Management of retained products of conception in a tertiary centre: a 20-year retrospective cohort study

Abstract

Background

Retained products of conception (RPOC) are defined as the persistence of trophoblastic tissue or placenta inside the uterine cavity after pregnancy. Management is challenging because there are no clearly defined diagnostic criteria, evidence-based guidelines, or treatment protocols. Our aim was to determine the success and complication rate of different methods of RPOC management at our tertiary centre in the last 20 years.

Methods

We retrospectively collected data from patients with RPOC treated in our Clinic from 2003 to 2021 in three-year intervals. The following data were obtained: age, type of RPOC, type of treatment, complications, histopathological evaluation of the acquired tissue, and the need for transfusion.

Conclusions

Our study shows that hysteroscopy and D&C are highly successful methods of RPOC, however, the complication rate in D&C is significantly higher. Moreover, less invasive treatment of RPOC using expectant and medical approach is plausible, especially in asymptomatic patients.

Background

The term retained products of conception (RPOC) defines the persistence of trophoblastic tissue or retained placenta inside the uterine cavity after pregnancy [1]. The clinical presentation of RPOC includes haemorrhage, endometritis, pain, fever, or a persisting dilated cervix with ultrasound findings that show interruptions of the endometrial stripe, visible areas of mixed echogenic material and the presence of low resistance doppler flow [2–5]. Endometrial thickness alone is found to be non-diagnostic for RPOC even in the presence of clinical symptoms. Furthermore, diagnostic criteria for RPOC may differ and consensus still does not exist [4]. It can occur after approximately 6% of pregnancies, with the incidence being even higher after spontaneous miscarriage or medical termination of pregnancy [6].

The management of patients with RPOC is challenging because there are no evidence-based guidelines or treatment protocols [5]. For stable patients with RPOC, based on both clinical and ultrasound findings, possible treatment includes expectant management, medical management or surgical management [4]. In the past, dilatation and curettage (D&C) was regarded as the standard surgical method for the treatment of RPOC. Its main advantage represents the possibility of immediate removal of the RPOC. However, it can represent a higher risk of complication including uterine perforation, infection, development of intrauterine synechiae (Asherman’s syndrome), lacerations of cervix, and very rarely bowel and bladder damage, broad ligament haematoma, incomplete evacuation and anaesthetic complications [4, 7]. Hysteroscopic (HSC) removal of RPOC could represent superior method of surgical treatment due to earlier conception rates, less risk of intrauterine adhesions formation and incomplete evacuation [4, 5, 8]. Medical or expectant treatment represents an alternative for patients wishing to avoid surgical management [4].

The main goal of our study was to determine the success and complication rate of different methods of RPOC management at our tertiary centre in the last 20 years. Moreover, we aimed to analyse the temporal trends in RPOC management.

Materials and methods

We conducted a single-centre retrospective cohort study in which we included women with RPOC, who were treated at Clinic for Gynaecology and Perinatology, University Medical Centre Maribor, Slovenia.

The primary aim of our study was to determine the success and complication rates of different methods of RPOC management. Our secondary aim was to analyse the temporal trends in RPOC management at our facility. IRB approval was obtained for the study, approval number UKC-MB-KME-31/22.

Using our centre’s computer database, we included women who were treated at our Clinic from 2003 to 2021 in three-year intervals. Patients were identified by using ICD-10 codes for spontaneous miscarriage, medical termination of pregnancy, any other type of abortion, complications after abortion/miscarriage and retained placental tissues with or without bleeding! Due to large number of patients identified using these codes, three-year interval sampling was used, which enabled us to cover larger period of time and to gain better insight into temporal trends of RPOC treatment. After identifying these patients, their computer files were manually examined by two authors to identify patients with RPOC.

Inclusion criteria were patients diagnosed with RPOC after delivery, spontaneous miscarriage, medical treatment of miscarriage, or termination of pregnancy, treated in our Clinic. Exclusion criteria were patients with RPOC up to 6 weeks after delivery, as they are treated at our department for perinatology, inevitable miscarriages (lat. abortus in tractu), and patients with suspected molar pregnancy.

