Derm Cases · Dermatology / Obstetrics
OSCE — dermatoses of pregnancy: ICP, polymorphic eruption, and pemphigoid gestationis
An 8-minute OSCE station on distinguishing intrahepatic cholestasis of pregnancy, polymorphic eruption of pregnancy, and pemphigoid gestationis; prioritising bile-acid testing and fetal risk in ICP; and medication safety in pregnancy.
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Study tools
Target exams
NEET-PGINICETUSMLEPLABMRCP
Prompt
An 8-minute OSCE station on distinguishing intrahepatic cholestasis of pregnancy, polymorphic eruption of pregnancy, and pemphigoid gestationis; prioritising bile-acid testing and fetal risk in ICP; and medication safety in pregnancy.
Brief (to candidate)
A 32-year-old at 32 weeks’ gestation has severe generalised pruritus worse at night with excoriations and no primary blisters. Another patient at 36 weeks has urticarial plaques in striae after first pregnancy with twins. You have 8 minutes to differentiate pregnancy dermatoses, order key tests, and plan obstetric liaison.
[6]Candidate instructions
- Differentiate ICP, PEP/PUPPP, pemphigoid gestationis, and atopic eruption of pregnancy.
- Prioritise serum bile acids and LFTs for itch in pregnancy.
- State fetal risks and delivery planning concepts for ICP.
- Outline first-line therapies (UDCA for ICP; topical steroids for PEP; specialist care for PG).
- Flag unsafe drugs in pregnancy (e.g. methotrexate, oral retinoids, mycophenolate).
Examiner checklist (mark each domain / 10)
| Domain | Key actions expected |
|---|---|
| ICP | Intense pruritus (often palms/soles) in late pregnancy ± minimal rash; raised bile acids; associated adverse perinatal outcomes — urgent obstetric pathways when bile acids high[1][2][7] |
| PEP (PUPPP) | Pruritic urticarial papules/plaques often starting in striae, spares umbilicus commonly; third trimester, more in primips/multiples; maternal disease, fetal risk generally low[4][6] |
| Pemphigoid gestationis | Autoimmune blistering; urticarial plaques → vesicles/bullae; often periumbilical; immunofluorescence gold standard; maternal/fetal implications — dermatology–obstetric care[9] |
| Investigations | Bile acids + LFT for itch; skin biopsy/DIF if PG suspected; do not dismiss itch as “just stretch marks” without labs when severe |
| ICP management | Ursodeoxycholic acid commonly used for maternal itch; monitor bile acids; plan timing of delivery with obstetrics per local thresholds; early neonatal vitamin K considerations as per obstetric protocols[8][3] |
| Drug safety | Avoid methotrexate, oral retinoids, mycophenolate, thalidomide; prefer pregnancy-compatible topicals; check each systemic with current guidance[11][12] |
| Communication | Explain maternal vs fetal risk differences (ICP vs PEP); safety-net reduced fetal movements / obstetric emergency features |
Model key actions
- For severe pregnancy itch, order bile acids/LFTs same day logic and liaise obstetrics for possible ICP.[1][7]
- Diagnose PEP when striae-centred urticarial papules without high bile acids/blisters.[4][6]
- Suspect pemphigoid gestationis if periumbilical blistering; avoid teratogenic dermatologics.[9][11]
Common errors
- Ignoring itch without bile acid testing.
- Treating ICP as “eczema” only with moisturisers and no obstetric plan.
- Missing pemphigoid gestationis.
- Prescribing methotrexate/isotretinoin in pregnancy.
- Reassuring high bile-acid ICP without fetal risk discussion.
References10ShowHide
- [1]Smith DD, Rood KM. Intrahepatic Cholestasis of Pregnancy. Clinical Obstetrics and Gynecology, 2020.PMID 31764000
- [2]Dajti E, Tripodi V, Hu Y, et al. Intrahepatic cholestasis of pregnancy. Nature Reviews Disease Primers, 2025.PMID 40707479
- [3]Williamson C, Geenes V. Intrahepatic cholestasis of pregnancy. Obstetrics and Gynecology, 2014.PMID 24901263
- [4]Himeles JR, Pomeranz MK. Recognizing, Diagnosing, and Managing Pregnancy Dermatoses. Obstetrics and Gynecology, 2022.PMID 36075066
- [6]Ambros-Rudolph CM, Müllegger RR, Vaughan-Jones SA, et al. The specific dermatoses of pregnancy revisited and reclassified: results of a retrospective two-center study on 505 pregnant patients. Journal of the American Academy of Dermatology, 2006.PMID 16488288
- [7]Ovadia C, Seed PT, Sklavounos A, et al. Association of adverse perinatal outcomes of intrahepatic cholestasis of pregnancy with biochemical markers: results of aggregate and individual patient data meta-analyses. Lancet, 2019.PMID 30773280
- [8]Chappell LC, Bell JL, Smith A, et al. Ursodeoxycholic acid versus placebo in women with intrahepatic cholestasis of pregnancy (PITCHES): a randomised controlled trial. Lancet, 2019.PMID 31378395
- [9]Huilaja L, Mäkikallio K, Tasanen K Gestational pemphigoid. Orphanet Journal of Rare Diseases, 2014.PMID 25178359
- [11]Murase JE, Heller MM, Butler DC. Safety of dermatologic medications in pregnancy and lactation: Part I. Pregnancy. Journal of the American Academy of Dermatology, 2014.PMID 24528911
- [12]Butler DC, Heller MM, Murase JE. Safety of dermatologic medications in pregnancy and lactation: Part II. Lactation. Journal of the American Academy of Dermatology, 2014.PMID 24528912