Small vessel vasculitides affecting the kidney destroy the integrity of the capillary wall and are grouped according to their appearance on immunofluorescence/immunohistochemistry. This chapter will concentrate on rapidly progressive glomerulonephritides of anti-glomerular basement membrane (GBM) and pauci-immune type, associated with anti-neutrophil cytoplasmic antibodies (ANCA). Both diseases usually cause a rapid decline in kidney function and show necrotizing, crescentic glomerulonephritis. Thrombotic microangiopathy (TMA) is a differential diagnosis of vasculitis. Childhood hypertension concludes this chapter.

During your call duty, a healthy 32-year-old primigravida at 22+3 weeks’ gestation, confirmed by first-trimester sonography, presents to the obstetrics emergency assessment unit of your hospital center with new-onset, asymptomatic port-wine-colored urine with chills and an oral temperature of 39.1°C at home; she also notes a two-day history of headache, now accompanied by visual changes. Your obstetric trainee informs you that clinical history is not suggestive of an infectious etiology, although comprehensive investigations are pending. She has no obstetric complaints, and fetal viability was ascertained upon presentation. Routine prenatal laboratory investigations, aneuploidy screening, and fetal morphology survey were unremarkable. The laboratory urgently notifies you that the platelet concentration is 12 × 109/L, confirmed on manual count; other requested laboratory tests are in progress.