Management of Coccygeal Anomalies Detected on Fetal Ultrasound
For coccygeal anomalies detected on fetal ultrasound, a detailed ultrasound examination should be performed to assess for additional anomalies, followed by fetal MRI after 22 weeks gestation if the anomaly is incompletely characterized, with consideration for genetic testing if associated anomalies are present. 1
Initial Assessment
- When a coccygeal anomaly is detected on routine ultrasound, a detailed ultrasound examination should be performed to look for additional markers and anomalies, either at the same time or scheduled for the near future 1
- The detailed ultrasound should focus on evaluating for associated anomalies, particularly those involving the central nervous system, gastrointestinal tract, and urinary system, as these may commonly co-occur with coccygeal anomalies 1
- Coccygeal anomalies may represent various conditions including sacrococcygeal teratomas, which can be associated with high-output cardiac failure and hydrops fetalis if highly vascularized 1
Advanced Imaging
- Fetal MRI is indicated following ultrasound examination when information about the coccygeal anomaly is incomplete or additional details are needed for management planning 1
- MRI is ideally performed at or after 22 weeks gestation, though it may be valuable between 18-22 weeks in certain clinical scenarios 1
- MRI can provide important information that may confirm or complement ultrasound findings and potentially alter patient management, particularly for planning prenatal or postnatal interventions 1
- MRI is especially helpful for evaluating retroperitoneal and pelvic anomalies, which includes the coccygeal region 1
Genetic Evaluation
- If the coccygeal anomaly is associated with other structural abnormalities, fetal karyotyping, fluorescence in situ hybridization studies, and/or chromosomal microarray analysis should be offered 1
- Genetic testing can be performed via amniocentesis or fetal blood sampling, with the latter allowing direct analysis of fetal hematocrit if anemia is suspected 1
- Genetically transmitted disorders account for about one-third of cases with multiple anomalies, so a complete family history is imperative 1
Follow-up Monitoring
- Repeat transabdominal ultrasound should be performed for growth monitoring, delivery planning, and postnatal management in the setting of identified coccygeal anomalies if the pregnancy is continued 1
- If the coccygeal anomaly appears to be a sacrococcygeal teratoma, close monitoring for development of hydrops fetalis is essential, as these tumors can be very vascular and lead to high-output cardiac failure 1
- For isolated minor coccygeal anomalies without other markers or structural abnormalities, follow-up ultrasound at 32 weeks gestation may be appropriate to reassess the finding and evaluate fetal growth 1
Delivery Planning and Postnatal Management
- Delivery planning should consider the size and nature of the coccygeal anomaly, with potential need for cesarean delivery if the anomaly is large or likely to cause dystocia 1
- Multidisciplinary consultation with pediatric surgery, neurosurgery, and neonatology should be arranged prior to delivery for complex coccygeal anomalies 1
- Postnatal evaluation should include MRI to better characterize the anomaly and assess for intraspinal extension, as sacrococcygeal dimples can be associated with fibrolipoma of the terminal filum in approximately 16.7% of cases 2
Common Pitfalls to Avoid
- Failure to perform detailed ultrasound when a coccygeal anomaly is detected, potentially missing associated anomalies that could impact prognosis and management 1
- Inadequate imaging before 18 weeks gestation, which may result in incomplete anatomic surveys and missed anomalies 3
- Overlooking the potential for intraspinal extension of coccygeal anomalies, which may require neurosurgical intervention postnatally 2
- Neglecting to consider the possibility of sacrococcygeal teratoma, which may require fetal intervention in cases complicated by hydrops fetalis 1