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Sirenomelia: The mermaid syndrome: Report of two cases

Authors:
Setu Rathod at Mahatma Gandhi Medical College and Research Institute
Setu Rathod
Sunil Kumar Samal at Mahatma Gandhi Medical College and Research Institute
Sunil Kumar Samal
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Sirenomelia (mermaid syndrome) is a rare congenital fetal anomaly with characteristic feature of complete or partial fusion of lower limbs. Although, this syndrome is incompatible with life due to the association of several congenital visceral abnormalities; however, there are few reports of surviving infants. Our first case was a live born, normally delivered at term by a 27-year-old third gravida of lower socioeconomic status with history of tobacco use. Examination of the baby revealed caudal dysgenesis having fusion of lower limbs, single leg with 1 foot and 5 toes. There was no identifiable external genitalia and anus. The second case was a 34 week, 1.6 kg preterm infant of unidentified sex born to a 28-year-old primigravida mother with overt diabetes mellitus. Incidentally, both the infants died few hours after birth and we report these cases due to their rarity and term live birth.
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264Journal of Natural Science, Biology and Medicine | January 2015 | Vol 6 | Issue 1
Case Reports
Sirenomelia: The mermaid syndrome: Report
of two cases
Abstract
Sirenomelia (mermaid syndrome) is a rare congenital fetal anomaly with characteristic feature of complete or partial fusion
of lower limbs. Although, this syndrome is incompatible with life due to the association of several congenital visceral
abnormalities; however, there are few reports of surviving infants. Our fi rst case was a live born, normally delivered at term
by a 27-year-old third gravida of lower socioeconomic status with history of tobacco use. Examination of the baby revealed
caudal dysgenesis having fusion of lower limbs, single leg with 1 foot and 5 toes. There was no identifi able external genitalia
and anus. The second case was a 34 week, 1.6 kg preterm infant of unidentifi ed sex born to a 28-year-old primigravida
mother with overt diabetes mellitus. Incidentally, both the infants died few hours after birth and we report these cases due
to their rarity and term live birth.
Key words: Caudal regression syndrome, mermaid syndrome, Potter’s facies, sirenomelia
Sunil Kumar Samal,
Setu Rathod
Department of Obstetrics and Gynaecology, Mahatma Gandhi Medical College and Research Institute,
Puducherry, India
Address for correspondence:
Dr. Setu Rathod, 4-D, Type II Staff Quarters, Mahatma Gandhi Medical College and Research Institute,
Pillaiyarkuppam, Puducherry - 607 402, India. E-mail: seturathod@gmail.com
INTRODUCTION
Sirenomelia is a rare and fatal congenital defect
characterized by varying degrees of lower limb fusion,
thoracolumbar spinal anomalies, sacrococcygeal agenesis,
genitourinary, and anorectal atresia.[1] The incidence
of sirenomelia is 0.8-1 case/100,000 births with male
to female ratio being 3:1.[2] The rarity of the case is
obvious from the fact that many a gynecologist might
not have come across a case of sirenomelia in their whole
professional carrier. There is a strong association with
maternal diabetes where relative risk is 1:200-250 and up
to 22% of fetuses with this anomaly will have mothers
with diabetes.[3,4] We report two cases of sirenomelia
where maternal drug abuse and overt diabetes may have
been the cause of this rare anomaly.
CASE REPORTS
Case 1
A 27-year-old unbooked G3P1L1A1 at 39 weeks 5 days of
gestational age with previous one live vaginal birth and one
fi rst trimester spontaneous abortion was admitted in the
labor room with pain in the abdomen. She had no history
of prior antenatal care and belonged to a tribal community
with lower socioeconomic status. There was history of
tobacco use both before and during pregnancy. She was
otherwise healthy with no known history of genetic or
congenital anomaly in her family.
On examination, she was observed to be in the second
stage of labor with cephalic presentation and regular fetal
heart rate. She delivered a term 2.5 kg baby with multiple
congenital anomalies. The Apgar score was 3 at 1’ and 0
at 5 min. The baby died within 30 min postbirth in spite
of resuscitation attempts by neonatologist. On physical
examination, the infant showed narrow chest, bilateral
hypoplastic thumb, fused lower limbs with a single foot
and 5 toes, absent external genitalia, imperforate anus
and umbilical cord with single umbilical artery [Figure 1].
