Interstitial Cystitis: Symptoms, Diagnosis, Treatment & Red Flags

Interstitial cystitis—now usually written IC/BPS for interstitial cystitis/bladder pain syndrome—is a chronic, non-infective bladder pain condition. The American Urological Association defines it as an unpleasant sensation (pain, pressure or discomfort) perceived to be related to the urinary bladder, associated with lower urinary tract symptoms of more than six weeks duration, in the absence of infection or other identifiable causes. It is a clinical diagnosis built on history and exclusion rather than a single biomarker or imaging finding.

The pathophysiology is multifactorial and still incompletely understood. Working models combine glycosaminoglycan-layer dysfunction allowing urinary solutes to permeate the urothelium, mast cell activation with neurogenic inflammation, central sensitisation of pelvic afferents, and pelvic floor muscle hypertonicity. Some patients clearly carry an inflammatory bladder phenotype with classic Hunner lesions on cystoscopy, while many more have a normal-looking bladder with sensitised lower urinary tract circuitry that overlaps with widespread chronic pain syndromes such as fibromyalgia and irritable bowel syndrome.

Population estimates depend heavily on the case definition used. The RAND Interstitial Cystitis Epidemiology study suggested 3–7% of US adult women carry IC-compatible symptoms and NIDDK currently states that 4–12 million people in the United States may be affected. Women predominate roughly five-to-one over men in clinic series; mean age at diagnosis sits in the 40s but presentation in adolescence and beyond age 60 is well described. Misdiagnosis as recurrent urinary tract infection, overactive bladder, chronic prostatitis or unspecified pelvic pain is common—often delaying definitive care by several years.

Splitting IC/BPS into Hunner and non-Hunner phenotypes at first cystoscopy is one of the highest-yield decisions available to the team. The two patterns have different histology, different long-term trajectories and—critically—different responses to therapy. Treating Hunner-positive disease with months of behavioural and oral therapy alone delays a treatment that often works rapidly; treating non-Hunner disease with repeated cystoscopy and ablation exposes patients to procedures that will not help.

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The European Society for the Study of Bladder Pain Syndrome (ESSIC) further classifies cystoscopic findings (1, 2, 3) and biopsy findings (A, B, C), giving combinations such as 3C for Hunner lesions plus inflammatory infiltrate. Bedside teams rarely use ESSIC notation directly but should recognise that any documented Hunner lesion changes both the urgency and the type of next intervention.

The hallmark is the temporal pattern: bladder pain or pressure that worsens with bladder filling and is partially relieved by voiding, accompanied by urgency and frequency that exceed what diuresis or fluid intake would predict. Patients commonly describe a chronic baseline overlaid with episodic flares lasting hours to weeks and triggered by diet, menstruation, sexual activity, prolonged sitting or stress.

Common features

• Suprapubic, urethral or vaginal pain, often described as pressure, rawness or burning rather than sharp colic.
• Urinary frequency exceeding eight voids per day, often with small volumes.
• Severe urgency without the explosive incontinence pattern typical of detrusor overactivity—patients race to the toilet to relieve pain rather than to avoid leakage.
• Nocturia disrupting sleep and amplifying daytime fatigue.
• Pain during intercourse—dyspareunia in women and ejaculatory pain in men—commonly persists after the act.
• Pelvic pain radiating to lower back, perineum, vulva or testes; pelvic floor tenderness on examination.

Atypical or under-recognised presentations

• Men presenting as "chronic prostatitis" with normal expressed prostatic secretions on culture.
• Adolescents with daily school absences for "bladder infections" that never grow on culture.
• Postmenopausal women with vulvar burning and superficial dyspareunia mistakenly attributed solely to genitourinary syndrome of menopause.
• Patients with predominant urinary symptoms after pelvic surgery, radiation or chemotherapy, where iatrogenic cystitis has unmasked or amplified IC physiology.

Flare anatomy

Patients usually identify a small constellation of personal triggers. A useful flag for the bedside is the question, "What three things, if you eat or drink them today, will cost you tonight?" The answer almost always names some combination of coffee, tea, soda, alcohol, citrus, tomato, spicy food and artificial sweeteners—and that personalised list will guide the next two months of behavioural therapy more reliably than any standardised "IC diet" handout.

No single cause has been confirmed. Most working models converge on a multi-hit picture in which a susceptible urothelium meets recurrent inflammatory or infective insults and develops sustained sensory amplification.

