Society for Maternal-Fetal Medicine (SMFM)

Created in partnership with the Society for Maternal-Fetal Medicine, SMFM was established in 1977 to “give Maternal-Fetal Medicine (MFM) physicians and scientists a place to share knowledge, research and clinical best practices in order to improve care fo

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Since the 1900s, based on the belief that activity restriction results in uterine quiescence and increased blood flow to the uterus, obstetrical care providers have recommended activity restriction to prevent preterm birth (PTB), and it remains a common intervention for PTB prevention in multiple clinical settings (Table 1). 

Restriction of activity is also used in management of pregnancy complications such as preterm premature rupture of membranes (PPROM), gestational hypertension, preeclampsia, fetal growth restriction (FGR), placenta previa, threatened miscarriage, and complications of multiple gestations. Activity restriction has been prescribed in nearly 20% of all pregnancies at risk for PTB.

Survey data from 2009 demonstrated that over 80% of maternal-fetal medicine subspecialists recommended activity restriction in women with cervical dilation, threatened preterm labor, and PPROM.

A growing body of literature suggests that activity restriction fails to provide benefit, and in fact, confers significant physical and psychosocial risks for pregnant women, including deconditioning, inadequate maternal weight gain and lower infant birth weight, bone loss, increased risk of thromboembolic events, and significant financial costs and maternal stress. 

The American College of Obstetricians and Gynecologists (ACOG) and other obstetric experts do not recommend the prescription of activity restriction and specifically "bed rest" for the prevention or treatment of preterm labor.

Nevertheless, activity restriction continues to be commonly recommended by obstetricians and maternal-fetal medicine subspecialists.

What is the definition of activity restriction in pregnancy?

One of the difficulties in determining the benefits and harms associated with activity restriction is that no standard definition exists for this term. The terms "bed rest" and "activity restriction" are often used synonymously but may denote significantly different levels and intensity of activity. "Activity restriction" is typically used as a general term to describe some form of reduction in normal activity, while "bed rest" is usually considered the most restricted form of activity restriction. 

Bed rest has been variously defined in research studies as limited ambulation of not more than 1 to 2 hours per day with bathroom use and bathing permitted

; confinement to bed with bathroom use permitted

; or resting three times a day for 1 hour.

Additional restrictions of activity may include pelvic rest and cessation from exercise, heavy lifting, and employment. Pelvic rest has been variously defined as refraining from placement of anything in the vagina, with or without cessation of sexual intercourse and other sexual activities (such as orgasm).

In addition to the lack of a standard definition, there are no universally accepted objective measurements for activity restriction. Measures of activity restriction used in most studies are based on patient report in which subjects may be asked to keep a diary of their activity to quantify data. 

The lack of objective measurements, such as heart rate or electronic activity monitoring, complicates the interpretation of research data and further limits the quality of available evidence.

What is the evidence regarding the benefits of activity restriction to prevent PTB in women with singleton pregnancies?

Two randomized clinical trials (RCTs) conducted by Elliott et al7 and Hobel et al8 found no differences in the rates of PTB in women who were prescribed activity restriction during pregnancy and those who were not prescribed this intervention. In addition to the lack of defined objective measurement of activity restriction, these two trials are limited by additional factors, including insufficient detail about methodology, absence of baseline characteristics of some of the study participants, and inclusion of both singleton and multiple gestations.

Some evidence suggests harm resulting from activity restriction. A secondary analysis of the Maternal-Fetal Medicine Unit (MFMU) Preterm Prediction Study9 found that women who were assessed as being at increased of PTB at 23 to 24 weeks of gestation and who were prescribed activity restriction were twice as likely to have a preterm delivery than those who were not prescribed activity restriction. 

Study limitations included a lack of a consistent definition of activity restriction, absence of information regarding patient compliance with activity restriction, and the possibility that it was primarily the women at the highest risk for PTB who were prescribed activity restriction.

In a secondary analysis of a trial of nulliparous women with singleton gestations and cervical length less than 30 mm who were randomized to treatment with 17-α hydroxyprogesterone caproate or placebo, Grobman and colleagues 20 found that PTB at less than 37 and less than 34 weeks of gestation was more common when women were placed on any type of activity restriction, whether inpatient or outpatient. 

After controlling for potential confounders, they found an increase in the risk of delivery at less than 37 weeks of gestation and at less than 34 weeks of gestation (aOR 2.28, 95% CI 1.36–3.80) in women placed on activity restriction.

A small pilot study used quantitative methods to study the effect of maternal activity on the rate of PTB.

