INTRODUCTION
Sacrococcygeal teratoma is a rare tumour, occurring in approximately 1 in 40,000 live births. They arise from the caudal end of the spine, usually protruding from the inferior end of the infant’s spinal column and displacing the anus forwards. They are much more common in girls, with the female to male ratio being at least 3:1. It is generally agreed that sacrococ- cygeal teratoma is the result of continued multiplica- tion of totipotent cells from Hensen’s node, which fail to involute at the end of embryonic life.
These are true neoplasms. Willis defined the term teratoma as follows: “A teratoma is a true tumour or neoplasm composed of multiple tissues of kinds for- eign to the part in which it arises”. By definition, then, sacrococcygeal teratomata are composed of several types of tissue, usually derived from two or three germ layers.Within any one tumour, the cells can vary from totally benign (even forming well-formed teeth, hair or other organs) to cells that appear frankly malignant. However, many sacrococcygeal teratomata contain malignant-looking cells (usually described as
“immature”), but if they are completely excised they do not recur. For this reason, the diagnosis of malig- nant sacrococcygeal teratoma can only be made if there are distant metastases. The risk of malignancy depends on the site and the extent of the tumour and the age at diagnosis. Tumours diagnosed after 2 months of age have a high risk of being malignant.
Tumours that are largely “exophytic”, i.e,. those that protrude from the caudal end of the baby with only a small intra-abdominal component, tend to be benign.
However, those that have a large intra-abdominal component, have a higher risk of behaving in a malig- nant fashion. In general, as long as a complete resec- tion is obtained, the risk of recurrence is low.
These tumours used to be diagnosed when they presented as a large sacral mass after a difficult deliv- ery, or with an obstructed delivery. However, the most common presentation now is an antenatal diag- nosis by ultrasound. Series reporting the antenatal diagnosis of sacrococcygeal teratomata have revealed that the majority of the fetuses diagnosed as having a sacrococcygeal teratoma are likely to die before delivery. Most of the fetuses who have died following antenatal diagnosis had tumours with a
It is, therefore, entirely possible that these fetuses die of heart failure as the fetal heart is unable to pump sufficient blood to nourish both the tumour and the rest of the fetus. Certainly, in most of the antenatal series reported, fetal hydrops (non-immune hydrops) is very common, and is associated with an increased risk of fetal demise.
Most cases presenting as neonates to paediatric surgeons will have a large skin-covered mass pro- truding from the coccygeal region, pushing the anus and vagina anteriorly. There may be large veins vis- ible on the surface, and these usually drain into the surrounding structures. Large tumours may have ruptured (in which case they will bleed profusely) or may have an ulcerated area on the surface. Neonates with a tumour approaching the size of the rest of their body may be delivered prematurely and will often have features of non- immune hydrops. In all cases, the tumour is firmly attached to and may be said to arise from the anterior surface of the coccyx.
It may displace the coccyx posteriorly, but almost without exception, the sacrum is normal.
An abdominal ultrasound will determine the size and consistency of any pelvic or abdominal compo- nent. It may be necessary to fill the bladder with water to allow it to be used as a sonic window.
Magnetic resonance imaging should clearly distin- guish between sacrococcygeal teratoma and anterior meningocele, and may be able to detect the occasion- al extension of the tumour through the sacral hiatus into the spinal canal.
These lesions are best resected within the first 24 h after birth, since the gut is not usually colonized in the first 24 h after birth, reducing the risk of infec- tion if the field is contaminated by stool during the resection. Peri-operative antibiotics are given imme- diately before surgery commences and continued for 24–48 h post-operatively. If the infant has been fed, or is several days old, then a formal bowel prepara- tion may be advisable. Blood should be cross- matched, and adequate intravenous access is vital. An arterial line may also be useful during the operation.
It is useful to obtain blood for α-fetoprotein levels before surgery as a baseline, in order to confirm post-operatively that α-fetoprotein levels continue to Kevin C. Pringle
Figure 41.1
The patient is anaesthetized, intubated and posi- tioned prone with a roll under the hips. The roll is positioned so that the infant’s weight is taken on the anterior superior iliac spines. It is vital that the abdo- men be left hanging free to ensure that respiration is not inhibited by the baby’s weight. For this reason, the baby’s shoulders should be supported either by a smaller roll lying transversely across the apex of the chest at the level of the medial ends of the clavicles, or by two rolls running parallel to the spine, each supporting the glenohumeral joints. A catheter should be placed in the bladder to measure urine output throughout the procedure. Many authorities state that the anus should be prepared out of the field. The author finds that approach both inconven- ient and impractical, as access to the anus is often
required during the procedure. The cautery pad can usually be placed across the shoulders. A clear plas- tic drape may conserve body heat and assist in pre- vention of hypothermia.
