What diagnostic workup is necessary before prescribing Viagra (sildenafil) for erectile dysfunction?

Pre-Prescription Workup for Viagra (Sildenafil) in Erectile Dysfunction

Before prescribing Viagra for erectile dysfunction, you must perform a thorough medical and sexual history, physical examination including vital signs and genital exam, and obtain morning serum total testosterone levels—this is a mandatory laboratory test per AUA guidelines. 1

Essential History Components

Medical and Sexual History:

• Age, comorbid conditions (diabetes, cardiovascular disease, depression, neurological disorders), prior surgeries, current medications, family history of vascular disease, and substance use 1
• Onset and severity of ED symptoms, whether difficulty involves achieving versus maintaining erections, presence of nocturnal/morning erections (suggests psychogenic component), situational factors (partner-specific, context-specific), and prior erectogenic therapy use 1
• Use validated questionnaires such as the International Index of Erectile Function (IIEF) or Erection Hardness Score to quantify severity and establish baseline 1

Required Physical Examination

Vital Signs and Cardiovascular Assessment:

• Measure pulse and resting blood pressure (lying and standing) to identify hypotension (BP <90/50 mmHg is a contraindication to sildenafil due to vasodilatory effects) 1, 2
• Critical caveat: In patients with parkinsonism, measure lying AND standing blood pressure before prescribing, as sildenafil can unmask or exacerbate orthostatic hypotension, particularly in multiple system atrophy 3

Genital Examination:

• Assess penile skin lesions, urethral meatus placement, and palpate the stretched penis from pubic bone to coronal sulcus for occult deformities or plaques (Peyronie's disease) 1
• Digital rectal exam is NOT required for ED evaluation 1

Mandatory Laboratory Testing

Morning Serum Total Testosterone:

• This is the ONLY mandatory lab test with a moderate-strength AUA recommendation (Evidence Level: Grade C) 1, 4
• Testosterone deficiency is defined as total testosterone <300 ng/dL with symptoms; low testosterone may explain PDE5 inhibitor failure and requires separate management 1, 4

Selective Additional Laboratory Tests:

• Glucose/HbA1c: Consider measuring as diabetic men respond less robustly to sildenafil and have more severe baseline ED 1, 4
• Lipid profile: Recommended because ED is a cardiovascular risk marker as strong as smoking or family history of MI; the Princeton Consensus Conference identifies ED as an independent predictor of future cardiac events 1, 4
• Renal function (creatinine, eGFR): If kidney disease suspected, as PDE5 inhibitors require dose adjustment in moderate-to-severe renal impairment 4
• Liver function tests: If hepatic disease suspected, as severe liver disease contraindicates PDE5 inhibitor use 4

Important note: The AUA guidelines explicitly state that "with the possible exception of glucose/hemoglobin A1c and serum lipids, no routine serum study is likely to alter ED management" 1

Cardiovascular Risk Stratification

Counsel patients that ED is a cardiovascular risk marker requiring evaluation:

• ED warrants assessment for underlying cardiovascular disease and other health conditions 1
• Use American College of Cardiology/American Heart Association atherosclerotic CVD risk assessment with categories: low (<5%), borderline (5-7.5%), intermediate (7.5-20%), and high (>20%) 1
• For borderline/intermediate-risk patients aged 40-60 years, consider coronary artery calcium scoring 1

Contraindications to Screen For

Absolute Contraindications:

• Concurrent use of organic nitrates (any form, any schedule) due to severe hypotension risk 2
• Resting hypotension (BP <90/50 mmHg) 2
• Severe left ventricular outflow obstruction 2

Relative Contraindications/Cautions:

• Anatomical penile deformities (angulation, cavernosal fibrosis, Peyronie's disease) or conditions predisposing to priapism (sickle cell anemia, multiple myeloma, leukemia) 2
• Bleeding disorders or active peptic ulceration (safety unknown) 2
• Retinitis pigmentosa (prescribe with caution) 2
• Patients on antihypertensive therapy, with fluid depletion, or autonomic dysfunction 2

Medication Review

Identify drugs that may cause or worsen ED:

• Antihypertensives (thiazide diuretics, beta-blockers), antidepressants (SSRIs, tricyclics), antipsychotics, antiandrogens (GnRH analogues, 5α-reductase inhibitors), and recreational drugs 1

Check for CYP3A4 inhibitors requiring dose adjustment:

• Ritonavir, saquinavir, ketoconazole, erythromycin, or cimetidine necessitate starting with lower sildenafil doses (25 mg) 5

Psychosocial Assessment

Screen for psychological contributors:

• Depression, anxiety, relationship conflict, and psychosexual issues may be primary or secondary contributors to ED 1
• Consider referral to mental health professional to promote treatment adherence, reduce performance anxiety, and integrate treatments into sexual relationships (Moderate Recommendation; Evidence Level: Grade C) 1

When Specialized Testing Is NOT Needed Initially

The following tests are NOT required before starting sildenafil:

• Nocturnal penile tumescence and rigidity testing 1
• Penile Doppler ultrasound or dynamic duplex ultrasonography 1
• Specialized endocrinological or psychodiagnostic evaluation 1

These specialized tests are reserved for: primary ED not caused by acquired organic disease, young patients with pelvic/perineal trauma who might benefit from revascularization, patients with complex psychiatric disorders, or those with penile deformities requiring surgical correction 1

Practical Algorithm Summary

1. History: Comprehensive medical/sexual history with validated questionnaire (IIEF or Erection Hardness Score) 1
2. Physical: Vital signs (including orthostatic BP if parkinsonism), genital examination 1, 3
3. Mandatory lab: Morning serum total testosterone 1, 4
4. Selective labs: Glucose/HbA1c and lipid profile (especially if cardiovascular risk factors present) 1, 4
5. Screen contraindications: Nitrate use, hypotension, severe cardiac disease 2
6. Medication review: Identify ED-causing drugs and CYP3A4 inhibitors 1, 5
7. Cardiovascular counseling: Discuss ED as cardiovascular risk marker 1