The 1st trimester ultrasound; What have we learned?

GLYNIS SACKS M.D VANDERBILT CENTER FOR WOMEN’S IMAGING TRS February 2020

 I have no conflicts of interest Introduction

 Cesarean section predisposes to scar as well as placenta accreta spectrum

 Not two separate entities but the consequence of a single abnormality.

 Left untreated, scar pregnancies may transform into placenta increta or percreta C-section scar

 Uncommon but increasing in frequency and potentially devastating

 Thought to occur when the blastocyst implants on fibrous scar tissue within the wedge-shaped myometrial defect in the anterior lower uterine segment at the site of a prior C-section scar

 Fibrosis after multiple C-sections may decrease vascularity which limits healing. Multiple previous C-section deliveries also increase the risk of scar implantation because of the larger scar surface area

 Incidence increasing with a resultant increase in placenta accreta, and massive hemorrhage C-section scar pregnancy

 Call be classified into different subtypes depending on:

 Gestational age at diagnosis

 Presence or absence of cardiac activity

 Myometrial thickness of lower uterine segment

 Appearance of the uterine-bladder interface

 Reliable diagnostic criteria for timely diagnosis are necessary given the potential for serious complications. Placenta Accreta Spectrum

 May result from defective development of the decidua basalis allowing the trophoblastic tissue to invade the myometrium

 Defect of the endometrial-myometrial interface leads to failure of normal decidualization in the area of the scar

 Allows abnormally deep placental anchoring villi

 Cesarean scar pregnancy is a precursor to PAS

 Counselling is challenging

 Identify those cases amenable to successful pregnancy outcome

 Postnatal treatment Terminology

 Placenta Accreta

 Vera

 Increta

 percreta  Morbidly Adherent Placenta  Placenta Accreta Spectrum Placenta Accreta Spectrum

 Significant cause of maternal morbidity & mortality  Risk factors  Previous C-section  Placenta previa  IVF-ET Placenta Accreta Spectrum

Courtesy of Phillipe Jeanty Why are we concerned?

 Placenta accreta spectrum poses a significant risk to the pregnant patient

 Incidence is increasing from 1:2500 – 1:533 pregnancies  40-60% of cases are only diagnosed at the time of delivery  71% of patients require a hysterectomy  25% of patients lose more than 5 liters of blood  Mortality rate of cesarean hysterectomy is 10% in patients with a placenta percreta Placenta Accreta Spectrum

 Outcomes are optimized when deliveries are performed at Level 3 or 4 maternal care facilities

 Before the onset of labor ~34-36 weeks

 Cesarean hysterectomy with the placenta left in –situ

 Comprehensive multidisciplinary team

 Gynecologic oncologist

 Interventional radiologist Placenta Accreta Spectrum

 Does 1st trimester ultrasound have a role in predicting patients at risk for placenta accreta?

 What is the connection with scar pregnancy implantation? 80 No Previa Placenta Previa

70

60

50 Accreta 40

30

20 % Placenta % 10

0 0 1 2 3 4 5 Number of Prior C- Sections 1st trimester findings

 Cesarean scar pregnancy  Not an ectopic as it is within the uterine cavity  Either implants on the scar In the dehiscence (“niche”) at the hysterotomy site C-section scar pregnancy

 May present with pelvic pain & bleeding  ~ 33% of patients are asymptomatic

 Transvaginal ultrasound diagnostic

 Spectrum

 Severe cases with little or no surrounding myometrium with risk of rupture

 Less severe cases evident later with placenta accreta and increased maternal morbidity Scar pregnancy; progression

 Implantation of the trophoblast may occur along the surface of the scar  Followed by growth towards the uterine cavity  Portion of the trophoblast remains anchored  Placenta accreta spectrum in the 3rd trimester

 Deep implantation in the scar  Growth toward the bladder  Minimal or absent myometrium  Increased risk of hemorrhage & uterine rupture 1st trimester significance

 Important to recognize in failed IUP  May result in torrential hemorrhage if D&C is performed blindly

Scar implantation Early Diagnosis

 Can we identify those patients at risk early in pregnancy Counseling Early Referral 1st trimester findings in Accreta

 Implantation on or in the hysterotomy scar  (low & anterior)  Presence of hypoechoic lacunae within the placenta  Thinning of the retroplacental-myometrial zone  Irregular or disrupted bladder interface  Irregular placental-myometrial interface  increased vascularity with “bridging” vessels Placenta Accreta Spectrum

 Following scar implantation, varying degrees of placental invasion may be seen with those pregnancies that develop in the endometrial cavity