For every patient included, the following data was obtained: age, type of RPOC (after delivery, after spontaneous miscarriage, after medical termination of pregnancy, after surgical termination of pregnancy, after medical treatment of missed abortion, and after surgical treatment of missed abortion), type of primary treatment, type of secondary treatment, presence of haemorrhage before treatment, complications, success rate, histopathologic evaluation of the acquired tissue and the need for transfusion. Successful treatment was defined as complete evacuation of RPOC (empty uterine cavity at the end of HSC and negative ultrasound findings at the follow-up after D&C, expectant, and medical management, respectively) and absence of RPOC symptoms using only one type of treatment. Complications were established on the basis of additional visits to our clinic due to symptoms (bleeding, signs of infections) or ultrasound findings at patients’ primary care gynaecologist that showed signs of RPOC.

The statistical analysis was performed using SPSS Statistics 21.0 programme. Basic patients’ characteristics were calculated using simple statistics. Mann-Whitney U test was used to compare numerical data between groups and Chi-square/Fisher’s exact test to compare categorical data between groups. Statistical significance was set at p < 0.05.

Results

Using our inclusion criteria (Fig. 1), we included 590 patients with the average age of 31.6 ± 6.1 (range 16–44) years and median of two pregnancies (range 1–11), one delivery (range 0–5), one medical termination of pregnancy (range 0–6) and median of zero spontaneous miscarriages (range 0–6). The haemorrhage as the symptom of RPOC was present in 341 cases (57.8%) (Table 1).

Fig. 1.

Flowchart of patients’ identification and inclusion. *ICD-10 codes for codes for spontaneous miscarriage, medical termination of pregnancy, any other type of abortion, complications after abortion/miscarriage and retained placental tissues with or without bleeding were used

Table 1.

Basic patients’ characteristics. Legend: MTP – medical termination of pregnancy, MTMM – medical treatment of missed miscarriage, STP – surgical termination of pregnancy, STMM - surgical termination of missed miscarriage

Variable	All patients	Patients with RPOC after delivery (N = 126)	Patients with RPOC after spontaneous miscarriage (N = 30)	Patients with RPOC after MTP (N = 224)	Patients with RPOC after MTMM (N = 60)	Patients with RPOC after STP (N = 108)	Patients with RPOC after STMM (N = 36)
Age (years ± SD, range)	31.6 ± 6.1 (16–44)	29.9 ± 5 (19–44)	33.3 ± 5.9 (18–42)	33.3 ± 5.9 (19–44)	33.8 ± 45 (23–43)	28.6 ± 7 (16–44)	33 ± 5.9 (21–43)
Pregnancies (median, range)	2 (1–11)	1 (1–6)	1 (1–5)	3 (1–10)	2 (1–7)	4 (1–11)	2 (1–9)
Deliveries (median, range)	1 (0–5)	1 (0–4)	0 (0–2)	2 (0–5)	1 (0–4)	2 (0–5)	1 (0–5)
MTP (median, range)	1 (0–6)	0 (0–2)	0 (0–2)	1 (0–6)	0 (0–2)	2 (1–6)	0 (0–3)
Spontaneous miscarriags (median, range)	0 (0–6)	0 (0–4)	1 (0–3)	0 (0–3)	1 (0–4)	0 (0–2)	1 (0–6)
Present hemorrhage (number, percentage)	341/580 (57.8%)	80/126 (63.5%)	20/30 (66.7%)	152/224 (67.9%)	32/60 (63.5%)	36/108 (33.3%)	21/36 (58.3%)

The highest proportion of RPOC was after medical termination of pregnancy (38.4%), followed by RPOC after delivery (21.6%), surgical termination of pregnancy (18.5%), and medical treatment of missed abortion (10.3%). In patients with RPOC after delivery, 22.6% delivered with Caesarean section.