A chevron incision is made in the skin over the dorsum of the mass. It is continued down to fascial layers. It is preferable not to dissect beyond the level of the deep fascia at this stage of the dissection.
There are often several large veins in the subcutane- ous tissue on either side of the midline. These should be divided between ties. The incision should be placed so as to preserve as much normal skin as pos- sible. Excess skin can always be trimmed later if nec- essary. The apex of the chevron should be over the lower sacrum.
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Figure 41.2
In the midline, the dissection should continue direct- ly down to the sacrococcygeal junction, or even down to the fourth or fifth sacral vertebra. The edges of the sacrum are defined, and a clamp is passed across the sacrum at this level, keeping the tips of the forceps against the ventral surface of the bone (or cartilage) to ensure that the forceps pass between the sacrum and the underlying middle sacral vessels, which are usually substantial vessels, supplying the bulk of the blood supply to the tumour. Once this manoeuvre is complete, the sacrum (which is usual- ly completely, or at least largely, cartilaginous) can be divided with a scalpel and the tumour displaced slightly inferiorly to expose the middle sacral vessels.
This manoeuvre needs to be carried out with cau- tion, as occasionally the bulk of the venous drainage from the tumour passes through the sacral hiatus and into the epidural plexus. Failure to recognize this possibility can result in a substantial, rapid loss of blood. This can usually be controlled using simple pressure, taking care to maintain the pressure until the bulk of the arterial inflow has been divided.
However, even after that has been accomplished,
there may be continuing blood loss from the epidu- ral plexus, requiring the use of bone wax to control it.
It may be necessary to divide some of the attach- ments of the thinned-out remnants of the levators to the edges of the lower end of the sacrum and coccyx to enable the distal portion of the sacrum and coccyx to be displaced caudally. The middle sacral vessels are then ligated in continuity and divided. This early division of the middle sacral vessels is essentially the same as the procedure advocated by Smith and col- leagues. This manoeuvre opens a plane of dissection that is outside the tumour capsule, but deep to the thinned-out remnants of the levators and the gluteus maximus. The levators may be so thin as to be almost invisible, but they will contract on stimulation, either with a muscle stimulator or the electrocautery. The dissection should continue laterally in this plane either side of the midline until the muscles are lost in the fascia of the tumour. At this point, they can be divided along a line parallel to the skin incision. This will allow the tumour to be further displaced in a caudal direction.
Figure 41.1
Figure 41.3
Attention is then directed to the pelvic extension of the tumour. Using blunt dissection with peanut swabs in the plane anterior to the middle sacral ves- sels, it is usually possible to displace the pelvic com- ponent of the tumour anteriorly until its upper extent is reached. This is normally an essentially avascular plane anterior to the sacrum, although some vessels feeding into the tumour from the inter- nal iliac vessels may be encountered laterally. These can usually be controlled with cautery. In most cases, the tumour can be dissected out from the pelvis and rolled inferiorly over the patient’s legs.
Figure 41.4
This manoeuvre exposes the upper end of the rec- tum, which can be identified by a Vaseline gauze pack or by passing a finger in through the anus. The tumour can be dissected off the rectum with a com- bination of sharp and blunt dissection, and rolled inferiorly until the plane of dissection moves away from the rectum and the anal canal. At all times dur- ing this dissection, it is best to try to maintain the plane of dissection on the capsule of the tumour and to preserve all normal structures no matter how dis- torted and thinned-out they are. As the tumour is rolled inferiorly, it eventually becomes apparent that the plane of dissection has reached the subcutaneous tissue along the inferior surface of the tumour, pos- terior to the anus. Once the dissection has reached this point, the dissection can be terminated as long as the inferior skin flap that has been developed is of sufficient length to allow easy closure of the wound.
