Retained placenta is a condition in which all or part of the placenta or membranes remain in the uterus during the third stage of labour. Retained placenta can be broadly divided into:

failed separation of the placenta from the uterine lining
placenta separated from the uterine lining but retained within the uterusA retained placenta is commonly a cause of postpartum haemorrhage, both primary and secondary.Retained placenta is generally defined as a placenta that has not undergone placental expulsion within 30 minutes of the baby’s birth where the third stage of labor has been managed actively. Signs and symptoms
Risks of retained placenta include hemorrhage and infection. After the placenta is delivered, the uterus should contract down to close off all the blood vessels inside the uterus. If the placenta only partially separates, the uterus cannot contract properly, so the blood vessels inside will continue to bleed. A retained placenta thereby leads to hemorrhage. Management
Drugs, such as intraumbilical or intravenous oxytocin, are often used in the management of placental retention. It is useful ensuring the bladder is empty. However, ergometrine should not be given as it causes tonic uterine contractions which may delay placental expulsion. Controlled cord traction has been recommended as a second alternative after more than 30 minutes have passed after stimulation of uterine contractions, provided the uterus is contracted. Manual extraction may be required if cord traction also fails, or if heavy ongoing bleeding occurs.
Type 2: Spiny keratoderma (also known as "Porokeratosis punctata palmaris et plantaris," "Punctate keratoderma," and "Punctate porokeratosis of the palms and soles") is an autosomal dominant keratoderma of late onset that develops in patients aged 12 to 50, characterized by multiple tiny keratotic plugs, resembling the spines on a music box, involving the entire palmoplantar surfaces. : 509 
Type 3: Focal acral hyperkeratosis (also known as "Acrokeratoelastoidosis lichenoides," and "Degenerative collagenous plaques of the hand") is a late-onset keratoderma, inherited as an autosomal dominant condition, characterized by oval or polygonal crateriform papules developing along the border of the hands, feet, and wrists. : 509  It is considered similar to Costa acrokeratoelastoidosis. Ungrouped
Palmoplantar keratoderma and spastic paraplegia (also known as "Charcot–Marie–Tooth disease with palmoplantar keratoderma and nail dystrophy") is an autosomal dominant or x-linked dominant condition that begins in early childhood with thick focal keratoderma over the soles and, to a lesser extent, the palms. : 513 
Palmoplantar keratoderma of Sybert (also known as "Greither palmoplantar keratoderma," "Greither syndrome," "Keratosis extremitatum hereditaria progrediens," "Keratosis palmoplantaris transgrediens et progrediens" "Sybert keratoderma," and "Transgrediens and progrediens palmoplantar keratoderma") is an extremely rare autosomal dominant keratoderma (a skin condition involving horn-like growths) with symmetric severe involvement of the whole palmoplantar surface in a glove-and-stocking distribution. : 509  It was characterized by Aloys Greither in 1952. It was characterized by Virginia Sybert in 1988. An autosomal recessive form which is known as Mal de Meleda has been described. This is associated with mutations in the Secreted Ly-6/uPAR-related protein 1 (SLURP1) gene.