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Year : 2021  |  Volume : 29  |  Issue : 3  |  Page : 226-228

Skeletal defect at first-trimester ultrasound scan

Department of Obstetrics and Gynaecology, Centro Hospitalar Tâmega E Sousa, Porto, Portugal

Date of Submission29-Apr-2020
Date of Decision19-May-2020
Date of Acceptance02-Jun-2020
Date of Web Publication24-Aug-2020

Correspondence Address:
Marília Freixo
Department of Obstetrics and Gynaecology, Centro Hospitalar Tâmega E Sousa, Porto
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/JMU.JMU_62_20

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How to cite this article:
Freixo M, Soares E, Coelho M, Marinho C, Rocha J, Rodrigues G. Skeletal defect at first-trimester ultrasound scan. J Med Ultrasound 2021;29:226-8

How to cite this URL:
Freixo M, Soares E, Coelho M, Marinho C, Rocha J, Rodrigues G. Skeletal defect at first-trimester ultrasound scan. J Med Ultrasound [serial online] 2021 [cited 2021 Dec 6];29:226-8. Available from: http://www.jmuonline.org/text.asp?2021/29/3/226/293254

  Section 2 – Answer Top

Case description

We report the case of a nulliparous 36-year-old Portuguese female at 14 weeks of gestation for her first prenatal visit in our hospital. The medical history was unremarkable without known underlying conditions (medical or surgical).

In ultrasound (US) performed at 14 weeks and 3 days, we found a singleton live fetus with normal amniotic fluid volume. Fetal biometry was not consistent with late period date because the crown-rump-length was found to be smaller than expected. The fetal anatomy above the midthorax, including the heart and the intracranial structures, appeared normal. Below this level, however, a sudden termination of spine at the lumbosacral level was seen [Figure 1]. In the transverse section, the sacrum was missing, and the iliac wings are positioned in midline close to each other [Figure 2].
Figure 1: Ultrasound: Abrupt termination of spine at lumbosacral level

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Figure 2: Ultrasound: Missing sacrum

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The lower limbs were akinetic and were kept in the fixed flexion [Figure 3] and [Figure 4]. The fetus had club feet [Figure 5]. The bladder was not observed, and the bowel was hyperechogenic [Figure 6].
Figure 3: Ultrasound: Transversal view - Fixed flexion of lower limbs 15

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Figure 4: Ultrasound: Fixed flexion of lower limbs

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Figure 5: Ultrasound: Club feet

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Figure 6: Ultrasound: Hyperecogenic bowel

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First trimester combined screening was performed and revealed a reduced risk for trisomy 21 (1:13,494), trisomy 18 (1:91,068), and trisomy 13 (1:76,419) with pregnancy-associated plasma protein-A = 0.68 MoM and free beta-human chorionic gonadotropin = 0.60 MoM.

Taking into account the US findings, a cytogenetic study was proposed, which revealed a normal array-comparative genomic hybridization. The postabortion study confirmed the US findings.

  Interpretation Top

The US findings included an absence of the lumbosacral spine, flexion contractures of the lower extremities, club feet, and hyperecogenic bowel. Before establishing a final diagnosis, it is important to consider all pathologies with caudal defects such as body-wall complex and segmental spinal dysgenesis (SSD), vertebral, anorectal, cardiac, tracheoesophageal, renal and limb (VACTERL) complex, Currarino syndrome (CS), and syringomyelia. Bladder exstrophy, omphalocele, and sacral myelomeningocele can be demonstrated in the body-wall complex. SSD is a rare congenital abnormality in which a segment of the spine and spinal cord fails to develop properly.[1] Severe forms of the disease are commonly associated with cardiac, renal, and respiratory problems with overlapping feature of VACTERL complex (anomalies). CS is characterized by the triad of anorectal malformations, sacral bone defects, and presacral mass and in sirenomelia we had complete or partial fusion of lower limbs.

