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Puerperium - Anatomy & Physiology (view source)

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==Introduction==
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* Immediately following parturition, the female enters a period of reproductive repair called the '''puerperium''' and begins lactation.  For a period of time these two processes overlap.   
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|linkpage =Reproductive System - Anatomy & Physiology
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|linktext =Reproductive System
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|maplink = Reproductive System (Content Map) - Anatomy & Physiology
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|sublink1=Reproductive System - Anatomy & Physiology#The Puerperium
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|subtext1=PUERPERIUM
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* Immediately following parturition, the female enters a period of reproductive repair called the '''Puerperium''' and begins lactation.  For a period of time these two processes overlap.   
   
* During the puerperium '''uterine involution''' and return to ovarian function occurs.
 
* During the puerperium '''uterine involution''' and return to ovarian function occurs.
 
** '''Involution''' is the reduction in size and remodelling of the endometrium so that the uterus can initiate and sustain another pregnancy.
 
** '''Involution''' is the reduction in size and remodelling of the endometrium so that the uterus can initiate and sustain another pregnancy.
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* The time required for complete uterine involution and [[Female_Reproductive_Tract_-Oestrous_Cycle_-_Anatomy_%26_Physiology|ovarian activity]] to resume varies among species.
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* The time required for complete uterine involution and [[Oestrous Cycle - Anatomy & Physiology|ovarian activity]] to resume varies among species.
 
* In many polyoestrous animals, the shortest possible puerperium is desirable because eligibility for a subsequent pregnancy is of high economic importance.
 
