Placenta Accreta Risk after Myomectomy

Explanation

Placenta accreta spectrum arises when the decidua basalis is deficient at the implantation site, allowing trophoblast to invade the myometrium, so any procedure that breaches or scars the endometrium raises the risk. Prior cesarean delivery, especially with a placenta previa overlying the scar, is the commonest antecedent, but non-cesarean uterine surgery matters as well: a 2025 systematic review and meta-analysis found a pooled odds ratio of 2.29 for placenta accreta spectrum after any prior myomectomy, and one included study reported an odds ratio of 5.1 when the uterine cavity was breached during laparoscopic myomectomy. This woman has documented entry into the endometrial cavity, so her risk is substantially increased even though she has never had a cesarean delivery or curettage. A nationwide cohort of more than 1.3 million pregnancies similarly found accreta spectrum in 0.96 percent of women with prior myomectomy versus 0.20 percent without, and the risk rises much further when placenta previa coexists. Fibroid location modifies but does not abolish this risk: submucosal and hysteroscopically resected fibroids carry the highest odds, whereas purely subserosal excision without cavity entry is the least damaging, which is why the operative report and not the patient recollection should guide counselling. She should also be counselled about uterine rupture in labour and intrauterine adhesions, and many surgeons advise planned cesarean delivery after cavity entry. In a future pregnancy she needs ultrasound assessment of placental location with targeted evaluation for accreta markers such as loss of the clear zone, placental lacunae, bladder wall interruption and abnormal vascularity. If accreta spectrum is suspected, delivery should be planned at a centre with the surgical, blood bank and critical care resources to manage it.

Why each option

A.

Correct. Documented breach of the endometrial cavity at myomectomy leaves implantation site scarring and raises accreta spectrum risk several fold.

B.

No uterine operation reduces the risk of abnormal placental adherence, and cavity entry moves the risk in the opposite direction.

C.

Unchanged risk would apply only to superficial subserosal excision without cavity entry, which is not what her operative note describes.

D.

The risk is quantifiable from published cohorts and meta-analyses of prior myomectomy, so declining to estimate is not appropriate.

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