 In this study, 49 pregnant women assessed as high risk for PTB wore a smart band activity tracker continuously for a week between 24 and 32 weeks of gestation. 

The primary outcome was the rate of PTB at less than 37 weeks of gestation, and a secondary outcome was the rate of PTB at less than 34 weeks of gestation. 

In all, 37 of the participants delivered preterm, and 12 delivered at 37 weeks of gestation or later. The median number of steps per day was significantly lower in participants who delivered preterm. In addition, regression analyses found an inverse association between the number of median steps per day and PTB.

In summary, although the evidence is limited and the quality generally low, available data do not demonstrate a benefit of activity restriction in women at risk for PTB, and some data suggest that this approach increases the risk of PTB. 

We recommend against the routine use of activity restriction in pregnant women at risk for PTB based on preterm labor symptoms, arrested preterm labor, or shortened cervix. (GRADE 1B)

What is the evidence regarding the benefits of activity restriction in women with hypertension, PPROM, multiple gestations, and FGR?

In addition to prevention of PTB, management of hypertensive disorders of pregnancy, PPROM, multiple gestation, and FGR are common reasons for antepartum hospital admission and frequently lead to a recommendation for activity restriction. 

With regard to hypertensive disorders, it has been hypothesized that activity restriction might result in a decrease in systolic blood pressure and an improvement in placental perfusion. 

At present, the evidence regarding use of activity restriction for the prevention or management of hypertensive disorders in pregnancy is too limited to inform recommendations.

Women with PPROM are typically managed with inpatient admission and are also placed on activity restriction or bed rest in an attempt to prolong gestation and prevent umbilical cord prolapse. However, we identified no studies examining the effects of this practice on pregnancy outcomes.

Inpatient bed rest in mid- to late gestation was once recommended routinely for women with multiple gestations. A 2010 Cochrane review12 identified 7 RCTs that included 713 women assigned to routine inpatient bed rest versus hospitalization only if complications developed. 

These trials did not demonstrate any difference in the rates of PTB or perinatal mortality. The only detectable benefit of hospital bed rest was a decrease in the number of neonates born weighing less than 2500 g. 

A later Cochrane review in 201713 investigated the effect of strict bed rest (defined as resting in bed as much as possible with minimal physical activity) or partial bed rest (defined as rest for a few hours during the day with no other physical activity restrictions) in the hospital versus routine care on perinatal outcomes in women with a multiple gestation and found no differences in the risk of very PTB, perinatal mortality, low birth weight, small-for-gestational-age (SGA) infants, or PPROM. 

Similar findings were noted for partial bed rest. While strict bed rest was associated with a higher mean birth weight, it was not associated with a decrease in SGA infants.

A few studies have examined maternal outcomes in women with multiple gestations on activity restriction, such as weight gain and indicators of mental health status. Maloni and colleagues found that maternal stressors, symptomatic side effects, and depressive symptoms were all increased, and maternal weight gain was suboptimal in patients placed on hospital bed rest.

We recommend against the use of routine inpatient hospitalization and activity restriction for the prevention of PTB in women with multiple gestations. (GRADE 1A)

FGR is often attributed to placental insufficiency, and activity restriction or bed rest is often prescribed to improve placental perfusion. 

However, a Cochrane review15 found only a single RCT that allocated women with growth-restricted fetuses to either bed rest in the hospital or work restriction at home (no subjects were allocated to normal activity). No differences were found in infant birth weight, Apgar scores, cord pH, or operative delivery rate. 

Given the lack of data definitively demonstrating that activity restriction improves perinatal outcome in pregnancies complicated by FGR, PPROM, or hypertensive disease of pregnancy, coupled with evidence of adverse effects of activity restriction, we suggest that activity restriction not be prescribed for treatment of pregnancies complicated by FGR, PPROM, or hypertensive disease. (GRADE 2B)

What are the potential maternal risks of activity restriction?

Obstetric care providers frequently recommend activity restriction due to a perception that activity restriction has little associated harm. Studies in nonpregnant adults have revealed that clinically significant physiologic changes affecting multiple organ systems occur after only a few days of immobility (Table 2).

In nonpregnant adults, lying supine during strict activity restriction shifts the position of the internal organs. 

The abdominal viscera are displaced upwards against the diaphragm, which increases the effort required by the inspiratory muscles, decreases oxygen inspiration, and ultimately impairs gas exchange. 

Furthermore, cardiovascular and physical deconditioning occur in addition to muscle atrophy and a prolonged decrease in cardiac output. 

