Fertility-preserving management of heterotopic cesarean scar pregnancy after laparoscopic repair for cesarean scar disorder: a case report

Abstract

Heterotopic pregnancy involving cesarean scar implantation is rare and difficult to manage when continuation of a viable intrauterine pregnancy is desired. Evidence is particularly limited for cases occurring after surgical repair for cesarean scar disorder.

A 40-year-old woman with three previous cesarean deliveries underwent laparoscopic repair for symptomatic cesarean scar disorder before assisted reproductive technology. After transfer of two blastocysts, transvaginal ultrasonography showed a viable intrauterine pregnancy together with a cesarean scar pregnancy of the in-the-niche type with minimal overlying residual myometrium. Because the patient wished to continue the intrauterine pregnancy, selective treatment of the scar gestation was performed. Ultrasound-guided local potassium chloride injection led to gradual regression of the cesarean scar pregnancy without significant bleeding or procedure-related complications. The intrauterine pregnancy continued under close surveillance, and an elective repeat cesarean delivery at 37 weeks resulted in the birth of a healthy neonate. Histopathology of residual tissue at the repaired scar was compatible with a placental remnant.

Selective local potassium chloride injection may be considered a fertility-preserving option for heterotopic cesarean scar pregnancy after surgical repair for cesarean scar disorder in carefully selected patients. Early diagnosis, careful counseling, and management in a tertiary care setting are essential.

Highlights

• •Heterotopic cesarean scar pregnancy after scar repair is rare.
• •Selective local potassium chloride injection treated the scar pregnancy.
• •The viable intrauterine pregnancy continued to delivery at 37 weeks.
• •An exogenic, in-the-niche scar pregnancy carries high rupture risk.
• •Early diagnosis and tertiary-center care supported a live birth.

1. Introduction

Cesarean section (CS) rates have risen steadily; globally, approximately one in five births is now by CS [1]. A cesarean scar defect, or uterine niche, is commonly identified on ultrasonography after CS, with its prevalence varying by imaging modality and diagnostic criteria [2], [3]. A symptomatic niche—causing postmenstrual spotting, pelvic pain, or infertility—is termed cesarean scar disorder (CSDi) [2], and surgical repair is considered in selected women who desire future fertility [3], [4]. Deficient scar healing has also been linked to obstetric complications, including cesarean scar pregnancy (CSP), placenta accreta spectrum (PAS), placenta previa, and uterine rupture [3], [5]. When a CSP is allowed to continue, it may progress to PAS, with a substantial risk of uterine rupture and life-threatening hemorrhage [6]. CSP is an uncommon ectopic pregnancy implanting at or within a previous hysterotomy scar, and early diagnosis is essential to limit hemorrhage and preserve fertility [5], [7].

Heterotopic pregnancy—simultaneous intrauterine and extrauterine gestations—is rare and remains uncommon even with assisted reproductive technology (ART). Heterotopic pregnancy involving both an intrauterine pregnancy (IUP) and CSP is particularly rare, with only limited cases reported [8], [9], [10]. Management is challenging because treatment must reduce the maternal risks of CSP while preserving the viable IUP. Reported CSP approaches include surgical resection, uterine artery embolization, systemic or local methotrexate, and selective embryo reduction with targeted injection [5], [7], [11], but evidence is limited, especially when the IUP is to be continued. Data on pregnancy complications after CSDi repair are also scarce, so management of heterotopic CSP after scar repair must be individualized.

This report describes a heterotopic pregnancy comprising a viable IUP and CSP after laparoscopic repair for CSDi, in which selective ultrasound-guided potassium chloride (KCl) injection into the scar gestation achieved regression of the CSP, continuation of the IUP, and live birth.

2. Case Presentation

A 40-year-old woman (gravida 5, para 3) was referred for management of a heterotopic pregnancy. She had had three previous cesarean deliveries (the first for breech presentation). She had hypertension treated with nifedipine 40 mg daily, with blood pressure well controlled from early pregnancy; she had no other notable medical history.

Before this pregnancy, she had secondary infertility and persistent postmenstrual bleeding. Transvaginal ultrasonography showed a cesarean scar defect of 29 × 13 mm with a residual myometrial thickness (RMT) of 2.0 mm (Fig. 1A), and cesarean scar disorder (CSDi) was diagnosed. To optimize the scar before assisted reproductive technology (ART), she underwent laparoscopic cesarean scar repair with hysteroscopic assistance; at 5 months postoperatively, the myometrial thickness had recovered to 8.3 mm (Fig. 1B).

Fig. 1.

Imaging findings before and after cesarean scar disorder repair.

(A) Pre-treatment transvaginal ultrasound demonstrating a large cesarean scar defect with thin residual myometrium measuring 2.0 mm (arrows).

(B) Post-treatment ultrasound showing restoration of myometrial thickness at the scar site to 8.3 mm (arrows).

