The term involution describes the return of the uterus to a pelvic organ, the next stage during the process of recovery.
At the end of the third stage of labour the uterus is in midline, approximately 2cm below the level of the umbilicus, with the fundus resting at the sacral promontory.
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At this time the uterus weighs approximately 1000 g.
Within 12 hours the fundus may rise approximately 1cm above the umbilicus.
The fundus descends 1-2cm every 24 hours.
By 6th day postpartum the fundus is halfway between the umbilicus and the symphysis pubis.
At two weeks post delivery the uterus should not be palpated (Resnik, 2004).
By the end of the first week it will weigh approximately 500g.
By 6 weeks following delivery, the uterus recedes to a weight of 50-60 g.
Therefore, most of the reduction in size and weight occurs in the first 2 weeks, at which time the uterus has shrunk enough to return to the true pelvis. Over the next several weeks, the uterus slowly returns to its nonpregnant state, although the overall uterine size remains larger than prior to gestation.
This is as a result of the decrease in the hormones progesterone and estrogen which causes autolysis (the self-destruction of excess hypertrophied tissue of the additional cells laid down during pregnancy). The musles, fibrous and elastic tissue has to be disposed of. The phagocytes deal with fibrous and elastic tissues by phagocytosis, while the muscle fibres are digested by the proteolytic enzymes, a process called autolysis. Finally, the waste products find their way to the kidneys for elimination.
The endometrial lining rapidly regenerates, so that by the seventh day, endometrial glands are already evident.
By the 16th day, the endometrium is restored throughout the uterus, except at the placental site.
Placental site
It undergoes a series of changes in the postpartum period.
Immediately after delivery, the contractions of the arterial smooth muscle and compression of the vessels by contraction of the myometrium ("physiologic ligatures") result in hemostasis.
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The size of the placental bed decreases by half, and the changes in the placental bed result in the quantity and quality of the lochia that is experienced.
Postpartum vaginal blood /Fluid loss (Lochia)
Immediately after delivery, a large amount of red blood flows from the uterus until the contraction phase occurs. It is like that of a menstrual flow for the first 2hours.
Thereafter, the volume of vaginal discharge (lochia) rapidly decreases.
The duration of this discharge, known as lochia rubra, consists of blood, decidual and trophoblastic debris.
The red discharge progressively changes to brownish red or pink, with a more watery consistency called lochia serosa. It contains old blood, serum, leukocytes, and tissue debris.
The discharge continues to decrease in amount and color and eventually changes to yellow called lochia alba. It takes about 1 week up to 6weeks after delivery (sellers, 2010).
It consist of Leukocytes, decidua, epitherail cells,mucus, serum, and bacteria.
The amount of flow and color of the lochia can vary considerably. Fifteen percent of women have continue to have lochia 6 weeks or more postpartum. Often, women experience an increase in the amount of bleeding at 7-14 days secondary to the sloughing of the eschar on the placental site. This is the classic time for delayed postpartum hemorrhages to occur.
Cervix
The cervix is soft immediately after birth. It begins to rapidly revert to a nonpregnant state, within 2-3 days postpartum, it shortens, becomes firm and regain its form, but it never returns to the nulliparous state and attains a jagged slit shape.
By the end of the first week, the external os closes such that a finger cannot be easily introduced.
Lactation delays the production of cervical and other estrogen influenced mucus and mucosal characteristics
55 Vagina
The decrese in estrogen is responsible for the thinness of the vagina mucosa and the absence of rugae.
The vagina also regresses but it does not completely return to its prepregnant size.
Resolution of the increased vascularity and edema occurs by 3rd week, and the rugae of the vagina begin to reappear in women who are not breastfeeding within the same period.
Mucus remains atrophic until menstruation starts.
Thickening of the vaginal mucosa occurs with the return of the ovarian function.
At this time, the vaginal epithelium appears atrophic on smear.
This is restored by weeks 6-10; however, it is further delayed in breastfeeding mothers because of persistently decreased estrogen levels.
Perineum /Pelvic muscle support
The perineum has been stretched and traumatized, and sometimes torn or cut, during the process of labour and delivery.
The swollen and engorged vulva rapidly resolves within 1-2 weeks.
Most of the supportive tissues of the pelvic floor that was torn during childbirth may require up to 6 months regaining tone.
Kegel exercises will help to strengthen the perineal muscles and encourage healing. The muscle tone may or may not return to normal, depending on the extent of injury to muscle, nerve, and connecting tissues.
Abdominal wall
The abdominal wall remains soft and poorly toned for many weeks. The return to a prepregnant state depends greatly on maternal exercise.
Ovaries
The resumption of normal function by the ovaries is highly variable and is greatly influenced by breastfeeding the infant.
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The woman who breastfeeds her infant has a longer period of amenorrhea and an ovulation delay due to the persistent levels of serum prolactin, which hinders stimulation of (FSH).
The mother who does not breastfeed may ovulate as early as 27 days after delivery.
Most women have a menstrual period by 12 weeks; the mean time to first menses is 7-9 weeks.
In the breastfeeding woman, the resumption of menses is highly variable and depends on a number of factors which including how much and how often the baby is fed and whether the baby's food is supplemented with formula.
The delay in the return to normal ovarian function in the lactating mother is caused by the suppression of ovulation due to the elevation in prolactin.
Half to three fourths of women who breastfeed return to periods within 36 weeks (6months) of delivery.
Many women ovulate before their first postpartum menstrual period occurs; there is need to discuss contraceptive options early in puerperium.
BREASTS
Soon after birth, there is a decrease in the concentrations of hormones, estrogen, progesterone, HCG, prolactin, cortisol, and insulin, which stimulate breast development during pregnancy.
Lactogenesis is initially triggered by the delivery of the placenta, which results in falling levels of estrogen and progesterone, with the continued presence of prolactin.
Before milk production begins, the breasts secrete colostrum, a thin, yellowish fluid that helps maintain the blood glucose level in the breastfeeding infant.
Nipple stimulation by the infant causes the release of the hormone oxytocin from the posterior pituitary gland, which triggers the release of the hormone prolactin from the anterior pituitary.
Prolactin initiates milk production, and the breasts become full (engorged), as well as warm and tender, between postpartum days 3 and 4.
Clients often refer to this as having their milk "come in." There may be a slight elevation in body temperature during this time.
57 Colostrum
The colostrum is the liquid that is initially released by the breasts during the first 2-4 days after delivery.
High in protein content, this liquid is protective for the newborn.
The colostrum, which the baby receives in the first few days postpartum, is already present in the breasts, and suckling by the newborn triggers its release.
The process, which begins as an endocrine process, switches to an autocrine process; the removal of milk from the breast stimulates more milk production.
Over the first 7 days, the milk matures and contains all necessary nutrients in the neonatal period.
The milk continues to change throughout the period of breastfeeding to meet the changing demands of the baby.