Obstetrics and Gynecology - A. M. Gromova 2000

Clinical Course and Management of the Puerperium
Course of the Postpartum Period
Changes in the Reproductive Organs During the Postpartum Period

The most significant changes in the postpartum period occur in the woman's Reproductive System, particularly in the Uterus.

Uterine Involution

During the first hours after delivery, significant tonic contractions of the uterus take place. Against the Background of increased Muscle tone, peripheral muscle contractions (afterpains) occur, which help reduce the size of the uterus. Consequently, the uterine walls thicken, and the uterus assumes a spherical shape, slightly flattened in the anteroposterior direction.

At the beginning of the postpartum period, the uterine fundus is located 13–15 cm above the Pubic Symphysis; the length of its cavity (from the external os of the cervical canal to the fundus) reaches 15–20 cm, and the wall thickness in the fundus region is 4–5 cm. Immediately after childbirth, the transverse dimension of the uterus is 12–13 cm, and its mass is 1000 g. The anterior and posterior walls of the uterus lie in apposition to each other.

The uterus contracts in the direction from the fundus to the cervix. The contractile capacity of the lower uterine segment and the cervix is significantly lower; therefore, the uterine wall is thinner in the lower segment. The vaginal portion of the cervix hangs into the Vagina, its edges are thinned, and it often presents lateral tears and superficial injuries (fissures). As a result of the contraction of the uterine body and the circular layer of the myometrium surrounding the internal os, a clear boundary is established between the upper and lower segments of the uterus. In the first days of the postpartum period, the uterine fundus comes into contact with the abdominal wall, and an angle open anteriorly is formed between the uterine body and the cervix (anteflexio uteri). This is facilitated by the relaxation of the ligamentous apparatus and the supine position of the parturient woman. During the first postpartum days, uterine mobility is increased, which is also explained by the stretching and insufficient tone of its ligamentous apparatus. The uterus is easily displaced upward, especially when the Urinary Bladder is overdistended.

The reduction in the size and mass of the uterus is facilitated by the contraction of its Muscles and the associated morphological changes. The contracting muscles compress the walls of Blood and Lymphatic vessels. The vascular lumens narrow, and many of them become occluded and undergo obliteration. As a result, There is a sharp restriction in the Blood supply to the myometrium Cells, leading to their fatty degeneration, breakdown, and resorption.

The state of uterine contraction is assessed by the level of the fundus. During the first 10–12 days postpartum, the uterine fundus descends daily by approximately 1–1.5 cm. On the first postpartum day, the fundus is located at the level of the umbilicus (due to increased tone of the pelvic floor muscles), which is higher than immediately after delivery. On each subsequent day, the level of the fundus decreases by one fingerbreadth. On the second day, the fundus is located 12–15 cm above the pubic symphysis; on the fourth day, 9–11 cm; on the sixth day, 8–10 cm; on the eighth day, 7–8 cm; on the tenth day, 5–6 cm; and by the twelfth to fourteenth day, it lies behind the pubic bone. By the end of the 6th–8th postpartum week, the size of the uterus corresponds to that of a non-pregnant woman (in lactating mothers, it may even be smaller). By the end of the first week, the uterine mass decreases by more than half (to 500–600 g), by the second week to 350 g, by the third week to 200 g, and by the end of the postpartum period to 60–70 g.

Uterine involution depends on the woman's general health, age, parity, and the course of Pregnancy and labor. In cases of Multiple pregnancy, polyhydramnios, macrosomia, and labor dystocia, uterine involution is delayed (subinvolution of the uterus).

The healing of the inner surface of the uterus proceeds in a unique way. Following the detachment of the Placenta and fetal membranes, this surface represents a large wound, particularly in the placental site, because the Superficial layer of the decidua is shed during labor. On the denuded uterine wall, only the basal layer of the endometrial Epithelial Tissue and remnants of the deep glandular layer of the decidua can be detected. A large number of small cells appearing among the remnants of the decidual tissue form a layer of granulation tissue—the granulation wall. The latter is rapidly covered by an epithelial layer derived from glandular remnants. The proliferation of the epithelium leads to the regeneration of the wound surface and its transformation into a typical mucous membrane. The wound surface in the area of the placental site is completely covered by a thin layer of mucosal cells by the tenth day of the postpartum period. The restoration of a fully functional endometrium is completed only eight weeks after childbirth.

Lochia

During the healing process of the inner surface of the uterus, postpartum discharge appears. Fragments of decidual tissue, remnants of fetal membranes, and blood clots undergo phagocytosis and active proteolysis, forming a wound secretion known as lochia. The Nature of lochia changes in accordance with the cleansing and healing processes of the uterine cavity. In the first 2–3 days postpartum, the lochia is bloody (lochia rubra); starting from the 3rd day, it becomes serosanguineous with a predominance of leukocytes (lochia rubroserosa); and by the 7th–9th postpartum day, it becomes serous (lochia serosa). The total amount of lochia in the first eight days reaches 500–1500 g.

Lochia has a neutral or alkaline reaction and a specific stale odor. From the tenth postpartum day, the lochia acquires a seromucous character (lochia alba). By the 5th–6th week, uterine discharge ceases. Sexual intercourse is permitted no earlier than the eighth week of the postpartum period.

The involution of the cervix lags behind that of the uterine body in terms of intensity. Immediately after childbirth, the cervical canal easily admits a hand. 10–12 hours postpartum, the canal becomes cone-shaped, the internal os admits 2–3 fingers; one day postpartum, due to the contraction of the circular Muscles surrounding the internal os of the cervical canal, the internal os admits two fingers, and the cervical canal assumes a funnel shape. On the third day, the internal os admits only one finger. By the tenth day, the cervical canal is fully formed. The external os closes during the third week of the postpartum period. The cervix acquires a cylindrical shape instead of its pre-labor conical shape, and the external os becomes transversely slit-like.

The ligamentous apparatus, which was in a relaxed state during the first days after delivery, gradually regains its normal tone and by the third week returns to its pre-pregnancy state.

Changes in the Ovaries

The ovaries undergo significant changes in the postpartum period. The regression of the corpus luteum concludes, and follicular maturation begins. In the majority (55–60%) of non-lactating women, menstruation resumes at 6–8 weeks postpartum. In most lactating mothers (80%), menstruation is suppressed for several months or throughout the entire period of breastfeeding.

The first postpartum menstruation is often "anovulatory," meaning that the follicle matures, but ovulation does not occur and a corpus luteum is not formed. The follicle undergoes regression, and at this time, the breakdown and shedding of the uterine mucosa begin, in which proliferation processes have occurred (under METABOLISM/18.html">The Influence of estrogenic Hormones), but secretory transformation of the endometrium has not taken place. Over time, the ovulation process, and consequently menstrual function, is fully restored.