Hepatitis caused by a viral infection. Different hepatitis viruses have distinct transmission routes and long-term behavior, so liver inflammation alone does not identify which virus is involved.

A highly transmissible viral disease caused by measles virus. Respiratory transmission and systemic effects distinguish it from a rash defined only by appearance.^[ref]

A viral disease whose effects differ greatly with developmental context. Infection during pregnancy can harm fetal development, connecting a relatively mild maternal illness with potentially serious congenital effects.

The density of a vapor relative to a specified reference gas at the same temperature and pressure.

The myometrium is the smooth-muscle layer of the uterus. Its organized contractile activity generates uterine contractions, while its growth contributes to the large change in uterine size during gestation. It lies outside the endometrium and has a distinct mechanical role.

A uterine segment is a region of the uterus distinguished anatomically or functionally. In obstetric descriptions, the upper contractile region and the developing lower segment behave differently during late pregnancy and labor. The boundaries depend on the developmental state rather than being a separate permanent organ.

Uterine atony is inadequate contractile tone of the uterus. After placental separation, effective myometrium contraction helps compress vessels; deficient contraction can therefore contribute to bleeding. The term describes impaired muscular function rather than a torn vessel by itself.

Uterine inversion is turning of the upper uterine wall inward into, and potentially beyond, the uterine cavity. It is a change in the organ's anatomical configuration, distinct from simple descent of an otherwise normally oriented uterus.

Endometritis is inflammation of the endometrium. It identifies the tissue involved, while timing and cause require further description. It is distinct from endometriosis, in which endometrium-like tissue occurs outside its normal uterine location.

A hysterectomy is surgical removal of the uterus. The term alone does not establish whether the cervix, ovaries or other nearby structures are also removed; those anatomical distinctions require specification. Removal of the uterus and removal of a gonad are therefore different procedures.

A uterine contraction is shortening and force generation by the myometrium. Patterns vary across reproductive states, including coordinated activity during childbirth. Local muscle activity, global coordination and the resulting pressure are distinct measurements of the same organ's mechanical behavior.

The endometrium is the mucosal lining of the uterus. Its structure responds to ovarian hormones, supporting preparation for implantation; part of the lining is shed during menstruation when the appropriate hormonal support declines. It differs from the deeper contractile myometrium.

A projection into or through the uterine cavity. The term describes form and attachment, not one histological diagnosis.

A collection of fluid around a testis within its surrounding sac. It is distinct from a solid testicular mass or an inguinal hernia, although all can produce scrotal swelling.^[ref]

Inability to empty the bladder adequately. It can arise from outflow obstruction or impaired bladder function, distinguishing a shared clinical result from its different mechanical and neural causes.

Infection involving the urinary tract; a contaminated sample or asymptomatic bacteriuria is not automatically symptomatic infection.

Inflammation involving the renal interstitium.

Injury affecting renal tubular cells, assessed with the clinical course, renal function and other findings.

A stone formed in the urinary tract; symptoms and treatment depend on its composition, location, obstruction and associated infection.

Operative extraction of a stone through an incision. Historically the term often concerned a bladder stone; the anatomical route and stone location must be specified to distinguish different procedures.