Resumption of physical activity is often difficult and impaired. Following several weeks of bed rest, there is a decrease in metabolism and appetite, as well as skin breakdown, nerve compression, and shifts in hormone levels, including cortisol, thyroid hormone, and aldosterone. 

Alterations in hormonal levels can affect sleep cycles and lead to insomnia and can also impair the function of the immune system.

Several studies in the pregnant population have reported similar adverse effects of prolonged inactivity. Pregnant women are also affected by physical deconditioning and loss of muscle mass. 

One study examined muscle metabolism in the gastrocnemius muscle after prolonged antepartum inactivity and identified impairment of oxygenation indicative of deconditioning.

Postpartum, women had protracted symptoms of deconditioning, including muscle soreness and impaired mobility. Similarly, inactivity in pregnancy has been shown to impair maternal weight gain. In one study, inadequate weight gain was correlated with low fetal birth weight across all gestational ages.

RCTs are needed to compare women with high-risk pregnancies who are ambulatory with those on bed rest to analyze the extent to which bed rest, underlying maternal-fetal disease, or both contribute to inadequate maternal weight gain and poor intrauterine growth.

As in nonpregnant adults, prolonged inactivity in pregnant women is associated with negative effects on bone health. Studies of pregnant women treated with strict bed rest found an increased rate of trabecular bone loss19 and an increase in bone resorption markers, one of which continued to increase gradually over time and persisted into the postpartum period.

Evidence suggests that inpatient activity restriction is associated with higher rates of gestational diabetes mellitus (GDM) among women admitted to the hospital for antepartum management of pregnancy-related complications.

One retrospective study found that the risk of GDM increased by 4% for every day a pregnant woman remained on the inpatient unit. While data in pregnancy are limited, elevated blood glucose levels have been well documented in nonpregnant patients placed on activity restriction.

Another serious concern with prolonged bed rest is the potential increased risk of thromboembolic events. 

In general, inactivity increases the risk for venous thromboembolism (VTE), which is compounded by the hypercoagulable state of pregnancy. In one study, Kovacevich et al found a significant increase in the risk of thromboembolic events in pregnant women treated with bed rest lasting 3 days or more compared with those not on bed rest (15.6 cases per 1000 women vs 0.8 cases per 1000 women; 

What are the psychosocial effects of activity restriction?

Activity restriction in pregnancy can also cause significant emotional and psychological distress. 

Compared with women with uncomplicated pregnancies, high-risk women on bed rest have more anxiety and depression. The negative psychosocial effects of bed rest are apparent with both inpatient and outpatient management, although hospitalized patients are known to have more sources of stress.

In particular, the extended time in bed can result in negative feelings, perseveration, and excessive worrying that can manifest as somatic symptoms. Women reported anxiety about the threat of losing their unborn child, guilt about separation from other children and loved ones, and concern for loss of employment or financial stability. The loss of wages can lead to significant financial concerns and is often a major source of stress for women.

Many women who are placed on hospitalized bed rest express frustration and anger resulting from a lack of control or the perception that hospitalization confers minimal clinical benefit. Bed rest can also be associated with family disruption, leading to emotional stress for the spouse and other children. Separation from one's family has been shown to be the most significant stressor for some women.

Social support from family, friends, and professionals is an important mediator of stress and depressive symptoms. Strain on these relationships compromises an important coping mechanism.

Little evidence supports the routine use of activity restriction for preterm birth and other obstetric conditions, and some data indicate adverse impact on obstetric outcomes. In addition, prolonged inactivity is associated with a variety of negative physiological and psychological effects (Table 3). 

Given the lack of data definitively demonstrating that activity restriction improves perinatal outcome, coupled with evidence of adverse effects, we suggest that activity restriction should not routinely be prescribed.

For more on activity restriction, read Dr. Spong's editorial from the September issue of 

1. Kovacevich GJ, Gaich SA, Lavin JP, Hopkins MP, Crane SS, Stewart J, et al. The prevalence of thromboembolic events among women with extended bed rest prescribed as part of the treatment for premature labor or preterm premature rupture of membranes. 

2. Sprague AE. The evolution of bed rest as a clinical intervention. 

3. Sciscione AC. Maternal activity restriction and the prevention of preterm birth. 

4. American College of Obstetricians and Gynecologists. Practice Bulletin No. 171: Management of Preterm Labor. Obstet Gynecol 2016 Oct;128(4):e155-64.

5. Maloni JA. Lack of evidence for prescription of antepartum bed rest. 

6. McCarty-Singleton S, Sciscione AC. Maternal activity restriction in pregnancy and the prevention of preterm birth: an evidence-based review. 

