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General Information


  • medical-urological emergency of a prolonged penile erection lasting > 4-6 hours in absence of sexual stimulation1,2


  • ischemic (low-flow or veno-occlusive) priapism accounts for ≥ 95% of all cases, and is considered a medical emergency (similar to penile form of compartment syndrome) and requires prompt assessment and intervention1,2
    • characterized by persistent, markedly rigid, painful erection with absent or decreased venous outflow
    • aspirated blood from corpus cavernosum will have an abnormal blood gas analysis (hypoxia, hypercapnia, acidosis)
    • most cases are idiopathic, but etiologic factors may include medications (oral or intracavernosally injected) or blood disorders including sickle cell anemia (most common cause in children)
    • may result in permanent erectile dysfunction if left untreated for ≥ 48 hours from symptom onset
  • nonischemic (high-flow, arterial) priapism is rare, non-emergent, and often associated with history of perineal or penile trauma in preceding 2-3 weeks1,2
    • characterized by persistent painless, semi-rigid, non-sexual erection
    • normal blood gas values
    • typically results from unregulated arterial blood flow to corpora cavernosa due to trauma-induced arteriocorporal fistulas and occasionally pseudoaneurysm
    • not associated with erectile dysfunction
  • stuttering (intermittent, recurrent) priapism consists of intermittent, recurrent, and self-limited episodes of prolonged and painful erection similar to ischemic priapism2,3
    • reported to be common in patients with sickle cell disease, particularly children; may also be idiopathic or due to neurologic disorder
    • pathophysiology is typically similar to ischemic priapism, but cases of stuttering nonischemic priapism have been reported
    • duration is typically < 3 hours, but some episodes may persist and progress to emergent ischemic events requiring immediate attention
    • episodes may be nocturnal
  • partial priapism (idiopathic partial segmental thrombosis of the corpus cavernosum)1
    • very rare nonischemic condition of corporal thrombus
    • limited to a single crura (proximal portion of corpus cavernosum)
    • etiology is unknown but is associated with trauma, drug usage, sexual intercourse, congenital web within corpora cavernosa, and hematological disease
    • usually resolves spontaneously with analgesic treatment
  • malignant priapism is rare, and may be due to regional infiltration by tumor or metastasis 1
    • resultant priapism may be ischemic or nonischemic
    • usually secondary to genitourinary tumors
    • most common cause of priapism in children


General References Used

  1. Hatzimouratidis K, Giuliano F, Moncada I, et al. European Association of Urology (EAU) Guideline on Male Sexual Dysfunction. EAU 2018
  2. Shigehara K, Namiki M. Clinical Management of Priapism: A Review. World J Mens Health. 2016 Apr;34(1):1-8full-text
  3. Kousournas G, Muneer A, Ralph D, Zacharakis E. Contemporary best practice in the evaluation and management of stuttering priapism. Ther Adv Urol. 2017 Sep;9(9-10):227-238full-text

Recommendation Grading Systems Used

  • European Association of Urology (EAU) uses Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system
    • strength of recommendation
      • Strong or Weak based on:
        • overall quality of existing evidence
        • magnitude of effect (individual or combined effects)
        • certainty of results (including precision, consistency, heterogeneity, and other statistical or study-related factors)
        • balance between desirable and undesirable outcomes
        • patient values and preferences
        • certainty of patient values and preferences
    • levels of evidence
      • Level 1a - meta-analysis of randomized trials
      • Level 1b - ≥ 1 randomized trial
      • Level 2a - ≥ 1 well-designed controlled study without randomization
      • Level 2b - ≥ 1 other type of well-designed quasi-experimental study
      • Level 3 - well-designed nonexperimental studies; such as comparative studies, correlation studies, and case reports
      • Level 4 - expert committee reports or opinions or clinical experience of respected authorities
    • Reference - EAU guideline on male sexual dysfunction (EAU 2018)