Plausible mechanisms

• Glycosaminoglycan (GAG) layer dysfunction: a thinned or porous protective layer allows urinary potassium and other solutes to permeate urothelium and trigger nerve and muscle irritation.
• Mast cell activation and neurogenic inflammation: mast cell degranulation in submucosa drives oedema, vascular dilatation and afferent nerve sensitisation.
• Central sensitisation of pelvic afferents: spinal and supraspinal "wind-up" explains why mild bladder filling triggers disproportionate pain and why widespread pain syndromes overlap.
• Pelvic floor dysfunction: high-tone, hypertonic pelvic floor muscles contribute to suprapubic and perineal pain and explain why pelvic floor physical therapy works for many patients.
• Autoimmune contribution (especially Hunner subtype): dense lymphoplasmacytic histology supports an immune-mediated component that is consistent with response to corticosteroid injection and oral cyclosporine.

Risk profile

• Female sex; age 30–60 at presentation, peaking in the 40s.
• Documented or assumed history of recurrent urinary tract infections, particularly when antibiotic courses repeatedly fail.
• Pelvic surgery, pelvic radiation, history of pelvic inflammatory disease or sexual or pelvic trauma.
• Coexisting chronic fatigue syndrome, fibromyalgia, irritable bowel syndrome, vulvodynia or migraine.
• Anxiety, depression and post-traumatic stress disorder.
• Male patients sometimes present after long courses of empirical chronic prostatitis treatment.

The 2022 AUA guideline and the European Association of Urology chronic pelvic pain guideline both endorse a clinical, exclusion-led diagnosis. Avoid over-investigation early on—patients accumulate scopes, urodynamics and dipsticks far in excess of what most management decisions need.

Core history

• Bladder pain, pressure or discomfort with urgency and frequency for more than six weeks.
• Pain that worsens with bladder filling and is partially relieved by voiding.
• Trigger pattern (food, drinks, menses, sexual activity, stress, prolonged sitting).
• Prior urological or gynaecological surgery, radiation, malignancy work-up, sexual or pelvic trauma.
• Antibiotic history—what was prescribed, what grew on culture, what symptoms persisted.
• Comorbid pain conditions: fibromyalgia, IBS, vulvodynia, chronic prostatitis (men), endometriosis.
• Mental health screening—mood, anxiety, sleep and impact on relationships and work.

Bedside and ward tools

• Voiding/bladder diary over 3–7 days capturing void times, volumes, urgency scores and fluid intake.
• Validated symptom questionnaires—O’Leary-Sant Interstitial Cystitis Symptom and Problem Indices, or the Pelvic Pain and Urgency/Frequency (PUF) scale.
• Pain map (suprapubic, perineal, vulvar, vaginal, low back, posterior thigh).
• Pelvic floor and pelvic exam—external genital exam, vaginal/rectal exam for tender pelvic floor muscle bands, focal trigger points and assessment for endometriosis or prolapse.
• Post-void residual via intake-output monitoring patterns and ultrasound to exclude retention.

Initial laboratory and imaging

• Urinalysis with microscopy to detect leukocytes, nitrites, haematuria and crystalluria.
• Mid-stream urine culture with antibiotic sensitivity to exclude UTI and sterile pyuria.
• Urine cytology when red flags raise the question of bladder malignancy.
• Chlamydia and gonorrhoea testing when sexually transmitted disease is plausible.
• Pelvic ultrasound (transvaginal in women) when pelvic pathology is suspected; further imaging is targeted, not routine.
• Serum tests are usually unremarkable; consider checking renal function and inflammatory markers if systemic features point elsewhere.

Cystoscopy and hydrodistension

Cystoscopy is not required to diagnose IC/BPS and the AUA guideline lists it as an option rather than a mandate at first presentation. It is indicated when first- and second-line therapy fails, when red flags are present, when Hunner lesions are clinically suspected (older age, severe pain, glomerulations on previous studies) or when bladder cancer must be excluded. Hydrodistension under anaesthetic both visualises Hunner lesions and provides modest, time-limited symptomatic relief in some patients. Urodynamics is not routinely needed and should be reserved for selected refractory cases or when voiding dysfunction needs characterisation.