7. Elliott JP, Miller HS, Coleman S, Rhea D, Abril D, Hallbauer K, et al. A randomized multicenter study to determine the efficacy of activity restriction for preterm labor management in patients testing negative for fetal fibronectin. 

8. Hobel CJ, Ross MG, Bemis RL, Bragonier JR, Nessim S, Sandhu M, et al. The West Los Angeles Preterm Birth Prevention Project. I. Program impact on high-risk women. 

9. Levin HI, Sciscione A, Ananth CV, Drassinower D, Obican SG, Wapner RJ. Activity restriction and risk of preterm delivery. 

10. Grobman WA, Gilbert SA, Iams JD, Spong CY, Saade G, Mercer BM, et al. Activity restriction among women with a short cervix. 

11. Zemet R, Schiff E, Manovitch Z, Cahan T, Yoeli-Ullman R, Brandt B, et al. Quantitative assessment of physical activity in pregnant women with sonographic short cervix and the risk for preterm delivery: A prospective pilot study. 

12. Crowther CA, Han S. Hospitalisation and bed rest for multiple pregnancy. 

13. da Silva Lopes K, Takemoto Y, Ota E, Tanigaki S, Mori R. Bed rest with and without hospitalisation in multiple pregnancy for improving perinatal outcomes. 

14. Maloni JA, Margevicius SP, Damato EG. Multiple gestation: side effects of antepartum bed rest. 

15. Gulmezoglu AM, Hofmeyr GJ. Bed rest in hospital for suspected impaired fetal growth. 

16. Greenleaf JE. Physiological responses to prolonged bed rest and fluid immersion in humans. 

J Appl Physiol Respir Environ Exerc Physiol

17. Maloni JA, Schneider BS. Inactivity: symptoms associated with gastrocnemius muscle disuse during pregnancy. 

18. Maloni JA, Alexander GR, Schluchter MD, Shah DM, Park S. Antepartum bed rest: maternal weight change and infant birth weight. 

19. Promislow JH, Hertz-Picciotto I, Schramm M, Watt-Morse M, Anderson JJ. Bed rest and other determinants of bone loss during pregnancy. 

20. Kaji T, Yasui T, Suto M, Mitani R, Morine M, Uemura H, et al. Effect of bed rest during pregnancy on bone turnover markers in pregnant and postpartum women. 

21. Merriam AA, Chichester KM, Patel KN, Hoffman KM. Bed rest and gestational diabetes: more reasons to get out of bed in the morning. 

22. Maloni JA, Chance B, Zhang C, Cohen AW, Betts D, Gange SJ. Physical and psychosocial side effects of antepartum hospital bed rest. 

Articles

Little evidence supports the routine use of activity restriction for preterm birth and other obstetric conditions, and some data indicate adverse impact on obstetric outcomes. 

Society for Maternal-Fetal Medicine Consult Series #50: The role of activity restriction in obstetric management 

Cesarean scar pregnancy (CSP) is a complication in which an early pregnancy implants in the scar from a prior cesarean delivery. Incidence and recognition of this condition appear to have increased over the past two decades, perhaps due to high worldwide cesarean delivery rates. The clinical presentation is variable, and many women are asymptomatic at presentation. CSP can be difficult to diagnose in a timely fashion. Ultrasound is the primary imaging modality for CSP diagnosis.

Expectantly managed CSP is associated with high rates of severe maternal morbidity such as hemorrhage, placenta accreta spectrum (PAS), and uterine rupture. Given these substantial risks, pregnancy termination is recommended after CSP diagnosis. Several surgical and medical treatments have been described for this disorder, but at this time, optimal management remains uncertain. 

The Society for Maternal-Fetal Medicine Consult series #49 on cesarean scar pregnancy: Summary of Recommendations

Cesarean scar pregnancy (CSP) is a complication in which an early pregnancy implants in the scar from a prior cesarean delivery. Incidence and recognition of this condition appear to have increased over the past two decades, perhaps due to high worldwide cesarean delivery rates. The clinical presentation is variable, and many women are asymptomatic at presentation. CSP can be difficult to diagnose in a timely fashion. Ultrasound is the primary imaging modality for CSP diagnosis. Expectantly managed CSP is associated with high rates of severe maternal morbidity such as hemorrhage, placenta accreta spectrum (PAS), and uterine rupture. Given these substantial risks, pregnancy termination is recommended after CSP diagnosis. Several surgical and medical treatments have been described for this disorder, but at this time, optimal management remains uncertain.