* In many polyoestrous animals, the shortest possible puerperium is desirable because eligibility for a subsequent pregnancy is of high economic importance.
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== Myometrial Contraction and Expulsion of Lochia ==
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* Myometrium undergoes strong, repeated contractions.
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* The purpose of these contractions is:
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** Facilitate discharge of fluids and tissue debris from the [[Uterus - Anatomy & Physiology|uterus]].
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** Compress the uterine vasculature and help minimize possibility of haemorrhage.
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** Reduce the overall size of the [[Uterus - Anatomy & Physiology|uterus]].
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* In most species, frequent post-partum suckling occurs and [[Pituitary_Gland_- Anatomy & Physiology#Oxytocin|oxytocin]] is secreted. 
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* In suckled animals, uterine contractions occur on a frequent basis.
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** In dairy cows, the calf is usually removed 24 hours after parturition and milking takes place only 2-3 times a day.
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*** Oxytocin episodes are reduced.
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*** Myometrial contractions not as frequent
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*** Delayed uterine involution
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*** Delayed uterine involution limits fertility.
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=== Reduction in Uterine Volume ===
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* Immediately after parturition, the uterus undergoes rapid but highly coordinated atrophy.
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* Uterine mass rapidly reduced to non-pregnant size.
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* All species: marked size reduction in the first several days after parturition.
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* Most species: myometrial contractions occur in 3-4 minute intervals for the first several postpartum days.
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* Strong myometrial contractions subside within several days.
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=== Lochia ===
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* Shortly after parturition, a discharge called '''lochia''' is expelled from the vulva.
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** Lochia is a blood- tinged fluid containing '''remnants of the foetal placenta and endometrial tissue'''.
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* Lochial discharge is normal in all species.
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** In dairy cows, lochial discharge occurs at day 2-9 postpartum.
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*** Increase in blood and tissue debris in the lochia is normal, occurs day 5-10.
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**** Due to sloughing of caruncular surfaces that leaves vascular 'stubs' that leak blood.
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* Reduction of lochia in the uterus with myometrial contractions occuring for the first 7-10 days.
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** In dairy cows, up to 2000ml is expelled from the uterus in the first 2-3 days after parturition.
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*** By 14-18 days, locial discharge is almost non-existent in most cows.
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==Endometrial Repair==
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=== Vasoconstriction ===
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* After separation of foetal '''cotyledons''' from maternal '''caruncles''' (within 8-12 hours of delivery of the neonate) vasoconstriction occurs at the base of the maternal caruncle.
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=== Necrosis ===
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* Irreversible cell death that leads to sloughing of the caruncular mass leaving necrotic tissue in the lochial fluid inside the [[Uterus - Anatomy & Physiology|uterus]].
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* Some blood is released from the caruncular stalk generating a blood-tinged fluid.
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=== Sloughing ===
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* About 5 days after parturition.
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* Caruncles lose cellular organization and integrity.
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* Chunks of the caruncles detach from the surface.
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* Remnants of blood vessels exposed on the surface.
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=== Repair ===
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* After the decidual tissue of the caruncle has sloughed into the uterine lumen, the caruncle begins to undergo repair.
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* Eventually covered again with endometrial epithelium.
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* At the same time caruncular repair is taking place, the intercaruncular endometrial surfaces undergo repair.
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* Epithelium of the intercaruncular area repairs at a faster rate than the caruncles.
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** Repair of intercaruncular endometrium is usually complete by day 8 post-partum.
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* Delay in caruncular repair compared to intercaruncular epithelium is because a large mass of caruncular tissue must undergo necrosis and sloughing before surface epithelial repair can take place.
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=== Species Differences ===
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* Once again, the most significant example is in the dairy cow. This is the example shown above.  However, there are significant species differences.
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'''''Time Required for Uterine Involution and Resumption of Ovarian Activity in Various Species'''''
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{| style="width:75%; height:200px" border="1"
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!'''Species'''
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!'''Alpaca'''
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!'''Beef Cow'''
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!'''Bitch'''
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!'''Camel'''
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!'''Dairy Cow'''
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!'''Ewe'''
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!'''Llama'''
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!'''Mare'''
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!'''Queen'''
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!'''Sow'''
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|-
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| '''Time Required for Complete Uterine Involution (days)'''
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| 20
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| 30
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| 90
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| 30-50
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| 45-50
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| 30
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| 20
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| 21-28
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| 30
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| 28-30
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|-
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| '''Time Required for Resumption of Ovarian Activity'''
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| 5-10 days
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| 50-60 days (inhibited by lactation)
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| 150 days (long natural postpartum anoestrus)
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| 25-40 days or up to 1 year (inhibited by lactation)
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| 18-25 days
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| 180 days (short day breeder)
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| 5-10 days
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| 5-12 days
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| 30 days
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| 7 days (inhibited by lactation)
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|-
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|}
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==Elimination of Bacterial Contamination of the Reproductive Tract==
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Generally, parturition in domestic animals occurs in a non-sterile environment.  As a result, bacterial contamination of the reproductive tract, especially the [[Uterus - Anatomy & Physiology|uterus]], is an inevitable sequela to parturition.
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* The postpartum tract containing lochia is an ideal environment for the growth of bacteria.
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* Even though myometrial contractions remove the large volume of lochia, bacterial growth can continue.
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* Bacterial contamination is not always associated with pathology.
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* Normal post-partum events eliminate the bacterial flora within a reasonable time.
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* Elevated oestrodiol promotes leukosis in the uterus and elsewhere in the tract.
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* In some cases, high numbers of bacteria can overwhelm the natural defence mechanisms, resulting in [[Healing and Repair - Pathology#Female|postpartum uterine infection]].
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* Conditions that predispose the uterus to infection are:
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** Retained foetal membranes
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** [[Dystocia]]
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** Delay in lochial expulsion due to weak myometrial contractions.
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==Factors Influencing the Puerperium==
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=== Uterine Involution ===
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==== Age ====
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* More rapid in primiparia than pleuriparia
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==== Season ====
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* More rapid in spring and summer months.
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==== Suckling vs Milking ====
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* Results are contradictory
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* May be a breed influence on the time taken to return to ovarian cyclicity
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==== Climate ====
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* Heat stress can accelerate and inhibit the speed of involution.
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==== Periparturient Abnormalities ====
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* Dystocia, retained placenta, hypocalcaemia, ketosis, twin calves and metritis delay involution.
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* Periparturient problems cause a delay of the process of involution by ~5-8 days.
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==== Delayed Return to Ovarian Cyclicity ====
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* Inhibits involution
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=== Restoration of the Endometrium ===
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* Retained foetal membranes and metritis inhibit healing.
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* Return to ovarian cyclicity may have an influence.
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=== Return to Ovarian Cyclicity ===
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This can be affected by; periparturient abnormalities, milk yield, nutrition, breed, parity, season, climate and suckling intensity and milking frequency.
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==Species Differences in the Puerperium==
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===[[Puerperium - Cow|Cow]] ===
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===[[Puerperium - Mare|Mare]] ===
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===[[Puerperium - Sheep and Goat|Ewe & Nanny Goat]] ===
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===[[Puerperium - Sow| Sow]] ===
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===[[Puerperium - Bitch| Bitch]]===
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===[[Puerperium - Cat| Cat ]]===
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[[Category:Pregnancy and Parturition]]
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[[Category:Bullet Points]]
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