A Tumour at the Base of the Spine: What Families Can Expect Before Birth, After Surgery, and Years Later

Four studies from the Czech Republic, South Korea, Italy and China, published in 2025 and 2026, on predicting risk in sacrococcygeal teratoma

A sacrococcygeal teratoma is a tumour that grows at the base of a baby's spine before birth. It is the most common tumour found in newborn babies, it is almost always non-cancerous, and most babies who have one go on to do well after surgery to remove it. Four studies published between April 2025 and July 2026 looked at how doctors can tell, at each stage, which babies face the greatest risks — before birth, during the operation, and in the years that follow.

Each of the four follows a different part of the journey. A team at University Hospital Brno in the Czech Republic looked back at sixteen pregnancies to see which ultrasound features actually predicted what happened afterwards [1]. A hospital in Seoul, South Korea, studied 97 children who had surgery, seeking a better way to judge how big a tumour really is [2]. An Italian group gathered every published report of treatment given to a baby before birth — 814 cases [3]. And a hospital in Lanzhou, China, followed 46 children for three to seven years after surgery to see how their bladders were working [4].

What this tumour is, and why it is usually not cancer

Sacrococcygeal teratoma happens in roughly one in every 35,000 to 40,000 births, and is about three to four times more common in girls than boys [5]. The name describes where it sits: sacrococcygeal means the area of the tailbone, and teratoma is the medical word for a growth made up of several different kinds of tissue mixed together.

That mixture is the key to understanding it. Very early in pregnancy there is a small cluster of cells near what will become the tailbone that can still turn into almost any kind of tissue. If a few are left behind, they can keep growing and produce a lump containing bits of many tissue types — sometimes skin, sometimes fat, occasionally cartilage or even hair [6]. That is why these tumours are usually benign: they are a growth in the wrong place rather than a cancer.

Doctors sort them into four types, using a system created in 1974 that describes how much of the tumour sits outside the body and how much deep inside the pelvis [7]. Type I is almost entirely on the outside; type IV entirely inside, hidden. The system tells a surgeon how to plan the operation — but as you will see, it is surprisingly poor at predicting how a child will do.

How families used to face this diagnosis, and what changed

For most of medical history these tumours were discovered at birth, and the response was straightforward: remove the lump, take out the tailbone as well to stop it growing back, and hope for the best. Routine pregnancy ultrasound changed that. From the 1980s onwards these tumours started being found at the twenty-week scan, months before birth — a real advance, but one that created a difficult new situation. Instead of a problem to be fixed after delivery, parents were now given news in mid-pregnancy about something that might get worse over the coming weeks.

The reason things can get worse is not cancer. It is blood flow. A large tumour needs a large blood supply, and the baby's heart has to pump all of that extra blood. If the tumour grows fast and has many blood vessels, the heart can be asked to do more than it can manage — high-output heart failure, which can lead to fluid building up throughout the baby's body (a condition called hydrops) and, in the worst cases, to the baby dying before birth. Hospitals in Philadelphia developed the approach still used today: watch these pregnancies closely with repeated scans and heart ultrasounds, and treat only when the heart starts to struggle [8]. A team in Houston later created the first real measurement tool, comparing the volume of the tumour to the weight of the baby, and found that a ratio above a certain point before 24 weeks marked out the pregnancies most likely to run into trouble [9]. A French group added another distinction: tumours that were large, full of blood vessels and growing quickly did badly, while tumours that were large but mostly fluid-filled did well [10].

What all of this left out was the child after they went home — a question that has only recently begun to get the attention it deserves [11].

What the scans can tell you, and what they cannot

The Czech study is small, but honest and complete: it reports what happened to every one of the sixteen pregnancies [1]. Ultrasound found 87.5% of the tumours before birth — three very early, at 13, 14 and 16 weeks, and most of the rest at the routine twenty-week scan.

The clearest finding concerns what the tumour looked like. Six of the seven tumours found before birth that went on to delivery were mostly cystic — fluid-filled rather than solid — with few blood vessels and no sign of strain on the baby's heart. All six of those babies did well. The one mostly solid tumour ended badly: that baby was born at 25 weeks during a sudden, unplanned labour and died shortly afterwards.