There were also prominent epicanthal folds, hypertelorism,
downward curved nose, receding chin, low-set soft
dysplastic ears and small slit-like mouth suggestive of
Potter’s facies [Figure 2]. Autopsy was declined by the
parents. Intrapartum and the postpartum period of mother
was uneventful.
Case 2
A preterm baby weighing 1.6 kg was delivered vaginally
at 34 weeks gestation by a 23-year-old primigravida with
an unsupervised pregnancy. Postpartum investigation
revealed the presence of diabetes mellitus. There was no
history of drug intake and radiation exposure. The Apgar
score was 3 at 1’ and same at 5 min following which the
baby was shifted to neonatal intensive care unit, but died
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265 Journal of Natural Science, Biology and Medicine | January 2015 | Vol 6 | Issue 1
Case Reports
12 h postbirth due to severe respiratory distress. There was
very scanty amniotic fl uid drained at the time of delivery.
The new born baby had gross anomalies like narrow chest
indicating lung hypoplasia, fused both lower limbs and feet
with 10 toes, absence of external genitalia, imperforate
anus and single umbilical artery [Figures 3 and 4].
Examination of the fused lower limbs showed the presence
of all thigh and leg bones thus classifying our patient as
Type I of Stocker and Heifetz classifi cation. The infant
also had features of Potter’s facies including prominent
infraorbital folds, small slit-like mouth, receding chin,
downward curved nose, and low-set ears. Ultrasonography
revealed bilateral renal agenesis. On autopsy, there was an
absence of both kidneys, ureters, urinary bladder, seminal
vesicle, and urethra. The gastrointestinal system ended in
a blind loop at the rectosigmoid area and was fi lled with
meconium. Two pea sized gonads suggestive of testes were
seen bilaterally posterior to pubis. Right pneumothorax
with collapsed right lung was evident. Examination of
brain, heart, liver, adrenal glands, and pancreas revealed
normal anatomy.
DISCUSSION
Anomalies observed in sirenomelia are described as the
most severe form of caudal regression syndrome.[5] Fusion
of the lower extremities, presence of single umbilical
and persistent vitelline artery are major features of
sirenomelia.[6]
Although the primary molecular defect resulting in
sirenomelia remains unclear, two main pathogenic hypotheses
namely the vascular steal hypothesis and the defective
blastogenesis hypothesis are proposed. According to vascular
steal hypothesis,[7] fusion of the limbs results from a defi cient
blood fl ow and nutrient supply to the caudal mesoderm,
which in turn results in agenesis of midline structures and
subsequent abnormal approximation of both lower limb
Figure 4: Photograph of baby showing imperforate anus
Figure 1: Photograph of the baby showing fusion of lower limbs,
hypoplastic thumb, absent external genitalia and features of Potter’s
facies
Figure 2: Sirenomeliac baby with narrow chest and Potter’s facies
(prominent infraorbital folds, small slit-like mouth, receding chin,
downward curved nose, and low-set soft dysplastic ears)
Figure 3: Sirenomeliac baby with fused lower limbs containing 10 toes,
Potter’s facies, narrow chest, and absent external genitalia
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266Journal of Natural Science, Biology and Medicine | January 2015 | Vol 6 | Issue 1
Case Reports
fields. However in defective blastogenesis hypothesis,[8]
the primary defect in development of caudal mesoderm is
attributed to a teratogenic event during the gastrulation stage.
Such defect interferes with the formation of notochord,
resulting in abnormal development of caudal structures.
Maternal diabetes, tobacco use, retinoic acid and heavy metal
exposure are possible environmental factors.[9] In our fi rst
case, there was history of tobacco use before and during
pregnancy, while in the second case the mother had overt
diabetes.
Sirenomelia is usually fatal within a day or two of birth
because of complications associated with abnormal
kidney and urinary bladder development and function.
