January 23, 2014

Puerperium period (Involution of uterus)

Puerperium is the period following childbirth during which the body tissues,
specially the pelvic organs revert back approximately to the pre-pregnant state
both anatomically and physiologically.

Duration -
Puerperium begins as soon as the placenta is expelled and lasts for approximately
6 weeks when the uterus becomes regressed almost to the non-pregnant size.
The period is arbitrarily divided into -
a) Immediate - within 48 hours
b) Early - upto 7 days
c) Remote - upto 6 weeks.

Involution of the uterus - 

Anatomical consideration - 
Uterus -
Immediately following delivery, the uterus becomes firm and retracted with
alternative hardening and softening. The uterus measures about 20*12*7.5 cm
(length, breadth & thickness) and weight about 1000 gm. At the end of 6 weeks,
its measurement is almost similar to that of the non-pregnant state and weight
about 60 gm.

Lower uterine segment -
Immediately following delivery, the lower segment becomes a thin, flabby,
collapsed structure. It takes a few weeks to revert back to the normal shape
and size of the uterus, that is the part between the body of the uterus and
internal opening (os) of the cervix.

Cervix - 
The cervix contracts slowly; the external os admits two fingers for a few days
but by the end of first week, narrow down to admit the tip of finger only.

Physiological consideration - 
The physiological process of involution is most marked in the body of the uterus.
Changes occur in following component -
a) Muscles
b) Blood vessel
c) Endometrium.

Muscles -
There is marked hypertrophy and hyperplasia of muscle fibers during pregnancy
and the individual muscle fiber enlarges to the extent of 10 times in length and
5 times in breadth. During puerperium, the number of muscle fibers is not
decreased but there is number of muscle fibers is not decreased but there is
substantial reduction of the myometrial call size.

Blood vessels -
The changes of the blood vessels are pronounced at the placental site. The arteries
are constricted by contraction of its way and thickening of the intima followed by
thrombosis. New blood vessels grow inside the thrombi.

Endometrium -
Following delivery, the major part of the decidua is cast off with the expulsion of
the placenta and the membranes, more at the placental site. The endometrium left
behind varies in thickness from 2-5 mm. The superficial part containing the
degenerated decidua, blood cells and bits of fetal membranes becomes necrotic
and is cast off in lochia. Regeneration occurs from the epithelium of the uterine
gland mouths and interglandular stromal cells. Regeneration of the epithelium is
completed by 10th day and the entire endometrium is restored by the day 16,
except the placental site it takes about 6 weeks.

Clinical assessment of involution -
The rate of involution of the uterus can be assessed clinically by noting the height
of the fundus of the uterus in relation to the symphysis pubis. The measurement
should be taken carefully at fixed time every day, preferably by the same observer.
Bladder must be emptied beforehand and preferably the bowel too, as the full
bladder and the loaded bowel may raise the level of the fundus of the uterus.
The uterus is to be centralised and with a measuring tape, the fundal height is
measured above the symphysis pubis. Following delivery, the fundus lies about
13.5 cm above the symphysis pubis. During the first 24 hour, the level remains
constant, thereafter there is a steady decrease in height by 1.25 cm in 24 hours,
so that by the end of second week the uterus becomes a pelvic organ.

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