 Signs of PAS include

 Focal uterine “bulge”

 Obliteration of normal placental-myometrial interface

 Vascularized lacunae thought to represent areas of hemorrhage or infarction

 Increased flow Early Increta Early Increta

Accreta in the 1st trimester

> 3 lacunae Turbulent flow Location of scar pregnancies

Ilan Timor-Tritsch NYU Scar pregnancy

 “empty” uterine cavity with visualization of the endometrial echo

 Gestational sac in the anterior lower uterine segment

 Thin/absent myometrium between the gestational sac and the bladder wall C-section Scar Pregnancy

Low anterior sac Above the cervix Scar pregnancy

Thin/no myometrium between the placenta & bladder Scar implantation

5 weeks 6 days

Scar implantation

8 weeks 5 days

 Delivered at 31 weeks

 Placenta previa & accreta. Uterine Position

Anteverted-retroflexed Thin or no myometrium between placenta and bladder

C-section scar pregnancy

 Sonography  Detection of placenta and/or gestational sac in hysterotomy scar  Yolk sac &/or embryo with or without cardiac activity  Marked peritrophoblastic color Doppler flow  Thin or absent myometrial layer between sac and bladder  Closed endocervical canal

 Differential diagnosis  Cervical ectopic  in progress  Normal low implantation “in-progress” Cervical ectopic Cervical ectopic

Scar pregnancy

 Low anterior implantation of the gestational sac  Center of the sac in the lower half of the uterus  Not reliable after 9 weeks  Placenta remains in close proximity to the hysterotomy site. Placenta anchored in hysterotomy scar Placenta Increta Scar Pregnancy

Post 1 dose Methtrexate  Turbulent flow  Bridging vessels C-section scar pregnancy

 MRI If ultrasound is equivocal

 Even late detection of placenta accreta allows appropriate surgical planning C-section scar ectopic C-section scar pregnancy

 Optimal management uncertain  uterine rupture or unstable patient = surgery  Avoid D & C (profuse bleeding)  Methotrexate, KCl or hypertonic glucose Local vs systemic  Bilateral uterine artery embolization or intracervical vasopressin  ? Scar revision C-scar pregnancy: management

 Management options are influenced by

 Gestational age at diagnosis

 Severity of abnormal placentation

 Clinical stability

 Desire for future fertility Treatment options

 Systemic Methotrexate

 Relatively low efficacy if beta hCG is > 5000 mIU

 High rates of future pregnancies if successful

 Slow regression of trophoblastic tissue  Local Methotrexate with/without systemic Methotrexate

 If beta hCG > 10,000 mIU  Uterine Artery embolization

 Requires further intervention in > 80% of cases  Hysteroscopy

 Direct visualization & vascular coagulation Treatment Options

 Minimally invasive treatment of scar & cervical pregnancies using a cervical ripening double balloon catheter

 Upper balloon in the uterine cavity serves as an anchor.

 Lower balloon at the level of the gestational sac

 Foley catheter as an adjuvant therapy to prevent or control bleeding after local Methotrexate or KCl injection

 Early expulsion of the balloon Heterotopic Pregnancy

C-section scar ectopic

Normal IUP June 25,2018 July 17,2018 s/p 3 doses Methotrexate

September 6,2018 October 3,2018 Be Aware 31 weeks

Conclusions

 Prevalence of Placenta Accreta Spectrum is increasing

 Patients can be identified in the 1st trimester

 Major risk factors

 Placenta previa

 Previous C-Section

 Imaging findings

 Lacunae

 Abnormal vascularity

 MRI

 Ambiguous findings

 Posterior placenta Conclusions

 Sonographic evaluation

 Can detect 50-80% of cases

 Includes transabdominal & transvaginal evaluation

 Highest resolution transducer possible

 Doppler imperative

 Abnormal Doppler may be due to different levels of expression of vascular endothelial growth factors and their receptors in the abnormally adherent placentas. Conclusions

 Combining ultrasound, Doppler & MRI if necessary allows early recognition of Cesarean scar pregnancies

 Allows effective fertility preserving treatment

 D&C for unrecognized failed scar pregnancies may lead to significant blood loss

 High risk of hysterectomy

 local methotrexate better than systemic methotrexate

 Offers fertility preservation in asymptomatic patients Conclusions

Not all scar pregnancies result in PAS

All cases of PAS began with implantation involving the scar On the scar In the “niche” (worse outcome)

Early identification of patients at risk is essential

All patients with a history of prior C-sections should be scanned at ~ 7 weeks in future pregnancies