The most prevalent type of treatment of RPOC was D&C (54.6%), with HSC being the second most frequent (27.2%). Medical management (9.9%) and expectant management (8.2%) were used the least. There were significant differences in success rates of different types of primary treatment (p-value < 0.001), the most successful were HSC with 96.9% and D&C with 94.3% success rate. Success rates of expectant management (79.2%) and medical treatment (58.6%) were lower. Secondary treatment due to incomplete evacuation of RPOC after primary treatment was needed in 57 (9.7%) patients. The most prevalent type of secondary treatment were D&C (54.4%) and HSC (40.4%). Expectant (3.5%) and medical treatment (1.8%) were chosen in minority. Of 159 patients, who had HSC management, only 14/159 (8.8%) needed two HSC sessions and only 1/159 (0.6%) needed three sessions. In patients who underwent hysteroscopy, RPOC were most frequently removed by hysteroscopic graspers (49.7%) or mechanical hysteroscopic tissue removal systems (25.7%), while resectoscopy was necessary in only 7.1% of cases. The choice of type of primary treatment in regards of presence of haemorrhage did not show statistical significance (p-value = 0.55).

When investigating type of primary treatment according to different types of RPOC (Table 2), there were statistically significant differences (p-value < 0.001). As seen from Table 2, patients with RPOC after surgical termination of pregnancy or surgical treatment of missed miscarriage were more likely to be treated with D&C, while patients with RPOC after delivery were more likely to be treated with HSC.

Table 2.

Type of primary treatment according to different type of RPOC. legend: legend: D&C – dilatation and curettage, HSC – hysteroscopy, MTP – medical termination of pregnancy, MTMM – medical treatment of missed miscarriage, STP – surgical termination of pregnancy, STMM - surgical termination of missed miscarriage

		Primary treatment				Total (N)
		D&C	HSC	expectant	medical
Type of RPOC	After delivery (N (%))	42 (33.3%)	82 (65.1%)	1 (0.8%)	1 (0.8%)	126
	After spontaneous miscarriage (N (%))	16 (53.3%)	12 (40.0%)	2 (6.7%)	0 (0%)	30
	After MTP (N (%))	104 (46.4%)	36 (16.1%)	39 (17.5%)	44 (19.7%)	223
	After MTMM (N (%))	22 (36.7%)	26 (43.3%)	5 (8.3%)	7 (11.4%)	60
	After STP (N (%))	100 (92.6%)	2 (1.9%)	1 (0.9%)	5 (4.6%)	108
	After STMM (N (%))	34 (94.4%)	1 (2.8%)	0 (0%)	1 (2.8%)	36

Majority of patients (88.2%) did not have any complications during or after treatment. However, when complications occurred, they were mild (bleeding, infection, anaemia, etc.). There were differences in complication rates in different types of primary treatment (p-value < 0.001). We observed more complications in the D&C (15.5%) and medical treatment (27.3%) groups in comparison to HSC (1.3%) or expectant management (4.2%) (Table 3). There were also significant differences in different types of complications according to primary treatment. For example, the rate of heavy bleedings was the highest in medical treatment group (12.7%), followed by D&C (3.5%). No heavy bleedings were reported in HSC and expectant management group. The rates of endometritis were also highest in D&C (6%) and medical treatment (7.3%) groups. Endometritis after HSC was reported in only 0.6% of cases. The rate of blood transfusions was very low, only 1.6%. Results of histopathological evaluation of acquired tissue were obtained in 257 cases, with 86.8% being the trophoblastic tissue, that confirmed diagnosis of RPOC. In one case, molar pregnancy was diagnosed.

Table 3.

Presence of complication in different types of primary RPOC treatment. legend: legend: D&C – dilatation and curettage, HSC – hysteroscopy

		Primary treatment				Total (N)
		D&C	HSC	expectant	medical
Presence of complication	No (N (%))	267 (84.5%)	152 (98.7%)	46 (95.8%)	40 (72.7%)	505 (88.1%)
Total (N)		316	154	48	55	573

Statistically significant increase in hysteroscopic methods of treatment of RPOC was observed with decrease in proportion of D&C (p < 0.001). While in 2003 all patients with RPOC were treated with D&C, this percentage decreased to 20% in 2021. On the other hand, the percentage of HSC increased from 0% in 2003 to 45.9% in 2021 (Fig. 2). Complication rate did not increase despite decrease of D&C rates and increase in other RPOC management methods (p-value = 0.253) (Fig. 3). As seen from Table 4, the most common complications in all types of RPOC treatment were bleeding and infection.

