial Andrology

9. PRIAPISM

Evidence Acquisition and limitations
The Panel conducted systematic reviews on the medical and surgical management of ischaemic and non-
ischaemic priapism and a dedicated systematic review on the overall management of priapism related to sickle
cell disease. The results of these systematic reviews are presented below in the guidelines and the limitations
of the studies that were assessed are highlighted.

Most studies had the same limitations and methodological bias: lack of published protocols, retrospective
and usually single-arm design, lack of randomisation and blinding, incomplete outcome data, and selective
reporting. Additionally, most studies included small numbers of patients, reported non-standardised patient
characteristics, and had short (or even unreported) follow-up times and, in general, they reflected single-unit
practices.

The definitions of priapism and outcomes (such as success and related complications) were inconsistent
across the literature and few of the trials met the clear definitions that were set by the Panel for use in the
systematic reviews. Hence, any attempt to draw clinically meaningful conclusions and offer evidence-based
guidance based on systematic assessment of the literature was a challenging task. These limitations highlight
the urgent need for clear and commonly accepted definitions of conditions and outcomes that should be used
by researchers in the future so that robust evidence can be developed to support relevant guidelines and
clinical practice recommendations.

The Panel acknowledged the evidence-related limitations, and in accordance with the GRADE approach
endorsed by the European Association of Urology Guidelines Office, also took into consideration the benefits/
harms balance and the patient ideals, views and preferences prior to finalising the relevant recommendations
(for/against, weak/strong).

Priapism is a persistent or prolonged erection in the absence of sexual stimulation that fails to subside. It can
be divided into ischaemic, non-ischaemic and stuttering priapism.

9.1 Ischaemic (Low-Flow or Veno-Occlusive) Priapism
9.1.1 Epidemiology, aetiology, pathophysiology and Diagnosis
Ischaemic priapism is a persistent erection marked by rigidity of the corpora cavernosa and by little or no
cavernous arterial inflow [1243]. Ischaemic priapism is the most common subtype of priapism, accounting for >
95% of all episodes [1243, 1244]. It presents as a painful rigid erection that is characterised clinically by absent
or reduced intracavernous arterial inflow, although proximally there is a compensated high velocity picture
with little flow distally [1245]. In ischaemic priapism, there are time-dependent metabolic alterations within the
corpus cavernosum progressively leading to hypoxia, hypercapnia, glucopenia and acidosis [1246, 1247].

Ischaemic priapism that lasts beyond 4 hours is similar to a compartment syndrome, and characterised by the
development of ischaemia within the closed space of the corpora cavernosa, which severely compromises
the cavernosal circulation. Emergency medical intervention is required to minimise irreversible consequences,
such as smooth muscle necrosis, corporal fibrosis and the development of permanent erectile dysfunction (ED)
[1248, 1249]. The duration of ischaemic priapism represents the most significant predictor for the development
of ED. In this context, interventions beyond 48-72 hours of onset may help to relieve the erection and pain, but
have little clinical benefit in preventing long-term ED [1250].

Histological analysis of corporal smooth muscle biopsies shows that at 12 hours, there are features of
interstitial oedema, progressing to destruction of the sinusoidal endothelium, exposure of the basement
membrane and thrombocyte adherence by 24 hours. At 48 hours, thrombi in the sinusoidal spaces and smooth
muscle necrosis with fibroblast-like cell transformation are evident [1251]. This implies that by 48 hours there
appears to be smooth muscle necrosis and irreversibility of these ischaemic changes. A case-control study
comparing corporal biopsies from patients with priapism lasting 48-72 hours with control penile tissues
retrieved from autopsies demonstrated a significantly lower percentage of smooth muscle fibres, with an
increase in elastic fibres and collagen [1248, 1252].

No specific pathophysiological causes of ischaemic priapism can be identified in most cases [1243, 1253],
although the common aetiological factors include sickle cell disease (SCD), haematological dyscrasias,
neoplastic syndromes, and several pharmacological agents (e.g., intracavernosal PGE1 therapy) (Table 32).
Ischaemic priapism may occur (0.4-35%) after intracavernosal injection of erectogenic agents [551, 1243,

106 SEXUAL AND REPRODUCTIVE HEALTH - MARCH 2021