Lower urinary tract dysfunction following sacrococcygeal teratoma resection in neonates: a long-term clinical follow-up study

Introduction

Sacrococcygeal teratoma (SCT) is a common solid tumor in neonates, SCTs occurring in 1 in 30.000–40.000 live births. The incidence is higher in female infants than in male infants. Most cases can be detected during the fetal period, and surgical resection of the tumor is the main treatment method (1-4). SCT can induce lower urinary tract dysfunction (LUTD) through mass effect and surgery-related sequelae, including frequent micturition, enuresis, urinary incontinence, dysuria, and urinary retention (5,6). Previous studies have reported that the incidence of LUTD following surgery ranges from 19% to 51%. Some cases can persist into adulthood, leading to upper urinary tract damage and significantly impairing the quality of life in adulthood (6-9). Current studies have found that the abnormality rate of urodynamic studies (UDS) conducted after SCT surgery is as high as 79% (9,10), this indicating that LUTD following SCT surgery may be underestimated.

This study mainly analyzed the incidence of LUTD in patients who underwent SCT surgery in our hospital during the neonatal period through follow-up, and preliminarily evaluated the lower urinary tract function of these children after SCT surgery based on the results of UDS. The purpose of this study is to remind clinicians to pay attention to the lower urinary tract function of such patients and implement early clinical intervention to reduce the occurrence of adverse outcomes. We present this article in accordance with the STROBE reporting checklist (available at https://tau.amegroups.com/article/view/10.21037/tau-2026-0325/rc).

Methods

This study employed a retrospective observational cohort study. A retrospective summary and analysis were conducted on the clinical data of neonates who underwent surgical resection of SCT from January 2012 to January 2021. A total of 46 cases were included, among which 15 were male infants and 31 were female infants. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Ethics Committee of Gansu Provincial Maternity and Child-care Hospital (Gansu Provincial Central Hospital). Informed consent was waived in this retrospective study.

Inclusion criteria: (I) age ≤28 days; (II) surgical treatment performed within 28 days after birth; (III) pathological examination after surgery confirmed teratoma; (IV) complete clinical data available, and the age of the child at follow-up was over 3 years old. Exclusion criteria: (I) complicated with structural malformations of other systems; (II) complicated with other reproductive system tumors; (III) poor general condition that precludes surgical treatment; (IV) poor follow-up compliance.

Data collection

Gansu Provincial Maternity and Child-care Hospital (Gansu Provincial Central Hospital) for surgical treatment from January 2012 to January 2021. All the children included in the study received uniform perioperative management, laboratory tests, imaging examinations and surgical treatment in our hospital. The overall follow-up time for all cases was at least 3 years.

Brief surgical procedures

The pediatric patients were placed prone with the lower abdomen elevated. Preoperative digital rectal exam assessed tumor size and the relationship with surrounding tissues (Figure 1). A reverse V-shaped incision was made, and a needle-tipped electrosurgical knife was used to reach the tumor capsule. Sharp and blunt dissection was performed along the capsule. To protect the rectum and urethra, a urinary catheter and anal tube were placed preoperatively, or the anterior wall was dissected using a finger as a landmark. The lateral walls and the upper pole of the tumor were dissected. The coccyx and satellite lesions were resected, and the tumor was sent for pathology (Figures 2,3). For neonatal types I-III and some type Ⅳ tumors, surgery is typically completed via sacrococcygeal incision alone; if not feasible, a transabdominal approach is used. After confirming no nerve injury or bleeding, the rectal walls, anal sphincter, and pelvic cavity were closed layer by layer. A negative-pressure drain and anal tube were placed (Figure 4).

Figure 1 Neonatal sacrococcygeal teratoma (type I).

Figure 2 Gross appearance of the lesion.

Figure 3 Microscopic examination of the lesion. (HE staining, ×100). HE, hematoxylin and eosin.

Figure 4 Postoperative appearance of the surgical incision.