SMFM consult series #49 on cesarean scar pregnancy

What is cesarean scar pregnancy, and what is its incidence?

CSP occurs when an embryo implants in the fibrous scar tissue of a prior cesarean hysterotomy. Although sometimes called a “cesarean ectopic pregnancy,” these gestations are, in fact, within the uterine cavity and, unlike true ectopic pregnancies, may result in a liveborn infant. This condition presents a substantial risk for severe maternal morbidity complicated by challenges in securing timely diagnosis, as well as uncertainty regarding optimal treatment once identified.

The true incidence of CSP is unknown, as the condition is likely underdiagnosed and underreported. Reported single-center estimates of incidence range from 1:1800 to 1:2656 of overall pregnancies. Although relatively uncommon, reported international experience with CSP appears to be increasing, likely as a result of high contemporary cesarean delivery volume. Other factors, including improved imaging with ultrasound and magnetic resonance imaging (MRI), increased utilization of transvaginal ultrasonography (TVUS), and possibly increased physician awareness, may also contribute to a perceived increase in incidence.

Although the pathogenesis of CSP is incompletely understood, the mechanism has been postulated to involve blastocyst implantation within a microscopic dehiscence tract in the scar from a prior cesarean delivery. Due to the fibrous nature of scar tissue, these inherently deficient implantation sites are at risk for dehiscence, PAS, and hemorrhage as the CSP enlarges.

CSP and placenta accreta appear to have similar disease pathways and may exist along a common disease continuum. Histopathologic analyses for both groups are characterized by myometrial or scar tissue villous invasion with little or no intervening decidua.

Implantation patterns of CSP can be categorized as either endogenic (also referred to as “on the scar”) or exogenic (“in-the-niche”). Endogenic is defined as growing within the uterine cavity and exogenic as arising from a gestational sac deeply implanted into the scar that may grow toward the bladder or abdominal cavity (Figure 1).

These ultrasonographic appearances may influence obstetric prognosis. It has been suggested that early first-trimester determination of whether a CSP is growing “on the scar” or “in the niche” of the prior cesarean hysterotomy may be used to predict subsequent pregnancy outcomes. In one small, retrospective experience, patients with pregnancies growing “on the scar” had variable obstetric outcomes, whereas those with pregnancies growing “in the niche” all underwent hysterectomy with PAS at delivery.1

How does CSP present clinically, and are there known risk factors?

Although second-trimester diagnoses have been reported, CSP usually presents in the first trimester. In one review of published CSP case series, the average gestational age at diagnosis was 7.5 +/- 2.5 weeks.2 The clinical presentation is variable, ranging from asymptomatic ultrasonographic detection to a presentation with uterine rupture and hemoperitoneum, typically in the absence of a timely diagnosis. In the review mentioned above, about one-third of cases were asymptomatic, and approximately one-third presented with painless vaginal bleeding. Nearly one-quarter of presentations involved pain, with or without bleeding. Women with a ruptured CSP may also present with hemodynamic collapse. 

Although by definition prior cesarean delivery is a prerequisite for CSP development and placenta previa may modify this risk, it is not clear if the number of prior cesarean deliveries further increases risk. A review of the literature reveals that 52% of CSP cases occur in women with a single prior cesarean delivery.3-5 Previous delivery for breech presentation appears to be a more common indication in women who later develop CSP. No published data exist regarding an association between hysterotomy closure technique and CSP.

TVUS is the optimal modality for evaluation of suspected CSP, as it provides the highest image resolution (Figures 2 and 3). Grayscale combined with color Doppler ultrasound is recommended for CSP diagnosis. One group suggests combining TVUS with a transabdominal ultrasonogram with a full maternal bladder to provide a “panoramic view” of the uterus and the relationship between the gestational sac and bladder.6 The initial finding of a low, anteriorly located gestational sac should raise concern for a possible CSP and warrants further investigation. When evaluating women with suspected CSP, a high degree of clinical suspicion is needed as a missed or delayed diagnosis can result in uterine dehiscence, hemorrhage, loss of fertility, or maternal death. 