In literature approximately 300 cases[5] are reported
worldwide of which 14 are from India. In most of
the cases the diagnosis was performed after birth. In
antenatal period, sirenomelia can be diagnosed as early
as 13 weeks by using high resolution or color Doppler
sonography.[10,11] The condition is usually incompatible
with life due visceral abnormalities especially that of
renal system. Exceptional cases without renal agenesis
have survived, the best example being Tiffany Yorks,
a 13-year-old girl who was born with fused legs. Over
the years, she has undergone numerous operations to
separate her lower extremities.[12]
The facial abnormality usually found in sirenomeliac infants
known as Potter’s facies, which includes large, low-set ears,
prominent epicanthic fold, hypertelorism, fl at nose and
receding chin. In both of our cases, features of Potter’s
facies were present. When features of Potter’s facies are
combined with oligamnios and pulmonary hypoplasia it
is known as Potter’s syndrome,[13] which was present in
our second case. In our fi rst case, the right thumb was
hypoplastic, which was also previously reported.[14] Stocker
and Heifetz classifi ed Sirenomeliac infants from Type I
to Type VII according to the presence or absence of
bones within the lower limb.[15] Although we did not have
radiographs to classify our case with certainty, nevertheless
based on external examination, we suggest our fi rst and
second case belonged to Type IV (partially fused femurs
and fused fi bula) and Type I (all thigh and leg bones are
present), respectively.
CONCLUSION
Sirenomelia is a rare and lethal congenital anomaly. When
diagnosed antenatally, termination should be offered.
However, prevention is possible and should be the goal.
Regular antenatal checkup with optimum maternal blood
glucose level in preconceptional period and in fi rst trimester
should be maintained to prevent this anomaly.
ACKNOWLEDGMENT
We would like to thank the Department of OBGYN, SCB
Medical College, Cuttack for their valuable support and co-
operation of patients and their families admitted to this hospital.
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How to cite this article: Samal SK, Rathod S. Sirenomelia: The mermaid
syndrome: Report of two cases. J Nat Sc Biol Med 2015;6:264-6.
Source of Support: Nil. Confl ict of Interest: None declared.
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... The abnormalities seen in sirenomelia are described as the most severe form of caudal regression syndrome [4]. The fusion of the lower limbs, the presence of a single umbilical and persistent vitelline artery are the main features of the Sirtomelia [4]. ...
... The abnormalities seen in sirenomelia are described as the most severe form of caudal regression syndrome [4]. The fusion of the lower limbs, the presence of a single umbilical and persistent vitelline artery are the main features of the Sirtomelia [4]. Although the cause of sirenomelia is unknown, two primary pathogenic hypotheses have been proposed: vascular steal and abnormal blastogenesis [4]. ...
... The fusion of the lower limbs, the presence of a single umbilical and persistent vitelline artery are the main features of the Sirtomelia [4]. Although the cause of sirenomelia is unknown, two primary pathogenic hypotheses have been proposed: vascular steal and abnormal blastogenesis [4]. The primary defect in the development of caudal mesoderm is attributed to a teratogenic event during the gastrulation stage. ...
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Introduction and importance: Sirenomelia is a life-threatening condition caused by a rare developmental abnormality. According to the research, the incidence of sirenomelia is estimated to be between 1.5 and 4.2 per 100,000 newborns. Around 15% of cases of sirenomelia are related to a twin pregnancy, most commonly in monozygotic cases, with a 7% incidence. We're reporting on a mermaid syndrome case involving twins, one of whom was healthy and the other had sirenomelia. Case presentation An 18-year-old female and her first child arrived at the hospital maternity ward, and she had never been there before, and when an ultrasound was performed, it was discovered that she had two babies in her womb and on of them has clung to each other's legs, and a by elective cesarean section was performed to remove the babies, which resulted in the extraction of two boys, one of whom is healthy and the other is clinging to each other's legs. Clinical discussion Sirenomelia is a deadly congenital condition that affects the caudal part of the embryonic body. Although the most evident feature is the fusing of the lower limbs, Approximately 49.5 percent of pregnancies are terminated voluntarily due to fetal malformations, according to reports. The abnormality is thought to be caused by a combination of genetic predisposition and a trigger element in the environment, while the exact cause is unknown and thought to be complex. In cases of surviving sirenomelia, treatment can be administered using a multidisciplinary approach. Conclusion Mermaid Syndrome is a fatal congenital abnormality with a bleak outlook. Sirenomelia can be diagnosed by ultrasonography. Oligohydramnios and fused lower limbs are important symptoms that aid in diagnosis during the first trimester of pregnancy, with probable termination of the pregnancy indicated if identified early.
