Delivery of Placenta
A low lying placenta may be situated within the isthmocele or attached
to the previous scar depending on its level (within or above the
endocervical canal). If the placenta is not adherent, it will separate
spontaneously with or without uterotonics. If it is adherent, manual
removal will be required. Regardless of method of placental delivery,
both leave a non-retractile isthmocele which may be bleeding profusely
from the retracted muscle rings at its boundary and the numerous
bridging vessels lying in the serosa. We recommend a posterior rather
than an anterior starting approach for the manual removal of the
placenta to reduce the risk of bleeding from the aberrant vessels
present anteriorly where the tissue planes are obscured. This has the
added advantages of reducing risk of bladder injury and helping in
identification of the posterior myometrial defect as described in the
original method.
If manual removal is required, we advocate the following steps:
1 . After uterine entry the operator’s right hand is inserted
through the incised isthmocele and directed towards the upper border of
the placental attachment on the posterior uterine wall (Fig. 1) from
where detachment is initiated, working laterally, bilaterally, to expose
the posterior uterine wall defect (Fig. 2).
2. The exposed retracted inferior and superior posterior
muscles are then grasped with Green Armytage clamps (Fig.
3). In some instances, the sheared
posterior defect may be large and the inferior myometrial boundary
difficult to identify. Recognition may be aided by the assistant’s right
hand raising the outer aspect of the uterus below the utero sacral
ligament facilitating application of the Green Armytage clamps to the
lower posterior retracted muscle within.
3. Once the lateral aspects of the placenta are reached the
operator’s left index and middle fingers are inserted into the
endocervical canal to the anterior fornix (Fig. 4) to lift the cervix
(Fig. 5) and allow the retracted anterior inferior muscle edges to be
identified and clamped, before detaching any residual attached placenta.
This muscle ring is normally found at the level of the internal cervical
os and needs to be isolated prior to application of clamps to avoid
damage to the bladder base. Once the anterior ring of inferior muscle
has been caught securely, the bleeding starts to slow and the bladder
can be separated safely from the lower segment of the uterus working
from the lateral aspects medially.
4. The myometrial defect, the boundaries of which are shown in
Figure 6, is then repaired as previously described. (10). Success of
this technique involves correct recognition of the retracted muscles at
the boundary of the myometrial defect and repair of the muscle edges. As
the posterior myometrial defect is closed and the uterine angles are
secured the bleeding slows further allowing completion of the repair.
Any redundant fascia forming the isthmocele, if not already ruptured, is
incorporated into the anterior repair to build up the anterior uterine
wall at the site of the scar and reduce the bleeding from the overlying
aberrant vessels which can be difficult to control.