Diagnostic criteria have been proposed to enhance ultrasonographic detection of CSP.4,7,8 One approach proposes the following ultrasonographic criteria to diagnose CSP: (1) an empty uterine cavity and endocervix; (2) placenta, gestational sac, or both embedded in the hysterotomy scar; (3) a triangular ( ≤8 weeks of gestation) or rounded or oval (> 8 weeks of gestation) gestational sac that fills the scar “niche” (the shallow area representing a healed hysterotomy site); (4) a thin (1-3 mm) or absent myometrial layer between the gestational sac and bladder; (5) a prominent or rich vascular pattern at or in the area of a cesarean scar; and (6) an embryonic or fetal pole, yolk sac, or both with or without fetal cardiac activity (Figure 4). All of these criteria may not be observed. Especially with very early diagnosis and before fetal cardiac activity, the woman must have confirmation of pregnancy (for example, a positive pregnancy test result). Bulging or ballooning of the lower uterine segment in the midline sagittal transabdominal view has also been considered to be supportive of CSP diagnosis. 

Distinguishing CSP from other clinical entities with a similar ultrasonographic appearance is challenging. CSP may be misdiagnosed as either cervical ectopic pregnancy, spontaneous abortion in transit, or low implantation of an intrauterine pregnancy. Given the importance of prompt diagnosis, referral to an experienced center for a second opinion may be preferable to ongoing follow-up examinations that are likely to lead to a delay in diagnosis.

Are other modalities useful for diagnosis?

Transvaginal three-dimensional (3D) ultrasound and 3D power ultrasound have been used in an attempt to enhance accuracy of CSP diagnosis. However, data are insufficient to support a benefit of routine use of 3D ultrasound for diagnosis or management of CSP. Magnetic resonance imaging (MRI) has been used as an adjunct to ultrasound for diagnosis of CSP, although its incremental benefit over ultrasound alone is unknown. MRI may provide useful information regarding the degree of invasion and whether there is evidence of PAS. Most authors do not recommend MRI as a routine component of CSP evaluation. In cases in which ultrasound imaging is inconclusive, MRI could be considered as an adjunct study. Given the risks associated with delayed diagnosis, use of multiple ultrasound imaging approaches, as well as modalities such as MRI, are likely preferable to serial ultrasound examinations.

Hysteroscopy and laparoscopy can be used to confirm a diagnosis at the time of planned operative intervention. With laparoscopic examination, CSP has been described as an ecchymotic bulge with a “salmon-red” appearance beneath the bladder at the level of the prior cesarean scar with an otherwise normal-appearing uterus.

Although few recognized CSPs continue to a viable gestational age, some CSPs have resulted in live births often associated with PAS, cesarean hysterectomy, and massive hemorrhage at delivery. Series describing outcomes of expectantly managed CSPs all involve small case numbers and high hysterectomy rates, ranging from 50% to 100% and usually associated with PAS. In case series of women managed expectantly, most required additional treatment, and more than 50% had severe complications.9-13

Due to the high risk of severe maternal morbidity, expectant management is not recommended for a recognized CSP, and pregnancy termination is generally advised as soon as the diagnosis is confirmed. For cases in which a CSP is suspected but the diagnosis is not certain, short-interval follow-up, a second opinion, or additional imaging with MRI should be considered to make a timely diagnosis without undue delay. We recommend against expectant management of cesarean scar pregnancy (GRADE 1B).

An exception to the recommendation against expectant management involves early CSP that is definitively diagnosed as nonviable. In this situation, expectant management may be pursued with serial ultrasound surveillance, quantitative beta-hCG measurements, and monitoring for maternal symptoms such as bleeding or pelvic pain. It can take several months for a nonviable CSP to resolve spontaneously, and expectant management of nonviable CSP has been associated with development of a uterine arteriovenous malformation (AVM). Uterine AVM in this clinical context has been associated with persistent, severe vaginal bleeding and may require umbilical artery embolization or even hysterectomy.

What CSP treatment modalities have been reported?

Surgical, medical, and minimally invasive therapies, as well as various combinations of such treatments, have been described, including hysteroscopy, laparoscopy, laparotomy, open surgery, transvaginal surgery, dilation and curettage (D&C, including both sharp and vacuum aspiration techniques), uterine artery embolization (UAE), methotrexate (MTX) (both local guided injection and systemic administration), direct potassium chloride (KCl) injection, needle-guided sac decompression, high-intensity focused ultrasound (HIFU), and use of balloon catheters, and combinations of these methods (Table 1).14-16

The optimal treatment is not known. Systematic reviews have been inconsistent with regard to identification of a single optimal CSP treatment modality that best balances procedural success and risks. Data regarding optimal CSP therapy consist primarily of case series with varying levels of clinical experience, institutional capability, provider skill, and case complexity. Randomized controlled trials comparing treatment approaches are limited, as are those comparing medical and surgical approaches.

