This is very important to know if you do OB anesthesia.
Ultrasound in Obstetrics & Gynecology
Author: D. Jurkovic MD
Cesarean scar pregnancy is still considered a novel clinical entity, although the first reports describing its clinical presentation appeared nearly a quarter of a century ago1. It was recognized from the outset that Cesarean scar pregnancy could be a challenging condition to manage, with the potential to cause serious harm to maternal health2. Due to their relative rarity, Cesarean scar pregnancies have proved difficult to study and there is still a lack of agreement regarding the most appropriate diagnostic criteria and optimal strategies to treat this condition3. Furthermore, we know very little about the prevalence of scar pregnancies and their natural history. There is continuing debate as to whether Cesarean scar pregnancy should be classified as a form of ectopic pregnancy, and the most authoritative audit of maternal mortality in the UK does not even recognize it as a separate clinical entity4.
In symptomatic women with an early Cesarean scar pregnancy, decisions regarding initiation of treatment are relatively simple, as they are driven by the patient’s pressing clinical needs5, 6. However, with better awareness of this condition and the liberal use of transvaginal scanning in early pregnancy, the diagnosis of Cesarean scar pregnancy is being made increasingly in asymptomatic or minimally symptomatic women with wanted live pregnancies attending for first‐trimester dating or reassurance scans; in these women, decisions regarding management are much harder to make. A small number of cases reported in the literature indicate that early scar pregnancies may develop into placenta previa/accreta, with potentially serious adverse effects on maternal health3, 7–9. Although the evidence supporting early intervention in these cases is not very strong, the fear of serious complications and medicolegal concerns often tip the balance towards termination of pregnancy.
The paper by Timor‐Tritsch and colleagues10 in this issue of the Journal will therefore be welcomed by all of those involved in early pregnancy care. These authors provide evidence that the histological appearance of first‐trimester scar pregnancy resembles that of abnormally adherent placenta in the second trimester of pregnancy. This supports the long‐held view that scar pregnancy may indeed be a precursor of placenta previa/accreta.
Is this evidence sufficiently strong to conclude that all women diagnosed with live first‐trimester scar pregnancy should be offered termination? Sceptics among us will point out that the study may have been affected by publication bias, as only the most severe forms of the condition, resulting in massive bleeding and hysterectomy, were included. Some would also argue that the study may suffer from verification bias, as only cases with suspected abnormally adhered placenta were included. Although every single case of ongoing scar pregnancy described by Timor‐Tritsch et al.10 eventually required major surgery or life‐saving hysterectomy, there is a possibility that cases with a better outcome remained undiagnosed or unreported and were therefore not included. Only recently, I came across a woman in my own unit who was diagnosed with a first‐trimester scar pregnancy, declined the offer of termination and ended up having an uneventful pregnancy and uncomplicated delivery by Cesarean section. Many women diagnosed with scar pregnancy, however, have young families and the prospect of prolonged hospitalization and the risks associated with advanced scar pregnancy are often unacceptable to them. Elective surgical or medical termination of first‐trimester scar pregnancy is relatively straightforward, with a low risk of significant maternal morbidity and hysterectomy11, 12. Furthermore, the majority of women are able to conceive without difficulty following successful treatment of scar pregnancy and the risk of recurrence appears to be low13. All these factors favor active intervention. On the other hand, there will always be women who will refuse termination of pregnancy on moral or religious grounds, as well as those who will put the wellbeing of their unborn child ahead of their own and that of their family. Whatever a woman’s preference may be, there are simply insufficient data currently available to allow her to make a truly informed choice.
The spectrum of possible adverse outcomes of first‐trimester scar pregnancy ranges from early pregnancy failure followed by spontaneous resolution to second‐trimester loss complicated by severe bleeding and hysterectomy. The main difficulty in counseling women diagnosed with asymptomatic scar pregnancy is our lack of understanding of the natural history of the condition and our inability to predict the likelihood of different outcomes. In cases with early oligohydramnios, bradycardia and early intrauterine growth restriction, however, the likelihood of early pregnancy failure is high, and in these women intervention may be delayed for a week or two in an attempt to spare them from making difficult decisions regarding whether to terminate a live pregnancy. In women in whom the pregnancy is likely to progress beyond the first trimester we are still unable to answer several key questions. Is the pregnancy likely to progress beyond the second trimester, when the baby would have a chance of survival? What is the risk of uterine rupture? Will hysterectomy definitely be required? What is the risk of the placenta invading the bladder and other pelvic organs? We can only obtain answers to these questions by studying the natural history of a large number of scar pregnancies in women who opt for expectant management. Bearing in mind the rarity of the condition and medicolegal concerns, it is very unlikely that a single unit, however large it may be, would be able to collect sufficient data for meaningful conclusions to be reached.