Fig. 2.

Temporal trends in primary treatment of RPOC between years 2003 and 2021. Legend: D&C – dilatation and curettage

Fig. 3.

Temporal trends in complication rate of RPOC treatment between years 2003 and 2021

Table 4.

Complications according to different type of RPOC. legend: legend: MTP – medical termination of pregnancy, MTMM – medical treatment of missed miscarriage, STP – surgical termination of pregnancy, STMM - surgical termination of missed miscarriage

		Complications (%)
		None	Bleeding	Infection	Anaemia	Intrauterine adhesions	Other
Type of RPOC	After delivery	92.9	4	0.8	0.8	0.8	0.8
	After spontaneous miscarriage	86.7	3.3	6.7	0	0	3.3
	After MTP	84.7	3.2	3.7	6.5	1.4	0.5
	After MTMM	88.3	1.7	5	3.3	0	1.7
	After STP	91.5	0.9	7.5	0	0	0
	After STMM	88.2	3.1	4.4	3	0.7	0.7

Discussion

To date, there is no standard approach to treatment of RPOC. At our centre, the management of RPOC has changed significantly in the past years. Currently, we opt for D&C only in cases of heavy bleeding or infection, while asymptomatic patients are treated by HSC, expectantly or medically.

In the past, blind D&C was most widely used first-line method of RPOC management [1]. Its main advantage is possibility of immediate evacuation of RPOC, even in the patients with heavy bleeding. However, this blind surgical technique is related to higher occurrence of complications. Moreover, the pathogenesis of development of intrauterine synechiae after D&C is related to damage of the basal layer of the endometrium, with the generation of intracavitary granulation tissue at the margins that fuse to form fibrous tissue bridges. The incidence of intrauterine synechiae after D&C is estimated to be between 15% and 40% [1, 9–12]. Intrauterine adhesions can negatively affect reproductive outcomes with pregnancy loss of up to 90%. Furthermore, infertility, oligomenorrhea, amenorrhea and cyclic pain may occur. With the increasing number of D&C, the probability of intrauterine adhesions formation increases [10, 13].

Higher incidence of complications after D&C encouraged trend to less invasive types of RPOC management (e.g. medical and expectant management) and use of direct visualisation techniques, such as HSC or resectoscopy. Our study showed statistically significant increase in minimally invasive and hysteroscopic methods of RPOC management. Since the introduction of outpatient HSC at our clinic 20 years ago, we managed to decrease the percentage of D&Cs in RPOC treatment from 100 to 20%. Meanwhile, more than 45% of patients after RPOC are treated with HSC. The main advantage of HSC is that targeted removal of the pathologic condition during the procedure minimizes the trauma to the healthy endometrium, with both short- and long-term potential benefits [1, 6, 9]. Meta-analysis show that the technique is effective, safe, with low rate of infections and low rate of intrauterine adhesion formation. HSC can be performed through as an office procedure, consequently lowering the cost relative to D&C through reduced facility- and anaesthesia associated costs [1]. Our study showed that HSC was a very effective method with success rate of 96.9%. Moreover, over 90% of patients who underwent hysteroscopy, needed only one treatment session. In our experience, the introduction of mechanical hysteroscopic tissue removal systems was especially beneficial in patients with RPOC, as it enables us to remove relatively large amounts of residual trophoblastic tissue in an office environment. Moreover, this procedure can mostly be performed in one session. Since the introduction of this type of RPOC treatment by Hamerlynck et al. in 2013 [14], this method has been increasingly used [15]. In our centre, more than 25% of patients that underwent hysteroscopic removal of RPOC, were treated using mechanical hysteroscopic tissue removal systems, while smaller RPOC were removed using hysteroscopic forceps. We believe that development of our outpatient HSC also enabled us to have relatively low percentages of resectoscopy for RPOC treatment (7.1%), which requires both general anaesthesia and cervical dilatation.