ART was performed at another institution. Eleven months after repair, pregnancy followed transfer of two blastocysts in a hormone replacement cycle. Early ultrasonography showed two gestational sacs—one intrauterine and one at the cesarean scar—and a heterotopic pregnancy with a viable intrauterine pregnancy (IUP) and a cesarean scar pregnancy (CSP) was diagnosed (Fig. 2A, B). The crown–rump length was 11.6 mm in the CSP and 15.7 mm in the IUP. The scar gestation was deeply implanted within the niche, growing toward the bladder and serosa with a barely measurable overlying myometrium, consistent with an exogenic (in-the-niche) type CSP [12], [13].

Fig. 2.

Transvaginal ultrasound findings of heterotopic pregnancy and its management.

(A, B) Early pregnancy ultrasound demonstrating heterotopic pregnancy with a cesarean scar pregnancy (arrows) and a viable intrauterine pregnancy (arrowheads). The crown–rump length measured 11.6 mm in the cesarean scar pregnancy and 15.7 mm in the intrauterine pregnancy. The scar gestation was an exogenic (in-the-niche) type with minimal overlying residual myometrium.

(C) Follow-up ultrasound after selective local potassium chloride injection showing regression of the cesarean scar pregnancy with preservation of the intrauterine pregnancy.

(D) At 16 weeks and 4 days, a 35.1 × 15.8-mm anechoic space remained around the treated cesarean scar pregnancy; it decreased gradually and was no longer detectable on ultrasonography toward term.

At the tertiary center, given her strong wish to continue the IUP, a fertility-preserving strategy was chosen. After counseling about hemorrhage, uterine rupture, progression to placenta accreta spectrum, and IUP loss, selective treatment of the CSP was undertaken; systemic methotrexate was deemed inappropriate because the IUP was to be preserved.

Under transvaginal ultrasound guidance, potassium chloride (KCl) was injected into the CSP gestational sac, which regressed gradually without significant bleeding or complications (Fig. 2C). The scar gestation was then followed by transvaginal ultrasonography every two weeks. A 35.1 × 15.8-mm anechoic space around the treated CSP persisted at 16 weeks and 4 days (Fig. 2D), then decreased gradually and was no longer detectable on ultrasonography toward term. The IUP progressed uneventfully, and the hypertension remained controlled with nifedipine.

Because of her history of three previous cesarean deliveries and coexisting hypertension, and in line with the patient's preference, an elective repeat cesarean delivery was performed at 37 weeks through a lower transverse abdominal incision and a low transverse uterine incision, delivering a healthy neonate weighing 3190 g. Residual tissue at the repaired scar was removed and submitted for histopathological examination, which showed decidual tissue and fetal membranes with residual chorionic villi and extensive coagulative necrosis, compatible with a placental remnant and with no evidence of malignancy (Fig. 3A, B). The estimated blood loss was approximately 1800 mL; oxytocin was administered as the uterotonic agent, and recovery was uneventful for mother and infant.

Fig. 3.

Histopathology of residual tissue from the cesarean scar pregnancy removed at cesarean delivery (hematoxylin and eosin staining).

(A) Residual tissue from the repaired scar, showing decidual tissue and fetal membranes with extensive coagulative necrosis.

(B) Residual chorionic villi within the placental remnant.

There was no evidence of malignancy. Scale bars, 100 μm (original magnification ×200).

3. Discussion

This case illustrates fertility-preserving treatment of a heterotopic pregnancy comprising a viable intrauterine pregnancy (IUP) and cesarean scar pregnancy (CSP) after laparoscopic repair for cesarean scar disorder (CSDi); selective local potassium chloride (KCl) injection achieved CSP regression and allowed the IUP to reach live birth. Repair of a symptomatic niche may be offered to selected women, although data on subsequent reproductive and obstetric outcomes remain limited [2], [3], [4]. Standardized sonographic assessment, including residual myometrial thickness (RMT), is important for treatment selection and counseling [2], [14]; here, postoperative imaging confirmed that the myometrial thickness had been restored before assisted reproductive technology (ART).

Ultrasound characterization of the CSP guides risk stratification. According to the direction of gestational-sac growth, CSPs are classified as endogenic (toward the uterine cavity) or exogenic (into the niche, toward the bladder and serosa) [12], and the first-trimester crossover sign offers a reproducible descriptor of the sac–endometrium relationship [13]. The exogenic, in-the-niche type with thin or absent overlying myometrium carries higher risks of rupture and placenta accreta spectrum (PAS) and is generally unsuitable for expectant management [6], [7]; the present CSP was of this type, supporting early definitive treatment.

Heterotopic CSP occurs mainly after ART and previous cesarean delivery [8]. Early transvaginal ultrasound diagnosis is critical [5], [7], and the Society for Maternal-Fetal Medicine (SMFM) advises against expectant management of cesarean scar ectopic pregnancy and emphasizes individualized counseling [7]. Systemic methotrexate is unsuitable when the IUP is to be preserved, so local ultrasound-guided treatment is preferred. Under continuous transvaginal ultrasound guidance, a fine needle is advanced into the gestational sac or the fetal thorax or heart, and KCl is injected slowly until asystole is achieved, avoiding the intrauterine gestation. Reported variations include intracardiac, intrathoracic, or intragestational injection, with or without sac aspiration or cervical cerclage [9], [15], [16]. An ultrasound-guided laparoscopic approach combining aspiration and induced fetal cardiac arrest has also been described for interstitial heterotopic pregnancy and may be relevant when a transvaginal route is unfavorable [17]. First-trimester treatment is generally preferred. Table 1 summarizes reported fertility-preserving cases.