CSP treatment decisions are guided by a principal goal of preserving maternal health, followed by a secondary goal of preserving fertility when possible. Management decisions should be determined after considering pregnancy viability, gestational age, maternal health, future family planning wishes, physician skill and experience, and institutional resources. Preferred management may differ between institutions based upon resources, personnel, and clinical experience. Even with efforts to tailor treatment strategies to individual patients and clinical presentations, there remains a substantial risk of complications with any management approach.

What are the recommended treatment approaches for CSP?

Among surgical management options, transvaginal and laparoscopic CSP resection appear to have low complication rates.17-19 A potential advantage of these approaches is that the scar tissue can be excised and the surrounding myometrium reapproximated at the time of CSP removal. It is unknown if this practice decreases risk of CSP reoccurrence. 

D&C alone, without adjuvant treatments, has been associated with high complication rates, including hemorrhage and perforation, due to an inability to completely access and remove trophoblastic tissue outside of the endometrial cavity and because scar tissue contracts poorly after curettage.14 As with PAS, sharp curettage may sever deeply invading blood vessels, exposing the patient to ongoing bleeding. In addition to a high complication rate, additional treatment is reported to be required after 52% of D&C cases. It should be noted that the published literature incompletely distinguishes between sharp curettage and vacuum aspiration, which may provide different success and complication rates with CSP management.14 We suggest operative resection (with transvaginal or laparoscopic approaches when possible) or ultrasound-guided vacuum aspiration be considered for surgical management of CSP and that sharp curettage (D&C) alone be avoided (GRADE 2C).

While sharp curettage alone is not recommended as a primary CSP treatment, higher efficacy and lower complication rates have been reported with ultrasound-guided vacuum aspiration.20 Shirodkar placement as an adjunct to D&C has also been described, in which the cerclage suture is placed prior to D&C and only secured in the setting of hemorrhage to minimize bleeding.21

Gravid hysterectomy is an alternative surgical option that may be considered for definitive management of CSP. This approach may be particularly appropriate for early second-trimester CSP presentations or for women who do not desire future fertility.

When pursuing medical treatment of CSP, local or intragestational injection of MTX is a preferred approach, with or without accompanying systemic MTX. Standalone systemic MTX is not recommended due to a higher reported risk of complications.7, 22 Although a small randomized trial of systemic versus local MTX demonstrated no difference in overall cure rates23, reviews suggest a high risk of complications with intramuscular MTX alone24, 25, and local MTX appears to be a more effective approach. In a literature review by Cheung et al, of 96 cases of intragestational MTX for CSP, success was achieved in 73.9% after a single local MTX injection and increased to 88.5% after an additional local or intramuscular MTX injection.25 Intragestational injection is typically performed with a 20-gauge needle under ultrasound guidance using a transvaginal approach. Sac aspiration may be performed prior to injection to verify appropriate needle placement. Optimal dosing for local MTX injection ranges from doses of 1 mg/kg of maternal weight to 50 mg. Varying dosages of systemic MTX have been reported in management of CSP; in general, these dosages are comparable to those used for ectopic pregnancy. We suggest intragestational MTX for medical treatment of CSP, with or without other treatment modalities (GRADE 2C). We recommend that systemic MTX alone not be used to treat CSP (GRADE 1C). 

When following women with CSP who have been treated medically, the gestational mass can take weeks to months to resolve. A transient increase in beta-hCG levels and CSP mass size can be observed after MTX therapy. One study of 22 women following local conservative CSP treatment reported a mean time to resolution of 88 days (range 26-177).8 An understanding of this anticipated posttherapy course may help to minimize unnecessary additional treatments. During the posttreatment observation period, patients should be monitored for concerning symptoms such as hemorrhage or uterine AVM development. Interval ultrasonographic surveillance may be helpful to observe for CSP resolution. 

Intragestational KCl has also been described for treatment of CSP in a small number of cases. This approach may be particularly appropriate for management of CSP heterotopic pregnancies with a coexisting intrauterine pregnancy, as MTX exposure may have embryocidal or teratogenic consequences for the intrauterine cotwin. As with MTX, ultrasound-guided KCl injection can be accompanied by sac aspiration. Hysteroscopic and laparoscopic approaches for treating CSP heterotopic pregnancies have also been described.

UAE is a minimally invasive procedure that has been used in various combinations to treat CSP. It has been reported as a standalone procedure, as well as in combination with D&C, MTX, and hysteroscopy, which complicates comparisons between studies.14 UAE may be a uterine- and fertility-preserving procedure, although reported outcomes in the setting of CSP vary significantly, and its role as an adjunct to other management approaches requires further study.

