GYNAECOLOGY AND OBSTETRICS
Year : 2005 | Volume
: 15 | Issue : 3 | Page : 373--376
Epigastric heteropagus: A rare occurrence
R Malik, VK Pandya, P Awasthi, A Sharma
Department of Radiodiagnosis & Imaging, Gandhi Medical College & Associated Hamidia Hospital, Bhopal, India
Department of Radiodiagnosis & Imaging, Gandhi Medical College & Associated Hamidia Hospital, Bhopal and Department of Radiodiagnosis & Imaging, Gandhi Medical College & Associated Hamidia Hospital, Bhopal
|How to cite this article:|
Malik R, Pandya V K, Awasthi P, Sharma A. Epigastric heteropagus: A rare occurrence.Indian J Radiol Imaging 2005;15:373-376
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Malik R, Pandya V K, Awasthi P, Sharma A. Epigastric heteropagus: A rare occurrence. Indian J Radiol Imaging [serial online] 2005 [cited 2020 Aug 10 ];15:373-376
Available from: http://www.ijri.org/text.asp?2005/15/3/373/29158
Conjoined twins are one of the rarest congenital anomalies and are classified into symmetric & asymmetric types. The asymmetric form is known as heteropagus. With heteropagus cases, the dependent portion (parasite) is smaller than the host (autosite). Asymmetric parasite twinning with the parasite attached at the host's epigastrium is extremely rare & is known as epigastric heteropagus. The present case is also an epigastric heteropagus.
A one-day-old full term boy was born to a 20 yrs old gravida-1, para-1 mother. The mother had no history of drug intake, radiation exposure or illness during pregnancy. The infant was found to have a parasite attached to its epigastrium. The birth weight of this heteropagus twin was three kgs.
The parasite had well formed pelvis, lower limbs & abdomen with small thorax, small upper extremities & malformed small head showing rudimentary openings for mouth, nostrils and eyes.
A plain radiograph [Figure 1] of the twin showed normal skeleton of the host with no bony anomaly; however the parasite had an accessory bony pelvis with well developed set of lower limbs. Its upper limbs had well formed humeri with hypoplastic forearms & absent hands bilaterally. The lumber spine was normal whereas dorsal & cervical spines were small & hypoplastic. There were air filled bowel loops of normal calibre in the host abdomen with the presence of air in the rectum. However the parasite's abdomen was homogeneously opaque with no air filled bowel loops.
On gastrograffin study [Figure 2] there was normal passage of contrast through the host GIT which revealed normal calibre & anatomy. No opacification was seen of the parasite's GIT excluding the possibility of sharing or herniation of intestines between the twins.
On USG there was a common liver herniating into the parasite's abdomen through the connecting isthmus between the twins [Figure 3]. The larger portion of liver looked to be situated into the parasite abdomen occupying majority of its abdominal volume.
Gall bladders of normal size & shape were seen in both parasite & the host suggestive of functioning biliary tree [Figure 4].
The host had normal sized spleen in left hypochondrium, normal pancreas, normal looking kidneys in place & a normal urinary bladder.
The host also had normally developed scrotum containing the testes.
The parasite showed no kidneys, a small urinary bladder and fluid filled dilated bowel loops [Figure 5]A.
On echocardiography [Figure 5]B single heart was seen situated in host thorax, showing normal situs & chamber sizes. There was mild physiological thickening of right ventricular walls.
Then the twins were subjected to CT scan examination, which revealed normal thoracic anatomy of the host [Figure 6] however liver lying in left hypochondrium [Figure 7]. The kidneys were paraspinal & normal in size & shape, with a normal looking bladder [Figure 8].
Surgical separation was performed on the 3rd day after birth. The parasite was attached to the autosite by skin, subcutaneous tissue, muscles & fascial layers. The two mirror image livers were joined by a substantial bridge of tissue. There were two separate gall bladders although the precise anatomy of the extra hepatic biliary tree could not be defined accurately.
There was no herniation of the gut across the isthmus.
The parasite had fluid distended bowel loops both ends of which were blind, rudimentary renal tissue in paraspinal regions bilaterally, and small urinary bladder in the pelvis.
The parasite was separated successfully & the host's thoracoabdominal wall defect was reconstructed.
Discussion:- Conjoined twins
- Are identical twins who develop with a single fertilized ovum (monozygotic).
- Are always the same sex & race.
- Are more often female than male, at a ratio of 3:1, although monozygotic male twins are more common.
- Occur as often as once in every 40,000 births but only once in every 2,00,000 live births as most conjoined twins are born prematurely & 40 % are still born.
- Are more likely to occur in India or Africa than in China or united states.
- May be caused by any number of factors being influenced by genetic & environmental conditions.
Embryology: Division of the zygote during the first three days postconception results in the formation of dichorionic diamniotic twins.
Division of inner cell mass between fourth & eighth day postconception results in monochorionic diamniotic twins.
Division of the embryonic disc after day eight postconception results in monochorionic monoamniotic twins.
Incomplete division of embryonic disc results in conjoined twins. Division of the embryonic disc after day 13 postconception is usually incomplete, resulting in varying degrees of fusion of embryos.
Types of conjoined twins-
The site & extent of twin fusion are infinitely variable & nomenclature is usually based on the fused anatomic region followed by the suffix "pagus" the Greek term for fastened. The following is a convenient basic classification to closely define individual cases.
1.Inferior conjunction- lower body is single or twins joined by some lower portion of body.
- Diprosopus: two faces with one head and body
- Dicephalus: two heads with one body
- Ischiopagus: joined by inferior sacrum and coccyx
- Pygopagus: joined by posterolateral sacrum and coccyx
2. Superior conjunction: upper body is single or twins joined by some upper portion of body.
- Dipygus- Single head, thorax, abdomen with two pelves & four legs.
- Syncephalus- Facial fusion with or without thoracic fusion
- Craniopagus- Cranial union only.
3. Middle conjunction: fusion of midportion of the body, separate above & below
- Thoracopagus: thoracic fusion
- Omphalopagus (xiphopagus): joined from umbilicus to xiphoid cartilage
- Thoraco-omphalopagus: thoracic & abdominal fusion
- Rachipagus: vertebral fusion above sacrum
4. Rare forms of conjoined twins
- Parasitic twins: asymmetric conjoined twins, one being small, less formed & dependent upon the other.
- Fetus in fetu: situation in which an imperfect fetus is contained completely within the body of its sibling.
The prenatal sonographic diagnosis of conjoined twins is relatively straightforward when fusion of fetal parts is noted; however, a careful approach is necessary to avoid misdiagnosis. The diagnosis should be considered whenever a twin pregnancy is seen that has a single placenta & no visible separating amniotic membrane. When the diagnosis is uncertain & degree of fusion difficult to assess, MRI should be considered. Faster pulse sequence currently available for MRI negate the need for fetal paralysis for these studies.
Prenatal diagnosis & exact characterization of the anomalies are essential determinants of optimum management.
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