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... Mother's age less than 20 or above 40 years, along with gestational diabetes and hypertension are important risk factors. 11 Teratogenicity in pregnancy, such as smoking, environmental hazards, drug abuse, alcoholism, use of tobacco, excessive use of caffeine, and radiography. Symptoms that should be observed in ultrasonography include lower limbs fusion, renal atrophy or agenesis, single umbilical absence or fusion of genitalia, renal insufficiency, and imperforated anus, single lower limb, and foetal heart rate. ...
... Patients with mermaid syndrome have typical appearance of fused lower limbs, larger umbilical artery which is separated from the upper abdominal artery, and sometimes involvement of aortic branches. 11 Guidera et al reported a case in 1991 with orthopaedic abnormalities and pelvic dysplasia, fused lower abdominal and genital region, and calcanei osseous fusion with abnormal femurs, fibula, tibia, and general abnormalities. 9 Their patient appeared with a fusion of lower limbs and imperforated anus. ...
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Mermaid syndrome (Sirenomelia) is a rare fatal congenital anomaly. The prevalence is reported to be 1 in 100,000 births. The baby appears to have a fish-like tail and joined legs featuring a mermaid at the time of birth or during antenatal screening. Most of these patients die shortly after birth, denoting rare survival rate. Gastrointestinal and genitourinary obstruction with single umbilical artery are the clinical symptoms. Two important hypotheses support the Sirenomelia disorder: the artery steal hypothesis, called the vitelline artery, and the blastogenesis defect hypothesis. There is no known reason for MS, but certain risk factors need to be identified, which include mother aged more than 40 years or less than 20 years at the time of giving birth, cousin marriage, exposure to teratogenic agents, and family history. A case of this rare congenital disorder was seen in Civil Hospital Faisalabad, Pakistan, which was referred from Duniyapur, District Lodhran, Pakistan. The neonate presented with fused lower limbs, congenital heart disease, and high-grade fever. The mother had a history of gestational diabetes mellitus and hypertension. The baby had fused legs, unidentified internal and external genital system, thumbs anomaly, bile in vomit, and despite life-saving efforts, the patient expired after five days of birth. There is lack of information regarding symptoms and a lack of prenatal screening for MS. Hence, there is a need to create awareness among health care professionals to identify the disease on screening for early diagnosis.
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... Sirenomelia (mermaid syndrome) is a rare congenital fetal anomaly (Samal, et al., 2015;Taee, et al., 2018), in which a newborn born with legs joined together featuring a mermaid-like appearance (head and trunk like humans and tail like fish), and in most cases die shortly after birth. Gastrointestinal and urogenital anomalies and single umbilical artery are clinical outcome of this syndrome. ...
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Sirenomelia is an extremely rare anomaly, an incidence of 1 to 4.2 in 100,000 births, in which a newborn born with legs joined together featuring amermaid-like appearance (head and trunk like humans and tail like fish), and in most cases die shortly after birth. Gastrointestinal and urogenital anomalies and single umbilical artery are clinical outcome of this syndrome. There are two important hypotheses for pathogenesis of mermaidsyndrome: vitelline artery steal hypothesis and defective blastogenesis hypothesisThe cause of the sirenomelia is unknown, but there are some possible factors such as age younger than 20 years and older than 40 years in mother and exposure of fetus to teratogenics. Here, we introduced 39 year old mother’s first neonate with Sirenomelia syndrome. The mother had gestational diabetes mellitus and neonate was born with single lower limb, ambiguous genitalia, and thumb anomalies, and 4 days after birth, the neonate dieddue to multiple anomalies and imperforated anus.
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... The relative risk ratio for sirenomelia and maternal diabetes is 1:200-250, and it has been shown that this ratio is 22% in fetuses with abnormalities [8,[13][14][15][16].The male/female ratio is 2.7-3 [8,13,17,18]. Two factors were relevant in this case: the mother's age of 20 years and the male gender. ...
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... [1,2] Its outcome is nearly always fatal, with death occurring in the perinatal period owing to renal tract abnormalities and associated complications. [3] We present a patient with sirenomelia with cardiac abnormalities, which are not commonly reported in patients with this condition. ...
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... Sirenomelia and maternal diabetes have a substantial correlation and the relative risk ratio is 1/200-250, and it was reported to be 22% among fetuses with anomalies. The ratio of boys to girls is 2.7 : 1 [5,14]. In the case presented by us, we were able to detect as risk factors the sex of the fetus (male), maternal gestational diabetes and mother's smoking status. ...
