Human health and medicine

Sean Barbabella

Sean P. Barbabella, Navy captain and osteopathic emergency and tactical medicine physician, is Physician to the President since March 7, 2025, succeeding Kevin O'Connor; Purple Heart and Legion of Merit recipient who authored Trump's 2025 health memos.

Sean Conley

Sean Conley is an American osteopathic physician and Navy commander who served as Physician to the President 2018-2021, handling Donald Trump's COVID-19 care and the criticized October 2020 Walter Reed briefings, later joining DHS.

SEARCH trial

SEARCH (Sustainable East Africa Research in Community Health), NCT01864603, was a 2013-2017 cluster-randomized trial in 32 rural Ugandan and Kenyan communities testing universal HIV testing with immediate ART; it found no significant incidence difference but higher viral suppression and lower mortality.

SEARCH-Rio study

SEARCH-Rio (Signal-averaged ECG in Chagas Disease in Rio de Janeiro, NCT01340963) is a Brazilian prospective cohort of 100 chronic Chagas disease patients whose ECG variables predicted cardiac death and ventricular tachycardia, yielding a risk score non-inferior to the Rassi score.

Seasonal affective disorder

Seasonal affective disorder (SAD), or winter depression, is a recurrent seasonal depression coined by Norman Rosenthal in 1984; winter-pattern symptoms include oversleeping and carbohydrate cravings, treated with 10,000-lux light therapy, CBT-SAD, and bupropion.

Seasonal effects on suicide rates

Seasonal effects on suicide rates: replicated spring-early summer peak with autumn secondary peak, Monday highest day, flipped in Southern Hemisphere, not explained by sunlight; winter peak is a myth.

Sebaceous cyst

Sebaceous cyst, properly epidermoid or epidermal inclusion cyst, is a benign keratin-filled skin lump from a blocked hair follicle; the name is a misnomer, treated by excision with capsule, rarely turning cancerous.

Sebaceous gland

Sebaceous gland: skin exocrine gland secreting sebum (squalene, wax esters, triglycerides) by holocrine rupture of sebocytes; absent on palms and soles, dense on face; androgen-driven, central to acne and seborrhoeic dermatitis.

Sebaceous gland hyperplasia

Sebaceous gland hyperplasia (sebaceous hyperplasia) is a benign enlargement of sebaceous glands causing 1–3 mm yellow facial papules in middle-aged and older adults, sometimes confused with basal cell carcinoma; treated by lasers, cryotherapy, or isotretinoin.

Sebelipase alfa

Sebelipase alfa (Kanuma) is a recombinant human lysosomal acid lipase enzyme replacement therapy for LAL deficiency, including Wolman disease, produced in transgenic hen egg white; EU-approved August 2015, FDA December 2015.

Sebocystomatosis

Sebocystomatosis, also called steatocystoma multiplex (OMIM 184500), is a rare autosomal dominant disorder with KRT17 mutations causing multiple benign sebum-filled dermal cysts on the chest, axillae, and upper arms, typically appearing at puberty.

Seborrheic keratosis

Seborrhoeic keratosis (seborrheic keratosis, senile wart, basal cell papilloma) is a benign keratinocyte skin growth, extremely common after age 60, diagnosed clinically and by dermoscopy, treated by cryotherapy, curettage, or lasers.

Seborrhoea

Seborrhoea (seborrhea, oily skin, hypersteatosis) is excessive sebum secretion causing greasy skin, ICD-11 ED91.2. Distinct from seborrhoeic dermatitis; linked to acne, acromegaly, and Parkinson disease.

Seborrhoeic dermatitis

Seborrhoeic dermatitis, also called seborrheic eczema, is a common, relapsing eczema affecting oily areas like the scalp, face, and trunk, linked to Malassezia yeast and managed rather than cured.