Among the eight babies born alive, the picture over the following years was reassuring. One had a wound infection needing a second operation; two needed a temporary bag (a stoma) for a few months because the bowel became blocked; one had the tumour come back at age two and was treated with chemotherapy; one had mild ongoing urinary leakage. Five of the eight had no serious problems at all and were meeting all their milestones. One further detail cuts against the fear that finding a tumour early is bad news: the two tumours that turned out to be genuinely cancerous were the two missed on the scans and found only after birth.

It is also worth knowing that seven of the sixteen pregnancies were ended at the parents' request before 24 weeks — in four of those after scans showing several worrying features at once. That rate was much lower than the Czech national average over the same years, meaning this group of families was more likely than most to continue. Outcome figures always reflect who was included.

Why the size of the tumour compared with the size of the baby matters

The Korean study asked a deceptively simple question: when doctors say a tumour is "large," large compared with what? A tumour 10 cm across on a full-term baby weighing 3.5 kg is a very different problem from the same tumour on a premature baby weighing 1.8 kg.

So the team measured the tumour against the child — its volume compared with the baby's weight, and its length compared with the baby's length — in 97 children [2]. Both comparisons worked well. Children whose tumours were large relative to their own size were far more likely to need a blood transfusion during surgery, to need help breathing afterwards, to spend longer in intensive care (about 18 days rather than 10) and in hospital overall (about 22 days rather than 13), and to have the tumour come back (44% rather than 9%).

The most striking result was a negative one. Grouping children by the old four-type system — outside-the-pelvis types against inside-the-pelvis types — made no difference to any outcome at all. After fifty years, the classification that tells a surgeon how to operate turns out not to tell a family what to expect.

Treatment before birth: what it can achieve, and what it costs

The Italian study pulled together every published case of a baby treated in the womb for this tumour: 180 babies out of 814 [3]. Treatment is only offered when a baby is already in serious trouble — usually because fluid is building up or the heart is failing — so these are the hardest cases, not typical ones.

Just over half of the treated babies survived. The gentler procedures worked best: draining fluid from around the baby, or from a large fluid-filled part of the tumour, had survival rates above 90%. Procedures using heat or alcohol to destroy tumour tissue did considerably worse, at around 45%. Aiming treatment at the blood vessels feeding the tumour rather than at the tumour itself worked better — which makes sense, because the blood flow is the real danger.

One number deserves to be widely known. Among treated babies who survived the pregnancy but died afterwards, almost all died from complications of being born too early, not from the tumour or the procedure. This is why doctors increasingly favour delivering the baby once the pregnancy has passed about 28 weeks rather than performing a risky procedure in the womb. Treatment before birth also carries real risks for the mother, including bleeding and serious blood-pressure complications.

Why bladder problems can show up years later

The Chinese study followed 46 children for three to seven years after their operation [4]. All had the tumour completely removed as newborns, and by every surgical measure the operations went well.

Nine of the 46 — about one in five — had bladder problems by school age. Four needed to urinate very often, three had daytime wetting, one had difficulty passing urine and one wet the bed. When those nine had detailed bladder testing, eight showed a measurable abnormality: two had a bladder that did not empty properly and needed draining with a small catheter, and five had an overactive bladder treatable with medication.

What could not be predicted was who would be affected. It was not related to the child's sex, to how soon after birth they had surgery, to the surgical approach, to the tumour's type, or to whether the tumour was benign or borderline. Only one pattern emerged: among the type II tumours, children who developed bladder problems had had noticeably bigger tumours. That is a single finding in a small group and needs confirming, but it suggests the pressure of a large tumour on the pelvis before birth may matter as much as anything the surgeon does.

What this means for your family

If you have just been told your baby has a sacrococcygeal teratoma, three things are worth holding onto. The common pattern — a mostly fluid-filled tumour with few blood vessels and no strain on the baby's heart — carries a good outlook. Delivery is usually planned by caesarean section for a large tumour, with surgery in the first few days of life. And most children go on to grow up normally.

The one thing worth raising actively with your child's team is follow-up. Hospitals reliably check for the tumour coming back, using blood tests and scans over several years [12]. Bladder and bowel function is checked less consistently, and problems there can appear long after everything else has gone well. It is entirely reasonable to ask at each appointment how your child's bladder and bowel are being assessed, and to mention any difficulty with wetting, frequency or constipation even if it seems minor. These problems are treatable, and treating them early protects the kidneys.

What researchers are working on next

Every one of these four studies ends by saying the same thing: the groups are too small. This tumour is rare, no single hospital sees enough cases to answer the questions properly, and the clearest next step is pooling records across countries.