The pragmatic chain that primary-care, urology, gynaecology and pelvic-pain teams can run from first contact:

1. Confirm symptom duration and pattern. Bladder pain or pressure with urgency and frequency for more than six weeks; pain worse with filling, eased on voiding.
2. Exclude infection and malignancy red flags. Urinalysis, culture, history check for haematuria, smoking, age over 40 and weight loss; investigate further if anything points to urothelial malignancy or active infection.
3. Document the phenotype clues. Age, comorbid pain syndromes, pelvic floor tenderness on exam, prior cystoscopic findings if available.
4. Open with first-line behavioural care. Patient education, bladder and food diary, dietary trigger elimination, fluid optimisation, stress reduction, pelvic floor relaxation; structured pain assessment at every encounter.
5. Layer in pelvic floor physical therapy when pelvic floor tenderness or hypertonicity is identified—manual myofascial techniques, not Kegel-style strengthening.
6. Add second-line therapy if symptoms persist after 6–8 weeks. Choose between oral options (amitriptyline, hydroxyzine, pentosan polysulfate, cimetidine) and intravesical instillations (DMSO, heparin, lidocaine cocktail) based on phenotype and access.
7. Refer for cystoscopy when symptoms are refractory, red flags emerge or Hunner lesions are suspected; ablate or inject Hunner lesions when found.
8. Move to fourth-line procedural therapy—intradetrusor onabotulinumtoxinA or oral cyclosporine A under specialist supervision—when third-line steps fail.
9. Consider sacral neuromodulation at fifth line for refractory urgency or frequency.
10. Reserve major surgery (augmentation, diversion, cystectomy) as a last-resort sixth-line option in highly selected patients.

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The AUA 2022 stepped care framework anchors management. It is explicitly a menu not a stepwise prescription—clinicians and patients combine lines, switch within lines and revisit phenotype on every escalation. The key idea is to lead with low-risk, broadly effective interventions and reserve invasive options for refractory disease and Hunner lesion–driven phenotypes.

First line — education and behavioural change

• Frame IC/BPS as a chronic, manageable pain syndrome rather than a curable infection; this single conversation reduces emergency presentations more than most drugs.
• Bladder and food diary for 7–14 days; identify the patient’s two or three personal triggers and run elimination with rechallenge.
• Dietary trial of avoiding caffeine, alcohol, carbonated drinks, citrus, tomato, spicy foods, artificial sweeteners and acidic foods, then individualising.
• Fluid optimisation—avoid both dehydration (concentrated urine) and overload (driving frequency).
• Stress reduction strategies: cognitive-behavioural therapy, mindfulness, sleep hygiene and graded activity.
• Pelvic floor relaxation training and timed voiding.

Second line — pelvic floor physical therapy and pharmacology

• Manual pelvic floor physical therapy (myofascial release of the levator ani, obturator internus and pelvic connective tissue) is a guideline-recommended option when pelvic floor tenderness is found—Kegel-style strengthening is the wrong manoeuvre and often worsens symptoms.
• Oral analgesia with paracetamol and short-course ibuprofen or naproxen for flares; avoid chronic NSAID use in those with cardiorenal disease.
• Tricyclic antidepressants—amitriptyline 10 mg at night titrated to 25–75 mg, or nortriptyline if amitriptyline is poorly tolerated. Counsel on anticholinergic burden, drowsiness and orthostasis; QT prolongation risk in higher doses.
• H1 antihistamines—hydroxyzine 25–75 mg at night, particularly when allergic, atopic or sleep-disrupted phenotype dominates.
• Pentosan polysulfate sodium (PPS) 100 mg orally three times daily—FDA-approved for IC/BPS; onset slow (3–6 months); counsel about pigmentary maculopathy risk (Pearce et al., 2018) and arrange baseline plus annual ophthalmology review during therapy.
• Cimetidine 200–400 mg twice daily—lower-evidence option with H2 receptor antagonism; check for drug–drug interactions (warfarin, phenytoin).
• Neuropathic agents such as gabapentin and pregabalin for refractory pelvic pain or neuropathic overlay; duloxetine when comorbid depression or fibromyalgia coexists.
• Intravesical instillations—dimethyl sulfoxide (DMSO) 50% solution weekly for 6 weeks, intravesical heparin, or a lidocaine-based cocktail (lidocaine plus sodium bicarbonate ± heparin or triamcinolone). Use short-term lidocaine-based instillations to abort flares.