Synthesized Recommendation Grading System for DynaMed Content

  • The DynaMed Team systematically monitors clinical evidence to continuously provide a synthesis of the most valid relevant evidence to support clinical decision-making (see 7-Step Evidence-Based Methodology).
  • Guideline recommendations summarized in the body of a DynaMed topic are provided with the recommendation grading system used in the original guideline(s), and allow users to quickly see where guidelines agree and where guidelines differ from each other and from the current evidence.
  • In DynaMed content, we synthesize the current evidence, current guidelines from leading authorities, and clinical expertise to provide recommendations to support clinical decision-making in the Overview & Recommendations section.
  • We use the Grading of Recommendations Assessment, Development and Evaluation (GRADE) to classify synthesized recommendations as Strong or Weak.
    • Strong recommendations are used when, based on the available evidence, clinicians (without conflicts of interest) consistently have a high degree of confidence that the desirable consequences (health benefits, decreased costs and burdens) outweigh the undesirable consequences (harms, costs, burdens).
    • Weak recommendations are used when, based on the available evidence, clinicians believe that desirable and undesirable consequences are finely balanced, or appreciable uncertainty exists about the magnitude of expected consequences (benefits and harms). Weak recommendations are used when clinicians disagree in judgments of relative benefit and harm, or have limited confidence in their judgments. Weak recommendations are also used when the range of patient values and preferences suggests that informed patients are likely to make different choices.
  • DynaMed synthesized recommendations (in the Overview & Recommendations section) are determined with a systematic methodology:
    • Recommendations are initially drafted by clinical editors (including ≥ 1 with methodological expertise and ≥ 1 with content domain expertise) aware of the best current evidence for benefits and harms, and the recommendations from guidelines.
    • Recommendations are phrased to match the strength of recommendation. Strong recommendations use "should do" phrasing, or phrasing implying an expectation to perform the recommended action for most patients. Weak recommendations use "consider" or "suggested" phrasing.
    • Recommendations are explicitly labeled as Strong recommendations or Weak recommendations when a qualified group has explicitly deliberated on making such a recommendation. Group deliberation may occur during guideline development. When group deliberation occurs through DynaMed Team-initiated groups:
      • Clinical questions will be formulated using the PICO (Population, Intervention, Comparison, Outcome) framework for all outcomes of interest specific to the recommendation to be developed.
      • Systematic searches will be conducted for any clinical questions where systematic searches were not already completed through DynaMed content development.
      • Evidence will be summarized for recommendation panel review including for each outcome, the relative importance of the outcome, the estimated effects comparing intervention and comparison, the sample size, and the overall quality rating for the body of evidence.
      • Recommendation panel members will be selected to include at least 3 members that together have sufficient clinical expertise for the subject(s) pertinent to the recommendation, methodological expertise for the evidence being considered, and experience with guideline development.
      • All recommendation panel members must disclose any potential conflicts of interest (professional, intellectual, and financial), and will not be included for the specific panel if a significant conflict exists for the recommendation in question.
      • Panel members will make Strong recommendations if and only if there is consistent agreement in a high confidence in the likelihood that desirable consequences outweigh undesirable consequences across the majority of expected patient values and preferences. Panel members will make Weak recommendations if there is limited confidence (or inconsistent assessment or dissenting opinions) that desirable consequences outweigh undesirable consequences across the majority of expected patient values and preferences. No recommendation will be made if there is insufficient confidence to make a recommendation.
      • All steps in this process (including evidence summaries which were shared with the panel, and identification of panel members) will be transparent and accessible in support of the recommendation.
    • Recommendations are verified by ≥ 1 editor with methodological expertise, not involved in recommendation drafting or development, with explicit confirmation that Strong recommendations are adequately supported.
    • Recommendations are published only after consensus is established with agreement in phrasing and strength of recommendation by all editors.
    • If consensus cannot be reached then the recommendation can be published with a notation of "dissenting commentary" and the dissenting commentary is included in the topic details.
    • If recommendations are questioned during peer review or post publication by a qualified individual, or reevaluation is warranted based on new information detected through systematic literature surveillance, the recommendation is subject to additional internal review.

DynaMed Editorial Process

  • DynaMed topics are created and maintained by the DynaMed Editorial Team and Process.
  • All editorial team members and reviewers have declared that they have no financial or other competing interests related to this topic, unless otherwise indicated.
  • DynaMed content includes Practice-Changing Updates, with support from our partners, McMaster University and F1000.

Special Acknowledgements

  • DynaMed topics are written and edited through the collaborative efforts of the above individuals. Deputy Editors, Section Editors, and Topic Editors are active in clinical or academic medical practice. Recommendations Editors are actively involved in development and/or evaluation of guidelines.
  • Editorial Team role definitions
    Topic Editors define the scope and focus of each topic by formulating a set of clinical questions and suggesting important guidelines, clinical trials, and other data to be addressed within each topic. Topic Editors also serve as consultants for the internal DynaMed Editorial Team during the writing and editing process, and review the final topic drafts prior to publication.
    Section Editors have similar responsibilities to Topic Editors but have a broader role that includes the review of multiple topics, oversight of Topic Editors, and systematic surveillance of the medical literature.
    Recommendations Editors provide explicit review of Overview and Recommendations sections to ensure that all recommendations are sound, supported, and evidence-based. This process is described in "Synthesized Recommendation Grading."
    Deputy Editors oversee DynaMed internal publishing groups. Each is responsible for all content published within that group, including supervising topic development at all stages of the writing and editing process, final review of all topics prior to publication, and direction of an internal team.

How to cite

National Library of Medicine, or "Vancouver style" (International Committee of Medical Journal Editors):

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