This patient was referred to our prenatal diagnosis department for antenatal counseling and further investigation. At 15 weeks, the patient underwent amniocentesis. The cytogenetic examination revealed a karyotype 46 XY and a normal molecular study by Array-comparative genomic hybridization. The patient was counseled accordingly, and she elected for the termination of pregnancy.

Postabortion study confirmed the prenatal diagnosis, showing absent lumbosacral vertebrae, pelvic deformities, and femoral hypoplasia. Muscular atrophy of the lower extremities with extensive popliteal webbing and club feet was confirmed. The fetus had also urinary anomalies, with an isolated horseshoe kidney in the midline and collapsed bladder.

Given these findings, the diagnosis was consistent with a caudal regression syndrome.

Caudal regression is a rare syndrome which has a spectrum of congenital malformations involving approximately 1 in 25,000 live births ranging from simple anal atresia to absence of sacral, lumbar and possibly lower thoracic vertebrae, to the most severe form which is known as sirenomelia.[2]

This congenital abnormality includes agenesis of the lumbar spine, sacrum, and coccyx, as well as hypoplasia of the lower extremities. It is considered the most characteristic of all congenital anomalies associated with maternal diabetes mellitus.[3] Orthopedic, genitourinary, gastrointestinal, and cardiac anomalies can be associated.[4] In our case, club feet, flexion contractures of hips and knees were the orthopedic deformities, and we had also urinary anomalies.

The embryologic insult occurs at the midposterior axis mesoderm, and the lesion originates before the 4th weeks of gestation, but the etiology remains unclear.[5]

The prognosis is good when isolated sacral agenesis, but can be worse if associated with others abnormalities.

The diagnosis is done by US, but can be difficult before 19 weeks because the sacrum is not enough calcified.[6]

Detailed evaluation of the fetal spine and lower extremities is an important aspect of every prenatal US examination.

In the presence of normal amniotic fluid, the diagnosis can be made by demonstrating the termination of lumbar spine and small and abnormal lower extremities.[3] Both findings were present in this clinical case.

Furthermore, the detection of the abnormality was at 14 weeks of pregnancy. Early antenatal sonographic diagnosis is important in view of the dismal prognosis and allows for earlier and less traumatic termination of pregnancy.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images, and other clinical information to be reported in the journal. The patient understands that her name and initial will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Yanik H, Celikaslan N, Yildirim G, Ceylan Y. Prenatal diagnosis of caudal regression syndrome: A case report. BMC Pregnancy Childbirth 2001;1:8.  Back to cited text no. 1
Salsi G, Bellussi F, Pilu G, Gatta AN, Youssef A. Pregnancy in a woman with sacral agenesis from prenatal counseling to delivery: A case report. J Obstet Gynaecol Res 2020;46:784-6.  Back to cited text no. 2
Sonek JD, Gabbe SG, Landon MB, Stempel LE, Foley MR, Shubert-Moell K. Antenatal diagnosis of sacral agenesis syndrome in a pregnancy complicated by diabetes mellitus. Am J Obstet Gynecol 1990;162:806-8.  Back to cited text no. 3
Baxi L, Warren W, Collins MH, Timor-Tritsch IE. Early detection of caudal regression syndrome with transvaginal scanning. Obstet Gynecol 1990;75:486-9.  Back to cited text no. 4
Gabbe SG, Cohen AW. Diabetes mellitus in pregnancy. In: Bolognese RJ, Schwarz RH, Schneider J, editors. Perinatal Medicine: Management of the High Risk Fetus and Neonate. Baltimore: Williams and Wilkins; 1982. p. 336-47.  Back to cited text no. 5
Sharma S, Sharma V, Awasthi B, Sehgal M, Singla D. Sacral agenesis with neurogenic bladder dysfunction – A case report and review of the literature. J Clin Diagn Res 2015;9:RD08-9.  Back to cited text no. 6


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]


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