In an attempt to overcome these problems, a nationwide audit of scar pregnancies has been set up in the UK (http://www.birmingham.ac.uk/research/activity/mds/projects/ukepss/index.aspx). The majority of early pregnancy care in the UK is provided by staff in over 200 Early Pregnancy Units, all of which have been invited to join this project (http://www.earlypregnancy.org.uk/index.asp). The aims of the audit are to compare the efficacy of different management strategies for the treatment of first‐trimester scar pregnancy and to obtain data regarding the natural history of those which progress beyond 14 weeks’ gestation. The audit should also provide valuable information about the management of delivery in women with advanced scar pregnancy complicated by placenta previa/accreta and give some insight into the efficacy of novel treatment options, such as uterine artery embolization.
In order to ensure consistency of inclusion criteria, all participants in the audit have been provided with a detailed description of the diagnostic criteria and access to expert help in cases in which there is diagnostic uncertainty. This should also help to avoid false‐positive diagnosis of scar pregnancy in women with a normal pregnancy located low in the uterine cavity and those presenting in the cervical phase of miscarriage. There are approximately 800 000 maternities per year in the UK3. Bearing in mind the reported prevalence of scar pregnancy of approximately 0.5/1000 pregnancies4, 5, we can expect around 400 cases of scar pregnancy to occur in the UK each year. As the audit is unlikely to capture all cases and since only a minority of those included are likely be managed expectantly beyond the first trimester, it will probably be several years before we have collected sufficient information about the natural history of scar pregnancy. Inviting other countries to take part in the audit may be necessary in order to facilitate faster data collection.
Until more data are available, each woman diagnosed with live Cesarean scar pregnancy should be managed individually. She should be offered extensive counseling about potential clinical outcomes and a clear choice between expectant management and termination of pregnancy. She should also be informed about the uncertainties regarding the clinical significance and optimal management of this condition. The decision to terminate a wanted pregnancy is always very difficult and it should only be made with the full involvement of the pregnant woman, her family and other health professionals with expertise in providing antenatal care.
- 1Rempen A, Albert P. Diagnosis and therapy of early pregnancy implanted in the scar of caesarean Section. Z Geburtsh u Perinat 1990; 194: 46–48.
- 2Valley MT, Pierce JG, Daniel TB, Kaunitz AM. Cesarean scar pregnancy: Imaging and treatment with conservative surgery. Obstet Gynecol 1998; 91: 838–840.
- 3Timor‐Tritsch I, Monteagudo A. Unforeseen consequences of the increasing rate of cesarean deliveries: early placenta accreta and cesarean scar pregnancy. A review. Am J Obstet Gynecol 2012; 207: 14–29.
- 4O’Herlihy C. Deaths in early pregnancy. Saving mothers’ lives. Reviewing maternal deaths to make motherhood safer: 2006–2008 Report of the confidential enquiries into maternal deaths in the United Kingdom. BJOG 2011; 118 (Suppl 1): 83–87.
- 5Jurkovic D, Hillaby K, Woelfer B, Lawrence A, Salim R, Elson C. First‐ trimester diagnosis and management of pregnancies implanted into the lower uterine segment Cesarean section scar. Ultrasound Obstet Gynecol 2003; 21: 220–227.
- 6Seow K, Huang L, Lin Y, Yan‐Sheng Lin M, Tsai Y. Cesarean scar pregnancy: issues in management. Ultrasound Obstet Gynecol 2004; 23: 247–253.
- 7Herman A, Weinraub Z, Avrech O, Maymon R, Ron‐El R, Bukovsky Y. Follow up and outcome of isthmic pregnancy located in a previous caesarean section scar. Br J Obstet Gynaecol 1995; 102; 839–841.
- 8Ben‐Nagi J, Ofili‐Yebovi D, Marsh M, Jurkovic D. First‐trimester cesarean scar pregnancy evolving into placenta previa/accreta at term. J Ultrasound Med 2005; 24: 1569–1573.
- 9El‐Matary A, Akinlade R, Jolaoso A. Caesarean scar pregnancy with expectant management to full term. J Obstet Gynaecol 2007; 6: 624–625.
- 10Timor‐Tritsch IE, Monteagudo A, Cali G, Palacios‐Jaraquemada J, Maymon R, Arslan AA, Patil N, Popiolek D, Mittal KR. Cesarean scar pregnancy and early placenta accreta share common histology. Ultrasound Obstet Gynecol 2014; 43: 383–395.
- 11Jurkovic D, Ben‐Nagi J, Ofilli‐Yebovi D, Sawyer E, Helmy S, Yazbek J. The efficacy of Shirodkar cervical suture in securing hemostasis following surgical evacuation of Cesarean scar ectopic pregnancy. Ultrasound Obstet Gynecol 2007; 30: 95–100.
- 12Timor‐Tritsch I, Monteagudo A, Santos R, Tsymbal T, Pineda G, Arslan A. The diagnosis, treatment and follow up of cesarean scar pregnancy. Am J Obstet Gynecol2012; 207: 1–13.
- 13Ben‐Nagi J, Helmy S, Ofili‐Yebovi D, Yazbek J, Sawyer E, Jurkovic D. Reproductive outcomes of women with a previous history of Caesarean scar ectopic pregnancies. Hum Reprod 2007; 22: 2012–2015.