Ultrasound Parameters Associated with Methotrexate Treatment Success for Cesarean Scar Pregnancy

Objective: Cesarean scar pregnancy (CSP) is a rare occurrence that is associated with high morbidity. Various options for the treatment of CSP exist, including medical management with methotrexate. Our study aimed to evaluate whether certain ultrasound parameters were associated with the treatment success of CSP using methotrexate.

Methods: This was a retrospective study of women diagnosed with CSP and treated with methotrexate at a single tertiary center between 2010 and 2020. Ultrasound images that included bladder and CSP were reviewed. The myometrial thickness at the level of the CSP and the distance between the sac and bladder were measured ([Fig. 1]). Demographic details, mean gestational sac diameter measurement, and treatment modalities were extracted from the medical record. The primary outcome was treatment failure using methotrexate, defined as needing a subsequent treatment method for successful management of CSP. The ultrasound measurements between those who had successful treatment with methotrexate and those who failed were compared using Wilcoxon rank-sum test.

Results: Of the 27 patients with CSP analyzed, 12 (44.4%) had treatment failure and 15 (55.6%) had successful treatment. Demographics are presented in [Table 1]. The mean age in the cohort was 33.2 ± 5.0 years, and the mean body mass index was 30.9 ± 6.2 kg/m². The mean gestational age of diagnosis was 46.9 ± 7.0 days. The ultrasound parameters are presented in [Table 2]. The ultrasound parameters did not differ between patients with CSP who had a treatment failure and those who had treatment success.

Conclusion: Ultrasound parameters, mean gestational sac diameter, the myometrial wall thickness at the level of CSP, and the distance from the bladder to CSP sac, were not found to be associated with methotrexate treatment failure of CSP. Ultrasound measurement of these parameters may not aid in predicting methotrexate treatment success in patients with CSP.

Table 1 Demographics of women diagnosed with CSP

Age (years)	33.2 ± 5.0
Body mass index (kg/m2)	30.9 ± 6.2
Ethnicity
White	9 (33.3)
Hispanic	4 (14.8)
Black	4 (14.8)
Asian	9 (33.3)
Other	1 (3.7)
Gestational age at diagnosis (days)	46.9 ± 7.0
Beta hCG (mIU/mL)	20,478 [6,802–40,875]
Number of prior cesarean deliveries	2 [1–3]
Treatment
Single dose of Mtx	7 (26)
Double dose of Mtx	8 (29.6)
Multiple doses of Mtx	9 (33.3)
Intrasac injection of Mtx	3 (11.1)

Abbreviation: Mtx, methotrexate.

Note: Data presented as mean ± standard deviation, median [interquartile range], or N (%). Mtx: methotrexate

Table 2 Ultrasound parameters and treatment

	Treatment failure (N = 12)	Treatment success (N = 15)	p-Value
Myometrial thickness (cm)	0.23 [0.13–0.36]	0.24 [0.19–0.32]	0.85
Distance of sac to bladder (cm)	0.59 [0.51–0.71]	0.58 [0.36–0.76]	0.73
Mean gestational sac diameter (cm)	2.26 [1.30–2.62]	1.91 [1.31–2.57]	0.66

Note: Data presented as median [interquartile range].

Fig. 1 Ultrasound measurements. Notes: Measurement with straight ends (0.11cm) = Myometrial thickness at the level of the CSP. Measurement with round ends (0.30 cm) = Distance from the bladder to the CSP sac.

Publication History

Article published online:
17 September 2021