Novel cross-over sign in cesarean scar pregnancy helps predicts the risk of invasive placentation

power-point slide by ISUOG

First trimester ultrasound scan evaluating the relationship between the gestational sac and the endometrial line in women with cesarean scar pregnancy(CSP) helps predicts the development of abnormally invasive placenta (AIP) and consecutive intra and post-operative surgical morbidities reports the results of a retrospective case series published in Journal of International Society of Ultrasound in Obstetrics and Gynecology.

Recent advances in prenatal imaging and increase rate of cesarean sections have led to increased diagnosis of CSP. Although, most of the patients with CSP present with severe hemorrhage or rupture uterus, that requires emergency surgical management, few advance further, evolving into AIP.

There is no reliable marker that can predict whether a woman with CSP will end up in early abortion or further progress to develop placenta percreta or other less severe forms of AIP.

A novel ultrasound cross-over sign (COS) has recently been thought to predict the evolution of CSP into different forms of AIP so that the intraoperative and postoperative risk can be stratified.

A straight line is drawn from internal cervical os to the fundus of the uterus in sagittal view through the endometrium. The gestational sac is identified, and its superior-inferior diameter measured. The COS is classified according to the relationship of ectopic sac diameter with the endometrial straight line into COS-1 and COS-2.

This case series identified 102 women over a period of 8 years with AIP diagnosis confirmed by histopathological examination (HPE), of whom 68 patients had a first-trimester ultrasound with a diagnosis of CSP. The scans were read by sonographers who did not have any idea about the pregnancy outcome and pathology reports.  

COS sign was assessed as mentioned, and all patients received counseling regarding the prognosis, risk, and post-operative complications. Women with severe AIP were delivered early, as compared to less severe variants.

All women underwent cesarean hysterectomy with temporary occlusion of the internal iliac artery and ureteric stent in place. At HPE, 34 cases were diagnosed with placenta percreta, 13 with placenta increta and 21 with placenta accreta.

Pregnancies with COS-1 had early deliveries, longer operating time, more blood loss and required much more packed red blood cells during surgery mean as compared with those with COS-2+ or COS-2–.

Thus, predicting the likely course CSP diagnosed by COS sign in the first trimester can improve shared decision making between the patient and provider about the surgical difficulties endured, amount of blood loss and need for cesarean hysterectomy.

Large, multi-center studies to determine the role of COS sign in predicting the severity of AIP in CSP is needed in future.

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ACOG updates guidance on postpartum hemorrhage- calls for standard, coordinated, protocol based intervention

The American College of Obstetricians and Gynecologists (ACOG) recently released expanded guidelines for management of postpartum hemorrhage (PPH)—the leading cause of maternal mortality worldwide.

PPH is defined as total blood loss of 1000 ml or more along with signs or symptoms of hypovolemia within 24 hours after the labor, but can occur up to 12 weeks postpartum. Although Maternal Mortality Rates(MMR) have decreased worldwide in last 4 decades, it still accounts for 10% of all pregnancy related mortality.

Incidence varies, but 1-5% is reasonable estimate, with uterine atony accounting for 70-80% of cases PPH.

This practice bulletin discusses the risk factors along with evaluation, prevention, and management of maternal hemorrhage.

It also calls upon all obstetricians and other obstetric care providers to formulate standard protocols for recognizing, evaluating and management of maternal hemorrhage by multidisciplinary approach and implement it in every center.

Multidisciplinary teams, including physicians, nurses and midwives, should be trained to implement key elements in four categories, including readiness to respond; recognition and prevention measures; multidisciplinary response; and data reporting and systematic learning, including drills like simulation-based training.

ACOG also has partnered with multiple organization to implement the care bundle suggested by  Alliance for Innovation on Maternal Health (AIM), which many states have are already adapted.

It also lays emphasis on identifying the patients at risk of developing PPH, prenatally, during admission and during labor. It includes patients with vaginal lacerations, retained placenta, abnormally adherent placenta with previous cesarean section. All Ob-gyn should be aware of high risk of PPH in placenta previa with previous uterine scar.