Non-invasive methods including medical treatment and expectant management are generally used more often in asymptomatic patients. In the study by Vyas et al., imaging findings were better predictors of conservative management than clinical features. Endometrial thickness < 10 mm, absence of endometrial vascularity, and absence of enhanced myometrial vascularity were the sonographic findings that predicted successful non-invasive management [16]. Relatively high success rate of expectant management (79.2%) in our study shows that this non-invasive treatment in properly selected cases can be very efficient. Despite the significant trend to utilization of less invasive techniques, we did not observe rise in complication rates. Moreover, complication rates were smallest in patients who underwent HSC and expectant management as primary treatment. However, it is difficult to compare complication rates between surgical (D&C, HSC) and non-surgical treatment (medical and expectant management), especially in a retrospective study, because the decision on certain type of treatment is usually dependant on several factors, such as clinical symptoms and ultrasound findings. Thus, asymptomatic patients with thinner endometrium might have a higher chance of opting for expectant management, while symptomatic patients or patients with thicker endometrium might have a higher chance to be referred to surgical treatment. However, when comparing complication rate of surgical treatment techniques, HSC was associated with smaller complication rate than D&C. Overall, the rate of transfusions was very low regardless of treatment type.

In the study by Tarasov et al., no effect of the time interval from the end of pregnancy to hysteroscopic evacuation of RPOC in asymptomatic patients on reproductive outcome was observed. There was no significant difference in conception rate, mean time to subsequent pregnancy, nor the appearance of a new infertility problem [6]. Their study implies that potentially longer time until RPOC evacuation, associated with less invasive techniques, does not have negative reproductive outcomes, rendering those types of treatments more advantageous in asymptomatic patients with suitable sonographic findings. However, additional studies are needed in regard of optimal time for RPOC evacuation. Furthermore, hysteroscopic, medical, and expectant management of RPOC offer the advantage of outpatient treatment, avoid the need for general anaesthesia, reduce the cost of treatment and decrease the probability of intrauterine adhesions formation.

Limitations of our study include inherent weakness of the retrospective manner of the study. Furthermore, the diagnosis of RPOC and the choice of treatment was not performed in standardized manner. Another limitation of our study is that the incidence of complications might be underrated, as not all patients received follow-up at our centre, but mostly at their primary care gynaecologists. It is possible that some minor complications were already treated at primary care level or that patients were referred to another hospital in our region. Moreover, ultrasound measurements are not always included in our computer data files and subsequently, the effect of sonographic findings on RPOC management could not be investigated. However, considering lack of large-scale studies investigating direct comparison of different types of treatment for RPOC, we believe that our results could represent a valuable contribution to the existing knowledge in this field, especially because of our high volume of patients.

Conclusions

The medical and technological development in recent decades made transition to less-invasive treatment of RPOC possible. According to our results, hysteroscopy was a highly effective surgical treatment option, which can be mostly performed in an office setting and in only one session. Our decrease in D&C was not associated with an increased number of complications. Less invasive treatment of RPOC is plausible, as HSC, medical, and expectant management offer the advantage of outpatient treatment, and avoid the need for general anaesthesia.

Abbreviations

D&C

Dilatation and curettage

HSC

Histeroscopy

RPOC

Retained products of conception

Authors’ contributions

GP: conceptualization, data curation, formal analysis, methodology, writing – original draft, writing – review and editing; TS: conceptualization, data curation, formal analysis, methodology, writing – original draft, writing – review and editing; BŽA: conceptualization, writing – review and editing. All authors reviewed the manuscript.

Funding

No financial support was provided for conduction of this work.

Data availability

The data that support the findings of the current study is available from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

IRB approval of University Medical Centre Maribor Ethics Committee was obtained for the study, approval number UKC-MB-KME-31/22. Informed consent to participate was waived by University Medical Centre Maribor Ethics Committee, as this is a retrospective study. This research was performed in compliance with Helsinki declaration.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.