Ultrasound-guided placement and inflation of balloon and Foley catheters to tamponade a CSP gestational sac complicated by bleeding or as a prophylactic measure has been reported.15, 16, 26 Limited experience shows that this technique may be well tolerated and efficacious, supporting a potential option that warrants further study. 

How should CSP be managed in women who decline treatment?

Women who decline treatment of a CSP should be counseled about risk of significant obstetric complications, including PAS, massive hemorrhage, uterine rupture, severe maternal morbidity, and potentially maternal death. Management of such cases should include a very high index of suspicion for PAS with appropriate antepartum management and delivery planning. Women should be counseled regarding signs and symptoms of preterm labor or any symptoms suggesting uterine rupture. Repeat cesarean delivery is recommended between 34 0/7 and 35 6/7 weeks of gestation. As with other medically indicated late preterm births, betamethasone administration is recommended prior to delivery. In women who choose expectant management and continuation of a CSP, we recommend repeat cesarean delivery between 34 0/7 and 35 6/7 weeks of gestation (GRADE 1C).

As with PAS, delivery should occur at Level III or Level IV facilities with appropriate expertise and resources, including the capability to manage massive hemorrhage. A multidisciplinary team approach to delivery is recommended, and the team should be prepared for the potential need for cesarean hysterectomy and massive transfusion.

Women can become pregnant after uterine-preserving management of a CSP, although there appears to be an increased risk for recurrent CSP and other severe maternal morbidities. High rates of complications and severe maternal morbidity, including PAS, recurrent CSP, gravid hysterectomy, and uterine rupture, have been reported.27-30 Women considering pregnancy after a CSP should be informed that there is a significant risk of recurrence and severe maternal morbidity. We recommend that women with a CSP be advised of the risks of another pregnancy and counseled regarding effective contraceptive methods, including long-acting reversible contraception and permanent contraception (GRADE 1C).

Although a short interval between successful conservative CSP management and subsequent pregnancy may increase risk of recurrent CSP or PAS, there is no consensus about how long to wait before attempting another pregnancy for women who desire another pregnancy after counseling regarding the risks. Some experts have recommended waiting 12 to 24 months before attempting to become pregnant again, although there is limited supporting evidence.

Given the increased risk of CSP recurrence, some advocate evaluation of the uterus and cesarean scar by saline infusion sonohysterography prior to a subsequent pregnancy. However, it is not clear whether the detection of a defect is associated with higher risks and should influence counseling regarding the advisability of another pregnancy. Interpregnancy repair or revision of a cesarean scar has been reported using a variety of surgical modalities. However, data are insufficient to support a benefit to this practice.

Should a woman with a history of a CSP become pregnant, close ultrasonographic monitoring is recommended to confirm the presence of an intrauterine pregnancy and to exclude recurrent CSP or PAS. An initial ultrasound examination is recommended on presentation to prenatal care, ideally before 8 weeks of gestation, to confirm a normal intrauterine location. Repeat cesarean delivery is recommended between 34 0/7 to 35 6/7 weeks of gestation, prior to the onset of labor. Betamethasone administration is recommended prior to anticipated late preterm delivery. The delivery team should be prepared for obstetric hemorrhage and the potential need for cesarean hysterectomy.

Due to high worldwide cesarean delivery rates, an increased incidence of CSP has been recognized. CSP can be difficult to diagnose in a timely fashion, and this diagnosis should be considered in women with a prior cesarean delivery who are undergoing early first-trimester ultrasonography. Several surgical and medical treatments have been described for this disorder, but at this time, optimal management remains uncertain. For this reason, an international registry has been created for providers to submit data on diagnosis, natural history, and management (

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Cesarean scar pregnancy (CSP) is a complication in which an early pregnancy implants in the scar from a prior cesarean delivery. Incidence and recognition of this condition appear to have increased over the past two decades, perhaps due to high worldwide cesarean delivery rates. 

The clinical presentation is variable, and many women are asymptomatic at presentation. CSP can be difficult to diagnose in a timely fashion. Ultrasound is the primary imaging modality for CSP diagnosis.

Expectantly managed CSP is associated with high rates of severe maternal morbidity such as hemorrhage, placenta accreta spectrum (PAS), and uterine rupture. Given these substantial risks, pregnancy termination is recommended after CSP diagnosis. Several surgical and medical treatments have been described for this disorder, but at this time, optimal management remains uncertain. 

Author | Society for Maternal-Fetal Medicine (SMFM)

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