Third line — cystoscopy with intervention

• Diagnostic and therapeutic cystoscopy with hydrodistension under anaesthetic.
• Hunner lesion fulguration with electrocautery or laser, or intralesional triamcinolone injection.
• Repeat as needed; many Hunner-positive patients require periodic re-treatment.

Fourth line — intradetrusor onabotulinumtoxinA or cyclosporine A

• Intradetrusor onabotulinumtoxinA 100 U across multiple bladder injection sites under cystoscopic guidance; effective for refractory frequency, urgency and pain. Counsel on transient urinary retention; teach intermittent self-catheterisation pre-procedure and have a plan in place if post-void residual rises.
• Oral cyclosporine A 1.5–3 mg/kg/day under specialist supervision, with blood pressure, renal function, magnesium and potassium monitoring; particularly considered for refractory Hunner-positive disease.

Fifth line — sacral neuromodulation

Sacral neuromodulation (an implantable lead at S3) helps refractory urgency-frequency and pain in selected patients; pain alone is an off-label indication so most centres trial it for predominant urgency-frequency. A two-stage approach (test phase then permanent implant) limits unsuccessful permanent placement.

Sixth line — major surgery

Bladder augmentation, supratrigonal cystectomy with reconstruction or urinary diversion is a last-resort consideration for end-stage refractory IC, ideally after multidisciplinary review including pain medicine and clinical psychology.

Treatments to avoid or use cautiously

• Long-term oral antibiotics for "suspected UTI" in culture-negative IC—drives resistance without benefit.
• Long-term opioids—rarely effective, frequently harmful in chronic pelvic pain; restrict to short rescue courses with a clear stopping plan.
• Bacillus Calmette–Guérin (BCG) intravesical therapy—evidence does not support use for IC/BPS.
• High-pressure long-duration hydrodistension—older technique with limited current support; modern hydrodistension is brief and primarily diagnostic.
• Resiniferatoxin instillation—not recommended outside research.

Disease behaviour during pregnancy is variable—roughly a third of patients improve, a third stay the same and a third worsen, with many flares clustering in the first and third trimesters and around delivery. Plan ahead rather than react to flares.

Pregnancy and preconception

• Stop pentosan polysulfate before conception (anticoagulant-like effect; limited safety data) and avoid resumption during breastfeeding.
• Reassess oral neuromodulators—amitriptyline, nortriptyline, hydroxyzine, gabapentin and pregabalin against trimester-specific risk and lowest effective dose; involve obstetrics and clinical pharmacy early.
• Lean on behavioural therapy and pelvic floor physical therapy; intravesical lidocaine-based cocktails are reasonable options for severe flares with specialist supervision.
• Plan analgesia for labour—epidural or spinal anaesthesia is appropriate; coordinate with obstetric anaesthesia about post-partum bladder care.
• Postpartum review—reset oral therapies and pelvic floor physical therapy referral; screen for postnatal depression and anxiety, which interact with flare frequency.

Older adults

• Anticholinergic burden matters: amitriptyline, hydroxyzine and oxybutynin add cumulative falls, cognition and constipation risk—prefer the lowest effective dose and consider lower-anticholinergic alternatives.
• Hunner lesions are over-represented in older patients—do not delay cystoscopy when symptoms persist.
• Comorbid heart and renal disease shape NSAID, cyclosporine and tricyclic prescribing.

Men

• Many men are diagnosed late, after years labelled as chronic prostatitis/chronic pelvic pain syndrome.
• Consider IC/BPS in men with persistent suprapubic, perineal or ejaculatory pain plus negative cultures and normal expressed prostatic secretions.
• Pelvic floor physical therapy, neuromodulators and trigger-led behavioural change apply equally; intravesical instillations are technically harder but feasible.

Children and adolescents

Paediatric IC/BPS is rare but reported. Suspect it in adolescents with persistent dysuria, urgency and bladder pain, repeatedly negative cultures and normal upper tract imaging. Manage in a multidisciplinary paediatric pelvic pain clinic; avoid empirical chronic antibiotics and prioritise behavioural care.