Laboratory and imaging examinations

All patients underwent preoperative measurement of serum alpha-fetoprotein (AFP). Postoperatively, AFP levels were monitored at 1 month, then every 3 months during the first postoperative year, and thereafter every 6 months; a minimum follow-up duration of 3 years was mandated. The institutional reference range for AFP was defined as <7 ng/mL; values ≥7 ng/mL were classified as elevated. Preoperative imaging comprised sacrococcygeal and abdominopelvic color Doppler ultrasonography, as well as pelvic magnetic resonance imaging (MRI). Tumor classification according to the Altman system was based on preoperative MRI findings. The Altman subtypes are defined as follows: Type Ⅰ, predominantly extrasacral with complete external protrusion; Type II, predominantly extrasacral with >50% of the tumor volume externalized; Type III, predominantly presacral with ≤50% external component; Type Ⅳ, entirely presacral with no external component. Type IV tumors are rare (accounting for approximately 10% of cases) and typically manifest later in infancy or early childhood (11).

Investigation data and follow-up methods

General clinical data

The recorded data included age at admission, gender, body weight, clinical symptoms, AFP level, surgical approach, operation duration, blood loss volume, Altman classification, and histopathological classification.

Evaluation of lower urinary tract function

The LUTD of children after SCT surgery was initially evaluated mainly through outpatient medical records review and telephone follow-up. The evaluation was based on micturition diaries, which included parameters such as frequency of micturition, enuresis, urinary incontinence, and dysuria. Voiding diaries adhered to a standardized 48-hour protocol, documenting micturition frequency, voided volume, and incontinence episodes. Telephone interviews were conducted using a structured questionnaire aligned with International Children’s Continence Society (ICCS) terminology. Clinical interpretation of bladder function in children with delayed toilet training was performed with caution, given the potential immaturity of voluntary bladder control.

UDS assessment: post-void residual urine volume (PVR), voided volume, maximum urinary flow rate (Q_max), and urinary flow curve. Invasive urodynamic studies (IUDS) were performed in pediatric patients whose guardians provided informed consent and signed the informed consent form. The examinations were strictly conducted in accordance with the operational standards for pediatric urodynamics (12), and parameters including bladder capacity, detrusor activity, urinary incontinence, bladder compliance, and maximum detrusor pressure (Pdet) were recorded. UDS should be performed for all children with lower urinary tract symptoms (LUTS). For those unable to cooperate, non-invasive UDS (NUDS) should be conducted first. UDS should be performed at least six months after toilet training or when symptoms have persisted for more than three months.

Statistical analysis

The data were statistically analyzed using SPSS 23.0. Continuous variables were expressed as mean ± standard deviation and compared between two independent groups using the independent-samples t-test. Categorical data were analyzed using the Chi-square test or Fisher’s exact test when expected cell counts were less than five. Due to the small sample size, especially in the LUTD subgroup (n=9), only univariate analyses were performed, and no multivariate regression was used to adjust for confounders. Results should be considered exploratory. Statistical significance was set at two-sided P<0.05.