Three projects would help most. The first is connecting the before-birth measurements to the after-birth ones, so a scan at twenty weeks could say something about a child at five years, not just about survival. The second is agreeing a single standard way of assessing bladder and bowel function in every survivor. The third is following children for longer. A recent study of survivors at an average age of 17 found their quality of life measurably lower than that of other young people the same age, with urinary problems the biggest reason why [13]. None of the four studies here followed children past about seven years, so the outcome that will matter most across a lifetime is still largely unmeasured. Larger international collaborations are beginning to change that, including global efforts to track recurrence and long-term results across many countries at once [14].

References

  1. Jouzova A, Jouza M, Turek J, et al. Sacrococcygeal teratoma - prognosis based on prenatal ultrasound diagnosis, single-center experience and literature review. BMC Pregnancy Childbirth. 2025;25(1):469. doi:10.1186/s12884-025-07494-3 ↩
  2. Park J, Ha S, Kwon H, et al. Prognosis analysis of sacrococcygeal teratoma—compared with patient size. Front Pediatr. 2025;13:1513825. doi:10.3389/fped.2025.1513825 ↩
  3. Cianci MC, Fusi G, Morini F, et al. Fetal treatment of sacrococcygeal teratoma: state of the art. Front Pediatr. 2025;13:1410269. doi:10.3389/fped.2025.1410269 ↩
  4. Zhao B, Su J, Li Z, Zhao P. Lower urinary tract dysfunction following sacrococcygeal teratoma resection in neonates: a long-term clinical follow-up study. Transl Androl Urol. 2026;15(8):290. doi:10.21037/tau-2026-0325 ↩
  5. Swamy R, Embleton N, Hale J. Sacrococcygeal teratoma over two decades: birth prevalence, prenatal diagnosis and clinical outcomes. Prenat Diagn. 2008;28(11):1048–1051. doi:10.1002/pd.2122 ↩
  6. Phi JH. Sacrococcygeal teratoma: a tumor at the center of embryogenesis. J Korean Neurosurg Soc. 2021;64(3):406–413. doi:10.3340/jkns.2021.0015 ↩
  7. Altman RP, Randolph JG, Lilly JR. Sacrococcygeal teratoma: American Academy of Pediatrics Surgical Section survey—1973. J Pediatr Surg. 1974;9(3):389–398. doi:10.1016/S0022-3468(74)80297-680297-6) ↩
  8. Hedrick HL, Flake AW, Crombleholme TM, et al. Sacrococcygeal teratoma: prenatal assessment, fetal intervention, and outcome. J Pediatr Surg. 2004;39(3):430–438. doi:10.1016/j.jpedsurg.2003.11.005 ↩
  9. Rodriguez MA, Cass DL, Lazar DA, et al. Tumor volume to fetal weight ratio as an early prognostic classification for fetal sacrococcygeal teratoma. J Pediatr Surg. 2011;46(6):1182–1185. doi:10.1016/j.jpedsurg.2011.03.051 ↩
  10. Benachi A, Durin L, Vasseur Maurer S, et al. Prenatally diagnosed sacrococcygeal teratoma: a prognostic classification. J Pediatr Surg. 2006;41(9):1517–1521. doi:10.1016/j.jpedsurg.2006.05.009 ↩
  11. Partridge EA, Canning D, Long C, et al. Urologic and anorectal complications of sacrococcygeal teratomas: prenatal and postnatal predictors. J Pediatr Surg. 2014;49(1):139–143. doi:10.1016/j.jpedsurg.2013.09.042 ↩
  12. Lee WG, Shue EH. Antenatal and postnatal management of sacrococcygeal teratoma. Neoreviews. 2026;27(6):e355–e368. doi:10.1542/neo.27-6-020 ↩
  13. Madurga A, Abad J, López Canelada MV, et al. Beyond surgery: quality of life in survivors of sacrococcygeal teratoma. Cir Pediatr. 2026;39(3):108–114. doi:10.54847/cp.2026.03.15 ↩
  14. van Heurn LJ, Derikx JP, Hall N, et al. Malignant transformation and tumour recurrence in sacrococcygeal teratoma: a global, retrospective cohort study. Int J Surg. 2024;110(11):7177–7186. doi:10.1097/JS9.0000000000002045 ↩