Uterotonic agents should be the first line of treatment in case of atonic PPH, choice of a specific agent is at the discretion of the provider as none is identified as superior over other. Active management of third stage of labor should be implemented.

All hospitals, especially those in rural areas should be able to escalate the efforts quickly, and have a specific plan to go to next level of treatment or quickly refer patient to a specialty hospital.

Tranexamic acid can be given when primary line of therapy fails, it is especially found effective if given within 3 hours of birth.

Surgical approach includes Intrauterine balloon tamponade, but less invasive methods should always be used first. 

All hospitals should have functioning massive transfusion protocols and ‘hemorrhage carts’, with all the necessary medication in place.

The Practice Bulletin #183, "Postpartum Hemorrhage" is published in October issue of Obstetrics and Gynecology.

ACOG press release

Patient Safety Bundles on obstetric hemorrhage. 

Abnormally invasive placenta---Can we predict and do better?

Clinical Pearls:

• Previous cesarean section or uterine surgery is the single most important predisposing factors for Abnormally Invasive placenta.
• One cesarean section increases the risk of AIP seven fold in subsequent pregnancy.
• History of post-partum hemorrhage is also a risk factor for AIP and increases the risk 6 fold in current pregnancy.
• In 70% of cases, the diagnosis of AIP was missed during antenatal period.
• Increasing clinician awareness for incidence of AIP in the high risk patients leads to increased diagnosis in antenatal period.
• Avoiding unnecessary cesarean section is the only way to decrease the incidence of AIP.  

Lowering the Cesarean section rate in the population is the only most effective way in reducing the incidence of Abnormally invasive placenta(AIP) is the conclusion of a large, population based cohort study from the Nordic countries.

The Nordic Obstetric Surveillance Study (NOSS) required obstetricians’ collaboration in reporting AIP, uterine rupture, excessive blood loss and peripartum hysterectomy from 2009-2012. Due to paucity of cases at a single hospital the data was pooled and validated by National Health Registries. 

The data was analyzed and identified 205 cases of AIP amounting to an incidence of 3.4 per 10,000 deliveries.

The study was published in the current issue of British Journal of Obstetrics and Gynecology(BJOG).[1]

The study goal was to gauge the prevalence, risk prediction, predisposing factors, antenatal suspicion, maternal morbidity and birth complications in cases of AIP.

The study confirmed the association between AIP and previous cesarean section or any other previous uterine surgeries like endometrial ablation, and in vitro fertilization. The risk of AIP in subsequent pregnancy is seven fold with one prior Cesarean section to 56-fold after three or more CS.

Placenta previa was the single most important risk factor identified in nearly half of the pregnancies.

 In addition, patient who had postpartum hemorrhage in previous pregnancy have 6 times the risk of AIP in current pregnancy as compared to patients who did not have PPH.

An antenatal diagnosis of AIP can strikingly reduce the complication rate but in nearly two-third of patients (70%) of patients the diagnosis was missed. Of these, 39% had prior CS and 33% had placenta praevia.

Increased awareness about the risk factors among clinicians can raise the index of suspicion and led to more and more patients being diagnosed in prenatal period. Clinicians performing Ultrasound(USG) should have high index of suspicion in high risk women with previous uterine surgery or a placenta over uterine scar. These women should be offered additional sonography.

Nordic countries have lower rates of AIP than US, perhaps due to lower rate of cesarean section and high order cesarean births or better obstetrics facilities. 

But, the only sure way to decrease the incidence of AIP is to avoid unnecessary cesarean delivery, especially the first cesarean section.

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[1] Thurn L, Lindqvist PG, Jakobsson M, Colmorn LB, Klungsoyr K, Bjarnadóttir RI, Tapper AM, Børdahl PE, Gottvall K, Petersen KB, Krebs L, Gissler M, Langhoff-Roos J, Källen K. Abnormally invasive placenta—prevalence, risk factors and antenatal suspicion: results from a large population-based pregnancy cohort study in the Nordic countries. BJOG 2015; DOI: 10.1111/1471-0528.13547.