Results

General clinical data

A total of 46 pediatric patients who met the inclusion criteria and had complete clinical data were enrolled in this study, among whom 15 were male (32.61%) and 31 were female (67.39%), with a male-to-female ratio of 1:2.07. The age at admission ranged from 1 to 28 days, with a mean age of (9.7±10.1) days, and the mean birth weight was (3.53±0.74) kg. Of these patients, 6 were diagnosed prenatally, while the remaining patients were admitted due to a sacrococcygeal mass identified after birth; one patient presented with a ruptured and infected mass. The follow-up period ranged from 3 to 7 years, with a mean duration of (4.9±1.4) years. According to the Altman clinical classification, the patients were divided into 6 cases of Type Ⅰ (13.04%), 26 cases of Type Ⅱ (56.52%), 5 cases of Type III (10.87%), and 9 cases of Type Ⅳ (19.57%). The preoperative AFP levels of all 46 pediatric patients were positive, with a mean value of (35,411.0±62,377.2) ng/mL. Among them, the AFP levels of 4 patients failed to return to the normal range within 1 year of postoperative follow-up, ranging from 15.2 to 55.6 ng/mL, while the results of sacrococcygeal color Doppler ultrasound and MRI showed no abnormalities. All 46 pediatric patients underwent a single surgical procedure, with the age at surgery ranging from 2 to 28 days. Among them, 32 cases (69.57%) underwent surgery within 2 weeks, and 14 cases (30.43%) underwent surgery after 2 weeks. The surgical approach was via sacrococcygeal incision in 41 cases, and via combined transabdominal-sacrococcygeal approach in 5 cases (10.87%). Complete tumor resection was achieved in all patients. Intraoperatively, 30 lesions (65.22%) were cystic and 16 lesions (34.78%) were solid. The mean operation duration was (97.5±38.5) minutes, and the mean intraoperative blood loss was (5.9±4.3) milliliters. Postoperative pathological examination confirmed the diagnosis of SCT in all cases, including 43 cases (93.48%) of mature teratoma and 3 cases (6.52%) of immature teratoma.

Frequency distribution and comparison of LUTD among different groups of pediatric patients after SCT surgery

Lower urinary tract function was initially evaluated by recording a 2–3 days micturition diary for 46 pediatric patients. Among them, 37 cases (80.4%) had no LUTD, while 9 cases (19.6%) presented with LUTD, including 4 cases of frequent micturition, 3 cases of diurnal urinary incontinence, 1 case of dysuria, and 1 case of enuresis. The incidence of LUTD was 13.3% in male patients (1 case of frequent micturition and 1 case of weak micturition), and 22.6% in female patients (3 cases of frequent micturition, 3 cases of urinary incontinence, and 1 case of enuresis). Thirty-two pediatric patients (61.6%) underwent surgery within 2 weeks, among whom 6 cases (18.7%) developed LUTD. Fourteen patients (38.4%) underwent surgery after more than 2 weeks, with 3 cases (14.3%) developing LUTD. Forty-one patients were treated via the perineal-sacrococcygeal approach, and 8 cases (19.5%) developed LUTD. Five patients underwent surgery via the combined transabdominal-perineal approach, with 1 case (20.0%) developing LUTD. According to the Altman clinical classification, the incidence rates of LUTD were as follows: 1 case (16.7%) in Type I, 5 cases (19.2%) in Type II, 1 case (20.0%) in Type III, and 2 cases (22.2%) in Type IV. Among the 35 pediatric patients with a postoperative tumor diameter ≤10 cm, 6 cases (23.1%) developed LUTD; among the 11 patients with a postoperative tumor diameter >10 cm, 3 cases (27.3%) developed LUTD. According to the postoperative pathological classification, the incidence rates of LUTD were 20.9% and 0%, respectively. Comparisons of the postoperative LUTD incidence rates among subgroups stratified by gender, surgical timing, surgical approach, clinical classification, tumor diameter, and pathological classification showed no statistically significant differences (χ²=0.119, P=0.73; χ²=0.000, P>0.99; χ²=1.000, P=0.68; χ²=0.489, P>0.99; χ²=0.074, P=0.79; χ²=0.017, P=0.90), as presented in Table 1.

Comparison of tumor size between children with different classifications and those with or without LUTD

Comparisons of postoperative tumor size between pediatric patients with and without LUTD following surgical management of Type I, Type III, and Type IV SCT revealed no statistically significant differences (t=−1.876, P=0.13; t=1.264, P=0.30; t=0.050, P=0.96). In contrast, the comparison of tumor size between children with and without LUTD after Type II SCT surgery revealed a statistically significant difference (t=−2.781, P<0.05), as shown in Table 2.

