The Ultrasound Report
There is a pro forma developed by Delphi Consensus available which recommends the signs which should be reported. However, this needs to be drawn together by the sonographer into a useful interpretation of these signs.
Writing a useful ultrasound report
It is vital that the ultrasound report does not just try to second guess the histopathological findings (accreta/increta/percreta) or give a vague report such as "probably PAS". To be truly useful it should describe the clinical features the sonographer anticipates the surgeons will find at laparotomy.
Important PAS features the report should comment on
There should be a standard report including position of the placenta and fetal information including growth and presentation. Other features important to report on include:
1) Myometrial thickness
It is vital that the thickness of the myometrium is recorded as this may help differentiate between abnormally adherent and abnormally invasive placenta. It can also guide management particularly with regard to whether an extirpative approach would be appropriate in case of abnormally adherent placenta (accreta) and how successful tamponade and uterotonics might be if manual removal of placental is attempted.
It is vital the surgeons are aware of the degree of difficulty they will encounter when trying to reflect the bladder off the front of the uterus to facilitate hysterectomy. This make help to guide the management discussion with the patient (hysterectomy Vs intentional placental retention) and may guide the surgeons surgical plan. It is a potential marker for the cases that have the potential for massive blood loss compared to those that may be less difficult. It is also anecdotally correlated to how friable the tissues will be - the more neovascularity the more delicate the tissues tend to be.
3) Vascularity of the cervix/vagina
Commenting on the vascularity seen around the cervix and the upper 3rd of the vagina is vital for predicting how bloody the colpotomy will be. This can be a very challenging part of a caesarean hysterectomy as deep infiltration of placental tissue into the cervix or large vaginal varicosities can be the cause of significant bleeding at colpotomy and this can be very challenging if the woman has already lost blood. If it is known in advance that the colpotomy will be bloody it would be wise to ensure the woman is as stable as possible (eg any cell salvaged blood has been processed and given back to the woman) before colpotomy is performed.
4) Relationship to other structures
It is vital to know what other structures are involved (eg bulging into the broad ligament) or if the bulge of placenta is close to structures such as the uterine artery, ureters. This may guide the surgical management for example if we see the placental bulge is very close to the uterine artery we clip this artery at source rather than rely on taking a pedicle.
Any suspicion of parametrial involvement should be taken very seriously by the operating team and may prompt further investigations (second opinion USS or MRI) before delivery.