• Diagnostic discipline: document the AUA-aligned definition (bladder pain plus LUTS >6 weeks, no infection, no other identifiable cause) in the chart so colleagues do not retreat to "recurrent UTI" on the next admission.
• Antibiotic stewardship: require a positive culture (mid-stream, ideally clean catch) before each new course. Nitrofurantoin or ciprofloxacin are not analgesics; avoid empirical retreatment in culture-negative IC.
• Medication reconciliation: at every clinic visit and every hospital admission, confirm pentosan polysulfate, amitriptyline, hydroxyzine and instillation regimens via structured medication reconciliation; flag interacting OTC supplements (potassium-rich, citrus-based, cranberry).
• Catheter discipline: minimise indwelling catheter use; if catheterisation is needed, follow strict aseptic urinary catheterisation technique to limit infective insults that may worsen disease.
• Bladder instillation safety: intravesical lidocaine cocktails carry systemic absorption risk; observe for circumoral numbness, tinnitus, dizziness or arrhythmia; bladder retention time is typically 20–40 minutes. Document instillation volume, agents, retention time and adverse effects.
• Pentosan retinopathy: baseline ophthalmology review (Optos wide-field fundus imaging plus OCT) before starting and at least annually thereafter; counsel patients to report visual symptoms promptly.
• OnabotulinumtoxinA aftercare: teach intermittent self-catheterisation before injection and check post-void residual at 1–2 weeks; rule out infection if symptoms worsen rather than improve in the first month.
• Multidisciplinary mindset: coordinate urology, gynaecology, pelvic floor physical therapy, pain medicine and clinical psychology rather than escalating urological monotherapy alone.
• Mental health integration: screen for anxiety, depression and post-traumatic stress at diagnosis and at every escalation; treat them in parallel rather than after IC is "controlled".
• Bladder irrigation in flare: for severe in-patient flares, occasional supervised bladder irrigation with warmed saline or lidocaine-based cocktails can settle symptoms while oral therapy is rebuilt.

Symptom and flare metrics

• Pain score (numeric or visual analogue) at admission and per shift; map to suprapubic, vulvar, perineal or low-back regions.
• Urgency severity score (e.g. 0–4) and time to next void.
• Voiding diary—voids per 24 hours, void volumes, fluid intake.
• Trigger log (food, drink, stress, menses, intercourse, prolonged sitting).
• Sleep disruption from nocturia and pain.

Targeted physical assessment

• Suprapubic tenderness; palpate for masses, distended bladder.
• Perineal and pelvic floor tenderness on indicated exam (with chaperone).
• Skin over the perineum and inner thighs—check for chronic moisture-associated changes from frequent voiding.
• Mood, anxiety and sleep at every encounter; screen for safety concerns when pain is severe.

Labs and instrumentation

• Mid-stream urinalysis with microscopy and culture each time symptoms change abruptly.
• Post-void residual after onabotulinumtoxinA, after cystoscopy with hydrodistension, or whenever new retention symptoms emerge.
• Blood pressure, magnesium, potassium and renal function for those on cyclosporine A.
• Annual visual review for those on pentosan polysulfate.

Red flags requiring escalation

• New or worsening visible haematuria, especially in patients over 40 or smokers.
• Acute urinary retention with palpably distended bladder—catheterise and investigate underlying cause.
• Fever, rigors, flank pain or systemic illness suggesting pyelonephritis or sepsis.
• Severe dehydration from voiding restriction, vomiting or both.
• Sudden change in bladder pain pattern, weight loss or night sweats—revisit malignancy work-up.
• Suicidal ideation or severe depressive symptoms tied to chronic pain—activate mental health pathway.

Disease-related

• Chronic pelvic pain with central sensitisation, sleep deprivation, fatigue and reduced physical activity.
• Sexual dysfunction—dyspareunia, decreased libido, ejaculatory pain, relationship strain.
• Mental health burden—anxiety, depression, post-traumatic stress disorder; suicide risk in severe refractory disease.
• Fibrotic, low-capacity bladder in advanced Hunner-type disease—may drive surgical consideration.
• Comorbid pain amplification—worsening fibromyalgia, IBS or vulvodynia in flare cycles.