Analysis of LUTD urodynamic examination results in 9 children with SCT after surgery

All children underwent UDS after the age of 3 years, with an average examination age of 4.8 years. A total of 9 pediatric patients underwent NUDS, among which 7 patients received MUDS. Two family members were unable to consent to the invasive procedure. The urinary flow curve analysis included normal, tower, plateau, and staccato. Overall, the abnormality rate in UDS was approximately 88.9%. All the children who underwent UDS showed an increase in PVR in 2 cases, both of which were type IV. Q_max was reduced in both cases, with values of 1.70 and 3.04 mL/s. There was no active contraction of the detrusor muscle during urination, and these cases were diagnosed as neurogenic bladder. Detrusor overactivity (DO) was observed in 5 children during the filling phase, among which four cases had urinary incontinence. The classification included type II, type III and type IV, and one case had poor bladder compliance. Bladder capacity at capacity (BCC) was found to be larger than PVR in one child, with normal bladder compliance demonstrated. Further performance of voiding cystourethrography revealed bilateral grade Ⅳ vesicoureteral reflux, which accounted for the aforementioned findings. Active detrusor contraction during the voiding phase was identified in 5 children, with a mean maximum Pdet of 34.8 cmH₂O. The clinical manifestations included frequent micturition, enuresis and urinary incontinence. Children with DO were administered standardized anticholinergic therapy, while those with neurogenic bladder were instructed to perform clean intermittent catheterization and undergo regular follow-ups to monitor changes in upper urinary tract function. Detailed examination findings of all children are summarized in Table 3.

Discussion

SCT often presents as a sacrococcygeal mass, which is more common in females. Most are benign, and the pathological composition may be cystic, solid, or cystosolid, with mature or immature cellular features; malignant components are rare. Literature reports indicate that the Altman classification distribution of SCT is as follows: Type I (14–27.3%), Type II (25–54.5%), Type III (33.3–37.5%), and Type IV (7–18.2%) (13-16). In this study, the incidence rate among females was 2.07 times that among males. The incidence rates were 13.04% for Type I, 56.52% for Type II, 10.87% for Type III, and 19.57% for Type IV, which is consistent with literature reports. All patients underwent primary surgical resection, including coccygectomy. The procedure was performed during the neonatal period. Postoperative pathological examination revealed 43 cases (93.48%) of mature teratoma and 3 cases (6.52%) of immature teratoma. However, some literature reports indicate that teratomas carry a risk of malignant transformation, and this risk increases with age. Therefore, surgical intervention should be undertaken as early as possible after diagnosis (7,17). One of the biological characteristics of teratomas is their ability to produce AFP. However, not all teratomas produce AFP. Approximately 50% of children with benign teratomas have elevated AFP levels. In newborns, AFP levels physiologically increase within the first 9 months of life. Therefore, preoperative AFP test results lack diagnostic accuracy. However, during postoperative follow-up, serial AFP measurements can serve as an early indicator of tumor malignancy or recurrence (18-20). In this study, AFP levels were elevated in all neonates. At the 1-year follow-up, only 4 cases (8.7%) maintained AFP concentrations within a relatively low range, approximately 15.2–55.6 ng/mL, serial imaging examinations during follow-up revealed no residual tumor or recurrence. Due to the anatomical location and surgical requirements associated with SCT, the risk of LUTD significantly increases following surgery. The underlying pathophysiological mechanisms include lower urinary tract obstruction secondary to tumor compression and iatrogenic injury to the pelvic autonomic nerves during surgical resection. Clinical manifestations encompass urinary frequency, urgency, incontinence, and leakage (19,21,22). This study initiated follow-up at age 3 years and found that the incidence of LUTD following SCT surgery was 19.6%, with manifestations including urinary frequency, incontinence, enuresis, and weak urinary stream. According to the Altman classification, the incidence of LUTD was 16.7% in type I, 19.2% in type II, 20.0% in type III, and 22.2% in type IV. Khanna et al. (16) reported that 36.8% of patients developed LUTS following SCT resection, including urinary incontinence, enuresis, and weak urinary stream. Subsequent studies demonstrated an even higher prevalence of abnormal UDS findings. Shalaby et al. (23) found that, among 31 patients aged 5 to 35 years, 55% reported LUTS. No significant association was observed between complication occurrence and Altman classification. Given the small sample size, the study is susceptible to selection bias. In 2011, Berger et al. (19) reported that 50% of pediatric patients exhibited bladder dysfunction, which was observed across all Altman classification subtypes. Prior studies have indicated that SCTs with presacral components are associated with an increased risk of LUTD following surgery. Among patients with Altman type IV SCT, more than 50% developed LUTD. Among all patients diagnosed with LUTD, 50% had tumors predominantly located in the presacral region, including 52% of those with Altman types III and IV. It was also found that no significant differences were observed between these patients and those without LUTD. Several studies have further reported that LUTD may manifest years after SCT surgery and progressively worsen with age. Tailor et al. (24) reported that abnormalities in LUTD emerge early postoperatively, often manifesting within the first year following surgery. Hambraeus et al. (22) found that low gestational age is a predictor of LUTD and intestinal dysfunction, suggesting that early surgical intervention should be considered and that attention should be paid to lower urinary tract function in these children. These studies collectively indicate that, regardless of clinical classification, children with SCT require early and systematic assessment of lower urinary tract function both preoperatively and postoperatively to mitigate the potential adverse effects of LUTD on upper urinary tract integrity. Our study found no significant differences in the postoperative incidence of LUTD across gender, surgical timing, surgical approach, clinical classification, and pathological classification. This lack of observed differences may be attributable to the limited sample size, as most infants had not yet achieved toilet training and therefore could not undergo early assessment of lower urinary tract function. Salim et al. (8) found that a higher Altman classification, the presence of malignant components in the tumor, and reoperation were closely associated with poorer long-term functional outcomes, including LUTD and intestinal dysfunction. In some children with intestinal dysfunction following SCT, symptoms improved or resolved completely during later follow-up.

