Original Research|Articles in Press, 100924

Focal-occult placenta accreta: A clandestine source of maternal morbidity



      : Focal-occult placenta accreta spectrum (PAS) is known to lead to adverse obstetric morbidity outcomes, however direct comparisons with previa-associated PAS morbidity are lacking.


      : We sought to compare baseline characteristics, surgical and obstetric morbidity, and subsequent pregnancy outcomes of patients with focal occult PAS compared to patients with previa associated accreta.

      Study Design

      : A retrospective review was conducted of all pathologically confirmed PAS from 2018-2022 at a tertiary care center. Baseline characteristics, surgical, obstetric, and subsequent pregnancy outcomes were recorded. Focal-occult PAS was compared with previa-associated PAS across a range of morbidity characteristics including hemorrhagic factors, interventions, post-delivery re-operations, infections, and ICU admission. Statistical comparison was performed using Kruskal-Wallis/Chi-Square tests, and p <0.05 was considered significant.


      : 74 cases were identified; 43 focal-occult and 31 previa-associated PAS. 25.6% focal-occult vs 100% previa-associated PAS underwent hysterectomy. 1 focal-occult and 29 previa-associated PAS were diagnosed antenatally. Patients with focal-occult PAS did not differ from previa-associated PAS in mean maternal age (33.0 vs 33.1 years), BMI (Body Mass Index), or presence of previous dilation & curettage procedure (16.3% vs 25.8%) when compared to previa-associated PAS. Focal-occult PAS patients were significantly more likely to have a lower mean parity (1.5 vs 3.6 gestations), higher gestational age at delivery (36.1 vs 33.9 weeks), were less likely to have had a previous cesarean (12/43, 27.9% vs 30/31, 96.8%). Additionally, focal-occult PAS patients had fewer number of previous cesareans (mean 0.5 vs 2.3), were more likely to have had in-vitro fertilization (IVF) (20.9% vs 3.2%) and less likely to have anterior placentation. When contrasting clinical outcomes of focal-occult to previa-associated PAS, postpartum hemorrhage rates (71.0% vs 67.4%), mean quantitative blood loss 2099 mL (range 500-9516mL) vs 2119 mL (range 350-12,220 mL), mean units red blood cells transfused (1.4 vs 1.7), massive transfusion rate (9.3% vs 3.2%), ICU admission (11.6% vs 6.5%), were not significantly different, with a non-significant trend towards higher morbidity in focal-occult accreta patients. Focal occult accreta had higher incidence of reoperation/return to the OR (30.2 vs 6.5%, p=0.01). When comparing focal-occult to previa-associated PAS, the composite outcomes, including hemorrhagic morbidity (77.4% vs 74.4%), any maternal morbidity (83.9% vs 76.7%) and severe maternal morbidity (64.5% vs 65.1%) were not significantly different between groups. Nine focal-occult PAS patients had a subsequent pregnancy, and three of those had recurrent PAS.


      : Focal-occult PAS presents with fewer identifiable risk factors than placenta previa-associated PAS but may be associated with IVF pregnancy. Focal-occult PAS was observed to have higher incidence of reoperation when compared to previa-associated PAS, and no other statistically significant differences in morbidity outcomes were observed. The absence of different morbidity outcomes may be attributable to a lack of antenatal detection of focal occult accreta, and merits further investigation.


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