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... Classication of sirenomelia according to Stocker and Heifetz (Fig-5) Other classications, which focused on the degree of development of the fused legs denoted by the presence of feet has been abandoned. Sirenomelia used to be classied into three types according to the number of lower limb bones 11 presenta) Sirenomelia Dipus: Two feet and two fused legs giving the appearance of a ipper. b) Sirenomelia Unipus: One foot, two femurs two tibia, and two bulas. ...
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The Spectrum of Congenital Central Nervous System Anomalies Among Stillborn: An Autopsy Based Study
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Full-text available
  • Jul 2020
Background Congenital central nervous system (CNS) anomalies are the structural or functional abnormalities of the brain and spinal cord that occur during the intrauterine developmental process. Purpose The present study aims to detect the prevalence of congenital CNS anomalies among stillborn fetuses, the association between congenital anomalies and maternal factors, and also the association between autopsy and ultrasound findings. Methods This study was conducted on 50 stillborn fetuses, obtained from the Department of Obstetrics and Gynecology at JSS Medical College and Hospital, Mysuru. The fetuses were fixed in 10% formalin and autopsies were performed as per the standard fetal autopsy protocol. The congenital CNS anomalies were studied in detail. Results CNS anomalies were the most common congenital anomalies observed. Out of the total 50 stillborn fetuses studied, CNS anomalies were found in 17 fetuses and their occurrence was more common among male stillborn than females. Meningomyelocele was the most common anomaly, followed by anencephaly. The other anomalies documented were meningocele, encephalocele, meningoencephalocele, agenesis of the corpus callosum, craniorachischisis, bifid cerebellum with hypoplastic vermis, holoprosencephaly, and sirenomelia. Fisher’s exact test showed a significant association between maternal hypothyroidism and congenital CNS anomalies ( P < .05). The autopsy confirmed the ultrasound findings in 40 (80%) fetuses. There were significant additional findings observed in seven (14%) fetal autopsies and ultrasound diagnosis completely changed in three (6%) cases, after the final autopsy procedure. Conclusion The fetal autopsy is the single most directly evident investigation, which gives information that changes or significantly improves the clinical diagnosis. A multidisciplinary holistic approach toward pregnancy will help to detect any kind of abnormality in the fetus and thus to take a timely decision toward the management.
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Sirenomelia
Article
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  • May 2006
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Sirenomelia: A Rare Presentation
Article
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  • Jan 2012
We are presenting two cases of Sirenomelia (Mermaid Syndrome), which is an extreme example of the caudal regression syndrome. It invariably presents with lower limb fusion, sacral and pelvic bony anomalies, absent external genitalia, imperforate anus, and renal agenesis or dysgenesis. There are approximately 300 cases reported in the literature, 15% of which are associated with twinning, most often monozygotic. The syndrome of caudal regression is thought to be the result of injury to the caudal mesoderm early in gestation. One of our cases survived for 12 days after birth. This new born had an unusually high anorectal anomaly in which the colon was ending at the level of mid transverse colon, fused lower limbs and genital anomalies. Ultrasound of the abdomen revealed horseshoe kidney. Colostomy was performed on day 2 of life. The second case encountered was a stillborn baby on whom an autopsy was performed.
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Sirenomelia: A case report with literature review
Article
Full-text available
  • Jun 2013
We are presenting a case of Sirenomelia (Mermaid Syndrome), which is an extreme example of the caudal regression syndrome. It invariably presents with lower limb fusion, sacral and pelvic bony anomalies, absent external genitalia, imperforate anus, and renal agenesis or dysgenesis. There are approximately 300 cases reported in the literature, 15% of which are associated with twinning, most often monozygotic. The syndrome of caudal regression is thought to be the result of injury to the caudal mesoderm early in gestation. The case encountered was a stillborn baby. [Int J Reprod Contracept Obstet Gynecol 2013; 2(3.000): 430-432]
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Sirenomelia: A Rare Case of Foetal Congenital Anomaly
Article
Full-text available
  • Oct 2012
Sirenomelia, alternatively known as 'mermaid syndrome' is a very rare congenital deformity in which the legs are fused together, giving them the appearance of the tail of a mermaid'. Other birth defects are always associated with sirenomelia, most commonly abnormalities of the kidneys, large intestines, and genitalia. The present case is a one of sirenomelia associated with an absent right kidney, mild left hydronephrosis, single umbilical artery, and severe oligohydramnios. We discuss the findings, relative to the present literature and related etiopathogenesis.