The inferior skin flap can then be divided from the tumour and the tumour delivered from the field. A careful check of the tumour bed is carried out to ensure that meticulous haemostasis has been achieved.
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Figure 41.5
Attention is then directed to reconstruction of the pelvic floor and closure of the wound. The remnants of the levator sling are identified and the central por- tion is sutured to the perichondrium of the anterior surface of the sacrum using a 5/0 monofilament absorbable suture. This same suture is used for all subsequent muscle and fascial reconstruction. These initial fascial sutures, rather than the skin closure, should determine the siting of the anus. This aspect
of the reconstruction, therefore, should be carried out with care to ensure both a functional and a cos- metically pleasing result.
If a drain is to be placed, then it is placed at this stage, in the presacral space, led out through the gap in the levators and tunnelled out through the subcu- taneous tissue of the buttock. A closed suction drain is preferred.
Figure 41.3 Figure 41.4
Figure 41.6, 41.7
If there are remnants of the levators recognizable lat- eral to the midline, these are repaired with interrupt- ed 5/0 monofilament absorbable suture. The medial edges of gluteus maximus are then closed in the mid- line over the sacrum and the lower part of the leva- tor sling. The skin flaps are then trimmed to length.
If possible, the subcutaneous tissues are closed with a running 5/0 polyglycolic acid suture and the skin is closed with a running 5/0 polyglycolic acid subcutic- ular suture. A Steristrip and collodion dressing is then applied. If it is not possible to close the subcu- taneous tissue, then a subcuticular suture may not be adequate for skin closure. In this case, 5/0 nylon skin suture are placed. The rectum is packed with Vaseline ribbon gauze at the completion of the pro- cedure in an attempt to obliterate dead space. It is useful to suture a 2/0 silk suture to the end of this
pack to aid its retrieval, should the pack become dis- placed higher up the rectum in the immediate post- operative period.
The infant is nursed in a prone position for sever- al days post-operatively. The urinary catheter can be removed as soon as the baby’s condition is stable and the infant can be extubated as soon as its respiratory condition allows. The infant can usually be fed as soon as it is extubated. The Vaseline pack is usually removed in the first post-operative day by pulling on the 2/0 silk suture left attached to the distal end. Any drain can usually be removed within the first few days of the procedure.α-Fetoprotein levels should be determined immediately post-operatively and on discharge. The infant should then be followed at monthly intervals for 3 months and then at 3-month- ly intervals for a year.
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Figure 41.6
CONCLUSION
Follow-up should continue for at least 5 years. At each visit, a rectal examination will detect any local recurrence and an α-fetoprotein level will detect any distant spread. The α-fetoprotein level is often very high (of the order of 100,000 U or more) and even in normal babies may be over 10,000 U. These high lev- els usually take over a year to fall to normal adult lev- els. It is generally thought that as long as the α-feto- protein level continues to fall steadily, recurrence is unlikely. In the author’s experience, a steadily falling α-fetoprotein level does not rule out the possibility of either a local recurrence, or even a malignant recurrence. All of the local recurrences in the author’s series, and the malignant recurrence all developed in the context of a steadily falling α-feto- protein level. For this reason, the author has now developed a protocol of routine ultrasound examina- tions and rectal examinations at regular intervals for the first 3 years of life.
In the absence of distant metastases at presenta- tion, and if the excision is complete, then life expec- tancy should be normal, although the appearance of the buttocks usually leaves something to be desired.
Continence, surprisingly, is usually normal. However, the relatively late development of a hostile neurogen- ic bladder at the age of 3 years in one patient, does suggest that normal bladder function cannot be assumed to be present until well into the school years.
The prognosis for patients presenting with a malignant sacrococcygeal teratoma must be guard- ed. Modern chemotherapy has produced some improvement in survival, although the chemothera- py regimens are toxic and the tumour tends to be rel- atively resistant to therapy. However, this is a rela- tively uncommon circumstance.
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Pringle KC, Weiner CP, Soper RT et al (1987) Sacrococcygeal teratoma. Fetal Ther 2 : 80–87
Smith B, Passaro E, Clatworthy HW (1961) The vascular anato- my of sacrococcygeal teratomas: its significance in surgical management. Pediatr Surg 49 : 534–539
Willis RA (1962) The borderland of embryology and patholo- gy, 2nd edn. Butterworth, London
