Human health and medicine

Decompressive craniectomy

Decompressive craniectomy is a neurosurgical operation in which part of the skull is removed to lower intracranial pressure, mainly for severe stroke, brain swelling, and traumatic brain injury.

Decompressive hemicraniectomy

Decompressive hemicraniectomy is a neurosurgical operation that removes a large bone flap from one side of the skull to relieve pressure, used mainly for severe stroke and traumatic brain injury.

Decongestants, also called nasal decongestants, are vasoconstrictor medicines (pseudoephedrine, phenylephrine, oxymetazoline, xylometazoline) that relieve stuffy nose; topical use is limited to 5 days to avoid rebound congestion and rhinitis medicamentosa, and oral phenylephrine was found ineffective by FDA advisers.

Decortication

Decortication is a thoracic surgical procedure that removes the thick fibrous peel encasing a restricted lung so it can re-expand, used for organized empyema, trapped lung, and hemothorax.

Decreased appetite

Decreased appetite (anorexia, ICD-11 MG43.8) is reduced desire to eat, distinct from anorexia nervosa. Caused by illness, cancer, drugs, and emotions; affects about 29% of older adults and 60-80% of cancer patients.

Decreased libido

Decreased libido, reduced sexual desire; persistent distressed forms are hypoactive sexual desire disorder (HSDD, ICD-11 MB22.1, ICD-10-CM R68.82). Causes include medications, hormones, depression; treated with CBT, flibanserin, bremelanotide, testosterone.

Decreased white blood cell count

Decreased white blood cell count, or leukopenia, is a lower-than-normal blood leukocyte level (adults often <3,500-4,000/mcL), usually from neutropenia. Causes include drugs, chemotherapy, infection, marrow disease, and benign ethnic neutropenia; fever with agranulocytosis is an emergency.

Dee E. Fenner

Dee E. Fenner is an American urogynecologist who chairs Obstetrics and Gynecology at the University of Michigan and was elected to the National Academy of Medicine in 2025.

Deep brain stimulation

Deep brain stimulation (DBS) is neurosurgical implantation of electrodes and a pacemaker-like neurostimulator to treat Parkinson's disease, essential tremor, dystonia, OCD, and epilepsy; FDA-approved since 1997, with the first adaptive closed-loop system approved in February 2025.

Deep dermatophytosis

Deep dermatophytosis, or disseminated granulomatous dermatophytosis, is a rare, life-threatening invasion of dermis and subcutaneous tissue by dermatophytes, mainly Trichophyton rubrum, in CARD9-deficient or immunocompromised patients, with lymph node dissemination and terbinafine or itraconazole treatment.

Deep gluteal syndrome

Deep gluteal syndrome (DGS), formerly piriformis syndrome, is non-discogenic sciatic nerve entrapment in the deep gluteal space causing buttock pain and sciatica; diagnosed by provocation tests and pelvic MRI, treated conservatively first.

Deep hypothermic circulatory arrest

Deep hypothermic circulatory arrest (DHCA) is a cardiac and aortic surgery technique cooling the body to 15–25 °C to stop circulation safely; pioneered by Bigelow, Drew, and Griepp, now often replaced by moderate hypothermia with antegrade cerebral perfusion.

Deep inspiration breath hold

Deep inspiration breath hold (DIBH) is a radiotherapy technique in which patients hold a deep breath during treatment, moving the heart away from the beam to reduce cardiac dose.

Deep learning image reconstruction

Deep learning image reconstruction (DLIR, also DLR) is a medical imaging method using deep neural networks to denoise CT images, enabling lower radiation dose or faster scans.

Oct 20, 2026

Deep ovarian endometriosis

Deep ovarian endometriosis is deeply infiltrating endometrial disease within the ovary, typically an endometrioma. Also called B5 in ICD-11; scored in rASRM and ENZIAN; diagnosed by transvaginal ultrasound and MRI.

Deep sedation

Deep sedation is a drug-induced state in which a patient cannot be easily aroused but responds purposefully to repeated or painful stimulation, with possible airway support needed.

Deep transcranial magnetic stimulation

Deep transcranial magnetic stimulation (dTMS) is a form of transcranial magnetic stimulation using helmet-like coils that reach deeper brain regions, cleared for depression, OCD, and smoking cessation.

Deep vein thrombosis

Deep vein thrombosis (DVT) is a blood clot in a deep vein of the leg, pelvis, or arm, part of venous thromboembolism; diagnosed by duplex ultrasound, treated with anticoagulants, and complicated by pulmonary embolism and post-thrombotic syndrome.

Deepak Chopra (दीपक चोपड़ा)

Deepak Chopra (दीपक चोपड़ा), Indian-born American physician and author of Quantum Healing (1989), coined "quantum healing," founded the Chopra Center and Foundation, wrote 90+ books, and is widely criticized for pseudoscientific use of quantum physics.

Deepak Pandya

Deepak N. Pandya (1932-2020), Indian-American neuroanatomist and physician at Bedford VA and Boston University, mapped primate cortical connections, defined core-belt auditory cortex, and was father of astronaut Sunita Williams.

Defactinib

Defactinib (VS-6063, PF-04554878, FAKZYNJA) is an ATP-competitive FAK/Pyk2 inhibitor (IC50 0.6 nM). FDA-approved May 2025 with avutometinib for KRAS-mutated recurrent low-grade serous ovarian cancer; failed as mesothelioma monotherapy in COMMAND.

Default mode network

Default mode network (DMN), also called default network, a brain network of medial prefrontal, posterior cingulate, precuneus, angular gyrus, and temporal regions active at rest and during internal thought, suppressed during attention-demanding tasks; named by Raichle et al. 2001.

Defecation

Defecation is the expulsion of feces through the anus, coordinated by the enteric, spinal, and central nervous systems, the pelvic floor, and the anal sphincters; most people defecate 1 to 3 times daily.

Oct 20, 2026

Defecography

Defecography (evacuation proctography) is real-time fluoroscopic or MRI imaging of defecation to assess pelvic floor disorders such as rectocele, enterocele, intussusception, and dyssynergia.

Defibrillation

Defibrillation: electric shock treatment terminating ventricular fibrillation or pulseless ventricular tachycardia, via manual defibrillators, public-access AEDs, or implanted cardioverter defibrillators; biphasic waveforms, 150–360 J energies, and bystander AED use doubling or tripling survival distinguish it.