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This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
The Bottom Line
- OCD = obsessions and/or compulsions that are time-consuming (>1 h/day) or impairing
- Obsessions are intrusive unwanted thoughts/images/urges; compulsions neutralize anxiety
- First-line: exposure and response prevention (ERP) and/or SSRI
- OCD often requires higher SSRI doses and longer trials than depression
- OCD is ego-dystonic; OCPD perfectionism/control is ego-syntonic
Overview
OCD is characterized by obsessions, compulsions, or both. Common themes include contamination, harm, checking, symmetry, taboo thoughts, and fear of mistakes. Insight varies. Compulsions reduce anxiety transiently but reinforce the cycle.
Epidemiology
Lifetime prevalence is about 1-3%. Onset is often adolescence/young adulthood, with a childhood peak especially in males and tic-related OCD. Depression, tic disorders, body dysmorphic disorder, and anxiety disorders are common.
Clinical Features
Symptoms
Contamination fears with excessive washing/cleaning
Checking locks, stove, body symptoms, or repeated reviewing
Symmetry/counting/ordering rituals or mental neutralizing
Distressing violent, sexual, or blasphemous intrusive thoughts
Suicidality, severe depression, psychosis, inability to eat/drink, or dangerous compulsions
Signs
Chapped hands/dermatitis from washing
Late arrival, avoidance, or visible rituals
Poor insight or delusional intensity may mimic psychosis
Tics, hair pulling, or excoriation may coexist
Investigations
First-line
DSM-5-TR assessmentObsessions, compulsions, time burden, distress, impairment, insight, avoidance, family accommodation
Safety assessmentSuicide, self-harm, inability to function, severe depression, psychosis, harm from rituals
Comorbidity screenMDD, tic disorder, body dysmorphic disorder, eating disorders, substance use
Second-line
Y-BOCSSeverity scale for OCD and treatment monitoring
Pediatric assessmentAbrupt onset, tics, infection history, school impairment, family accommodation
Medication/substance reviewStimulants/substances can worsen anxiety; akathisia can mimic agitation
Specialist
CBT/ERP referralERP is central for moderate-severe OCD
Psychiatry referralSevere, refractory, poor-insight, suicidal, psychotic, pediatric complex, or augmentation cases
1
First-line treatment
- ERP: exposure to feared stimuli while preventing rituals
- SSRI at OCD-range dosing: fluoxetine, sertraline, fluvoxamine, paroxetine, or escitalopram; trial 8-12 weeks or longer
- Combine ERP + SSRI for moderate-severe disease or partial response
2
Alternatives/augmentation
- Clomipramine is effective but more anticholinergic/cardiotoxic
- Partial SSRI response with tics/severe symptoms: antipsychotic augmentation such as risperidone/aripiprazole under psychiatry
- Avoid benzodiazepines as primary OCD treatment
3
Family and severe disease
- Reduce family accommodation and reassurance rituals
- Address avoidance directly
- Intensive OCD programs or neuromodulation are specialist options for refractory disease
Complications
- Depression and suicide risk:
- Dermatitis/injury from rituals:
- Functional impairment from time-consuming compulsions:
- Family accommodation reinforcing symptoms:
- Poor insight resembling delusional disorder:
USMLE Step 2 CK Exam Tips
- 1OCD = ego-dystonic intrusive thoughts + rituals; OCPD = ego-syntonic perfectionism/control
- 2Best psychotherapy = ERP
- 3OCD needs higher SSRI doses and longer trials than MDD
- 4Clomipramine is effective but dangerous in overdose and anticholinergic
- 5Intrusive harm thoughts are usually feared/unwanted, not homicidal intent
- 6Tic-related OCD may respond to antipsychotic augmentation
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