Seborrhoeic dermatitis of the scalp

Seborrhoeic dermatitis of the scalp (ICD-11 EA81.1; dandruff is its mild form) is a chronic relapsing inflammatory scalp disease linked to Malassezia yeasts, sebum, and immune dysregulation, treated with antifungal and anti-inflammatory shampoos.

Seckel syndrome

Seckel syndrome (bird-headed dwarfism, OMIM 210600) is a rare autosomal recessive microcephalic primordial dwarfism with prenatal-onset short stature, bird-headed facies, and intellectual disability, caused by genes such as ATR, CENPJ, and CEP152.

Secnidazole

Secnidazole (Solosec) is a long-half-life 5-nitroimidazole antimicrobial given as a single 2 g oral dose for bacterial vaginosis and trichomoniasis; FDA-approved 2017 (BV) and 2021 (trichomoniasis), similar to metronidazole, possibly inferior to ornidazole.

Secobarbital

Secobarbital, known as quinalbarbitone in Britain and sold as Seconal in red capsules, is a short-acting barbiturate sleep medication discontinued in the United States in 2020.

Second branchial cleft anomaly

Second branchial cleft anomaly (second branchial cleft cyst or fistula): a congenital lateral neck malformation along the sternocleidomastoid border, the most common branchial anomaly, treated by complete surgical excision.

Second degree haemorrhoids

Second degree haemorrhoids (grade II, ICD-11 DB60.1) are internal haemorrhoids that prolapse on straining but reduce spontaneously. Treated first with fiber and lifestyle change, then rubber band ligation; recurrence is more common than after surgery but complications fewer.

Second plague pandemic

Second plague pandemic: Yersinia pestis epidemics from the Black Death (1346–1353), which killed 30–60% of Europeans, through recurrent waves including the pestis secunda until the early 19th century; originated in the Tian Shan, Central Asia.

Second Xiangya Hospital of Central South University

Second Xiangya Hospital of Central South University (中南大学湘雅二医院), founded 1958 in Changsha, a Triple-A tertiary teaching hospital with 3,500 beds; hosts China's National Medical Center for Mental Disorder and leads in psychiatry and endocrinology.

Second-degree atrioventricular block

Second-degree atrioventricular block (Mobitz I/Wenckebach, Mobitz II, 2:1, high-grade): intermittent failure of AV conduction on ECG; Mobitz II is infranodal, high-risk, and warrants pacing regardless of symptoms.

Sep 29, 2026

Second-look surgery

Second-look surgery is a reoperation performed in a patient clinically free of disease after chemotherapy, to detect persistent disease; once routine in ovarian cancer, it was abandoned after trials showed no survival benefit.

Secondary amenorrhoea

Secondary amenorrhoea (secondary amenorrhea) is the cessation of menses for over 3 months (regular cycles) or 6 months (irregular) after menstruation was established; pregnancy is the most common cause, then functional hypothalamic amenorrhoea and PCOS.

Secondary and therapy-related acute myeloid leukemia

Secondary and therapy-related acute myeloid leukemia is AML arising after a blood disorder, cytotoxic therapy, or inherited predisposition, accounting for about 25 to 30% of new AML diagnoses.

Secondary angle closure glaucoma

Secondary angle closure glaucoma: angle closure from an identifiable underlying disease (neovascularization, uveitis, ICE syndrome, tumors, aqueous misdirection, lens or drug causes) raising IOP and damaging the optic nerve, unlike primary pupillary-block angle closure.

Secondary antiphospholipid syndrome

Secondary antiphospholipid syndrome (SAPS, ICD-11 4A45.1) is antiphospholipid syndrome occurring alongside another autoimmune disorder, most often SLE; the 2006 consensus advises against the primary/secondary split.

Secondary childhood glaucoma

Secondary childhood glaucoma (ICD-11 9C61.42) is pediatric glaucoma from an underlying ocular anomaly, systemic disease, acquired condition, or cataract surgery; CGRN classification divides it into four subtypes, managed mainly with medications and tube shunts.