Postpartum Period or Puerperium
Postpartum period or puerperium is defined as the period in which the gravid uterus after the expulsion of foetus and foetal membrane returns to its normal non pregnant state.
Postpartum period or puerperium consists of:
- Uterine involution or regression of endometrium
- Restoration of endometrium or regression of endometrium
- Resumption of ovarian activity
- Elimination of bacterial contamination
1. Uterine Involution or Regression of Endometrium
Uterine involution or regression of endometrium is defined as reduction in the size and weight of the uterus following parturition.
Following the expulsion of the fetal membranes in the cow, the uterine contractions and peristalsis continue as strong rhythmical waves that gradually diminish through the fourth day.
The uterine muscle cell length is shortened from 750µm to 400µm one day latter. From 4th to 8th day there are only irregular undulations of the horn and muscle cell will reach 200µm length. It is indicated that the involution of uterus is rapid upto 4 days after parturition and then the rate of involution is slow between 4 and 9 days and after that rapid involution will occur between 10 and 14 days, after 14th day involution continues in slower rates.
The entire uterine contour may be palpable per rectum on 8th day of parturition in primiparous cows and in pluriparous cows on 10th day.
Weight of the uterus at the time of parturition is about 10kg; on day 6, 12, 25 and 50 are 5, 2, 1 and 0.5kg, respectively. Within 12-24 hours to 48 hours, the cervix will be closed and it is impossible to insert one hand into the cervix.
By 96 hours it will be reduced to 2 fingers. Uterine involution is completed by 26-52 days following parturition.
In retained placenta and infection, the uterine involution is delayed. The rate of involution between gravid and non-gravid horn varies depends upon the level of placental attachment in the non-gravid horn.
In the case of peri and post parturient complications and any metabolic diseases, the rate of uterine involution will be delayed.
2. Restoration of Endometrium
The maternal placenta involutes by the necrosis of the caruncular stalk and dissolution of the caruncle. Necrosis occurs, mainly due to vasoconstriction and leukocytic infiltration and dissolution occurs due to fatty infiltration, solution, sloughing and detachment of the entire superficial layer of the caruncle that became part of the uterine lochia.
The necrosis of the caruncle and its stalk is completed by 5th day postpartum. This dissolution and sloughing of caruncle are completed by 12th day post–partum, leaving a raw surface with protruding blood vessels where the stalk was attached.
The caruncles are returned to nearly their original size by the second or 3rd weak and about 25-30 days postpartum, epithelium covers the caruncle and repair is complete. Thus a 70 gm, caruncle by 48 hours after birth is reduced in size and weight to 26 gms and is quite small 5 days later.
Lochia
Usually lochia is a term used in human beings. The postpartum uterine discharge in farm animals is called secundus (or) second cleansing.
The lochia in the bovine uterus, the first 48 hours, after post partum is very high, about 1400–1600 ml, 8th day post partum decreased to 500 ml and 14 to 18th day – only few ml. Lochia or secundus consist of mucous, detritus, tissues, blood/blood clots and caruncular tissues.
Lochia is commenced about 3 to 4 days postpartum and increased until the ninth day. After the 9th to 12th day postpartum there is an increased amount of blood mixed with lochia, this is apparently originated from the surface of the caruncles and usually ceased about the 12th day.
Lochia is serosanguineous, mucosanguineous and mucoid in nature. The normal lochia will have pleasant odour and the abnormal odour of lochia indicates infection.
3. Resumption of Ovarian Activity or Cyclicity
Due to the prolonged block of progesterone, the pituitary is refractory to the GnRH stimuli (not responded), but it eventually recovers with time.
The observation of first heat after parturition is not an indication of true onset of cyclicity, because the cyclicity would have started few days earlier.
Usually onset of oestrus is observed between 33 to 90 days postpartum. Onset of estrus in buffaloes takes about 4-6 months. Onset of postpartum oestrus may be delayed due to suckling, high yielding, nutritive imbalance etc.
4. Elimination of Bacterial Contamination
During and after parturition chances for entering of microbes into the uterus will be more. These organisms are eliminated by phagocytosis by leucocytes. Hyperleucocytosis is found only during the first 2 to 3 days postpartum.
Lymphocytes are extremely numerous in the endometrium of infected uteri and also moderate in most bacteriologically sterile uteri. These infections in cows result in lochia assuming a white, yellow-white or grey mucopurulent character toward the latter part of puerperal period.
Accessory mechanisms involved in elimination of organisms are uterine contractions, uterine secretions and sloughing of the caruncles. If the onset of ovarian activity is delayed, the elimination of organisms from the uterus will be delayed.
