Human health and medicine

Perianal venous thrombosis

Perianal venous thrombosis (thrombosed external hemorrhoid, perianal hematoma; ICD-11 DB61, ICD-10-CM K64.5) is a clot in a vein of the external anal plexus, causing sudden severe perianal pain; treated conservatively or by excision within 72 hours.

Periaortic lymph nodes

Periaortic (para-aortic, lumbar) lymph nodes: retroperitoneal nodes along the aorta and IVC draining kidney, adrenal, gonads, and uterine corpus; seven imaging subgroups; PET-CT is the most accurate metastasis test.

Periapical abscess with sinus

Periapical abscess with sinus (ICD-11 DA09.61; dental sinus) is a periapical abscess draining pus through a sinus tract to oral mucosa or skin, treated by root canal therapy or extraction.

Periapical abscess without sinus

Periapical abscess without sinus, also called acute apical or dentoalveolar abscess, is pus at a tooth root tip without a draining sinus tract; ICD-10-CM K04.7, ICD-11 DA09.62, treated by root canal treatment rather than antibiotics.

Periapical periodontitis

Periapical periodontitis, also called apical periodontitis (ICD-11 DA09.7), is inflammation of the tissue around a tooth root apex caused by root canal infection, presenting as granuloma, cyst, or abscess and treated by root canal treatment.

Periapical radiography

Periapical radiography is an intraoral dental X-ray technique that captures an entire tooth, from crown to root tip, used to diagnose caries, root pathology, and periapical disease.

Periapical surgery

Periapical surgery, or apicectomy with root-end filling, is a dental procedure that removes the tip of a tooth root to seal it and clear persistent infection.

Periarthritis of wrist

Periarthritis of wrist (ICD-11 FB55.2) is inflammation of tissues around the wrist joints, an enthesopathy mapping to ICD-10 M77.2, covering tenosynovitis, de Quervain disease, and acute calcific periarthritis.

Peribulbar block

A peribulbar block is a regional anesthesia technique for eye surgery, injecting local anesthetic outside the muscle cone of the orbit; it is the most common regional technique for cataract surgery.

Pericapsular nerve group block

The pericapsular nerve group (PENG) block is an ultrasound-guided regional anesthesia technique introduced in 2018 that injects anesthetic between the psoas tendon and ilium to relieve hip fracture pain while largely sparing motor function.

Pericardial effusion

Pericardial effusion is abnormal fluid accumulation in the pericardial sac around the heart, graded by echocardiography as mild, moderate, or large. Causes include viral pericarditis, tuberculosis, and malignancy; severe cases cause cardiac tamponade requiring pericardiocentesis.

Pericardial window

A pericardial window is a surgical operation removing a small portion of the pericardium, the sac around the heart, so excess fluid drains continuously into the pleural cavity.

Pericardiectomy

Pericardiectomy is a cardiac operation that removes part or all of the pericardium, the sac around the heart, and is the definitive treatment for constrictive pericarditis.

Pericardiocentesis

Pericardiocentesis is needle drainage of fluid from the pericardial sac, the emergency treatment for cardiac tamponade. Echo-guided since 1979, it succeeds in about 97% of cases but recurs more often than surgical drainage.

Pericardiotomy

Pericardiotomy is a surgical incision in the pericardium, the fibrous sac surrounding the heart, to drain accumulated fluid, relieve cardiac tamponade, or give direct access to the heart; a limited-access form is called a pericardial window.

Pericarditis

Pericarditis is inflammation of the pericardium, frequently presenting as sharp chest pain that improves when sitting forward. Most cases have a benign course with treatment like NSAIDs and colchicine.

Pericardium

The pericardium, also known as the pericardial sac or heart sac, is the double-layered fibrous sac enclosing the heart, lubricating its movement and anchoring it within the chest.

Perichondritis of external ear

Perichondritis of external ear (ICD-11 AA04; ICD-10 H61.0) is infection of the perichondrium around outer-ear cartilage, usually after cartilage piercing or trauma, most often caused by Pseudomonas aeruginosa, risking cauliflower ear.

Periciazine

Periciazine (pericyazine, propericiazine; brands Neulactil, Neuleptil) is a sedating piperidine phenothiazine antipsychotic, ATC N05AC01, used for schizophrenia and short-term control of severe anxiety, agitation, and impulsive aggression.

Pericoronitis

Pericoronitis is inflammation and infection of gum tissue around a partially erupted tooth, usually a lower wisdom tooth. Local debridement is first-line; antibiotics are reserved for fever, spreading infection, or trismus, though dentists often overprescribe them.

Pericyte

Pericytes are mural cells embedded in the basement membrane of capillaries and microvessels, wrapping endothelial cells. Also called Rouget cells; they regulate blood flow, angiogenesis, and the blood-brain barrier, and lack a single specific marker.

Oct 20, 2026

Periendocarditis

Periendocarditis, also called acute endopericarditis, is simultaneous inflammation of the endocardium and pericardium, classified as ICD-11 code BB42 under acute or subacute endocarditis and ICD-10 I33.9.

Perifosine

Perifosine (KRX-0401, D-21266), an oral alkylphospholipid Akt inhibitor derived from miltefosine, tested in phase 3 trials for multiple myeloma and colorectal cancer; development ended after failed endpoints and withdrawn orphan designations.

Perifoveal exudative vascular anomalous complex

Perifoveal exudative vascular anomalous complex (PEVAC, also PVAC) is a rare idiopathic large aneurysmal lesion of the deep retinal capillary plexus near the fovea, diagnosed by exclusion, poorly responsive to anti-VEGF, distinct from type 3 MNV and MacTel.

Periglomerular cell

Periglomerular cell (PG cell, juxtaglomerular interneuron): small GABAergic interneuron surrounding olfactory bulb glomeruli, soma 5–10 µm, uniglomerular dendrites, dendrodendritic inhibition of mitral/tufted cells, dopaminergic TH+ subtype, adult-born, distinct from renal periglomerular usage.