Table 1.

Reported cases and case series of fertility-preserving management of heterotopic cesarean scar pregnancy.

Reference	Maternal age (years)	Conception	Treatment of the scar pregnancy	Intrauterine pregnancy outcome
Wang et al., 2007 [9]	NR	IVF–ET	TVUS-guided local injection into the scar gestation	IUP preserved; term live birth
Yu et al., 2016 [15]	33	IVF–ET	TVUS-guided intrathoracic KCl injection (16 + 4 weeks)	Cesarean at 37 + 6 weeks; healthy neonate
Tymon-Rosario & Chuang, 2018 [20]	40	NR	TVUS-guided KCl injection (12 + 3 weeks)	Septic abortion; IUP lost; hysterectomy
Ouyang et al., 2021 [8]	Case series (n = 20)	IVF–ET	Selective reduction (KCl injection / aspiration)	Majority resulted in live births
Kim et al., 2022 [16]	NR	NR	Selective KCl injection with cervical cerclage	Full-term live birth
Present case	40	ART (frozen–thawed ET)	TVUS-guided local KCl injection (exogenic type)	Elective cesarean at 37 weeks; healthy neonate

ART, assisted reproductive technology; ET, embryo transfer; IUP, intrauterine pregnancy; IVF, in vitro fertilization; KCl, potassium chloride; NR, not reported; TVUS, transvaginal ultrasound.

After selective reduction, close follow-up is essential. Serial transvaginal ultrasonography, performed every two weeks in this case, should confirm regression of the scar gestation and detect delayed complications. Particular attention should be paid to persistent or increasing vascularity at the scar, because enhanced myometrial vascularity, acquired uterine arteriovenous malformation (AVM), and uterine artery pseudoaneurysm have been reported after treatment or aspiration of CSP and can cause delayed, life-threatening hemorrhage [18]. Serum human chorionic gonadotropin is of limited value while a viable IUP continues, and surveillance for abnormal placentation and uterine rupture should continue as pregnancy advances.

Several points warrant emphasis. First, multiple-embryo transfer is a risk factor for heterotopic pregnancy, so single embryo transfer should be considered in women with prior CSDi or scar repair undergoing ART [8]. Second, the safety of continuing an IUP after scar repair and CSP treatment is uncertain; here, restored myometrial thickness before conception and intensive surveillance supported continuation, suggesting persistence of trophoblastic tissue at the scar site until delivery, which is compatible with the recognized biological continuum between CSP and PAS [19]. Third, elective repeat cesarean delivery at 37 weeks was chosen because of the three previous cesarean deliveries and coexisting hypertension, to avoid labor and the attendant risk of uterine rupture, while taking the patient's preference into account. Fourth, hemorrhage is the principal hazard: the estimated blood loss was approximately 1800 mL, managed with oxytocin. Treatment was undertaken early, under ultrasound guidance, in a tertiary setting with immediate surgical and interventional backup.

To date, reports of heterotopic CSP occurring after surgical repair for CSDi are exceedingly rare. This case suggests that selective local KCl injection may be a fertility-preserving option in carefully selected post-repair patients who wish to continue a viable IUP, with detailed counseling, early planning, and close multidisciplinary surveillance.

4. Conclusion

Selective ultrasound-guided potassium chloride injection may be considered for heterotopic cesarean scar pregnancy after cesarean scar disorder repair when continuation of a viable intrauterine pregnancy is strongly desired. Careful patient selection, thorough counseling, and close surveillance are essential in this uncommon, high-risk setting.

Contributors

Kenichiro Hirotani contributed to patient care, conception of the case report, acquiring the data, drafting the manuscript and revising the article critically for important intellectual content.

Teruhiko Kawamura contributed to patient care and revising the article critically for important intellectual content.

Takeshi Kuramoto contributed to patient care and revising the article critically for important intellectual content.

Kiyoko Kato contributed to patient care and revising the article critically for important intellectual content.

All authors approved the final submitted manuscript.

Patient consent

Written informed consent for publication of this case report, including anonymized clinical images, was obtained from the patient.

Provenance and peer review

This article was not commissioned and was peer reviewed.

Declaration of generative AI and AI-assisted technologies in the writing process

During the preparation of this work, the authors used OpenAI ChatGPT and Anthropic Claude in order to assist with language editing and to check reference formatting. After using these tools, the authors reviewed and edited the output as needed and take full responsibility for the content of the publication.

Funding

This work did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Declaration of competing interest

The authors declare that they have no competing interest regarding the publication of this case report.