Educational Disclaimer: This case study is for educational and informational purposes only. It does not constitute medical advice, clinical guidance, or a substitute for professional psychiatric evaluation. All diagnostic criteria referenced are from the DSM-5-TR (APA, 2022). Clinicians should rely on their professional training, direct patient assessment, and current evidence-based guidelines when making diagnostic and treatment decisions.

Clinical Vignette

Patient: "Ms. P," 28-year-old veterinary technician, referred after her hand-washing has caused dermatitis and she requested medical leave because she 'can't touch animals without decontaminating for 45 minutes.'

Chief Concern: "I know the washing is excessive, but if I don't do it I'm overwhelmed with the thought that I'm contaminated with bacteria that will make me fatally ill. I wash my hands 50-60 times a day and shower for 2 hours."

History of Present Illness: Ms. P reports a 5-year escalation of contamination obsessions and washing compulsions. Her obsessions center on the belief that touching animals, door handles, kitchen surfaces, or any public object contaminates her with harmful bacteria. She experiences intrusive images of bacteria entering her skin and making her fatally ill. These thoughts are ego-dystonic: she recognizes that her level of cleanliness far exceeds any reasonable threshold but 'the anxiety is unbearable if I don't wash.' Her compulsions include: washing hands 50-60 times daily (using antibacterial soap and very hot water, causing dermatitis), 2-hour showers with a specific ritualized sequence, changing clothes 4-5 times daily, and carrying hand sanitizer everywhere. She avoids touching doorknobs (uses elbows or paper towels), avoids public restrooms entirely, and has not eaten at a restaurant in 3 years. Her OCD has made her occupation (veterinary technician) untenable: she cannot handle animals without a 45-minute decontamination ritual afterward. She spends approximately 5-6 hours daily on washing and avoidance behaviors.

Past Psychiatric History: Brief therapy at age 23, discontinued. No medication trials. Mother suggested she 'just needs to relax.'

Family History: Brother diagnosed with OCD (checking subtype). Mother: 'very particular about cleanliness' (never diagnosed).

Mental Status Exam: Well-groomed (excessively so). Hands visibly raw and cracked (dermatitis). Uses tissue to touch chair in office. Mood 'exhausted.' Affect anxious. Speech normal. Thought process linear. Content: persistent contamination obsessions, recognizes them as excessive. No psychotic features. Insight good (recognizes irrationality). Judgment impaired by compulsive behavior.

Step 1: OCD DSM-5-TR Criteria

Criterion A: Presence of obsessions, compulsions, or both.

Obsessions: recurrent, intrusive thoughts of contamination and fatal illness from bacteria. These are unwanted (ego-dystonic) and cause marked anxiety. Compulsions: hand-washing (50-60x/day), 2-hour shower ritual, clothes changing, avoidance. Performed to reduce anxiety from obsessions. BOTH OBSESSIONS AND COMPULSIONS PRESENT.

Criterion B: Obsessions or compulsions are time-consuming (≥1 hour/day) or cause clinically significant distress or impairment.

5-6 hours daily spent on rituals. Career-threatening impairment (medical leave). Dermatitis from excessive washing. Social isolation (no restaurants, avoidance of public spaces). MET — far exceeds threshold.

Criterion C: Not attributable to substance or medical condition.

No substance use. Dermatitis is a consequence of the OCD, not a cause. MET.

Criterion D: Not better explained by another mental disorder.

Contamination obsessions are distinct from IAD (the fear is about contamination, not having a specific disease). Distinct from specific phobia (the anxiety is about contamination, not about a specific object). Distinct from GAD (worry is circumscribed to contamination, not multi-domain). MET.

Step 2: Insight Specifier and Contamination Subtype

DSM-5-TR requires an insight specifier for OCD:

With good or fair insight

Ms. P recognizes her cleaning is excessive: 'I know the washing is excessive, but the anxiety is unbearable if I don't wash.' She acknowledges the irrationality but cannot resist the compulsions. GOOD INSIGHT SPECIFIER APPLIES.

Contamination subtype features

Obsessions: contamination by bacteria/germs. Compulsions: washing, cleaning, avoidance. This is the most common OCD presentation. CONTAMINATION SUBTYPE CONFIRMED.

Functional Assessment

Ms. P's OCD is severe: 5-6 hours daily of rituals, career impairment, physical harm (dermatitis), and social isolation. The Yale-Brown Obsessive Compulsive Scale (Y-BOCS) would likely score in the severe range (25+). First-line treatment is Exposure and Response Prevention (ERP) combined with SSRI.

Diagnostic Formulation

Diagnostic Conclusion

Obsessive-Compulsive Disorder, with Good Insight (F42.2): Both obsessions (contamination) and compulsions (washing, avoidance) present. Time-consuming (5-6 hr/day), career-impairing, physically damaging. Good insight specifier. Contamination subtype. Treatment: ERP (graduated exposure to contaminants with response prevention of washing), SSRI at high-dose (fluoxetine 40-80mg or fluvoxamine 200-300mg — OCD typically requires higher SSRI doses than depression).

Teaching Points

  • OCD requires higher SSRI doses than depression. While MDD may respond to fluoxetine 20mg, OCD typically requires 40-80mg. The time to response is also longer: 8-12 weeks at adequate dose versus 4-6 weeks for MDD. Patients and clinicians must be prepared for this extended timeline.
  • Exposure and Response Prevention (ERP) is the gold-standard psychotherapy for OCD. For contamination subtype, exposure involves touching feared contaminants (doorknobs, public surfaces) while preventing the washing response. The patient learns that anxiety decreases naturally (habituation) without performing the compulsion.
  • The insight specifier has treatment implications. Good insight (Ms. P) is associated with better treatment response. Poor insight or absent insight/delusional beliefs about OCD content are associated with worse outcomes and may require antipsychotic augmentation.
  • Contamination OCD must be distinguished from Illness Anxiety Disorder. In OCD, the primary driver is the OBSESSION (intrusive thought of contamination) and the COMPULSION (washing to neutralize). In IAD, the driver is WORRY about having a disease, without ritualistic neutralizing behaviors. The distinction determines treatment: ERP for OCD; cognitive restructuring for IAD.
  • Family accommodation (family members facilitating avoidance or rituals) maintains and worsens OCD. Clinicians should assess for family accommodation and include family psychoeducation in the treatment plan.