Human health and medicine

Rectal resection

Rectal resection, including the low anterior resection, is surgery that removes all or part of the rectum, most often to treat rectal cancer using total mesorectal excision.

Rectal tenesmus (anal or anorectal tenesmus) is the persistent urge to pass stool despite an empty bowel, mainly from inflammatory bowel disease, proctitis, radiation, or rectal cancer, treated by addressing the underlying cause.

Rectocele

Rectocele (posterior vaginal wall prolapse): herniation of the rectum through the rectovaginal septum into the vagina. Causes include vaginal childbirth and chronic straining; treated first with fiber, fluids, pelvic floor therapy, and pessaries, then surgery.

Rectopexy

Rectopexy is a colorectal surgical operation that anchors a mobile rectum to the sacrum with sutures or mesh to cure rectal prolapse, performed by open, laparoscopic, or robotic access.

Rectovaginal fistula

Rectovaginal fistula (RVF), also called anovaginal fistula, is an abnormal passage between rectum and vagina, usually from childbirth injury or Crohn's disease; treated first conservatively, then surgically.

Rectum

The rectum (Latin intestinum rectum, straight intestine) is the 12-15 cm distal segment of the large intestine between the sigmoid colon and anal canal, a distensible reservoir for feces with superior, middle, and inferior rectal arterial supply.

Rectus abdominis muscle

Rectus abdominis, the paired "six pack" muscle of the anterior abdominal wall, runs from the pubic crest and symphysis to the xiphoid process and costal cartilages 5-7, flexes the trunk, and is segmented by tendinous inscriptions.

Rectus femoris muscle

Rectus femoris (Musculus rectus femoris): superficial two-headed quadriceps muscle of the anterior thigh, originating at the anterior inferior iliac spine and supraacetabular groove, extending the knee and flexing the hip, innervated by the femoral nerve (L2-L4).

Rectus sheath block

The rectus sheath block is a fascial plane nerve block that numbs the anterior abdominal wall, used mainly for pain control after midline abdominal surgery such as hernia repair.

Recurrence score

A recurrence score is a genomic test result, best known from the 21-gene Oncotype DX assay for early breast cancer, that estimates distant recurrence risk and chemotherapy benefit.

Recurrent cholesteatoma of postmastoidectomy cavity

Recurrent cholesteatoma of postmastoidectomy cavity is the regrowth of cholesteatoma, a skin tissue growth behind the ear, in the mastoid cavity remaining after surgery; recurrence reaches 39% at 15 years.

Recurrent erosion of cornea

Recurrent corneal erosion (RCE, recurrent erosion syndrome): repeated breakdown of the corneal epithelium causing sharp morning eye pain, usually after prior trauma (45–64% of cases) or epithelial basement membrane dystrophy; treated with lubricants, bandage lenses, and surgery.

Recurrent idiopathic neuroretinitis

Recurrent idiopathic neuroretinitis (RINR), a rare inflammatory optic neuropathy with recurrent painless visual loss, optic disc edema, and macular star; poor prognosis, treated with long-term azathioprine and prednisone.

Recurrent infections associated with rare immunoglobulin isotypes deficiency

Recurrent infections associated with rare immunoglobulin isotypes deficiency (ORPHA:183675) covers isolated IgG subclass deficiency, IgG subclass deficiency with IgA deficiency, and kappa chain deficiency, causing recurrent pyogenic sinopulmonary infections with normal total IgG.

Recurrent infections due to specific granule deficiency

Recurrent infections due to specific granule deficiency, also called neutrophil-specific granule deficiency or SGD (ORPHA:169142), is an ultra-rare autosomal recessive neutrophil disorder caused by CEBPE or SMARCD2 variants, causing infantile pyogenic infections, bilobed granule-poor neutrophils, and treatment with prophylactic antibiotics or HSCT.

Recurrent isolated sleep paralysis

Recurrent isolated sleep paralysis (RISP), also called fearful isolated sleep paralysis, is a REM parasomnia of repeated waking paralysis at sleep onset or offset. Coded ICSD-3 G47.51 and ICD-11 7B01.1; lifetime sleep paralysis prevalence 7.6% general population; treated with CBT, sleep hygiene, REM-suppressing antidepressants.

Recurrent laryngeal nerve

Recurrent laryngeal nerve (RLN, nervus laryngeus recurrens): vagus nerve branch supplying the larynx's intrinsic muscles; right loops under the subclavian artery, left under the aortic arch; injury is a key thyroidectomy complication.

Recurrent pericarditis

Recurrent pericarditis is the return of pericardial inflammation after a symptom-free interval of 4 to 6 weeks or longer, affecting 15 to 30% of patients after a first episode.

Recurrent pregnancy loss

Recurrent pregnancy loss (RPL), or recurrent miscarriage, is two or more spontaneous pregnancy losses before about 20-22 weeks, excluding molar and ectopic pregnancies; about half stem from embryonic aneuploidy, and most cases are unexplained.

Red blood cell distribution width

Red blood cell distribution width (RDW), also RDW-CV or RDW-SD, is a CBC parameter measuring variation in red blood cell size (anisocytosis), typically 12–15%, used to differentiate anemias and studied as a prognostic marker.

Red eye

Red eye: redness from inflammation of the eye's anterior segment; also called conjunctival hyperaemia. Most cases are benign conjunctivitis, blepharitis, or subconjunctival haemorrhage, but pain, photophobia, or reduced vision signal sight-threatening disease needing urgent ophthalmology referral.

Red Light

Red light, 620-750 nm visible radiation, is used in photobiomodulation (low-level light therapy) for skin, wounds, and pain, acting via mitochondrial cytochrome c oxidase; effects are biphasic and dose-dependent.

Red pulp

Red pulp (pulpa rubra) is the blood-filtering compartment of the spleen, about 75% of its tissue, made of cords of Billroth and venous sinuses where macrophages cull and pit aged red cells, recycle iron, and store platelets.

RED study

RED study: Ward's 2007 survey of 301 North American dentists on the recurring esthetic dental (RED) proportion, also called recurrent esthetic dental proportion, in smile design; 57% preferred the 70% RED proportion over naturally occurring anterior tooth width proportions.

RED-FLAG 2 study

RED-FLAG 2 (NCT05820217) is a French prospective observational study led by University Hospital, Angers, externally validating the pre-hospital Red Flag alert for severe haemorrhage in blunt trauma across six SAMU centers, 630 participants.

REDUCE-IT trial

REDUCE-IT (NCT01492361): 8,179-patient randomized trial of icosapent ethyl 4 g/day purified EPA versus mineral oil placebo in statin-treated patients with elevated triglycerides; 25% relative MACE reduction, mineral oil placebo controversy, contrast with null STRENGTH trial.

Reduced-intensity conditioning

Reduced-intensity conditioning (RIC) is a lower-dose preparative regimen for allogeneic hematopoietic stem cell transplantation that relies on donor immune effects rather than marrow eradication, developed in the late 1990s for older patients and those with comorbidities.