Human health and medicine

Peritoneal cytology

Peritoneal cytology is the microscopic examination of cells from peritoneal fluid or saline washings taken during surgery to detect free malignant cells, informing cancer staging, resectability, and treatment selection.

Peritoneal dialysis

Peritoneal dialysis (PD), a home-based kidney failure treatment filtering blood through the abdominal peritoneum via a catheter; includes CAPD and automated cycler PD, 4-6 daily exchanges, dextrose or icodextrin solutions, peritonitis as main risk.

Peritoneal equilibration test

The peritoneal equilibration test (PET) is a standardized clinical procedure measuring solute and water transport across the peritoneal membrane during peritoneal dialysis, introduced by Twardowski in 1987.

Peritoneal inclusion cyst

Peritoneal inclusion cyst, also called benign multicystic peritoneal mesothelioma, is a rare benign cystic peritoneal lesion in premenopausal women, linked to surgery, endometriosis, and pelvic inflammation, with low recurrence under current WHO definitions.

Peritoneal lavage

Peritoneal lavage, or peritoneal washing, is a procedure in which fluid is instilled into and withdrawn from the peritoneal cavity to detect blood, bowel contents, or cancer cells.

Peritonectomy

Peritonectomy is a surgical oncology procedure that strips resectable peritoneal metastases from the abdominal lining, usually combined with heated intraperitoneal chemotherapy (HIPEC), introduced by Paul Sugarbaker in 1995.

Peritoneovenous shunt

The peritoneovenous shunt, also called the LeVeen shunt, is an implanted device that drains ascitic fluid from the abdomen into the central veins through a one-way valve.

Peritonitis

Peritonitis is inflammation of the peritoneum, usually bacterial. Covers primary, secondary, tertiary, SBP, and dialysis-related forms, surgical principles from Körte and Kirschner, and mortality falling from near 100% to under 10%.

Peritonitis due to Streptococcus pneumoniae

Pneumococcal peritonitis, peritonitis due to Streptococcus pneumoniae (ICD-11 DC50.13), a rare 1.3% subset of invasive pneumococcal disease, classified as primary, secondary, or genitourinary, treated with antibiotics and surgery.

Peritonsillar abscess

Peritonsillar abscess, also called quinsy, is a collection of pus between the tonsillar capsule and superior pharyngeal constrictor muscle, most common in young adults and treated with antibiotics plus needle aspiration or incision and drainage.

Peritubular capillaries

Peritubular capillaries are tiny fenestrated blood vessels in the kidney cortex that surround the renal tubules, take up reabsorbed water and solutes, and supply tubular cells with oxygen.

Perivascular epithelioid cell neoplasm

Perivascular epithelioid cell neoplasm (PEComa), also called perivascular epithelioid cell tumor, is a rare family of mesenchymal tumors with dual melanocytic and smooth muscle differentiation, including angiomyolipoma, clear cell sugar tumor, and lymphangioleiomyomatosis, driven by TSC1/TSC2-mTOR or TFE3 alterations.

Periventricular leukomalacia

Periventricular leukomalacia (PVL), also called encephalopathy of prematurity, is white matter death around the brain ventricles in premature infants, caused by ischemia and infection, diagnosed by ultrasound or MRI, and strongly linked to cerebral palsy.

Perlman syndrome

Perlman syndrome is a rare autosomal recessive congenital overgrowth disorder caused by DIS3L2 gene variants, marked by large body size, kidney abnormalities, and frequent death in the newborn period.

Permanent atrial fibrillation

Permanent atrial fibrillation (ICD-11 BC81.32) is AF accepted by patient and physician with no planned sinus-rhythm restoration; a therapeutic decision, not a pathologic type, managed with rate control and anticoagulation.

Permanent colostomy

A permanent colostomy is an operation that brings one end of the colon through the abdominal wall as a lifelong stoma draining into an external pouch.

Permanent Dental Restoration

A permanent dental restoration is a filling intended to last indefinitely, replacing tooth structure lost to decay, fracture, or wear using amalgam, resin composite, glass ionomer, or resin-modified glass ionomer cement.

Oct 20, 2026

Permanent neonatal diabetes mellitus-pancreatic and cerebellar agenesis syndrome

Permanent neonatal diabetes mellitus-pancreatic and cerebellar agenesis syndrome (pancreatic and cerebellar agenesis, OMIM 609069) is an autosomal recessive PTF1A-related neonatal diabetes syndrome with cerebellar and pancreatic agenesis, lethal in the neonatal period.

Permanent vegetative state

Permanent vegetative state, also called chronic VS or unresponsive wakefulness syndrome, is a prognosis of irreversible wakeful unawareness after severe brain injury, declared 3 months (nontraumatic) or 12 months (traumatic) after onset.

Permethrin

Permethrin, a synthetic Type I pyrethroid insecticide first synthesized in 1973, is used in agriculture, mosquito control, treated clothing, and as 5% cream and 1% rinse for scabies and lice, acting on insect sodium channels.

Permissive hypotension

Permissive hypotension is a trauma resuscitation strategy that accepts systolic pressure below normal, typically 80–90 mmHg, until bleeding is controlled, and is excluded in patients with brain or spinal injury.

Pernicious anemia

Pernicious anaemia, also called Biermer's or Addisonian anaemia, is autoimmune gastritis causing loss of intrinsic factor and B12 deficiency; diagnosed via intrinsic factor and parietal cell antibodies, treated with lifelong B12 injections.

Peroral cholangioscopy

Peroral cholangioscopy (POCS) is an endoscopic technique that passes a small cholangioscope through the mouth into the bile ducts to diagnose strictures and remove difficult stones.

Peroral endoscopic myotomy

Peroral endoscopic myotomy (POEM) is an endoscopic operation that cuts the lower esophageal sphincter muscle to treat achalasia, performed through the mouth with no skin incision.

Peroxisomal acyl-CoA oxidase deficiency

Peroxisomal acyl-CoA oxidase deficiency, also called pseudo-neonatal adrenoleukodystrophy (pseudo-NALD), is a rare autosomal recessive ACOX1 (17q25.1) disorder of peroxisomal VLCFA beta-oxidation causing neonatal hypotonia, seizures, and regression, distinct from Mitchell syndrome (dominant ACOX1 gain-of-function).

Perpetrator trauma

Perpetrator trauma, also called perpetration-induced traumatic stress (PITS), is trauma arising from committing a wrong, first described among Vietnam War veterans in the 1970s.

Perphenazine

Perphenazine (Trilafon) is a high-potency first-generation piperazinyl phenothiazine antipsychotic for schizophrenia and severe nausea/vomiting; half-life 9-12 hours, CYP2D6-dependent, performed as well as atypicals in CATIE.

Perrault syndrome

Perrault syndrome, also called XX gonadal dysgenesis with deafness, is a rare autosomal recessive disorder causing sensorineural hearing loss in both sexes and ovarian dysfunction in 46,XX females, caused by biallelic variants in 12 genes, mostly mitochondrial.

Perry syndrome

Perry syndrome (parkinsonism with alveolar hypoventilation and mental depression) is a rare autosomal dominant neurodegenerative disease caused by DCTN1 mutations, causing parkinsonism, depression, weight loss, and nocturnal hypoventilation, with death typically within about five years.