There is currently some controversy regarding whether LUTD following SCT surgery results from tumor compression, surgical trauma, or both. We observed that, in Altman type II, a difference existed between patients with and without postoperative LUTD. In this small subgroup, larger tumor size was associated with LUTD, although this finding requires validation in larger cohorts. This suggests that the mass effect plays an important role in the development of LUTD following SCT surgery. The underlying mechanism may involve compression of the pelvic floor muscles by a large tumor, leading to impaired bladder and bowel control. During surgery, inadvertent injury to these muscles and associated nerves can result in urinary and fecal incontinence. Therefore, in addition to complete tumor resection during surgery, surrounding nerves and muscles must be carefully preserved to prevent excessive dissection (25). Hambraeus et al. (22) reported similar findings in a cohort study: children with lower urinary tract and intestinal dysfunction had significantly larger tumor diameters. LUTD was not observed in children with tumor diameters less than 9 cm, and constipation symptoms were milder. Both findings were potentially attributable to less extensive involvement of pelvic nerves and muscles. Partridge et al. (7) proposed that pelvic floor dysfunction may be present prenatally. Several single-center studies have also indicated that prenatal ultrasound examination is crucial for predicting pregnancy outcomes. A prenatal ultrasound finding of a cystic sacrococcygeal tumor is an important predictor of favorable functional outcomes in newborns (26).