Treatment-related

• Pentosan polysulfate pigmentary maculopathy—a dose- and duration-dependent retinal toxicity described by Pearce et al. (2018); presents as difficulty reading, paracentral scotomas or dark adaptation problems.
• Anticholinergic toxicity from amitriptyline or hydroxyzine—dry mouth, constipation, urinary retention, confusion in older adults.
• Cyclosporine A—nephrotoxicity, hypertension, gingival hyperplasia, hypertrichosis, magnesium and potassium imbalance, infection risk.
• OnabotulinumtoxinA—transient urinary retention requiring intermittent self-catheterisation; rare systemic toxin spread.
• Cystoscopy and hydrodistension—post-procedure dysuria, transient haematuria, infection, rare bladder rupture.
• Sacral neuromodulation—lead migration, infection at the implant site, paraesthesia, need for revision.
• Major surgery—stoma complications, bowel- or augmentation-related metabolic disturbances and small risk of malignancy in augmented bowel segments.

Primary prevention is not currently feasible because aetiology remains incompletely defined. Secondary prevention—reducing flare frequency and disease progression—is the realistic target. Encourage early diagnosis (avoiding the multi-year culture-negative "UTI" loop), trigger-led behavioural change, structured pelvic floor physical therapy, treatment of comorbid pain syndromes, sleep hygiene and mental health support. Stewardship of antibiotics and analgesics protects patients from iatrogenic harm; ophthalmology surveillance for those on long-term pentosan polysulfate prevents permanent visual loss. Smoking cessation and weight optimisation are useful general-health levers, particularly for cardiovascular and bladder cancer risk reduction in the same population.

IC/BPS is a chronic, fluctuating condition with a relapsing–remitting trajectory in most patients. Long-term cohorts show meaningful symptom improvement in the majority over years when stepped care is delivered consistently, but cure—defined as durable absence of symptoms off therapy—remains uncommon. Hunner-positive disease tends to be more inflammatory and progressive but often responds dramatically to lesion-directed therapy, sometimes with prolonged remission after fulguration or triamcinolone injection. Non-Hunner disease behaves more like a chronic pain syndrome and benefits most from sustained behavioural, physical and pharmacological care plus parallel treatment of comorbidities. Mortality from IC itself is low; the burden is on quality of life, mood, sleep and relationships, which is why coordinated multidisciplinary care, not maximal urological monotherapy, is the single most useful prognostic lever.

Subtle deterioration

The IC patient who is quietly deteriorating rarely arrives in extremis. Watch for the gradient: a rising urgency score over a fortnight, sleep cut to 4 hours by nocturia, weight loss tracking with food avoidance, mood collapsing under chronic pain and a pelvic floor that feels increasingly board-like on examination. None of those moments alone trigger a rapid response, but pattern recognition books an earlier urology and pelvic floor review and prevents the next emergency department presentation.

Communication friction

Patients arrive having been told their pain is "just stress", "all in your head" or "another UTI" for years. Believing the pain is the most clinically active intervention available at first contact—it shapes adherence to behavioural therapy, accuracy of bladder diaries and willingness to escalate to procedures when needed. Keep language precise ("chronic non-infective bladder pain syndrome"), avoid implying psychogenicity even when comorbid mood disorder is present, and frame mental health support as part of pain care rather than a substitute for it.

Bedside checklist

• Confirm a positive culture before each new antibiotic course—do not retreat empirically.
• Always ask about Hunner lesion findings on previous cystoscopy; they change the next move.
• Audit anticholinergic burden in older adults on amitriptyline, hydroxyzine and oxybutynin combinations.
• For pentosan users, document last ophthalmology review in the same line as the medication.
• Coordinate handover so the next team does not silently abandon trigger-led behavioural plans on admission.

Initial bundle: ABCDE primary survey if unwell; mid-stream urinalysis, culture, full blood count, renal function and inflammatory markers; bladder scan for post-void residual; structured numeric pain scoring; safe IV access. Avoid escalating IC-directed therapy (pentosan, instillations, neuromodulators) during an acute infective or oncological work-up. Loop in urology, gynaecology or general surgery early when red flags persist.

These NCLEX-style clinical judgment practice items focus on the nursing priorities for this condition — recognise cues, escalate red flags, take safe action and evaluate outcomes (NCSBN Clinical Judgment Measurement Model) — through Priority FIRST, SATA, deterioration trends, ordered-response, matrix and cloze formats on the topic of interstitial cystitis—exclusion-led diagnosis, AUA stepped care, dietary trigger coaching and Hunner-lesion phenotyping. Hit Check answers for layered rationales tied to the Clinical Judgment Measurement Model (cues → analyse → prioritise → take action → evaluate).