Early sonographic signs of placenta accreta spectrum disorder: A pictorial review

Purpose: Placenta accreta spectrum encompasses abnormal placental attachment disorders characterised by progressive invasion into the uterine wall. Its incidence is rising due to increasing caesarean section rates and advanced maternal age, posing significant risks such as haemorrhage, uterine rupture and hysterectomy. Early and accurate diagnosis is critical for optimizing maternal and neonatal outcomes. Findings: Diagnosis of placenta accreta spectrum is possible in early pregnancy using transvaginal ultrasound. Key indicators include caesarean scar pregnancy, anterior myometrial thinning, placental lacunae, loss of the clear zone, bladder wall interruption and uterovesical hypervascularity. These findings facilitate early counselling and tailored management to mitigate emergency surgical complications. Evaluating the gestational sac's relationship with the endometrial cavity in early pregnancy is essential in predicting pregnancy progression and associated risks, including uterine rupture or the need for caesarean hysterectomy. When transvaginal ultrasound provides limited views, transabdominal ultrasound may offer superior views to understand the relationship between the gestational sac and the endometrial cavity. Serial ultrasound monitoring is recommended in women with risk factors, particularly if they are symptomatic, to track pregnancy progression accurately. Conclusion: This pictorial review consolidates early gestational imaging findings to enhance diagnostic precision. It highlights standardised ultrasound criteria proposed by international consensus groups and explores magnetic resonance imaging as an adjunctive tool for cases with inconclusive ultrasound findings. By providing a comprehensive visual guide, this review aims to improve early detection, refine surgical planning and enhance maternal outcomes in placenta accreta spectrum management.