USD is an important diagnostic modality for assessing lower urinary tract function and can predict the risk of upper urinary tract injury in children with LUTD, particularly those with neurogenic bladder. UDS should be performed as early as possible (27). Berger et al. (19) found that bladder dysfunction after SCT surgery is very common. Among children who have undergone multiple surgeries, the incidence of LUTD is approximately 90%, and there is a strong correlation between clinical symptoms and UDS results. Khanna et al. (16) found that children without LUTS or abnormal ultrasound findings after SCT surgery may still have abnormal UDS results. Such children are at increased risk of undetected upper urinary tract injury and often develop urinary tract complications in adulthood. Therefore, early and close follow-up and intervention are needed. In our study, UDS was performed only in children with LUTS, and the rate of abnormal UDS results was 88.9%. Our study performed UDS only in symptomatic patients, which may have underestimated the true prevalence of bladder dysfunction. Previous studies suggest that asymptomatic patients can also have abnormal UDS findings. Meanwhile, delayed toilet training led us to overlook the assessment of lower urinary tract function. UDS performed after SCT surgery can reveal detrusor instability and abnormal maximum bladder capacity during the filling phase, and can also demonstrate whether the detrusor contracts voluntarily and whether detrusor-sphincter dyssynergia is present during the voiding phase (28,29). Kadakal et al. (30) found in their study that all patients evaluated by UDS had no DO and normal bladder compliance during the filling phase, and no urinary incontinence occurred. Among them, 10% of the patients had a BCC greater than the EBC. During the urination period, 8 patients exhibited normal urination time, BCC, Q_max, and urine flow curve, whereas only 1 patient exhibited a staccato urine flow curve. The results show that for Altman type I and type II patients, non-invasive assessment methods should be given priority. However, for SCT patients with pelvic components, invasive examinations may need to be conducted as early as possible. At the same time, the importance of long-term follow-up is emphasized—a finding that differs from those of previous studies. In the UDS of patients after spinal SCT-related bladder dysfunction surgery, it was reported that the abnormality rate during the filling phase was approximately 17.5–55.5%, including DO, decreased maximum cystometric capacity, and low-compliance bladder (16,31). In the study on UDS during voiding in children after SCT, it was reported that 45.4–50% of cases exhibited Detrusor-sphincter dyssynergia (31,32). In our UDS after SCT-related surgery, we observed 5 cases of DO during the filling phase, 4 of which exhibited uncontrolled DO leading to urinary incontinence. One case showed poor bladder compliance. In one child, the BCC exceeded PVR, and bladder compliance was normal. Voiding cystourethrography revealed vesicoureteral reflux, but the findings created a false impression of normal bladder compliance. In the voiding-phase study, 2 cases lacked active detrusor contraction and were diagnosed with NB. Based on previous studies, we recommend that, in addition to monitoring urinary system symptoms, children after SCT-related surgery undergo UDS assessment as early as possible. Video UDS can detect upper urinary tract injury at an early stage.

The limitations of our study include the relatively small number of patients, the lack of multi-center studies, and the absence of a control group, which may lead to bias in the results. UDS was performed only in patients with clinical symptoms or abnormal voiding diaries. Therefore, the true prevalence of subclinical or asymptomatic LUTD cannot be determined from this study. Selection bias may have led to an overestimation of LUTD severity in the analyzed subgroup and an underestimation in the overall cohort. Some of the research subjects did not receive toilet training, which might have led to the neglect of some LUTS, resulting in bias in the research results.

Conclusions

In this study, we preliminarily evaluated the lower urinary tract function of 46 children who underwent SCT surgery. For symptomatic patients with SCT, or those with large tumors, radiographic or surgical evidence of sacral involvement, or postoperative voiding dysfunction, early urodynamic evaluation is recommended. Routine screening of asymptomatic patients is not supported by the current data and requires further prospective study. In Altman type II, larger tumor size was associated with LUTD in this small subgroup, suggesting that mass effect may warrant further investigation as a potential risk factor. Long-term follow-up of lower urinary tract function is recommended for symptomatic patients. For selected cases, video UDS could potentially detect early upper urinary tract injury, though this requires further study.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://tau.amegroups.com/article/view/10.21037/tau-2026-0325/rc

Data Sharing Statement: Available at https://tau.amegroups.com/article/view/10.21037/tau-2026-0325/dss

Peer Review File: Available at https://tau.amegroups.com/article/view/10.21037/tau-2026-0325/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tau.amegroups.com/article/view/10.21037/tau-2026-0325/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Ethics Committee of Gansu Provincial Maternity and Child-care Hospital (Gansu Provincial Central Hospital). Informed consent was waived in this retrospective study.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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