atony

Atony is the absence or reduction of the normal tone of a body organ or tissue, reflecting insufficient contractile activity or loss of innervation. The term derives from the Greek a-, without, and tonos, tone.

In obstetrics, uterine atony is the failure of the uterus to contract after delivery and is a leading cause of postpartum hemorrhage. Risk factors include uterine overdistension, prolonged or rapid labor, infection, fatigue of the myometrium, tocolytic use, and retained placental tissue. Signs are heavy vaginal bleeding with a soft, boggy uterus. Management begins with urgent uterine massage and administration of uterotonic drugs such as oxytocin, methylergometrine, carboprost or misoprostol, along with IV fluids and blood products as needed. If bleeding persists, additional measures include tranexamic acid, removal of placental fragments, balloon tamponade, and surgical options (arterial ligation or hysterectomy) when conservative measures fail.

Atony also describes reduced tone in other organs, notably gastric atony (gastroparesis) causing delayed gastric emptying and dyspepsia, and bladder atony causing urinary retention. Neurogenic or drug-induced atony may follow nerve injury, spinal cord disease, or metabolic disturbances.

Diagnosis is primarily clinical and may be supported by imaging or motility studies where relevant. Treatment targets the underlying cause and maintaining organ function, with prognosis depending on the organ involved and the speed of intervention. See also postpartum hemorrhage, gastroparesis, and neurogenic bladder.