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Sirenomelia. Pathological features, antenatal ultrasonographic clues, and a review of current embryogenic theories
Article
Full-text available
  • Jan 1999
We aimed to discuss the prenatal diagnosis and pathological features of sirenomelia, and to review current embryogenic theories. We observed two sirenomelic fetuses that were at the 19th and 16th gestational week respectively. In the former, transvaginal ultrasound revealed severe oligohydramnios and internal abortion, whereas bilateral renal agenesis, absence of a normally tapered lumbosacral spine, and a single, dysmorphic lower limb were detected in the latter. In both cases, X-rays and autoptic examination allowed categorization on the basis of the skeletal deformity. Subtotal sacrococcygeal agenesis was present in both cases. Agenesis of the urinary apparatus and external genitalia and anorectal atresia were also found. Classification of sirenomelia separately from caudal regression syndrome is still debated. Recent advances in the understanding of axial mesoderm patterning during early embryonic development suggest that sirenomelia represents the most severe end of the caudal regression spectrum. Third-trimester ultrasonographic diagnosis is usually impaired by severe oligohydramnios related to bilateral renal agenesis, whereas during the early second trimester the amount of amniotic fluid may be sufficient to allow diagnosis. Early antenatal sonographic diagnosis is important in view of the dismal prognosis, and allows for earlier, less traumatic termination of pregnancy.
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From the Mermaid to Anal Imperforation: The Syndrome of Caudal Regression
Article
  • Apr 1961
Ifthemermaid legend evokes moreofmythology thanofpathology, itsorigin veryprobably lies in ancient observations ofcertain typesofhuman monstrosities. Humansirens arenotasrareasissometimes thought; Ihavebeenabletoexamine twocases within thepastyear, andduring thattimeIhave beentoldofseveral others. Ishall talktodayof theusual findings andattempt todrawcertain wider conclusions.
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Examining the Evidence for Vascular Pathogenesis of Selected Birth Defects
Article
  • Oct 2010
  • AM J MED GENET A
Vascular mechanisms have been proposed to be involved in the pathogenesis of a number of defects, including transverse-limb defects, intestinal atresias, gastroschisis, hydranencephaly, porencephaly, oromandibular-limb hypogenesis sequence, and oculoauriculovertebral spectrum (OAVS). Here, we examine the available clinical, epidemiologic, and experimental evidence for four defects (transverse-limb defects, intestinal atresias, gastroschisis, and OAVS) for which vascular pathogenesis has been hypothesized. Based on our review, transverse-limb defects appear to sometimes be due to vascular events related to placental vascular abnormalities, hypoperfusion, abnormal development of blood vessels, intrauterine compression, hemoglobinopathies, or exposure to vasoactive agents, although epidemiological studies have not consistently demonstrated the latter association. However, transverse-limb defects can also be due to abnormal developmental events, such as aberrant molecular signaling in the apical ectodermal ridge. Some intestinal atresias may have a vascular origin, with the hypothesis supported by experiments in canines. However, evidence is accumulating that a more common mechanism might be related to improper molecular signaling related to gut specification early in development. In contrast, evidence to support vascular pathogenesis for gastroschisis and OAVS is less compelling. Instead, these defects probably arise from interference with basic developmental events [e.g., body wall closure (gastroschisis) and neural crest cell development (OAVS)]. These conclusions are important for counseling parents of children with these defects and for guiding the design of future epidemiological studies and experiments to further characterize the causes of these defects.
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Caudal Regression Versus Sirenomelia: Sonographic Clues
Article
  • Jul 1993
Seven cases with the pathologic/autopsy diagnosis of caudal regression or sirenomelia in which antenatal sonography had been performed were reviewed. The three patients with caudal regression had similar findings on antenatal sonogram, including normal or increased amniotic fluid, mild dilation or normal urinary systems, nonfused extremities, and sacral agenesis. In the four patients with sirenomelia, common sonographic findings included marked oligohydramnios, suspected renal agenesis, and sacral agenesis. A history of maternal diabetes was elicited in all patients with caudal regression and in none of the patients with sirenomelia. Findings confirm recent articles in pediatric pathology suggesting that caudal regression is a separate entity, distinct from sirenomelia.
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